Turning [more anti-PD-1] non-responders into responders

Image source

Updated below: 10/19/16.

What is PV-10's clinical value proposition to Merck & Co. (pembrolizumab, Keytruda®) and Bristol-Myers (nivolumab, Opdivo®), among other Big Pharma in the oncology space? In no particular order, is it, among other things:

• As a primer, front-end, turner-on-of-the-engine, stepper-on-the-gas pedal, [insert your favorite over-, weakly- or wrongly-used analogy or metaphor],

• Synergism, where from an efficacy perspective 1 + 1 >> 2,

• Agnosticism to tumor type/cancer indication,

• Safety profile, and/or

• Turning cold tumors hot, and hot tumors hotter?

Industry discussion appears to recognize immune checkpoint inhibitors work — when/where they do work — in a portion of cancer patients. Is the summary clinical value proposition of PV-10 in combination with Keytruda/Opdivo to make the latter (i.e., these anti-PD-1 drugs) work better when and where they work? Or is PV-10's proposition, the more powerful one, to show it can make Keytruda/Opdivo work better where they do not work?

PV-10's clinical value proposition to Merck & Co. (pembrolizumab, Keytruda®) and Bristol-Myers (nivolumab, Opdivo®) is that it (PV-10) can turn more anti-PD-1 non-responders into responders than any other partner drug or investigational compound.

For this blog post, consider, among other things, two combinations with pembrolizumab (for advanced melanoma):

• Intralesional* agent electroporation with plasmid interleukin-12 (epIL-12) (ImmunoPulse, OncoSec), the combination of a medical device and an investigational agent, and

• Intratumoral* agent toll-like receptor 9 (TLR9) agonist SD-101 (Dynavax), an investigational agent too.

* Intralesional = intratumoral

OncoSec. OncoSec announced in November 2014 it would combine ImmunoPulse and pembrolizumab, UC San Francisco and OncoSec Medical Collaborate to Evaluate Investigational Combination of ImmunoPulse and Anti-PD-1 Treatment. Data from this investigator-initiated study were presented at AACR 2016 (April), "Positive Melanoma Clinical Data at American Association for Cancer Research (AACR) Annual Meeting 2016," where patients initially were treated with ImmunoPulse and, then, some went to receive systemic anti-PD-1/PD-L1 therapy. Notably, however, OncoSec announced this month data from the same study would be presented at SITC 2016 (November), "Acceptance of Late Breaking Abstract at Upcoming Society for Immunotherapy of Cancer (SITC) Annual Meeting 2016," where the focus would be on [clinical data from] patients with a low likelihood of response to an anti-PD-1 alone (i.e., anti-PD-1 failures).

Dynavax. Dynavax and Merck & Co. announced a collaboration in June 2015, Investigating the Combination of Immuno-Oncology Therapies. Initial clinical data of the combination of SD-101 and pembrolizumab in patients with metastatic melanoma was presented at ESMO 2016, "Phase 1b/2, Open-Label, Multicenter, Dose-Escalation and Expansion Trial of Intratumoral SD-101 in Combination With Pembrolizumab in Patients with Metastatic Melanoma." Preclinical work on SD-101 was presented at AACR 2016 by Dynavax observed, "These data provide a strong rationale for the clinical assessment of SD-101 in combination with agents blocking the PD-1/PD-L1 pathway in patients unresponsive to PD-1 blockade alone." Dynavax and Merck jointly observed on their ESMO 2016 poster, "Preclinical studies suggest that the immunostimulatory effects of SD-101 might also boost the activity of PD-1 checkpoint inhibitor therapy. In mouse models, SD-101 converted anti-PD-1 non-responders into responders by increasing the quantity and quality of tumor-specific T cells." {my underlined emphasis}

In order for Provectus CTO Dr. Eric Wachter, PhD to put Provectus in a position to garner a collaboration with a Big Pharma and its immune checkpoint inhibitor, he has to provide a compelling demonstration of the features of PV-10 in combination with an anti-PD-1 drug like pembrolizumab (e.g., clinical trial PV-10 in Combination With Pembrolizumab for Treatment of Metastatic Melanoma). The features of this demonstration would include (a) preliminary safety and efficacy results, (b) immune biomarkers to facilitate appropriate patient selection if and when the combination is approved, and, presumably, (c) the ability of PV-10 to better turn anti-PD-1 non-responders into responders.

Contesting anti-PD-1 non-responders into responders should be a big deal for Merck and Bristol-Myers because such contestation is all about eating more of the rest of the pie, much more so than fighting over the same sliver of it.

Updated (10/19/16): OncoSec. ref. "OncoSec (ONCS) Q4 2016 Earnings Call Transcript," Seeking Alpha

I referenced epIL-12 (and OncoSec) above because of the useful information regarding anti-PD-1 failures or non-responders. The oncology playing field continues to evolve, and combination therapy approaches clearly are evolving as well across multiple dimensions, like (i) determining which patients when and how [immune biomarkers], and (ii) expanding the addressable market from responders to non-responders.

Among other aspects of an analysis of epIL-12 (and OncoSec), which historically has been mentioned together with Amgen's T-Vec and Provectus' PV-10, like at ASCO 2014 (see "Expert Point of View: Axel Hauschild, MD," The ASCO Post, Caroline Helwick, July 25, 2014), (a) there does not appear to be an initial pathway to approval yet (if at all) for epIL-12 as a monotherapy and (b) the investigator-initiated study was neither designed nor powered to transition to a pivotal trial as a combination therapy. OncoSec hopes to secure agreement with (acquiescence by) the FDA on a pivotal/registration trial design by the end of the year. Initial pathways to approval, like what Provectus has with PV-10 as a monotherapy for locally advanced cutaneous melanoma, as with valuable beachfront property, is valuable drug treatment "real estate." Nevertheless, it is a good strategy for OncoSec to focus on PD-1 failures; using emerging biomarker data to select "likely" PD-1 failures, however, is likely to prove somewhat more challenging. It will be interesting to see how this plays out.

