November 18, 2014

Provectus notebook

Pilon-Thomas & Moffitt Cancer Center. Frequent medical writer of PV-10 Janet Fricker has an article out in Medical News Today today about Moffitt's poster presentations at SITC 2014 entitled Melanoma shows improved regression with combination of PV-10 and checkpoint inhibitor.

The article has an interesting quote from the cancer center's Dr. Shari Pilon-Thomas, Ph.D. about their work:
"The spirit of our study was to determine whether combining PV-10 with a checkpoint inhibitor would enhance the systematic immune responses of the initial injection of PV-10."
Phrased via slightly different editing: The spirit of the study was to determine whether combining ABC with XYZ would enhance the systematic immune responses of ABC. Not, whether combining XYZ with ABC would help XYZ.

Pfizer. Pfizer announced Monday it had (i) a PD-1 agent and (ii) licensed a PD-L1 agent from Merck KGaA (Germany), thus changing the competitive landscape to look more like the below:
Click to enlarge.
See blog post "Together, these studies support the induction of increased tumor-specific immunity after co-inhibitory blockade in combination with IL PV-10 therapy."
Interestingly and notably, Pfizer immediately guided 2014 and 2015 earnings downward as a result of the transaction and to recognize its upfront payment as a certain significant item.

Some preliminary opinions on the deal include:
Jacob Plieth, EP Vantage: "This disproves the notion that a handful of big names – Merck & Co, Bristol-Myers Squibb and  Roche – had already seized all the early promise in  PD-1/PD-L1 inhibition."
The Deal Pipeline: "Pfizer in May walked away from AstraZeneca after painting itself into a corner by describing a takeover proposal - one of a series - as "final..." The deal would have also given Pfizer access to AstraZeneca's own immuno-oncology treatment, which are known as anti-PD-L1 compounds...The New York company has now found a less contentious way to access the technology." 
Pfizer's view of its immuno-oncology pipeline now, in cancer-immunity cycle terms, is:
Click to enlarge. Pfizer presentation, November 17, 2014.
Merck & Co., (U.S.A.). Merck announced positive results from a Keytruda (PD-1) melanoma trial on Sunday. The comparator for late-stage patients in this trial was systemic chemotherapy, the co-primary endpoints were progression-free survival ("PFS") and overall survival ("OS"), a secondary endpoint was overall response rate ("ORR"), and additional data was collected on duration of OR, patient-reported outcomes (the EORTC QLQ-C30 questionnaire) and safety (adverse events).

Provectus' upcoming melanoma Phase 3 trial of earlier stage patients whose disease has not spread to distant sites (which is not late-stage disease, where the disease indeed has spread) has a comparator of systemic chemotherapy, a primary endpoint of PFS, and secondary endpoints of complete response rate ("CRR"), duration of CR, patient-reported outcomes (the Skindex-16 questionnaire), OS and safety (adverse events).

China. I thought the comments by Sinopharm A-THINK's CEO in Provectus' PR Provectus Biopharmaceuticals Extends Memorandum of Understanding with Sinopharm-China State Institute of Pharmaceutical Industry and Sinopharm A-THINK Pharmaceutical Co., Ltd that "...it is hopeful that a contract will be finalized in the coming weeks" were interesting. They become notable if and when a meaningful and material deal is consummated. I don't doubt part of the deal process is for both parties (Sinopharm and Provectus) to interact with the China Food and Drug Administration.

The Cancer-Immunity Cycle. The Medical News Today article about Moffitt, PV-10 and SITC also noted:
"The mechanism, [Dr. Pilon-Thomas] adds, is thought to be that injection of PV-10 into melanoma lesions results in tumor cells releasing antigens that induce T cell immunity, with the checkpoint inhibitors then "releasing the brakes" on the resulting T cells. Next, the team plans to investigate the types of immune cells released at the tumor site." {Underlined emphasis is mine}
"[T]he types of immune cells released at the tumor site" refers to cycle steps 5 and 6 in Chen & Mellman's (2013) Oncology Meets Immunology: The Cancer-Immunity Cycle:
"In the first step, neoantigens created by oncogenesis are released and captured by dendritic cells (DCs) for processing (step 1). In order for this step to yield an anticancer T cell response, it must be accompanied by signals that specify immunity lest peripheral tolerance to the tumor antigens be induced. Such immunogenic signals might include proinflammatory cytokines and factors released by dying tumor cells or by the gut microbiota (Figure 2, Table 1). Next, DCs present the captured antigens on MHCI and MHCII molecules to T cells (step 2), resulting in the priming and activation of effector T cell responses against the cancer-specific antigens (step 3) that are viewed as foreign or against which central tolerance has been incomplete. The nature of the immune response is determined at this stage, with a critical balance representing the ratio of T effector cells versus T regulatory cells being key to the final outcome. Finally, the activated effector T cells traffic to (step 4) and infiltrate the tumor bed (step 5), specifically recognize and bind to cancer cells through the interaction between its T cell receptor (TCR) and its cognate antigen bound to MHCI (step 6), and kill their target cancer cell (step 7). Killing of the cancer cell releases additional tumor-associated antigens (step 1 again) to increase the breadth and depth of the response in subsequent revolutions of the cycle." {Underlined emphasis is mine}
Click to enlarge. Chen & Mellman, Figure 1, http://www.cell.com/immunity/abstract/S1074-7613(13)00296-3
Australia. In November 2010 Provectus wrote in their press release Provectus Meets with the Therapeutic Goods Administration to Review Path for Approval of PV-10 in Australia:
"The recent meeting focused on manufacturing, characterization and specifications for PV-10, along with a review of clinical data and anticipated Phase 3 study design and endpoints. The proposed primary endpoint of progression free survival, which Provectus proposed to the U.S. Food and Drug Administration (FDA) earlier this year in its first end-of-Phase-2 meeting with FDA, was deemed appropriate for assessment of efficacy in light of established European Medicines Agency (EMEA) standards adopted by TGA. Use of interim data from the first half of Phase 3 study subjects, in conjunction with safety data collected in earlier studies of PV-10 for melanoma, was discussed to allow early evaluation for marketing approval for metastatic melanoma, and TGA agreed that these data should be sufficient for this review if the analysis confirmed efficacy."
I learned from folks in Australia that management will be there around the time of the annual scientific meeting of the Clinical Oncology Society of Australia (December 2nd to 4th). I would think visiting the TGA, Australia's FDA, would be on their trip itinerary.

In addition to sites in Australia for Provectus' melanoma Phase 1 and 2 clinical trials and the company's compassionate use program, and the work therein, investigator-initiated work was and is being done combining PV-10 with radiotherapy. Preliminary work (3 patients) was published in 2010 as A novel treatment for metastatic melanoma with intralesional rose bengal and radiotherapy: a case series in Melanoma Research. Follow-up investigator-initiated work by the same lead (Dr. Matthew Foote, M.D.) appears to be one patient short of full enrollment and treatment (25 patients).
Click to enlarge. Above screenshot taken from a presentation
by Dr. Sanjiv Agarwala, M.D. at the 2nd European Post-Chicago Melanoma Meeting (2010)
The average cost of drug R&D. A study by the Tufts Center for the Study of Drug Development out today said developing a new prescription medicine that gains marketing approval costs $2.6 billion. A related article on the study by FierceBiotech author John Carroll framed Tuft's estimate in the context of an estimate by Doctors Without Borders of $186 million.

Through September 30, 2014, Provectus has spent (balance sheet item Accumulated Deficit) $157 million for multi-indication viable PV-10.

November 15, 2014

"This determination is based on the paucity of data..."

Updated 11/16/14: See A Bridging Study to an NDA (November 16, 2014) on the blog's News page.

Copyright of (presumably) the Knoxville News Sentinel.
January 24, 2014 (December 16, 2013). On January 24th, following their December 16th Type C meeting with the FDA, Provectus issued press release Provectus's PV-10 Path to Initial Approval in U.S. Now Clear Per FDA Meeting Minutes in which the company highlighted the indication being sought (and patient population being targeted) as locally advanced cutaneous melanoma.

