"...systemic immunity induced by PV-10 tumor ablation"

An abstract of Moffitt Cancer Center's work, led I think by Dr. Amod Sarnaik, MD, a surgical oncologist, and Dr. Shari Pilon-Thomas, Ph.D., a medical researcher, to better understand PV-10's immunological activity through a Phase 1 feasibility study and be presented via poster at the 2014 annual meeting of the American Association for Cancer Research ("AACR"), was revealed today. According to ClinicalTrials.gov, "[t]he main purpose of this study is to find out more about how PV-10 works in melanoma tumors. Researchers also want to find out if there are changes in the body's immune cells (cells that fight infection and illnesses) after PV-10 is given, both inside the melanoma tumors and circulating in the blood."

At the 2013 AACR annual meeting last April, Moffitt's then abstract related to their murine model work on PV-10 concluded: "In total, these studies support the induction of tumor-specific T cell-mediated immunity after single treatment with IL-PV-10 in multiple histologic subtypes." The upshot of this appeared to me to be:

• One injection of PV-10 ("a single treatment," later heralded in Moffitt's August 2013 press release Single Injection May Revolutionize Melanoma Treatment, Moffitt Study Shows),
• Could bring about a natural, potentially permanent or very long-lasting immune response ("tumor-specific T cell-mediated immunity"),
• To the disease ("multiple histologic subtypes").

Multiple histologic subtypes. I don't think melanoma is one disease but rather has multiple histologic subtypes. Courtesy of a fellow shareholder and internist: "Interestingly, Rosenberg’s comments in a recent editorial makes the case for nurturing in vivo adaptive T-cell immunity such as PV-10 triggers. Adaptive as in dynamically adapt to the continuous mutations that occur, not try to identify, adopt and try to clone T-cells responding to some random tumor mutation." Rosenberg is Dr. Steven Rosenberg of the National Cancer Institute.

"All cancers contain multiple unique mutations and future progress in cancer gene therapy will likely result from the immunologic targeting of these mutated proteins. Melanomas contain an unusually large number of mutations probably due to the mutagenic action of ultraviolet light on the skin. The unique ability of TILs from melanoma to cause durable cancer regressions appears to result from attack against these individual cancer mutations. Smoking-induced lung cancers and cancers in patients with mutations in mismatch repair genes also have large numbers of sporadic mutations. The successful attack against unique antigens on melanoma suggests that TILs or gene-modified lymphocytes recognizing unique mutations on other cancers might be effective for use in therapy as well. Most other solid cancers, however, have anywhere from one-fifth to one-tenth the number of mutations compared with those present in melanoma and the targeting of these mutations represents a daunting problem. T cells reacting with sporadic or driver mutations on most cancers are likely to be infrequent though techniques for the identification of unique exomic mutations on individual cancers and the development of methods for obtaining T cells against them are rapidly being developed." Source: Cancer Gene Therapy (2014) 21, 45–47; doi:10.1038/cgt.2014.3, Finding suitable targets is the major obstacle to cancer gene therapy, Steven A Rosenberg).

Moffitt noted last year (2013) their ongoing work was to investigate the immune mechanism of PV-10 ablation in cutaneous melanoma patients (enrolled in the center's Phase 1 feasibility study).

This year (2014), Moffitt concluded: "In sum, these clinical and preclinical results increase our understanding of the cytotoxic and immunological mechanisms that may play a role in systemic immunity induced by PV-10 tumor ablation." The upshot of this appears to me to be:

• Ablation of tumors following PV-10 injection (mechanism #1 [cytotoxic mechanism] of action #1 [destroy injected tumors]),
• Leads to immunity around the body (mechanism #2 [immunological mechanism] of action #2 [destroy non-injected tumors]).

My further thoughts related to Moffitt's 2014 abstract:

Immunotherapeutic strategies incorporating intralesional (IL) ablative therapy to elicit a tumor specific immune response are under investigation as a non-surgical option to induce tumor regression of cutaneous neoplasms.

[My] takeaway: "Non-surgical option" is a translational outcome from Moffitt's work. By injecting PV-10 into tumors, turn un- or non-resectable melanoma into resectable. Make larger amounts of resectable disease much less before resecting it. Eliminate lesser amounts of disease without the need for resection or excision (surgery) at all.

Rose Bengal (RB) is a water-soluble xanthene dye that was originally used as an intravenous liver diagnostic and is in use by ophthalmologists to stain damaged cells in the eye. In murine models of breast cancer and melanoma, we have shown that IL injection of PV-10 (10% RB in saline solution) leads to ablation of injected tumors and regression of non-injected bystander tumors. In these models, increased anti-tumor T cell responses were measured, supporting the induction of systemic anti-tumor immunity after tumor ablation with PV-10.