Dynavax. This is a true treatment combination and company collaboration (compared to the OncoSec treatment combination, for which the clinical trial protocol is here). The results are interesting, if not very preliminary (e.g., efficacy from 5 patients, measurement [for purposes of the ESMO 2016 abstract] was made after only 12 weeks). One would have hoped they could have provided a few more details (e.g, the number of injections of SD-101 [presumably 11 in total], more details on patient stage [particularly Stage IV, like M1a, M1b and/or M1c], what the grade 4 SAE was, etc.).

A 25% serious adverse event (SAE) rate seems a bit high, and this is kind of an odd way to report safety data; usually this is reported as CTCAE Grade 3 or higher events since this includes both severe AEs and the subset of those that qualify as SAEs. Robert et al. reported 10.1-13.3% rate of Grade 3 or higher AEs for pembrolizumab alone (NEJM 2015;372:26).

Notably, investigators/clinical sites on the poster included Agarwala/St. Luke's. The trial itself also is recruiting at Huntsman Cancer Institute (Andtbacka).

Since this is a collaboration with Merck, it would appear the Big Pharma is not requiring rigorous safety testing before the project moves to Phase 2 (a Merck staffer is a co-author on the ESMO 2016 poster). The poster's Methods section notes the trial is a dose-escalation and dose expansion study. It shows data from dose-escalation (i.e., 2 mg, 4 mg, 8 mg), but does appear to refer to the dose expansion portion, which normally would be additional patients at the highest tolerated dose. The N = 6 at 8 mg is dose expansion but, again, if Merck wants to green light this work to a Phase 2 trial, [as a Big Pharma] they probably are not going to get significant push-back from the FDA or institutional review boards (IRBs). If a small biotechnology company has a major player backing it, it is possible to do things that are not plausible for outsiders (i.e., the golden rule). Finally, this study might give Amgen pause, since SD-101 appears to function similarly to T-Vec, may produce a more robust effect than T-Vec and, most importantly, is not a live virus.

The Day Big Pharma's Earth Stood Still

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Updated below: 9/1/16 and 9/10/16.

Prior to Bristol-Myers' failure of its anti-PD-1 drug and cancer immunotherapy nivolumab/Opdivo as a monotherapy for patients with advanced non-small-cell lung cancer (NSCLC), when in the "era" of anti-PD-1/PD-L1 therapy had one of these drugs or drug compounds failed a pivotal clinical trial.

Since the Big Pharma's announcement on August 5th of this "shocking" or "stunning" outcome, as of this writing, BMS' share price has fallen about 25% (while MRK's has risen about 7%, with a roughly flat S&P 500), which would be equivalent to a loss in market capitalization of about $30 billion.

The "era" of course can be measured in a mere handful of years. It was not that long ago, in 2011, when anti-CTLA-4 drug ipilimumab (Yervoy, Bristol-Myers) was approved for metastatic or advanced melanoma, while "relative" tremelimumab (Pfizer, subsequently licensed to AstraZeneca and MedImmune) failed its own pivotal melanoma trials.

Bristol's failure was attributed by some (or many) to a failure in trial design, and its share price was treated like that of a small biotechnology company that failed its pivotal study. When has that happened? Was failure really attributable simply and strictly to trial design, or was there a calculated risk-reward calculation that merely did not pan out? Consider that Bristol-Myers was running two pivotal trials essentially for the same indication and patient population; one of nivo as a monotherapy, and one of nivo and ipi as a combination regimen.

Nivolumab's August failure may have the exposed anti-PD-1/PD-L1 therapy in at least two ways. First, anti-PD-1/PD-L1 drugs need help. And second, combinations (two therapies and/or treatments) and cocktails (three or more) "now" are the order of the day for end-stage cancer patients.

What started out a few years ago as throwing poop on a wall and observing what stuck in regards to exploring combinations and cocktails for end-stage patients appears to have evolved into or towards thinking more about the poop before it is thrown and wondering what each poop in the pairing or triplet brings to the table individually and collectively in regards to baseline immunologic signalling, biomarkers, pharmacokinetics, etc. -- that is, clear, definable, understandable, synergistic value. See, for example, Immunological “ignition switch” (August 26, 2016) on the blog's Current News page.

What happens to a Big Pharma owner of an anti-PD-1/PD-L1 drug or agent if it doesn't find the right (i.e., synergistic) partner for its checkpoint inhibitor, and when a/one competitor does?

Updated (9/1/16): A Bristol-Myers (BMS) location visited this blog post yesterday (August). In July this same Internet Protocol (IP) address visited September 9, 2014 blog post Bristol-Myers vs. The Field (ex-Provectus):

"Last week Bristol-Myers filed a lawsuit against Merck over [anti-]PD-1 agent pembrolizumab (trade name Keytruda), which was approved last week by the FDA for late-stage or metastatic melanoma. 

Specifically, Bristol-Myers claims that Merck is violating the patent on its Opdivo mediation for tackling melanoma, which was recently approved in Japan and became the first so-called PD-1 inhibitor to win regulatory backing anywhere. A PD-1 inhibitor blocks a protein that acts as a brake on certain immune system cells and prevents them from attacking healthy tissue. (Bristol-Myers Sues Merck Over a Patent on its new Cancer Drug, The Wall Street Journal, September 8, 2014)"

In February this visitor exited via a link to November 5, 2015 press release, Reports Immune Mechanism of Action Data for PV-10 Presented at Society for Immunotherapy of Cancer Annual Meeting Authored by Researchers at Moffitt Cancer Center.