Provectus also discussed guidance from the FDA during the meeting:
  • The Agency agreed with Provectus that treatment of cutaneous and subcutaneous tumors in patients with locally advanced cutaneous melanoma (i.e., recurrent, in-transit or satellite melanoma that has not yet spread from the skin to distant sites) could provide clinical benefit to such patients, particularly if the measured objective responses in patients' disease correlated to a demonstrated treatment effect on one or more symptoms of their disease (e.g., pain, infection or significant bleeding), (1)
  • The Agency agreed to work with Provectus to quantify symptom control in this patient population, and
  • In reference to discussions on the potential for breakthrough therapy designation, "FDA advised Provectus to provide objective response rates with adequate information to evaluate the symptomatic treatment effects (e.g. pain, infection, bleeding) in patients presenting with locally advanced cutaneous melanoma who received PV-10 to all lesions."
Provectus wrote in the PR, constructing a quote for/from Craig:
  • "We are very pleased that the path to initial approval in the U.S. is now clear and PV-10 can be available to help patients in a more condensed time frame than if the Agency required an overall survival endpoint in a large randomized Phase 3 study." (2)
Finally, the company wrote, again via a quote from Craig:
  • "The Agency may yet recommend and it may be in the best interest of Provectus to undertake a small, short bridging study in patients where all tumor burden can be injected. This would allow more frequent dosing than was permitted in the Phase 2 study, presumably akin to the dosing schedule currently used to treat nearly 100 patients under our expanded access protocol, and allow symptomatic endpoints to be prospectively correlated with objective response criteria."
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  • Via a quote from the FDA's BTD denial letter: "We have reviewed your request and while we have determined that treatment of 'locally advanced cutaneous melanoma' meets the criteria for a serious or life-threatening disease or condition, the preliminary clinical evidence you submitted does not indicate that the drug may demonstrate substantial improvement over existing therapies on one or more clinically significant endpoints." 
  • Via a quote from Craig: "We are very happy that the Agency recognized that locally advanced cutaneous melanoma is a serious condition and consider that a win for melanoma patients. We believe that elimination of these patients' tumors is clinically relevant, but as we alluded to in our January 24, 2014 press release regarding our Type C meeting of December 16, 2013, a focused bridging study appears to be necessary to conclusively establish a link between complete response and symptom-based endpoints."
Additionally, the Agency letter also said:
  • This determination is based on the paucity of data on endpoints indicative of clinical benefit (e.g., pain, infection, significant bleeding) and our inability to determine the clinical significance of the reduction in the size in one to 10 target lesions in patients with locally advanced melanoma, who may have additional untreated cutaneous, subcutaneous, or visceral sites of disease. (3) The information provided on durability of response is also of unclear clinical significance given the modifications to RECIST.
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May 23, 2014. On the conference call convened to discuss the company's go forward approach in the wake of BTD denial, Eric said (edited from the call's transcript to remove sos and uhs):
The longer version of my answer is that definitely we were very encouraged by the guidance that we received from the Agency in that meeting.
That being said, I described myself recently as being a professional worrier. Maybe that’s good for someone who is responsible for clinical development in a small company. But I was worried about being able to conclusively demonstrate a correlation between this high level of objective response, and I’ll use that loosely. What I mean by that is objectively observable response, uh, evidenced by complete responses in patients. 
All of their disease is gone after PV-10 injections in 50 percent of those patients versus what I knew was very thin data concerning the types of symptoms that the Agency was suggesting should be shown, uh, improvement in. 
And we did our best with that study. Looked at, as I mentioned earlier, pain data, and we were able to draw some supporting evidence to show that there is definitely a trend in pain data that matches the trend in objectively observed response of tumors. 
The Quality of Life EORTC-QL2-C30 instrument, this 30-question questionnaire that’s principally designed for patients with late stage systemic disease maybe that are taking toxic chemotherapy, I had great concerns that that was not going to be valuable because we had already shown in the full analysis for [unintelligible] patients in studies that there were no clear trends evident other that the patients didn’t get worse and that proved to be correct. 
There was nothing that we could extract from that particular instrument. It was a measured risk submitting the application. (4) But again as I mentioned earlier, our logic seemed clearer that if we were making the patients' tumors disappear in 50 percent of the patients that was a very large effect size, and that was tantamount to making any symptoms that they might have been suffering from the tumor burden disappear. (5)
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November 13, 2014. Provectus issued press release Provectus Biopharmaceuticals' Protocol for Phase 3 Study Of PV-10 As Treatment for Melanoma Now Available Online to highlight the publication of its trial protocol on www.clinicaltrials.gov. The primary endpoint ("EP") is:
  • Progression-free survival ("PFS") -- a loco-regional disease-oriented EP.
The secondary EPs are:
  • Complete response rate ("CRR") -- a loco-regional disease-oriented EP,
  • Duration of complete response -- a loco-regional disease-oriented EP,
  • Change in total symptom score from baseline using the patient reported Skindex-16 instrument* -- a patient-reported outcome ("PRO"),
  • Overall survival ("OS") -- a distant disease-oriented EP, and
  • Number of participants with adverse events -- loco-regional & distant disease-oriented EP.
Among other aspects of the trial, there was the following cross-over provision:
  • Subjects in the comparator arm who have completed at least 1 cycle of dacarbazine or temozolomide and who meet the study protocol definition of disease progression but do not have evidence of distant cutaneous, subcutaneous, active nodal or visceral metastases will be eligible to enter the crossover portion of the study and receive PV-10.
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January. In January, and just prior to BTD denial, there would have been excitement at Provectus about the potential prospect of an expedited approval path for PV-10. Setting aside the speed of traveling along the path, the issue at hand would have been the path itself. There was agreement on the suitable patient population of PV-10: locally advanced cutaneous melanoma.

The January 24th PR's sentence above (2) implied no Phase 3 trial with OS as a primary EP. Locally advanced melanoma patients have a lengthy life expectancy that makes OS problematic as a primary EP. In addition, National Comprehensive Cancer Network ("NCCN") guidelines indicate "clinical trial" as the preferred treatment option for these patients.

But, the clinical significance of objective response (i.e., complete responders + partial responders) still was unclear to the FDA for these patients, stated in PR's sentence above (1). Since Provectus is attempting to establish new regulatory precedent in melanoma, the PR describes the Agency as advising the company to show them how to establish a link between observable response (such as objective response) and clinically significant change in patients (i.e., reduction of suffering, etc).

The BTD application would have attempted to link observable response metrics to clearly evident symptomatic benefit in sufficient patients to demonstrate preliminary evidence. These patients were the sub-group of 28 who had all of their disease treated in the Phase 2 trial (e.g., see PV-10 delivers greatest effects when all lesions are injected).

Although management thought their available data was compelling at the time, and hoped it also would prove compelling to the FDA as part of a BTD application, they understood further study (i.e., a so-called [but undefined] bridging study) may have been needed (i.e., collected at some point in the future) to provide sufficient evidence to support granting of BTD. Such a study would have served to support BTD, validate EPs to be used in any subsequent pivotal study, and provide crucial supportive safety and efficacy data for a new drug application ("NDA").

Management thus calculated their existing sub-group data may prove sufficiently compelling to the Agency to warrant granting BTD, which if achieved would have afforded Provectus the opportunity to comprehensively and quickly review the PV-10 melanoma development program with senior Agency staff to design efficient clinical demonstration of efficacy.

May. A partially skeptical FDA (from the seemingly multiple personalities of the BTD denial letter) said the subgroup data was not sufficiently compelling, and asked for more data.

Eric said on the conference call it was a measured risk. See May 23rd conference call transcript sentence above (4). His rationale was PV-10 making tumors disappear was tantamount to making patient suffering disappear. See May 23rd conference call transcript sentence above (4).

Shortly after the decision was communicated by Provectus, a shareholder with whom I regularly collaborate on this project conveyed feedback he had sought on the letter from folks who routinely interact with Agency staff on oncology matters. Their (these folks') view was not to read too much into the BTD denial letter, and that the FDA merely was asking for more information (data). The company had the right data, but not enough of it. See the May 16th BTD denial letter sentence above (3).