Takeaway: Confirmation of Moffitt's murine model work (for both melanoma and breast cancer) by the cancer center's human study results of local and systemic efficacy and results (for melanoma). This repeatability, from mice to humans, is consistent with Craig, Tim and Eric's ("Provectus'") repeatability experience in cell lines to mice to higher-level animals (like horses and dogs) to human clinical trials and the compassionate use program. It would appear Moffitt fully reproduced Provectus' work. Repeatability.

In our ongoing phase I clinical trial exploring melanoma regression in patients, IL PV-10 has led to a significant decrease of melA positive melanoma cells in the biopsies of both PV10-injected and non-injected lesions.

Takeaway: I think more specific confirmation of local and systemic efficacy by virtue of said cell decreases in injected and non-injected lesions, respectively.

This regression correlated with increased circulating CD3+T cells (p=0.03) in peripheral blood mononuclear cells (PBMC).

Takeaway: I think this confirms a primary immune response derived from PV-10 by virtue of more circulating CD3+ T-cells (naïve T-cells, I believe). I think a high or higher levels of this metric corresponds with a potent (or more potent) immune response. Update 3/6/14: As I later was informed, the CD3+ protein group is associated with the T-cell receptor. "The T cell receptor or TCR is a molecule found on the surface of T lymphocytes (or T cells) that is responsible for recognizing antigens bound to major histocompatibility complex (MHC) molecules." It's a very specific marker for T-cells.

T cells purified from PBMC from a melanoma patient produced increased IFN-gamma in response to autologous tumor after treatment with PV-10.

Takeaway: I believe this means feasibility study patients had tumor tissue banked from a resection or excision prior to PV-10 treatment. The patient then was treated with PV-10. Blood subsequently taken from him or her showed reactivity to previously resected tumor tissue; that is, Moffitt could specifically target the previously resected tumor tissue by using immune cells isolated from post-PV-10 treatment-drawn blood. I imagine if the human work was consistent with murine model work, blood drawn pre-PV-10 treatment would not have the same effect (i.e., it would not react).

Ex vivo models implemented to investigate this phenomenon indicate that the cytotoxicity induced by PV-10 is not apoptosis-dependent as evidenced by Annexin staining of melanoma cells following PV-10 treatment.

Takeaway: I think this is confirmation that while PV-10's ablation is apoptosis-like, it is not apoptosis-dependent. Management has previously described this cytotoxic mechanism as eliciting cell destruction naturally (a form of cell death that mimics both features of necrosis and apoptosis).

PV-10 directly induced necrosis of melanoma cells at 50 uM, but was not toxic to healthy fibroblasts at the same dose.

Takeaway: I think this is confirmation PV-10 targets diseased tissue only, and spares healthy tissue. Again, aspects of the drug's value proposition management has described for quite a while.

Further preclinical translational testing has shown that treatment of murine B16 cells with PV-10 leads to release of HMGB1, a soluble Damage Associated Molecule Pattern (DAMP) that is important for activation of dendritic cells (DCs). In the murine B16 melanoma model, there is a significant increase in the number of DCs infiltrating the tumor-draining lymph nodes after IL injection of PV-10. These findings suggest that PV-10 treatment leads to the release of DC activating factors and DC recruitment. Further studies to determine the role of PV-10 on T cell activation are ongoing.

Takeaway: Returning to their murine model work not previously presented or detailed, I believe, the potential for DC activation through HMBG1 release. In Moffitt's July 2013 PLoS paper, they hypothesized large amounts of tumor debris created by the rapid ablation that followed PV-10's injection into tumors, debris containing antigens (thus, large amounts of debris should mean large numbers of antigens), are taken up by DCs (see blog post, red underlined portion 4 in paragraph 3). DCs, antigen-presenting cells, present (display) antigens they've taken up to the body's immune system's T-cells. It's all about the T-cells. For example, "Cytotoxic T cells ("CTLs") specific for tumor antigens play a major role in the immunity against cancer." Will Moffitt show PV-10 specifically activates these CTLs?

I would presume this aspect of their human work, the confirmation of DC activation in patients in the feasibility study, will make-up their next presentation somewhere sometime (ASCO 2014?, a journal article?, another medical conference?).

In sum, these clinical and preclinical results increase our understanding of the cytotoxic and immunological mechanisms that may play a role in systemic immunity induced by PV-10 tumor ablation.

Takeaway: Moffitt now knows more (way more?) about PV-10's dual MOAs. PV-10's rapid tumor ablation leads to body-wide (systemic) immunity.

As with the 2013, more data, information and detail should be available on the 2014 poster, which I would expect the company to press release and make available on April 7th (the poster session is on April 6th, a Sunday).