A second BMS IP address from the same location (e.g., the same visitor from a different spot, a different visitor from a different spot) visited the blog's Current News page. This same IP address exited the three links below in May 2015 (I cannot recall yet from which blog post or news page these links came):

• GEN News Highlights, December 16, 2011, "Autophagy Key to Triggering Immune Responses to Cancer Post-Chemotherapy,"

• "Autophagy-Dependent Anticancer Immune Responses Induced by Chemotherapeutic Agents in Mice," Michaud et al., Science, 16 Dec 2011: Vol. 334, Issue 6062, pp. 1573-1577, and

• "Autophagy in Tumor Immunity," Amaravadi, Science, 16 Dec 2011: Vol. 334, Issue 6062, pp. 1501-1502.

Updated (9/10/16): One of the above BMS IP addresses visited the blog's landing page on September 7th.

A different location (and thus IP address) from the one location/2 IP addresses above brushed by (did not visit, but rather clicked on and then quickly closed the tab or went away) June 1, 2016 blog post Intralesional PV-10 for In-Transit Melanoma—A Single-Center Experience via Google Japan.

Checkpoint Inhibition Differentiation or Death: Proprietary Combinations with Protectable Agents

Updated below.

From this project's Twitter feed: Dr. Sally Church, PhD, ‏@MaverickNY

Click to enlarge. Tweet image source

How would Big Pharma distinguish each of its immune checkpoint inhibitors (CIs) from another? Efficacy? Tolerability? Cancer indication? Cost? Within groups (e.g., PD-1s, PD-L1s, etc.), efficacy and safety should equivalent. Different antibodies — for example, with the PD-1s, like nivolumab/Opdivo and pembrolizumab/Keytruda — function in almost identical fashion and differ only by means of manufacture and corporate decisions made with regards to clinical development (e.g., dose schedule, target indication). Magically, there is parity in pricing.

Based on drug sales to date and sales projections thus far, captured in part by @grhyasen's tweet graphic above, Bristol-Myers (nivolumab/Opdivo) and Merck & Co. (pembrolizumab/Keytruda) may be in no serious rush to differentiate their CIs beyond their current, respective corporate strategies. But Roche (atezolizumab/Tecentriq), AstraZeneca (durvalumab) and Merck KGaA/Pfizer (avelumab), all with "late to market" CIs, surely must be thinking about ways to differentiate their respective compounds.

Does meaningful, sustainable and profitable differentiation come in the form of combination, and thus in the form of a partner compound for a CI? In other words, could combination create branded differentiation — ultimately based on efficacy, tolerability, indication and cost of the combination. Proprietary combinations with protectable agents.

Novartis, one Big Pharma without a "lead CI" but having PD-1, TIM-3, LAG-3 and PD-L1 CIs within its pipeline, seems to have begun its brand differentiation by expanding its strategic thinking to include or focus on first-in-class combinations. See Pharmaceuticals and Oncology Business Units, Meet Novartis Management, May 24-25, 2016:

Click to enlarge. Fuzzy orange rectangle is mine

Click to enlarge. Fuzzy orange rectangle is mine

PV-10's, and thus Provectus', value proposition to the likes of Roche, AstraZeneca, Merck KGaA, Novartis, etc. might be to (a) combine their CI with PV-10 and (b) use Provectus' combo patent* to defend the unique combination thus formed — a proprietary combination with a protected agent.

* United States Patent No. 9,107,887, Eagle et al., August 18, 2015, Combination of local and systemic immunomodulative therapies for enhanced treatment of cancer

Updated (6/11/16): Deena Beasley, Reuters, June 11th, Regulator says too many drugmakers chasing same cancer strategy:

"A new type of cancer drug that takes the brakes off the body's immune system has given drugmakers some remarkable wins against the deadly disease, but a top U.S. regulator says too many companies are focused on the same approach. 

Dr. Richard Pazdur, head of the Food and Drug Administration's office of oncology products, was referring to therapies designed to disable the PD-1 protein that tumors use to evade the immune system...  

"People should ask themselves ... would we be better off spending those resources into looking at more novel drugs?" Pazdur told Reuters during the annual American Society of Clinical Oncology (ASCO) meeting in Chicago this week.... 

"As with everything in drug development, it is about reduction of risk," he said. But the number of similar drugs in development at the same time is a first in the oncology field, and latecomers to the PD-1 market will likely be relegated to "niche" indications, he added. 

Drug company executives disputed Pazdur's critique. In interviews with Reuters, they argued that the science around cancer is advancing rapidly, with a focus on how to best combine therapies to attack multiple mechanisms of the disease, determine which patients are most likely to respond to them and how long patients will need to be treated."

Blumenthal and Pazdur, Response Rate as an Approval End Point in Oncology, JAMA Oncol. 2016;2(6):780-781.

"Overall response rate (ORR) as a surrogate end point in oncology drug approval has a long history. In the 1970s, the US Food and Drug Administration (FDA) usually approved drugs on the basis of ORR. In the 1980s, after discussions with the Oncologic Drug Advisory Committee, the FDA determined that cancer drug approval should be based on more direct evidence of clinical benefit, such as improvements in overall survival (OS), tumor-related symptoms, or physical function.1 In the past decade, due to an improved understanding of the genomic underpinnings of cancer, better molecular characterization of tumors, and more precisely targeted agents, unprecedented rates of response have radically altered the therapeutic landscape in a number of malignant neoplasms. Therefore, ORR and duration of response as assessed in single-arm trials has served as the basis of accelerated approval and at times regular approval in a number of refractory malignant neoplasms, including non–small-cell lung cancer (NSCLC), lymphoma, melanoma, and myeloma."

This presumably works [very well] only for systemic drugs using standard RECIST. Provectus' pivotal melanoma Phase 3 is employing [standard] RECIST 1.1.