November.
 Several aspects of the protocol suggest an interesting [to me] description of Provectus' pivotal Phase 3 trial. These are:
  • The use of systemic chemotherapy (intravenous dacarbazine or oral temozolomide) as the trial's comparator. As I noted above, NCCN guidelines indicate "clinical trial" as the preferred treatment option for patients with locally advanced cutaneous melanoma, and not systemic chemotherapy,
  • The above mentioned cross-over set-up that permits switching after only one 28-day (4-week) chemotherapy cycle (and study protocol definition of disease progression, as well as no evidence of distant disease). The first EP assessment period is 12 weeks (4 weeks for the adverse event EP),
  • The anticipation that many (perhaps all) patients in the chemotherapy control arm would not develop distant disease after one cycle, and
  • The confounding of the OS EP, the so-called gold standard of distant disease-oriented EPs, due to crossover. Crossover would have an impact on the measurement of OS, but not PFS, CRR, duration of CR, patient-reported outcomes or adverse events. I have no doubt Eric knows it is unlikely there would be a statistically significant difference in the two arms** given the study size, as the Phase 3 trial does not appear to be powered for survival because there is no way to estimate what any difference might be (in light of crossover). In addition, the trial's patient population comprises Stage III patients with expected lengthy OS.
The above might allow one to describe Provectus' upcoming pivotal Phase 3 randomized control trial for locally advanced cutaneous melanoma as a "single-arm study" collecting more of the right data about PV-10 for the FDA.

As such, I think the trial may be much shorter in duration than expected, and provide the necessary supportive safety and efficacy data for a PV-10 NDA filing.


* The Skindex-16 health-related quality of life questionnaire was utilized in clinical trial work for basal cell carcinoma-approved vismodegib.

** There should be marginal survival benefit between or no statistically difference in the two arms, because the control arm would start out as patients receiving chemotherapy and then transform into the arm of patients who started out on chemotherapy and then switched over to PV-10. Thus, there likely would not be much difference in survival of (i) patients initially receiving PV-10 and (ii) patients receiving, say, 1 cycle or month of chemotherapy and then PV-10. It may be possible, however, to analyze the data for OS by modelling the absence of crossover through rank-preserving structural failure time (see Pfizer, sunitinib, gastrointestinal stromal tumours).

November 12, 2014

"These murine studies support combination therapy with IL PV-10 and co-inhibitory blockade."

Provectus issued a press release, filed an associated 8-K and made available Moffitt Cancer Center's PV-10-related poster from the 29th annual meeting of the Society for Immunotherapy of Cancer ("SITC") Monday. Of the conclusions provided by Moffitt, it struck me the key one was the first:
Moffitt affirmed there is a clinical rationale and value proposition, based on pre-clinical murine model work, to undertake a study (studies) combining PV-10 and each/any of the anti-PD-L1, -PD1 and -CTLA4 therapeutic agents.

❐ Moffitt's initial murine model work investigating PV-10 as a monotherapy -- "Intralesional Injection of Melanoma with Rose Bengal Induces Regression of Untreated Synchronous Melanoma In a Murine Model," Society of Surgical Oncology Annual Meeting, March 2012, and "Intralesional Injection with PV-10 Induces a Systemic Anti-tumor Immune Response in Murine Models of Breast Cancer and Melanoma," American Association for Cancer Research Annual Meeting, April 2013 -- demonstrated:
  • Regression in both injected and un-injected melanoma tumors,
  • Anti-tumor immunity (T-cell generation & activity), and
  • Increased survival (in mice).
❐ Moffitt followed up their mousie work with a human feasibility study of PV-10 as a monotherapy -- "Assessment of immune and clinical efficacy after intralesional PV-10 in injected and uninjected metastatic melanoma lesions," American Society of Clinical Oncology Annual Meeting, June 2014 -- that demonstrated:
  • Regression in both injected and un-injected melanoma tumors, and
  • Anti-tumor immunity (T-cell generation & activity).
❐ Moffitt continued their murine model work investigating PV-10 in combination with each of three categories of checkpoint inhibitors (anti-PD-L1, -PD1, -CTLA4) -- "Efficacy of Intralesional Injection with PV-10 in Combination with Co-Inhibitory Blockade in a Murine Model of Melanoma," Society for Immunotherapy of Cancer Annual Meeting, November 2014 -- that demonstrated:
  • Regression in both injected and un-injected melanoma tumors,
  • Anti-tumor immunity (T-cell generation & activity), and
  • Increased survival (in mice).
All of Moffitt's work, murine and human, involved a single intralesional injection of PV-10 per injected lesion. It would appear what Moffitt is doing with PV-10 the way they are doing it is procedural, meaning the cancer center is trying to better understand PV-10's tumor-specific immunity with scientific experimental methods, rather than with specific clinical or clinically translational approaches at this time. Ultimately, it seems Moffitt wanted to know if PV-10 worked, found out it did, then wanted to know how well it worked, and then found out how much it did -- as a single agent, and in combination with other agents.

All Moffitt posters -- SSO 2012, AACR 2013, ASCO 2014, SITC 2014 -- have been exclusively co-authored by Moffitt researchers/employees. It is interesting to note Provectus, it appears, freely allowed the cancer center to undertake this work without, it would seem, involvement or interference. I imagine the company, in addition to providing PV-10 drug product to Moffitt, compensates or pays or contributes funding to the cancer center and/or researchers in some form or fashion, like other biopharmaceutical companies do.

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The Methods section of Moffitt's SITC 2014 poster was sparse on experimental method detail, as was the Methods section of their AACR 2013 poster. As such, we will have to wait for an/the associated peer-reviewed paper that would describe the method(s) of the SITC work (as their 2013 PLOS One paper did for the AACR poster and work); specifically, the modifications the cancer center made to their PV-10 injection approach (contrasted with the AACR work's approach) to elicit and elucidate the value of PV-10 in combination with checkpoint inhibitors.

The 2013 "monotherapy" poster/paper appeared to show relatively greater interferon gamma production relative to control than the 2014 "combination therapy" poster did. PV-10's propensity to completely destroy and/or dramatically reduce injected and un-injected tumors -- the subject of Moffitt's August 2013 Single Injection May Revolutionize Melanoma Treatment, Moffitt Study Shows press release-- must have required modifications to the experimental design in order to facilitate the combination therapy murine model work (i.e., don't kill the tumor completely but "partially kill" it so as to observe and measure the subsequent effect of a checkpoint inhibitor on PV-10-damaged-but-not-destroyed-tumor), such as treating part of a large tumor, reducing PV-10 dose per volume, or diluting the concentration of the drug.

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Peter noted in the company's third quarter 10-Q:
We also have begun to consider co-development transactions with one or more pharmaceutical or biotech companies to combine PV-10 with immunology agents such as those referred to as immune checkpoint inhibitors...Furthermore, the strategy of the Company for the benefit of stockholders is a series of partnerships followed by an acquisition of the Company along the lines of Celgene-Abraxis, although there can be no assurance that such partnerships or acquisition will occur. An interim transaction could be a co-development deal like Roche-NewLink, Bristol-Celldex or AstraZeneca-Incyte. {Underlined emphasis is mine.}
NewLink published preclinical combination study work (their drug + anti-PD1/PD-L1 antibodies) at AACR 2014 (April)*, co-conducted by NewLink employees and Georgia Regents University Research Institute researchers/employees.
* "The current preclinical studies suggest a mechanistic rationale for a combining IDO pathway
inhibitors with agents targeting the PD-1/PD-L1/PD-L2 pathway."

Celldex published preclinical combo work (their drug + checkpoint blockade therapies) at SITC 2013 (November)*, conducted by Celldex employees.
* "These studies...support the initiation of combination trials with conventional and immune-based therapies."

Incyte filed a protocol for combining its subject drug with Bristol-Myers' anti-CTLA-4 agent Yervoy in 2012. From what I can gather (and I may be wrong) the trial of the combination therapy was initiated alone by Incyte (I cannot find any publication of preclinical work that may have preceded this trial). At an ASCO 2014 presentation of a Phase 1/2 melanoma study, principal investigators (that included Moffitt Cancer Center's Dr. Jeffrey Weber, M.D., Ph.D.) noted "[p]reclinical data support antitumor synergy for INCB024360 when administered with an antibody antagonist to checkpoint receptors," referencing a October 2013 (submitted)/February 2014 (published) SITC journal paper* (the paper, however, does not present preclinical combo work on the subject drug but another related Incyte compound), co-conducted by Celldex employees and the University of Chicago researchers/employees
* "These three combinations are attractive to pursue clinically..."
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Provectus published preclinical combination study work (PV-10 + anti-CTLA-4 mouse antibodies) in April at AACR 2013. Moffitt published their preclinical combination study work (PV-10 + anti-PD-L1, -PD1, and -CTLA4) in November at SITC 2014, of course.