Road tripping:

My proxy vote should be posted by June 14th.

PV-10 at AACR 2016: T cell mediated immunity after combination therapy with intralesional PV-10

Presentation Title: T cell mediated immunity after combination therapy with intralesional PV-10 and co-inhibitory blockade in a melanoma model

Author Block: Amy M. Weber, Hao Liu, Krithika N. Kodumudi, Amod A. Sarnaik, Shari Pilon-Thomas. H. Lee Moffitt Cancer Center, Tampa, FL

Abstract:

PV-10 is a 10% solution of Rose Bengal, a xanthene dye that was originally developed for ophthalmic use and later used in liver function studies. PV-10 was formulated for intralesional (IL) injection and is currently being investigated as a novel cancer therapeutic. In murine studies, we have previously shown that intralesional (IL) injection of PV-10 leads to a regression of both injected tumors and untreated bystander tumors. We have also shown that combination therapy of IL PV-10 with blockade of PD-1 and PDL-1 leads to increased anti-tumor immunity. In this study, we have examined the role played by specific immune cell populations in eliciting this response in a murine melanoma model. We first investigated the antigen specificity of CD8+ T cells in the spleens of mice treated with the combination therapy of IL PV-10 and systemic co-inhibitory blockade. We found that splenocytes from mice treated with the combination of IL PV-10 and anti PD-1 antibody have an increased mean percentage of OVA antigen-specific CD8+ T cells (5.77%) compared to single treatment with anti PD-1 antibody (3.8%) or IL PV-10 (3.60%) alone in OVA-expressing B16 tumor bearing mice. To investigate the role of T cell subsets in mediating an immune response, OVA-expressing B16 tumor bearing mice were treated with IL PV-10 followed by intraperitoneal injection of anti-PD-1 antibody. In addition, mice were given either 2.43 antibody to deplete CD8+ T cells, GK1.5 antibody to deplete CD4+ T cells, or PC61 to deplete regulatory T cells (Tregs). We found that depletion of CD4+ T cells in combination with IL PV-10 and anti-PD-1 antibody treatment resulted in an enhanced anti-tumor effect, with an average tumor size of 52.8 mm2 on day 25 compared to the control group (173.7 mm2), and depletion of Tregs resulted in an even greater anti-tumor effect, with an average tumor size of 1.2 mm2 on day 25 (p<0.05). In contrast, mice treated with the CD8+ depleting antibody exhibited diminished anti-tumor immunity compared to the control group, with an average tumor size of 200 mm2 on day 25. Together, these studies indicate that the effect of combination therapy with IL PV-10 and co-inhibitory blockade is mediated by CD8+ T cells, and that depletion of both CD4+ T cells and CD25+ Tregs significantly enhances anti-tumor immunity in a melanoma model.

{my bolded and underlined emphasis above}

The Early Obsolescence of Checkpoint Inhibitors

Image source

Take as a starting point Inman et al.’s 2007 article entitled Costimulation, coinhibition and cancer, and their statement therein: (underlined emphasis is mine):

“If sufficient co-stimulation is provided in the presence of adequate tumor-associated antigenic stimulation, the immune system will act against tumor antigen and, thus, destroy early tumors before they become fully established. Contrarily, if co-inhibitory signaling dominates, the immune system will be tolerized to tumor antigens, and the tumor will be permitted to grow unfettered and unmolested by the immune system. If neither co-stimulatory nor co-inhibitory signals dominate, the adaptive immune system may remain in a tenuous state of equilibrium, militating against tumor outgrowth with varying degrees of success.”

The essence of the authors’ view might be that the immune system is capable of decisively acting against cancer only in the situation where or circumstance that co-stimulation dominates co-inhibition. Take also as context to this starting point, however, that what we don’t know about the immune system probably dwarfs what we know about it.

The notion of “releasing the brakes” in the medical literature and mainstream press describes the approach of inhibiting cancer’s ability to suppress or block the body’s immune system from acting, and thus to evade attack. Although possibly coined in the early-2000s (see, for example, Tirapu et al.’s 2002 article entitled Effective tumor immunotherapy: start the engine, release the brakes, step on the gas pedal,...and get ready to face autoimmunity), use of the releasing-the-brakes phrase may have grown more widespread starting in the late-2000s and around the time of Dr. James Allison, Ph.D’s seminal work of blocking (inhibiting) the CTLA-4 protein receptor (using Bristol-Myers’ ipilimumab) and, later, the follow-up scientific exploration of blocking (inhibiting) PD-1 and PD-L1 ligands too (and associated PD-1 therapeutics pembrolizumab and nivolumab, for example, from Merck and Bristol-Myers, respectively).

Medical literature has more sparsely touched on, and mainstream press much less so, the other two components of the get-the-car-moving analogy (where the car is the immune system), “starting the engine” and “stepping on the gas pedal,” where these phrases relate to different aspects of stimulating the body’s immune system.

Possibly over-using the car analogy further, with the potential risk of over-simplifying it inappropriately, consider T cell immunity as a car at rest. More immunogenic tumors and their associated cancers like melanoma are like a car sitting on a slight incline. Release its brakes by treating the tumors (and thus the cancer) with checkpoint inhibitors, and the car may roll forward move some distance, notable or otherwise. With other less or non-immunogenic cancers, think of the car as sitting on a flat surface. Releasing the brakes does not enable the car to move any meaningful distance, if at all.

If you want to get the car to really move, you have to start its engine, and then step on its gas pedal. Releasing the brakes might help the car move farther and faster, but it also is quite possible the car may be able to move sufficiently without the need for further action other than to start its engine and/or stepping on its gas pedal.

The continued use of get-the-car-moving analogy of course requires the assumption the car can drive by itself; that is, the immune system can handle its own business once it has been started, and is appropriately up and running from stepping on the gas pedal.