The company should have sufficient data to establish the rationale for a combination study with a Big Pharma partner:
  • Preclinical from Moffitt's poster, and additional material not included on it,
  • Clinical, perhaps, and in context, from Moffitt's human feasibility study ("Six of 8 patients had metastatic disease refractory to previous ipilimumab, anti-PD-1 and/or vemurafenib therapy"), and
Arriving at an agreement on business terms of a so-called co-development deal is/will be another story; however, this information should be the hard data of PV-10's immunological activity (most of it generated independently of Provectus by Moffitt) that may facilitate a discussion, or two, with Big Pharma.

November 6, 2014

"Together, these studies support the induction of increased tumor-specific immunity after co-inhibitory blockade in combination with IL PV-10 therapy."

Moffitt Cancer Center's PV-10-related abstract from the 29th annual meeting of the Society for Immunotherapy of Cancer ("SITC") was made available today by SITC's Journal for ImmunoTherapy of Cancer. The company issued a press release and filed an associated 8-K, and the stock also was halted because of Moffitt and the abstract.
Efficacy of intralesional injection with PV-10 in combination with co-inhibitory blockade in a murine model of melanoma
PV-10 is a 10% solution of Rose Bengal that is currently being examined as a novel cancer therapeutic. We have previously shown that intralesional (IL) injection of PV-10 into a single subcutaneous B16 melanoma tumor led to regression of both the injected tumor and uninjected B16 lung lesions. Tumor regression correlated with the induction of systemic anti-melanoma T cell immunity. In melanoma patients, IL injection of PV-10 has led to regression of treated lesions as well as untreated bystander lesions. In this study, we have examined whether IL PV-10 and co-inhibitory blockade could improve anti-tumor immunity and regression of melanoma. B16 cells were injected into C57BL/6 mice to establish one subcutaneous tumor. Treatment of this lesion with a single IL injection of PV-10 alone led to partial regression of the injected B16 lesion. Systemic administration of anti-CTLA-4 or anti-PD1 antibodies in combination with IL PV-10 resulted in increased tumor regression and improved survival in this model. Treatment with PV-10 also led to the induction of T cells that produced IFN-γ (495 ± 198 pg/ml) in response to B16 cells but not to irrelevant MC-38 cells. Combination therapy with IL PV-10 and anti-CTLA-4 led to increased IFN-γ responses to B16 (1235 ± 191 pg/ml, p < 0.05). In another experiment simulating heavy tumor burden using a bilateral model, systemic administration of anti-PD-L1 antibodies in combination with IL PV-10 led to regression of the injected B16 lesion as well as a bystander subcutaneous lesion on the opposite flank (p < 0.01 compared to mice treated with anti-PD-L1 antibodies or IL PV-10 alone). Together, these studies support the induction of increased tumor-specific immunity after co-inhibitory blockade in combination with IL PV-10 therapy.
It strikes me there are two general takeaways:
  1. PV-10 works with everything, and
  2. Provectus' drug should expand the relevance and use of co-inhibitory blockade agents (i.e., PD-L1s, PD-1s, and CTLA-4s) from (a) late-stage cancer in the U.S. to (b) Stage III and IV disease globally.
In the context of Moffitt's abstract, and the underlying work from which it was drawn and written, PV-10 works with [at a minimum] co-inhibitory blockade agent categories PD-L1, PD-1 and CTLA-4. Reference material on this should be:
In the context of global and stage-related relevancy and use, challenges of approved and investigational co-inhibitory blockade agents include non-specificity, dose limiting toxicity, and cost:
  • PD-L1, PD-1 and CTLA-4 cancer immunotherapies are non-specific immunotherapies that do not achieve sufficient, let alone notable, levels of complete responses,
  • Their toxicity and side effects limit the amounts of them that can be given to patients. Side effects have to be, when possible, physician-managed, and
  • Their prohibitive cost to research and make, and thus price to sell, very likely will limit their use in the U.S., where the duration of use to achieve longer survival, ultimately ineffective as it is, would be more than $1 million per patient. Their cost/price should largely diminish or prohibit their use elsewhere in the world: "We've kind of maxed out what we're either willing or able to pay for these kinds of drugs, so it's a problem when you start combining them. It can't just keep going exponentially, so that eventually it will be $1 million a year to get treated -- that's crazy." (a quote from Moffitt's Dr. Jeffrey Weber, M.D., Ph.D., Reuters' New cancer therapy comes of age, cost a 'toxic' side effect, September 2014)
Presumably, combining with PV-10 would make these drugs more relevant and increase their use because:
  • An effective, long-lasting, sustainable immune response for late-stage patients (where all disease burden is not accessible to PV-10 injection) requires both their use and PV-10's: non-specific and specific immunotherapies, respectively. The human body has specific and non-specific immune system components: the innate and adaptive immune systems, respectively. See my blog post entitled PV-10 is not bigger than Mother Nature
  • Less of them would be used, potentially reducing or mitigating their dose limiting toxicities and side effects, and
  • The duration of their use then should be shorter were their combination with PV-10 to be more effective, reducing overall treatment cost. 
Returning to the detail of the abstract, specific takeaways include:
  • Moffitt touching on three keys to cancer treatment using PV-10 and a co-inhibitory blockade agent: (i) tumor regression, (ii) improved survival, and (iii) impact (tumor regression) on both treated and untreated lesions:
    • Systemic administration of anti-CTLA-4 or anti-PD1 antibodies in combination with IL PV-10 resulted in increased tumor regression and improved survival in this model.
    • In another experiment simulating heavy tumor burden using a bilateral model, systemic administration of anti-PD-L1 antibodies in combination with IL PV-10 led to regression of the injected B16 lesion as well as a bystander subcutaneous lesion on the opposite flank (p < 0.01 compared to mice treated with anti-PD-L1 antibodies or IL PV-10 alone).
  • Specificity works, by saying they achieved T-cell responses to B16 cells and not MC 38 cells. The study was focused on melanoma (i.e., B16 cells). MC 38 cells relate to or reference colon cancer.
    • Treatment with PV-10 also led to the induction of T cells that produced IFN-γ (495 ± 198 pg/ml) in response to B16 cells but not to irrelevant MC-38 cells.
  • Moffitt's previous pre-clinical work, published in 2013, Intralesional Injection with PV-10 Induces a Systemic Anti-tumor Immune Response in Murine Models of Breast Cancer and Melanoma (AACR 2013 poster, PLoS One paper), noted PV-10's ability to destroy tumors (i.e., complete responses). This work, and PV-10's ability to destroy tumors (i.e., complete response), was followed up in the cancer center's human feasibility study (ASCO 2014). The study design underlying their SITC 2014 revelations required Moffitt to wound -- and not destroy -- the tumors. In order to demonstrate the ability of PV-10 in combination with a co-inhibitory blockade agent to achieve tumor regression, improve survival, and impact both treated and untreated lesions, Moffitt had to inject tumors with a sub-optimal amount of PV-10 (i.e., "wound") so as not to achieve a complete response, and be able to show combinations could impact the tumor.
  • Reading the abstract, it struck me that Moffitt ordered the effectiveness of the co-inhibitory blockade agent in combination with PV-10 as, first, the PD-L1, and tied for second, the PD-1 and CTLA-4. Given that, which do you think of Big Pharma is more worried (as a non-combo partner, or non-owner of the PV-10 lead in the combo)?
Click to enlarge.

November 1, 2014

Florey, Chain & Heatley⎟Coley⎟sort of, maybe, possibly, conceivably, probably...

‘‘Drugs can only repress symptoms: they cannot eradicate disease. The true remedy for all diseases is Nature’s remedy .... There is at bottom only one genuinely scientific treatment for all diseases, and that is to stimulate the phagocytes. Stimulate the phagocytes. Drugs are a delusion.’’ -- Counsel of physician Sir Bloomfield Bonington in George Bernard Shaw’s 1906 play The Doctor’s Dilemma; the use of the quote comes from the article Dr William Coley and tumour regression: a place in history or in the future by Hoption Cann et al.
▸ Alexander Fleming discovered penicillin in 1928, while the discovery of penicillin's medical use was established more than a decade later by Howard Florey, Ernst Chain and Norman Heatley (source link: Wikipedia).

Penicillin was/is a discovery that changed the course of medicine.

▸ William Coley is a pioneer of cancer immunotherapy (late 1800s), and considered by many to be the "Father of Immunotherapy." According to Wikipedia (see immediately prior link):
"Coley developed the theory that post-surgical infections had helped patients to recover better from their cancer by provoking an immune response. He began to experiment by deliberately causing this phenomenon, injecting bacteria directly into people being treated – but because this had the adverse effect of causing infection he then switched to using dead bacteria."
Hoption Cann et al. (link at the top of the post) write about Coley's work:
"Coley considered several points crucial to a patient’s survival. First and foremost was to imitate a naturally occurring acute infection, and thus, inducing a fever was essential. Injections were optimally administered daily (or every other day) for the first month or two. To avoid immune tolerance to the vaccine, the dosage was gradually increased over time (depending on patient response). The vaccine was injected directly into the primary tumour and metastases, when accessible. Finally, a minimum six month course of weekly injections was followed to prevent disease recurrence." {Underlined emphasis is mine.}
Coley injected the bacteria/vaccine/toxins into cancerous tumors and cancer metastases.

▸ Why then, when writing about cancer immunotherapy and associated approved and investigational checkpoint blockade drugs like Yervoy (anti-CTLA-4, Bristol-Myers), Keytruda (anti-PD-1, Merck), Opdivo (anti-PD-1, Bristol-Myers), MPDL3280A (anti-PD-L1, Roche/Genentech), MEDI4736 (anti-PD-L1, AstraZeneca/MedImmune), etc., do some folks include what seems like obligatory yet obtuse nods to Coley? Google, for example, coley immunotherapy pd-1.

Coley's vaccine and these inhibitors both engage the immune system. But although the mechanism of action of Coley's vaccine (or Coley's toxins as it also was known) was and remains unknown, it is believed the approach led to specific and non-specific immune responses (paragraph source/sentence taken from: Rational approaches to human cancer immunotherapy, Davis et al.). Interestingly, according to Davis et al.'s article, Coley's injected-bacteria-into-accessible-tumors-and-metastases was, "[a]s late as 1934, “Coley’s toxins” was the only known systemic treatment for cancer" (article footnote). {Underlined emphasis is mine.} A treatment injected into tumors that generates an immune response is called a systemic treatment for cancer. Interesting...

Checkpoint blockade therapeutic agents are non-specific immunotherapies. "Non-specific immunotherapies don’t target cancer cells specifically. They stimulate the immune system in a more general way..."

CTLA-4s, PD-1s, PD-L1s, etc. are non-specific immunotherapies. 

"According to a 1965 article that was published in A Cancer Journal for Clinicians (1):

“In 1952, a bibliography of the literature, and, in 1953, a report on 30 inoperable cases which had been treated by Coley's mixed toxins and had survived thereafter for periods of from 1 to 47 years (20 cases had a survival of over 20 years) were published. The report is said to be based on a comparative analysis of over 1,200 cases treated with Coley's toxins, and 300 cases in which intercurrent infections played a part. Over 270  cases were said to have shown complete regression of the tumor, but the 30 inoperable cases were selected for the report because the diagnoses had been confirmed by microscopic examination, and some information on their subsequent history was available. Of the 30 tumors, 7 were classified as carcinoma, 19 as various types of sarcoma, 2 as malignant melanoma, and 2 as giant cell tumors.”

A complete response rate of 22% (270 out of 1200) was impressive by the standards of the 1960's and today. But, despite these results, the article states that the, “American Cancer Society has found no evidence that treatment with Coley's mixed toxins results in any objective benefit in the treatment of cancer in human beings.”  It is difficult to reconcile this conclusion with the results cited in the same article. Perhaps the results were simply not believed as they were authored by Mrs. Helen Coley Nauts, Executive Director of the New York Cancer Research Institute. Mrs. Nauts was the daughter of William Coley." (paragraph source link) {Underlined emphasis is mine.}

Coley's approach generated notable complete responses.

▸ Which brings us to a chicken-and-egg question. Which comes first, the complete response, or the immune response? For PV-10, successfully generating a complete response leads to a good to great immune response.

Per medical writer Walter Alexander's recent article PV-10 in Metastatic Melanoma: Rapid Responses Led Phase 3 (he's written about PV-10 before, including PV-10 Moves Forward):
The high-percent response rates in bystander lesions underscored the importance of elucidating the mechanism underlying PV-10's activity. That meant going back to bench investigations. The operant question for researchers, according to Shari A. Pilon-Thomas, PhD, Moffitt Cancer Center Immunology Program, was: "Is it just because you inject the drug and it goes everywhere and then kills tumor cells at other sites? Or is injecting PV-10 inducing a T-cell response, such that T-cells travel throughout the body and kill tumors in their various locations?
In a poster presentation at the 2013 meeting of the American Association of Cancer Research, she pointed to evidence suggesting that an immune-mediated process underlies PV-10 responses in untreated lesions. First, responses in untreated lesions occurred only when responses had occurred in injected lesions, and second, responses in bystander lesions typically were delayed in comparison with responses in injected lesions, Dr Pilon-Thomas noted. 
Dr Pilon-Thomas has previously shown in murine models that induced flank tumors treated with PV-10, as compared with placebo, were about a third of the size, and bystander lesions were about 30% smaller. At the same time, concentrations of interferon-gamma, a cytokine critical for innate and adaptive immunity (including tumor control) and for activating macrophages, were increased more than fivefold. 
These findings, along with those from other studies, led Dr Pilon-Thomas to conclude, "We think that when you inject PV-10 into a tumor, it destroys the tumor, releasing tumor fragments that are then taken up by immune cells. The immune cells travel to the lymph nodes where they 'educate' or activate T-cells, which can in turn travel anywhere in the body." 
Her research also showed that PV-10-induced immunity is tumor specific.
Further evidence of immune responses induced by PV-10 come from another study conducted at the Moffitt Cancer Center, this time involving eight patients with dermal and/or subcutaneous metastatic melanoma. The findings, presented at this year's ASCO annual meeting in a highlighted poster session by Amod Sarnaik, MD, a surgical oncologist at the Moffitt Cancer Center, showed that intralesional PV-10 was associated with a significant increase (P = .03) in circulating cytotoxic CD8+ T-cells, a potential mechanism for a tumor-specific immunologic effect secondary to tumor ablation. 
In this study of eight patients, each patient had two study lesions that were sampled by biopsy before treatment; one of the two lesions was injected with intralesional PV-10, and then both residual sites were completely excised 1 to 2 weeks after PV-10 injection. Tumors were compared before and after treatment to determine pathologic complete response (pCR). 
PV-10 resulted in pCR in the posttreatment biopsy specimens of both PV-10-injected and uninjected study lesions in four of the eight patients, and all eight exhibited at least partial regression of the injected lesion. 
Six of these eight patients had metastatic disease that was refractory to previous treatment with immunologics (ipilimumab [Yervoy, Bristol-Meyers Squibb Company] and anti-PD-1 therapy) and BRAF-mutation inhibitor (vemurafenib [Zelboraf, Hoffman-La Roche]). After PV-10, four of these six patients had pCRs in both the injected and uninjected lesions. {Underlined emphasis is mine.}
PV-10 generates a complete response in order to generate/which is followed by an immune response.

▸ On Wednesday of this past week, Forbes contributor Jon Fortenbury wrote about PV-10 and Provectus in a post entitled A New Cancer Drug Worked In Over 50% Of Patients In A Phase II Trial. On Thursday, he updated the post to "...to include comments from an outside expert and the company's response to his criticism." Forbes staff member and editor of the section Matthew Herper later weighed in under the Comments section with:
Click to enlarge.
On Thursday, Bristol-Myers issued a press release about PD-1 Opdivo's results for heavily pre-treated advanced squamous cell non-small cell lung cancer, generating a a Bloomberg headline: Bristol-Myers Immune Drug Improves Lung Cancer Survival:
An estimated 41 percent of the advanced lung cancer patients taking Opdivo were alive after a year on the drug, compared with 5.5 percent to 18 percent of these patients who historically have survived over that time-frame, Bristol-Myers said today in a statement. About 15 percent of the 117 patients in the mid-stage study responded to the treatment, one of a new class of cancer therapies that harnesses the body’s immune system to attack the disease.
"[P]atients in the mid-stage study responded to the treatment" above refers to objective response. If Opdivo were where we need to be in terms of better helping or utilizing the immune system, wouldn't Bristol-Myers have heralded complete response (objective response = complete response + partial response) more. The pharmaceutical company surely would have if the trial's CR were notable.