Now consider Winograd et al.’s 2015 article entitled Induction of T cell immunity overcomes complete resistance to PD-1 and CTLA-4 blockade and improves survival in pancreatic carcinoma. In particular, note the underlined sentences (my emphasis) from the article’s abstract:

“Disabling the function of immune checkpoint molecules can unlock T cell immunity against cancer, yet despite remarkable clinical success with monoclonal antibodies (mAb) that block PD-1 or CTLA-4 resistance remains common and essentially unexplained. To date, pancreatic carcinoma is fully refractory to these antibodies. Here, using a genetically engineered mouse model of pancreatic ductal adenocarcinoma in which spontaneous immunity is minimal, we found that PD-L1 is prominent in the tumor microenvironment, a phenotype confirmed in patients; however, tumor PD-L1 was found to be independent of IFN-γin this model. Tumor T cells expressed PD-1 as prominently as T cells from chronically infected mice, but treatment with PD-1 mAb, with or without CTLA-4 mAb, failed in well-established tumors, recapitulating clinical results. Agonist CD40 mAb with chemotherapy induced T cell immunity and reversed the complete resistance of pancreatic tumors to PD-1 and CTLA-4. The combination of αCD40/chemotherapy plus PD-1 and/or CTLA-4 induced regression of subcutaneous tumors, improved overall survival, and confered curative protection from multiple rechallenges, consistent with immune memory not otherwise achievable. Combinatorial treatment nearly doubled survival of mice with spontaneous pancreatic cancers although no cures were observed. Our findings suggest that in pancreatic carcinoma, a non-immunogenic tumor, baseline refractoriness to checkpoint inhibitors can be rescued by the priming of a T cell response with αCD40/chemotherapy.”

CD40 is a co-stimulatory protein, while chemotherapy has been understood to act in a stimulatory fashion through the subsequent release of cancer antigens.

Achieving T cell immunity almost if not actually by definition should mean overcoming resistance to cancer, thus overcoming checkpoint blockade and mitigating the need to artificially release the brakes.

Should stimulation via stimulatory therapeutics and therapies start the engine and enables the gas pedal to be stepped on sufficiently and appropriately (i.e., with minimal or manageable side effects or adverse events) so as to achieve T cell immunity, brakes may not be necessary once the car is moving (in context, and given the car [the immune system] can drive itself and not careen off the road because it then should know what it is doing).

Over time, however, road friction may start slowing the car down to the point where waning immunosurveillance (the immune system recognizing and eliminating continuously arising cancerous cells) no longer can protect the patient from relapse (analogous to how waning varicella zoster antibody titers may result in a bout of shingles). Keeping the brakes disengaged, especially with non-immunogenic tumors, should have some role going forward, making Merck, Bristol-Myers, Roche, AstraZeneca, Pfizer and other companies’ checkpoint inhibitors not necessarily obsolete as much as persnickety.

"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 company licensed their drug to Genentech/Roche in October 2014.

* "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.

• The company announced a combination collaboration of their drug with Bristol-Myers' PD-1 agent in May 2014.

* "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

• The company announced combination collaborations of their drug with Merck's PD-1 agent in February 2014, AstraZeneca's PD-L1 agent in May 2014, and Bristol-Myers' PD-1 agent also in May 2014.

* "These three combinations are attractive to pursue clinically..."

○          ○          ○          ○          ○          ○          ○

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

• Clinical, possibly, from Provectus' compassionate use program ("CUP"), where patients previously on checkpoint inhibitors who recurred from these may have sought help from PV-10 (Phase 2 patients were refractory to a median of 6 previous interventions, including immunotherapy (21%)).

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.

The Immune Checkpoint Inhibitor Global 4 (or 5)

In 2013 Citi equity research analyst Andrew Baum projected cancer immunotherapies "...will generate sales of up to $35 billion (a year) over the next 10 years and be used in some way in the management of up to 60 percent of all cancers" (see Immune system cancer drugs tipped to be a $35 billion market, Ben Hirschler, Reuters, May 22, 2013). The analyst and others in the investment community refer to the next generations of immune checkpoint inhibitors, anti-PD-1 and anti-PD-L1 agents, having moved past approved anti-CTLA-4 agent ipilimumab (Yervoy).

Players (2013 ranking by oncology sales) in the checkpoint inhibitor space include:

• Bristol-Myers (#9): CTLA-4 (approved ipilimumab/Yervoy), and PD-1 (approved internationally nivolumab/Opdivo),

• Merck & Co. (#8): PD-1 (approved pembrolizumab/Keytruda),

• Roche (#1): PD-L1 (investigational MPDL3280A), and

• AstraZeneca (#7): PD-L1 (investigational MEDI4736).

Farther behind, it seems, is Novartis (#3): PD-1 (potential candidates via its CoStim acquisition). It could be late for Novartis to bring a checkpoint inhibitor to market. By the time it gets its version out, Novartis should have four competitors with similarly functioning drugs.

Even before Baum made his bold claim, it was clear the FDA, researchers and industry understood the combination of checkpoint inhibitors and other agents and therapies would be the eventual approach for treating late-stage disease. As result, companies established various combination study relationships, and continue to do so.

Checkpoint inhibitor companies do this because PD-1s and PD-L1s should work more effectively in combination depending on the setting (e.g., co-inhibitory/co-stimulatory). Companies with no checkpoint inhibitors (and no robust immune system primers) do this because a combination should provide them an advantage for their treatments that would be surpassed if they did not do these partnerships at all, and potentially permit much earlier market access for their non-checkpoint inhibitor agent.