Certainly what was notable was the improved overall survival (the quote's "the advanced lung cancer patients taking Opdivo were alive after a year on the drug") compared to historical survival figures.

As for Herper, other journalists, commentators and opiners, aside from better survival figures that are of course very good things (longer survival is better than no or shorter survival), why do they not mention or say in the same breath that generations of immunco-oncology therapeutics agents that have come (Yervoy), are here (Keytruda, Opdivo), and are to come (MPDL3280A, MEDI4736) have not had/do not have notable or memorable complete responses?

Partial response, good. Complete response, best.

▸ To be fair, Herper, who probably has covered biotechnology companies and the subject of oncology longer than I've held Provectus shares, and who also believes this is biology's century, may not understand the conflation Fortenbury's article, upon further editing and insertion of the "outside expert's" quote, managed to achieve.

The article described Provectus' melanoma Phase 2 trial results and, in particular, the sub-group of patients who had all of their disease treated (i.e., injected with PV-10). Why was/is this relevant? As Fortenbury writes, "If PV-10, when injected in all the cancerous lesions of a melanoma patient for longer than 16 weeks, goes on to produce positive results in the next phase, it just may be a viable treatment option for many patients with aggressive, late-stage, locally advanced melanoma." The target population of the company's upcoming pivotal Phase 3 trial are patients with un-resectable locally advanced cutaneous melanoma, which means the melanoma (i) cannot be removed by surgery (non- or un-resectable), (ii) is located in or just under the skin (cutaneous and subcutaneous, respectively), and (iii) has not metastasized to distant sites like the lungs, liver or brain.

These patients need better options, like Eric, "...patients clearly need more options: single agent options and more options for finding successful combinations that can truly change the course of this vicious disease," and Dr. Agarwala, "I think it will be an option for many patients who have a cancer disease that’s localized or regional," were quoted in the Forbes article.

Locally advanced cutaneous (or subcutaneous) melanoma = Melanoma that has not spread or metastasized.

This is worth repeating: The upcoming pivotal Phase 3 trial will comprise Stage III patients. The disease in Stage III has not spread. Patients in which the disease has spread are Stage IV patients.

Stage III ≠ Stage IV.

▸ Conflation in the article occurs when Herper asks Fortenbury to have an "outside expert" opine: PD-1 Keytruda clinical investigator and UCLA Jonsson Comprehensive Cancer Center medical oncologist with multiple clinical interests Dr. John Glaspy, M.D., MPH is quoted. Medical oncologists (like Glaspy and PV-10 principal investigator Agarwala) see mainly stage IV patients, while surgical oncologists (like PV-10 principal investigator Dr. Merrick Ross, M.D. from MD Anderson Cancer Center ) see mostly stage III patients.

The data Fortenbury's article highlights show PV-10 as a monotherapy could be an important option for patients with locally advanced cutaneous melanoma. The FDA also appears to be considering this topic too. It announced on October 8th that "melanoma, specifically unresectable loco-regional disease" was a disease candidate for public comment. See Prescription Drug User Fee Act Patient-Focused Drug Development; Request for Comments (October 8, 2014) on the blog's News page.

Locally advanced cutaneous melanoma = Stage III = Melanoma disease has not spread  Stage IV = Metastatic melanoma with visceral disease and heavy tumor burden.

▸ Glaspy's words in the article:
John Glaspy, an oncology professor at UCLA, says that “it’s not clear” whether the result are important. If they are talking about lesions that were not directly injected with the drug, the results would be meaningful. “If they are talking about the injected lesion, not so much,” Glaspy says. 
When asked about it, he repeated: “Like I said, these SQ melanomas are an indolent disease, and it is not a big deal if you inject them and they regress.  I don’t think you have any evidence that anybody is cured.” {Underlined emphasis is mine}
It is not a big deal if tumors regress. They need to be destroyed. That's the big deal. Fifty percent of patients in the sub-group of Provectus' Phase 2 trial who had all of their disease treated achieved a complete response (total cancer disappearance) during a treatment period that was just 16 weeks.

Yervoy, Keytruda, Opdivo, MPDL3280A and MEDI4736 are far from curing melanoma patients because they are not achieving notable or memorable complete responses.

Partial response, not a big deal. Complete response, cured?

▸ One simple but I don't believe an over-simplistic way of looking at the situation could be surgical oncologists look at melanoma (and cancer at large) when it is first diagnosed or has not spread beyond control or has not metastasized. Medical oncologists look at melanoma (and cancer at large) when it has spread or looks like it is beyond control.

Surgical ocologists: PV-10. Medical oncologists: PV-10 + something else.

▸ Eric, in regards to, I believe, late-stage (Stage IV) patients (patients with distant metastases), in the Forbes article, "...more options for finding successful combinations that can truly change the course of this vicious disease," undoubtedly would have told Fortenbury about Moffitt Cancer Center presenting pre-clinical data on these combinations (i.e., PV-10 + [insert checkpoint blockade agent]) at the annual meeting of the Society for Immunotherapy of Cancer ("SITC") next week.

The idea behind combining PV-10 and a checkpoint blockader may be to generate both the specific and non-specific kinds or types of immune responses Coley's vaccine/toxins were believed to have generated. The goal of employing these kinds of combinations, to battle melanoma (cancer) once it has spread to distant sites, may be to generate both specific and non-specific immune responses.

Stage IV melanoma: PV-10 + one of (Yervoy, Keytruda, Opdivo, MPDL3280A, MEDI4736)

Yervoy, Keytruda, Opdivo, MPDL3280A, and MEDI4736 need help.

▸ Roche's Genentech's Dr. Daniel Chen, M.D., Ph.D. quoted Roche's Genentech's Dr. Ira Mellman, M.D., both co-authors of Oncology Meets Immunology: The Cancer-Immunity Cycle, at ESMO 2014:
Click to enlarge. Screen shot source: Biotech Strategy Blog.
The ultimate goal of cancer treatments is to completely eliminate a tumor. Complete response.

▸ Which brings me back to where I started this post, with Florey, Chain & Heatley, and Coley.

Dees, Scott and Wachter did not discover rose bengal. It can be traced back to Basel, Switzerland in 1882 when a German patent was granted to Ghnem for a new family of wool dyes. Dees et al. were not the first to use rose bengal in an oncology setting. Japanese researchers Ito and Watanabe did so in 1986. Rose bengal's therapeutic benefit is unrealized until a sufficient quantity is administered.

Craig postulated intratumoral injection, and thus the delivery of the drug via the tumor or lesion, was key. He thought it was critically important to the eventual immune response that PV-10 (rose bengal) be injected into a cancerous tumor or cancer metastases.

What kind of therapy is PV-10? From a 2013 Cancer Watch article entitled Back to Phase 1: Understanding Systemic Effects of PV-10:
Echoing [Moffitt Cancer Center's] Dr. Sarnaik, Eric Wachter, PhD, Provectus chief technology officer, said that he hopes that the findings of Dr. Sarnaik’s study will point toward rational judgments about combining PV-10 with other documented therapies. “We then might want to try two or more orthogonal therapies to stress tumor cells from several different angles simultaneously, for example an immune therapy plus a metabolic therapy (e.g., a kinase inhibitor), or in a rationally designed sequence.” In a hepatocellular carcinoma model, he added, PV-10 showed significant potential for synergy with 5-fluorouracil. Provectus recently initiated clinical testing of PV-10 with the multikinase inhibitor sorafenib, again bringing in two therapies with divergent mechanisms of action. 
Which category does PV-10 fall into? “I think we are getting a clearer picture of how it might be classified, but it has features of several previously unrelated categories, such as of adoptive cell transfer and vaccination,” Dr. Wachter said. “PV-10 initially reduces tumor burden through chemoablation—but then activates the immune system bringing in capacities completely orthogonal to the ablative tumor destruction,” he added. 
“Amod Sarnaik’s work may give us the molecular basis for closing the loop on one of the founding concepts for going into the clinic in the first place,” Dr. Wachter commented. “Back in the preclinical days at Provectus, Craig Dees, PhD, theorized that ablation of tumors with PV-10 might lead to unmasking of tumor antigenic material. I don’t think he anticipated that it would work as well as it does.” {Underlined emphasis is mine.}
Vaccines are too specific. They facilitate the expression of only one antigen. Vaccines are antigen specific.