For example:

• Pfizer (#11): Merck's PD-1 + targeted therapy (crizotinib/Xalkori),  + targeted therapy  axitinib/Inlyta), and + 4-1BB co-stimulatory agent (PF-05082566), 

• Amgen (#2): Bristol-Myers's CTLA-4 + intralesional (tamilogene laherparapvec or T-Vec), and Merck's PD-1 + intralesional (T-Vec),

• Celgene (#4): Bristol-Myers' PD-1 + targeted therapy (paclitaxel/Abraxane), and

• Novartis (#3): In addition to PD-1s and CAR (chimeric antigen receptor)-T cell therapy, Bristol-Myers' PD-1 + [separately] three targeted therapies (ceritinib/Zykadia, INC280, and EGF816).

SugarCone Biotech's Paul Rennert, in his September 2014 blog post Rational Immunotherapy Combinations: How’s That Work Again?, wrote about "...the question of how to parse the potential immunotherapy combinations that may soon become available, noting that different combinations may prove differentially useful across a wide range of oncology indications." His post is very informative. It is a not-so-simple process to understand and develop the appropriate rationale for why, what and how one combines different agents and therapies, as he clearly illustrates in a cursorily-populated table:

Click to enlarge.

Rennert goes on to write (where I look past his use of vaccines to the broader issue of how to generate many more antigens in order for PD-1s and PD-L1s to be more successful in their individual efforts towards the combination):

"There are other consequences in this new landscape. Nearly every oncology vaccine company claims that as soon as they run a combo trial with an anti-PD-1 or anti-CTLA4 antibody their particular vaccine approach will perform beautifully. There are a few problems with this, notably, very few of these companies have a chance in hell of getting an anti-PD-1 antibody via collaboration, and the rest will pay heavily for the privilege. Second we have no idea of how to rationally pair vaccines with immune checkpoint exposure in order to induce optimal responses. Third, there are not enough patients to go around, a simple fact in many indications."

As recent as the company's ESMO 2014 poster Provectus highlighted the combination study aspect of its business/corporate development strategy.

Click to enlarge.

The value proposition/rationale (but not necessarily the specific medical and scientific rationale and sequencing) for combining PV-10 with a checkpoint inhibitor seems straightforward:

• Immune checkpoint inhibitors have been and will be combined with intralesional agents. Thus far, Bristol-Myers & CTLA-4/ipilimumab/Yervoy and Amgen's T-Vec, Merck & PD-1/pembrolizumab/Keytruda and T-Vec. As expected, the combination of ipilimumab and T-Vec produced responses rates higher than the individual treatments themselves (ASCO 2014). That is, Response_A+B > Response_B > Response_A (A = ipilimumab, B = T-Vec).

• The combination produced notable immunologic signaling. This also was reported from the CTLA-4/ipilimumab and T-Vec combination study at ASCO 2014. The greater the immunologic signaling, the greater [one would imagine] the response and interaction of the immune system to fight and hopefully beat cancer. That is, perhaps, Signaling_A+B > Signaling_B > Signaling_A. The poster presented at ASCO of this work only conveyed the immunologic signaling of the combination.

• PV-10 kills tumors far better than T-Vec. PV-10 produce higher complete responses than T-Vec. The medical community has understood for a while the more antigens produced and presented as a result of tumor destruction (antigenization) the more likely the potential of a greater immune response by the body.

If T-Vec works, PV-10 should work better. But, how much better?

Dr. Agarwala noted in his October 12th presentation at the III Eurasian Melanoma and Skin Cancers Forum that intralesional therapies (PV-10 and T-Vec, since Allovectin-7 failed its metastatic melanoma Phase 3 trial) would form the backbone of combination therapies.

Click to enlarge.

The challenge for Big Pharma, perhaps for some of them more than others, is the lack of "hard data" about PV-10's strong immunologic properties. Presumably Moffitt Cancer Center's presentation on November 8th -- Coinhibition and Costimulation: Targets and Strategies session, Efficacy of Intralesional Injection with PV-10 in Combination with Co-Inhibitory Blockade in a Murine Model of Melanoma poster -- will provide it.

What makes Provectus think they can overcome Rennert's obstacles above?

First, does Provectus have a chance of collaborating with a PD-1 and/or PD-L1 owner? I think the company has a good chance, but the cost or benefit of doing so has yet to be determined (i.e., the details, considerations and concessions of a contractual relationship, and not so much the trial design itself). Obviously, the more a checkpoint inhibitor owner wants to combine with PV-10, the better for Provectus.

I think it's reasonable to believe the Global 5 are aware of PV-10's potential, and its possibilities in combination with immune checkpoint inhibitors. Due diligence begins with getting to know the compound, the available data and practitioners knowledgeable in its use, and then learning more about its combination potential. In regards to the former (i.e., getting to know PV-10), a Merck researcher purportedly attended Moffitt's Dr. Vernon Sondak's June 27th PV-10 presentation at the 4th European Post-Chicago Melanoma/Skin Cancer Meeting specifically to hear/learn more about the drug (a European-based Provectus shareholder routinely attends PV-10 data presentations at European medical conferences). Roche seems to be aware of PV-10, but questions the lack of "hard data" about the compound's immunologic signaling.

Second, how would Big Pharma and Provectus rationally pair immune checkpoint blockade with PV-10? Moffitt's upcoming SITC work presumably should begin to describe how to rationally pair, and dose and sequence PV-10 and a checkpoint inhibitor. It seems the immune system primer & activator/cancer antigen releaser should be given first, followed by the checkpoint inhibitor. In the ipilimumab + T-Vec trial noted above, the investigators sequenced the drugs in that way:

T-VEC was given intralesionally at week 1, week 4, and then every other week. Ipilimumab was given every third week starting at week 6. Treatment continued until dose limiting toxicity, intolerance, all injectable tumors disappeared or disease progression.