CTLA-4, PD-1 and PD-L1 therapeutic agents are not specific enough. They do not facilitate the expression of enough antigens.

PV-10 ablation of tumors presumably leads to the generation of antigens that are presented to the immune system in (i) as large a number as possible, (ii) pristine and not un- or non-denatured shape, (iii) whole pieces and not fragments, (iv) correct conformation/the right shape, and (iv) the right context.

PV-10: A paradigm shift in the treatment of cancer

October 23, 2014

More of Better > More or Less of Worse

In a February 2013 Cancer Watch article entitled Back to Phase 1: Understanding Systemic Effects of PV-10, Moffitt Cancer Center's Dr. Amod Sarnaik, M.D. said of the cancer center's Phase 1 feasibility study, result of which later were presented at AACR 2014 and ASCO 2014:
“A further impetus toward teasing out the precise mechanism of how PV-10 can exert a systemic immune response in patients is to allow us to rationally combine PV-10 treatment with some of the exciting emerging immunotherapies for metastatic melanoma”... 
...The focus at Moffitt, Dr. Sarnaik continued, is on discerning the presence of immune cell infiltrate in untreated tumors after PV-10 injections into other lesions. “We are really interested in harnessing immune cell infiltrate as a form of treatment,” he said, noting also that while creating cancer vaccines has been thought of traditionally as one of the Holy Grails of cancer research, cancer vaccines have turned out to be not strong enough to generate an adequate immune response... 
...“We generate large numbers of T-lymphocytes, but we don’t have control over their quality. We think one of the limitations is that the T cells you get out of the tumor just aren’t good enough.” PV-10, however, does cause an immune response, suggesting that a combination treatment may improve the quality of the T-lymphocytes and have a greater impact on the disease... {Underlined emphasis is mine}
A potent, long-lived systemic immune response to solid tumor cancers should:
(i) Originate at the tumor sites themselves, 
(ii) Require a broader array of tumor antigens to be released and presented, 
(iii) Require this array to be comprised of pristine, un- or non-denatured antigens (i.e., whole tumor antigens, not antigen fragments,), and 
(iv) Result from the subsequent, more comprehensive, T-cell response.
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MD Anderson Cancer Center surgical oncologist and Provectus principal investigator Dr. Merrick Ross, M.D., noted in a recent video, below, while speaking at the setting of ASCO 2014:
"The rapid lysis of the tumor and when the tumor is lysed it does not denature the antigen. So the antigens are expressed in a way where an inflammatory response can occur and therefore antigen presentation probably is up-regulated and enhanced, which could lead to a systemic host response." {My transcription, and underlined emphasis is mine}

The idea is to present as many un-denatured or pristine antigens as possible to dendritic cells ("DCs") and antigen presenting cells ("APCs"). Showing fewer pristine antigens or more denatured ones cannot generate a sustainable, systemic, specific, anti-tumor response. Showing more pristine ones should have the opposite and a much better effect.

Said another way, by a shareholder, blog reader and internist whose patients include those afflicted with cancer:
"Rapid lysosomal-mediated tumor lysis following IL injection of PV-10 uniquely produces pristine, un-denatured antigens that up-regulates antigen presentation to DCs and APCs with a resultant systemic immune response (to paraphrase Merrick Ross). The fidelity of these un-denatured tumor antigens (akin to injecting whole tumor antigens, not antigen fragments, into a patient) is what provokes a very accurate and specific immunological T-cell response that bystander tumors are vulnerable to (presuming they don’t possess too many mutated antigens due to selection pressure from previously therapies)." {My transcription, and underlined emphasis is mine}
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Roche's Genentech's Drs. Daniel Chen, M.D, Ph.D. and Ira Mellman, Ph.D.'s Oncology Meets Immunology: The Cancer-Immunity Cycle provides the opportunity to illustrate the interplay between (a) immune checkpoint blockade [Step #7] and (b) the creation, release and presentation of antigens [Steps #1 and 2], and the subsequent priming and activation of the immune system [Step #3]. I write interplay of these steps because they appear to be what industry thus far is focusing on when it considers combination therapies for late stage diseases, and permutations of treatments and therapeutics from each of these steps in an eventual combination.

The illustration below builds on (is revised by me of) Chen & Mellman's Figure 1:
The generation of immunity to cancer is a cyclic process that can be self propagating, leading to an accumulation of immune-stimulatory factors that in principle should amplify and broaden T cell responses. The cycle is also characterized by inhibitory factors that lead to immune regulatory feedback mechanisms, which can halt the development or limit the immunity. This cycle can be divided into seven major steps, starting with the release of antigens from the cancer cell and ending with the killing of cancer cells. Each step is described above, with the primary cell types involved and the anatomic location of the activity listed. Abbreviations are as follows: APCs, antigen presenting cells; CTLs, cytotoxic T lymphocytes.
Click to enlarge.
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Various types of treatments and/or therapeutics in Steps #1, #2 and #3 may create and release antigens ("Antigen Release"), present them to DCs and APCs ("Antigen Presentation"), and prime the body's T-cells ("T-Cell Priming).

See Chen & Mellman's section entitled Initiating Anticancer Immunity: Antigen Release.
Attempts to activate or introduce cancer antigen-specific T cells, as well as stimulate the proliferation of these cells over the last 20 years, have led to mostly no, minimal or modest appreciable anticancer immune responses. The majority of these efforts involved the use of therapeutic vaccines because vaccines can be easy to deploy and have historically represented an approach that has brought enormous medical benefit (reviewed by Palucka and Banchereau, 2013). Yet, cancer vaccines were limited on two accounts. First, until recently, there was a general lack of understanding of how to immunize human patients to achieve potent cytotoxic T cell responses. This limitation reflects continued uncertainties concerning the identities of antigens to use, their mode of delivery, the types of adjuvants required, and the proximal characteristics of the desired T cell response (Palucka and Banchereau, 2013). Second, the presence of the immunostat in the tumor microenvironment may dampen or disable antitumor immune responses before clinically relevant tumor kill can occur. Thus, as long as these negative signals are in place, the prospects for vaccine-based approaches used alone are likely to be limited. {Underlined emphasis is mine}
Therapeutic vaccination is not the only approach to accelerating and expanding the production of T cell immunity. Because anticancer T cells can be produced spontaneously, there is a growing appreciation that the tumor itself represents a type of endogenous vaccine. Accessing the naturally occurring source of cancer-associated antigens avoids problems associated with selection and delivery (Heo et al., 2013, van den Boorn and Hartmann, 2013). This approach is also convenient, but achieving it requires detailed knowledge around whether standard of care chemotherapy or targeted therapies are compatible with immunotherapies. Some therapies are thought to cause tumor cell death in a fashion that promotes immunity (reviewed in Zitvogel et al., 2013). However, it is unclear whether this effect can be accurately predicted and will, in any event, require empirical study. Chemotherapy, radiation therapy, and targeted therapies must also be evaluated for their effects on the immune system. Although it is assumed that many might be antagonistic, there are some reports that others might promote T cell activity (Demaria et al., 2005, Duraiswamy et al., 2013, Hiniker et al., 2012, Ott et al., 2013, Postow et al., 2012, Stagg et al., 2011, Zitvogel et al., 2013). {Underlined emphasis is mine}
See Chen & Mellman's section entitled Presentation, and T Cell Priming.
Another exciting development is that the initial demonstrations that genetically modified autologous T cells could be reinfused into patients to yield substantial clinical benefit, at least in certain B cell malignancies (Grupp et al., 2013; reviewed in Kalos and June, 2013). The most well developed of these is the use of “CARs,” or chimeric antigen receptors, in which a patient’s T cells are transfected with a construct encoding an antibody against a tumor surface antigen (typically CD19) fused to T cell signaling domains (Kochenderfer and Rosenberg, 2013). Similar approaches are under investigation with recombinant T cell receptors (reviewed in Kalos and June, 2013). The procedure avoids the need for immunization and may even overcome mechanisms of immune suppression by overwhelming the system through infusion of large quantities of the modified T cells. This can force the revolution of the Cancer-Immunity Cycle, enhancing the accumulation of stimulatory immune factors, and potentially promotes eventual self-propagation of the cycle. The potential limitations here, which are yet to be fully determined, include whether the approach can be extended to cancers beyond hematologic malignancies, whether the delivery of large numbers of monospecific T cells will cause resistance due to antigenic drift, and whether the toxicity issues already identified can be safely managed. {Underlined emphasis is mine}
See Chen & Mellman's section entitled T Cell Priming and Activation.
Whether tumor antigens are delivered exogenously or are captured and presented by DCs endogenously, another strategy for intervening in the Cancer-Immunity Cycle involves the control of T cell activation. This is the presumed primary mechanism of action of anti-CTLA4 antibodies, such as ipilimumab, which blocks the interaction of the major negative regulator of T cells (CTLA4) with its ligands B7.1 and B7.2 (CD80 and CD86; Qureshi et al., 2011). Thus, during antigen presentation in lymphoid organs (or in the periphery), the expansion of T cell responses is disinhibited, thereby promoting the production of autoreactive T cells, including tumor-specific T cells. The lack of selectivity in T cell expansion combined with the fundamental importance of CTLA4 as a checkpoint may underlie the significant immune-related toxicities seen in patients treated with ipilimumab (Hodi et al., 2010). {Underlined emphasis is mine}
This second illustration below builds on (is revised by me of) Chen & Mellman's Figure 2:
The numerous factors that come into play in the Cancer-Immunity Cycle provide a wide range of potential therapeutic targets. This figure highlights examples of some of the therapies currently under preclinical or clinical evaluation. Key highlights include that vaccines can primarily promote cycle step 2, anti-CTLA4 can primarily promote cycle step 3, and anti-PD-L1 or anti-PD-1 antibodies can primarily promote cycle step 7. Although not developed as immunotherapies, chemotherapy, radiation therapy, and targeted therapies can primarily promote cycle step 1, and inhibitors of VEGF can potentially promote T cell infiltration into tumors—cycle step 5. Abbreviations are as follows: GM-CSF, granulocyte macrophage colony-stimulating factor; CARs, chimeric antigen receptors. {Underlined emphasis is mine}
Click to enlarge.
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In the cancer immunity cycle, where certain drugs (based on known and yet to be known factors, notably stimulatory and inhibitory) promote a step (or potentially more than one step), who owns what "real estate" (i.e., who owns what drugs) should be key to understanding the competitive landscape, and where it eventually leads. As the researchers, industry and the FDA combine therapies to address the still unmet needs of late-stage cancer patients, ownership of cancer assets used in whatever combinations may and do work (and thus eventually are approved) translates into sales, profit and return on investment (in R&D).