I think Rennert's larger question is the whys of rationally pairing drugs, before getting around to the hows. I liken it to understanding what step or steps of the cancer immunity cycle each drug partner in a combination promotes.

Third, are there enough patients to go around? According to Provectus there are sufficient patients available because investigators have asked to use PV-10 in combination with other agents in studies when they are established. This too remains to be seen.

Speaking of Dr. Agarwala, he probably will make a similar presentation to the one he made in Suzdal, Russia at the 2014 Society for Melanoma Research Congress in Zurich, Switzerland (a satellite symposium sponsored by Amgen and entitled Oncolytic immunotherapy – engaging the immune system to target melanoma).

Immune Surveillance

Following up on my Juxtaposition blog post, there is the potential for a melanoma combination therapy Phase 1 (or 1b)/2 trial of PV-10 and a checkpoint inhibitor, which management briefly discussed on their 2Q14 conference call.

Eric: As Pete mentioned earlier, we're also looking beyond single-agent therapy with PV-10 to address the needs of patients with more extensive disease, particularly those with visceral tumors that are not injectable. One attractive and complementary approach may be to combine PV-10 with a systemic immunotherapy, such as an immune checkpoint protein inhibitor. Immune checkpoint protein inhibitors, such as anti-CTLA4, anti-PD-1, and anti-PD-L1 agents, are an important advance in the treatment of melanoma and other cancers, another subject of intense development in our industry. 

However, while these drugs represent an important step forward, like any drug they are not perfect and they might be improved. As was clearly presented by the medical oncology community earlier this summer at ASCO, using an agent like PV-10 to prime the immune system could be synergistic in combination with such a systemic agent. 

Our patent application on this strategy was published in 2012 and we've been vigorous by pursuing this approach since. The nonclinical research we first presented at the Society for Immunotherapy of Cancer Annual Meeting in 2012, together with ongoing translational clinical research on PV-10's mechanism of action that we were sponsoring at Moffitt Cancer Center and our own Phase 2 data, provide a rationale for combination testing of PV-10. 

This development track, separate from the Phase 3 study I discussed earlier, could represent a path forward for patients with significant disease burden not amenable to intralesional injection, and is a possible candidate for co-development with one or more pharmaceutical or biotech companies. {Underlined emphasis is mine}

Eric wouldn't insert statements about this topic into his comments until and unless at least minimally substantive progress has been made towards this end. He first addressed a combination study via St. Luke’s Cancer Center and Temple University's and principal investigator Dr. Sanjiv Agarwala, M.D.'s presentation at the 10th European Association of Dermato-Oncology (EADO) congress in May ("Commencement of combination studies in Stage IV disease in second half of 2014"). The reality of a combination study/trial probably is dependent on the partnering pharmaceutical company's, the one with the checkpoint protein inhibitor to be combined with PV-10, interest in and willingness to:

• At a minimum, run and shoulder the cost of a trial, aside from Provectus's minimal expense to provide PV-10 drug product,
• At a minimum (more than likely) make a one-time payment to Provectus, such as was the case in Bristol-Meyers' collaboration with Celldex Therapeutics, and
• Forego meaningful rights of first somethings, unless the partner fully compensates Provectus for this ask.

I summarized a number of previously announced and/or conducted combination studies in my Combinations (July 24, 2014) news items under the blog's News tab.

Click to enlarge.

Click to enlarge.

Although Provectus management has understood and communicated the potential for combination therapy involving PV-10 for the treatment of metastatic melanoma, noting this on the 2Q14 conference call (i.e., the Provectus-Pfizer patent application, the SITC 2012 poster presentation), they historically have not prioritized this potential regulatory pathway, and have been disinterested in and unwilling to allocate resources to conduct a typical combination study where companies share trial costs and the "non-CTLA-4/PD-1" (i.e., non-Bristol-Myers or Merck) partner conducts (sponsors) the trial.

There is no certainty a trial comes together, but it would appear Provectus is engaged in the kind of basic or fundamental conversations, data sharing and expectation setting necessary to contemplate a combination study and develop the associated relationship between the parties involved.

The consensus of melanoma key opinion leaders appears to be that “[t]he future lies in combinational approaches with drugs from the new melanoma landscape” (e.g., intralesional therapies, BRAF inhibitors, ipilimumab, anti-PD-1 antibodies). Moffitt Cancer Center's pre-clinical work combining PV-10 with other approved and investigational immunotherapeutic agents more than likely would be, and would have to be, the driving force behind any clinical combination study focused on metastatic melanoma patients with visceral disease (i.e., Stage IV M1b-c). The cancer center already has alluded to the completion and results of this pre-clinical work, which should form the rationale for a future clinical trial or trials, at ASCO 2014 by concluding "IL PV-10 may be rationally combined with systemic immunotherapy for the treatment of metastatic melanoma," and again at the 4th European Post-Chicago Melanoma & Skin Cancer Meeting 2014 by concluding "[p]reclinical data suggest PV-10 would be a good candidate to evaluate in conjunction with available systemic therapies and new agents in development."

I previously wrote about historical pre-clinical and some clinical work on PV-10 in combination with other treatments (systemic chemotherapy [pre-clinical], systemic immunotherapy [pre-clinical], radiotherapy [clinical]) in my "IL PV-10 may be rationally combined with systemic immunotherapy for the treatment of metastatic melanoma" blog post.