Step #1: Chemotherapies and radiation therapies likely produce more antigen fragments than whole antigens, but antigens nevertheless. Chemotherapies are commoditized (read: inexpensive, not so profitable, and growing obsolete). Radiation therapy is owned and delivered by physicians. There are numerous targeted therapies owned by various pharmaceutical companies. They may or may not generate whole and/or fragmented antigens, but it seems their owners are worried about the dismantlement of their franchises, as some rush to combine and partner with PD-1 and PD-L1 agents.

Step #2
: These agents presumably facilitate the presentation of the antigens released in Step #1, and include failed (or as yet ineffectively utilized) vaccines, CD40 agent owners (like Genentech-Roche, among others), and not-so-valuable-properties-because-of-widespread-use (read: un-patentable, like INF alpha).

Step #3: There potentially is more real estate here. Already owned includes, notably, Bristol-Myers' approved CTLA-4 agent (ipilimumab), and CD137, OX40 and CD27 agents by Pfizer and Roche, among others.

Step #7: The PD-1 owners include Bristol-Myers (Opdivo) and Merck (Keytruda). The PD-L1 owners include Roche and AstraZeneca. IDO owners include, among others, Incyte (non-exclusive combination study relationships/agreements with AstraZeneca, Bristol-Myers, Merck, and Roche) and NewLink (exclusive, now, to Roche)

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Celgene's expansion of its license relationship with Sutro today (building on 2012's initial arrangement), provides Celgene with real estate, and potentially special ones at that. In terms of real estate, while the Big Biotech can access CTLA4, PD-1 and PD-L1 via Sutro, it notably also gets LAG-3 and TIM-3 (the next generation of immune checkpoint inhibitors?).
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The illustration below builds on (is revised by me of) Chen & Mellman's Figure 3 (note LAG-3 and TIM-3 inhibitors, alongside PD-1 and PD-L-1):
Each step of the Cancer-Immunity Cycle requires the coordination of numerous factors, both stimulatory and inhibitory in nature. Stimulatory factors shown in green promote immunity, whereas inhibitors shown in red help keep the process in check and reduce immune activity and/or prevent autoimmunity. Immune checkpoint proteins, such as CTLA4, can inhibit the development of an active immune response by acting primarily at the level of T cell development and proliferation (step 3). We distinguish these from immune rheostat (“immunostat”) factors, such as PD-L1, can have an inhibitory function that primarily acts to modulate active immune responses in the tumor bed (step 7). Examples of such factors and the primary steps at which they can act are shown. Abbreviations are as follows: IL, interleukin; TNF, tumor necrosis factor; IFN, interferon; CDN, cyclic dinucleotide; ATP, adenosine triphosphate; HMGB1, high-mobility group protein B1; TLR, Toll-like receptor; HVEM, herpes virus entry mediator; GITR, glucocorticoid-induced TNFR family-related gene; CTLA4, cytotoxic T-lympocyte antigen-4; PD-L1, programmed death-ligand 1; CXCL/CCL, chemokine motif ligands; LFA1, lymphocyte function-associated antigen-1; ICAM1, intracellular adhesion molecule 1; VEGF, vascular endothelial growth factor; IDO, indoleamine 2,3-dioxygenase; TGF, transforming growth factor; BTLA, B- and T-lymphocyte attenuator; VISTA, V-domain Ig suppressor of T cell activation; LAG-3, lymphocyte-activation gene 3 protein; MIC, MHC class I polypeptide-related sequence protein; TIM-3, T cell immunoglobulin domain and mucin domain-3. Although not illustrated, it is important to note that intratumoral T regulatory cells, macrophages, and myeloid-derived suppressor cells are key sources of many of these inhibitory factors.
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Additionally, according to FierceBiotech, the real estate is special:
"Sutro's team believes it has devised a much better way to build ADCs--those precise cancer cell-killing constructs made up of a targeting antibody, linker and payload--and bispecifics, teeing up potentially best-in-class products that promise to be more efficiently and consistently manufactured. Using biochemical synthesis, they've hatched a technology that can bypass the current approach to biologics by genetically engineering drugs that are much simpler to make, more akin to small molecules." {Underlined and bold emphasis is mine}
PV-10's effectiveness is attributed to its physical chemistry and small molecule nature.
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Moffitt presents pre-clinical (murine model) data about PV-10 in combination with co-inhibitory blockade at SITC 2014 (Provectus' press release on the topic is here). Chen and Mellman note "inhibitors shown in red [in their Figure 3] help keep the process in check and reduce immune activity and/or prevent autoimmunity distinguish between checkpoint," but distinguish between CTLA-4, and PD-1 and PD-L-1:
"Immune checkpoint proteins, such as CTLA4, can inhibit the development of an active immune response by acting primarily at the level of T cell development and proliferation (step 3). We distinguish these from immune rheostat (“immunostat”) factors, such as PD-L1, can have an inhibitory function that primarily acts to modulate active immune responses in the tumor bed (step 7). "
The presentation could explain Moffitt's Dr. Jeff Weber, M.D., Ph.D.'s contention PV-10 may be the perfect immune system primer. What does being the perfect primer mean, and entail?

Provectus recently revised its Fact Sheet to note more work by Moffitt, this time on biomarkers:
What happened to the next cohort of the Phase 1 feasibility study? Of the total enrollment of 15 patients, 8 were reported on at AACR/ASCO 2014. April 2014 article PV-10 decreases melanoma cells in tumours, which followed AACR 2014, noted:
Studies are now underway in an additional seven patients to take biopsies and blood samples at more frequent time intervals after PV-10 injection to elucidate the pathways more clearly.
Moffitt's presentation could discuss whether or not PV-10 promotes steps #4, #5 and/or #6 of the cancer immunity cycle. If so, why and how?
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