A potential clinical trial combining PV-10 with a checkpoint inhibitor should be viewed in the context of other clinical trials and studies Provectus expects  hopes to commence in 2014 and/or 2015:

• Melanoma, PV-10: Phase 3 trial, locally advanced unresectable/unresected cutaneous melanoma, 2H2014,

• Dermatology, PH-10: Phase 1 trial, mechanism of action/feasibility study, 2H2014 (my estimate),

• Liver cancer, PV-10: Phase 2/3 trial, locally advanced, unresectable/unresected liver cancer (my speculation of the trial title), 1H2015 (my estimate); the trial also should include liver tumors caused by primary non-liver cancers (i.e., cancers metastatic to the liver), and

• Melanoma, PV-10: Phase 1 (or 1b)/2 trial, metastatic melanoma, 1H2015 (my estimate, if a deal is consummated in 4Q14); with a trial population similar to that of the ipilimumab+talimogene laherparepvec of mostly Stage IV M1b-c patients

I do not believe a deal between Provectus and a pharmaceutical company (and its checkpoint inhibitor), the first step towards an eventual clinical trial, would be consummated until Moffitt's preclinical combination study data is more broadly communicated. Meaning, neither Bristol-Myers nor Merck, for example, would even contemplate acceding to Provectus deal expectations until and unless Moffitt substantiates their above mentioned conclusions with very compelling data (i.e., together PV-10 makes your drug much better than your drug alone).

I think the venue for the cancer center's communication will be the 29th Annual Meeting of the Society of Immunotherapy for Cancer, November 6-9, 2014. Provectus first addressed combination treatment at the 2012 annual SITC meeting concluding the co-administration of PV-10 immuno-chemoablation with other systemic therapy could yield potent synergy in uninjected tumors.

But, more than just the pre-clinical drug combination study results, I also am very interested in other aspects of Moffitt's work, and Dr. Jeffrey Weber, M.D., Ph.D.'s comprehensive views on the utility and use of PV-10.

First, what is the basis for Weber's comment "PV-10 might offer the perfect way to prime the immune system?" Dr. Weber has said (paraphrasing) the utility of a primer is simply its ability to synergize with the immune agent in question in terms of clinical effect when given prior to the second agent. Moffitt data showing the strength of the systemic responses PV-10 can stimulate (i.e., efficacy of PV-10 plus a checkpoint inhibitor >> efficacy of the checkpoint inhibitor alone) should make this/his point.

Second, what is PV-10's role and participation in each step of the cancer immunity cycle (Chen & Mellman, 2013)? Under the blog's PV-10, and the Cancer Immunity Cycle tab I illustrate PV-10's involvement in steps 1 (release of cancer cell antigens), 2 (cancer antigen presentation), 3 (priming and activation) and 7 (killing of cancer cells). And although Dr. Weber has said (paraphrasing) one should prioritize which steps are the most important (presumably in order to determine how to utilize what agents in combination and why; for example, impacting on endothelial cells have been less promising as a therapeutic than many of the other steps), I'd like to understand Moffitt's view on PV-10's involvement in steps 4 (trafficking of T cells to tumors), 5 (infiltration of T cells into tumors) and 6 (recognition of cancer cells by T cells).

And third, what are Weber's thoughts about PV-10 in the context of or in regards to immune surveillance? Immune surveillance theory is:

The concept that the immune system protects the host against cancer was first posited by Ehrlich in 1909 (1) and modified in the 1950s by Burnet and Thomas (2, 3), who proposed that it was instrumental in eliminating precancerous or cancerous cells, through a “surveillance” function. However, the concept fell out of favor when studies in the 1980s indicated that tumors failed to develop more rapidly in nude mice (which lack T cells and B cells, but not NK cells) than in wild-type mice. It was resurrected in the 1990s, when a body of evidence emerged indicating that immunodeficient mice were at greater risk for spontaneous tumor development (4). These studies led to further refinement of the theory, now referred to as “cancer immunoediting,” encompassing three phases: elimination, equilibrium, and escape. (J Clin Invest. 2007;117(5):1130–1136. doi:10.1172/JCI32136)

In a February article of The American Journal of Managed Care, Weber said:

"Well, the Holy Grail of cancer immunology is to create a cancer vaccine. Provenge was the first and only cancer vaccine that was ever approved. But that is truly the mantra, that is, the immune system is the ultimate way to perform targeted therapy. So immunotherapy is targeted therapy, and its hallmark is memory." {Underlined emphasis is mine} 

And: "There are certainly data to suggest that this idea of immune surveillance is indeed valid. On the other hand, people on immunosuppressants don’t always present with 30 different types of solid tumors. Transplant patients often develop squamous skin cancers, especially virally related squamous skin cancers. So there are data to suggest that we always have immune surveillance to prevent cancer from developing." 

And: "You can divide immunotherapies into 4 or 5 categories: these include chemicals like cytokines; antibodies…cells, which are not really well developed; vaccines, which is always the Holy Grail to try to vaccinate someone against his or her own cancer. You’ve got 1 approved vaccine. One of the antibodies, which are the most exciting and promising, is approved. That’s ipilimumab, the anti-CTLA4 antibody. In terms of the cytokines, in 1996 and 1998 IL-2, interleukin-2, was approved for kidney cancer and for melanoma. The cell therapy is immature, and you will hear a lot more about the antibodies coming up in the next couple of years." {Underlined emphasis is mine} 

Recall that Moffitt said, following their initial murine model work, that:

"These murine studies confirm that PV-10 chemoablation results in both a direct effect on injected lesions as well as a systemic response that leads to regression of uninjected subcutaneous and lung lesions. Intralesional PV-10 treatment leads to the induction of tumor-specific immunity." (AACR 2013) {Underlined emphasis is mine} 

And that Provectus concluded at SITC 2012, by virtue of murine model work:

Chemoablation with PV-10 results in the induction of tumor-specific immunity. Immunodeficient mice exhibited no anti-tumor effect on re-challenge. Adoptive transfer of immunity only occurred following chemoablation in donor mice. Tumor-specific, long-term immunity and adoptive transfer implicate immune cell mediation. This immuno-chemoablative response to PV-10 is tantamount to “in situ vaccination.” (SITC 2012) {Underlined emphasis is mine}