It's all about the T-cells

I'm looking forward to reading Moffitt Cancer Center's American Association for Cancer Research ("AACR") annual meeting abstract next month, viewing the associated poster in April, and learning about what if anything they present at the American Society of Clinical Oncology ("ASCO") annual meeting in May/June. I presume they'll present something at ASCO because of Sondak's already scheduled PV-10 presentation at the 4th European Post-Chicago Melanoma/Skin Cancer Meeting. See Moffitt @ ASCO 2014? (February 10, 2014) under the blog's News tab.

There are three topics of their possible work I hope their poster presentation at AACR and any potential presentation(s) at ASCO would elucidate:

1. PV-10's "mechanism of immune response," or the mechanism by which the drug induces systemic immunity (I think PV-10's primary mechanism of action, rapid tumor ablation following injection, is understood),
2. Improved responses (i.e., tumor destruction and/or shrinkage) from combining PV-10 and other immunotherapies,
3. PV-10's role and responsibility with respect to adoptive cell therapy ("ACT").

Let's re-visit the Discussion section of Moffitt's July 2013 PLoS paper Intralesional Injection of Rose Bengal Induces a Systemic Tumor-Specific Immune Response in Murine Models of Melanoma and Breast Cancer.

Click on the figure to enlarge it: Discussion, portion 1

Click on the figure to enlarge it: Discussion, portion 2

While Provectus pursues the initial local path to approval for PV-10 of locally advanced cutaneous melanoma, Moffitt is more interested in PV-10's systemic properties and benefit, and more than likely its application to patients with metastatic melanoma and other late-stage solid tumor cancer indications. Some observations of the above, which was first presented at AACR 2013 and discussed more in the paper:

- First, in murine model work, Moffitt confirmed PV-10 generated an anti-tumor immune response that shrunk or destroyed untreated tumors (red underlined portions 1, 2 and 3 in paragraphs 1 and 2). They observed the systemic potential of PV-10 for both breast cancer and melanoma.

- Second, they hypothesized that large amounts of tumor debris created by the rapid ablation that followed PV-10's injection into tumors, debris containing antigens (thus, large amounts of debris should mean large numbers of antigens), are taken up by dendritic cells ("DCs") (red underlined portion 4 in paragraph 3). DCs, antigen-presenting cells, present (display) antigens they've taken up to the body's immune system's T-cells.

- Third, Moffitt suggested combining PV-10 with other immunotherapies may lead to better results in patients with metastatic melanoma (red underlined portion 5 in paragraph 4).

- Finally, fourth, they demonstrated immunity could be transferred from mice with PV-10 treated tumors to mice with untreated tumors, hypothesizing (I think) that more and better T-cells could be created using PV-10 (better ones) together with ACT (more of these better ones) to then use on more than one patient (red underlined portions 5 and 6 in paragraph 4).

There are T-cells, and then there are T-cells. There are different types of T-cells, each with a distinct function: helper, cytotoxic, memory, regulatory, natural killer, and mucosal associated invariant. "Cytotoxic T cells ("CTLs") destroy virally infected cells and tumor cells." "Regulatory T cells, formerly known as suppressor T cells, are crucial for the maintenance of immunological tolerance." "Natural killer T cells ("NKT cells")...are also able to recognize and eliminate some tumor cells and cells infected with herpes viruses."

CTLA-4 and PD-1 cell receptors are the so-called brakes of the immune system, limiting its response. Taking the brakes off by inhibiting these blockade receptors (with anti-CTLA-4/PD-1 agents) allows for a more active and vigilant immune system. CTLA-4 and PD-1 agents, I think, help out with or activate these regulatory T-cells.

PV-10, on the other hand, I think, helps out with or activates CTLs, by virtue of the drug's rapid ablation causing tumor debris containing antigens to be taken up by DCs that then display them to this type of T-cell. "For long it has been discussed whether ablated tumor debris is able to induce a systemic immune response."

So, while activating regulatory T-cells and CTLs (cytotoxic T-cells) both may result in tumor destruction and shrinkage, regulatory T-cell activation by checkpoint inhibitors is not permanent and eventually resisted or overcome, whereas CTL activation by PV-10 may result in [permanent?] immunity.

"CTLs specific for tumor antigens play a major role in the immunity against cancer." Will Moffitt show PV-10 specifically activates these CTLs?

If the checkpoint inhibitors remove the brakes of the immune system, allowing it to shrink tumors but not activate the specific T-cells responsible for destroying tumor cells, the utility of combining them with PV-10 would be to have these inhibitors reduce tumor burden and thus the "weight" on the immune system, thereby allowing it to be better stimulated by PV-10. Such combination use would be very helpful for late stage metastatic melanoma patients where tumor burden is high.

Moffitt has conducted trial work on both MK-3475 (Merck) and nivolumab (Bristol-Myers) PD-1 agents. Will Moffitt present combination work with PV-10 involving one of these agents?

"Adoptive T cell therapy involves the isolation and ex vivo expansion of tumor specific T cells to achieve greater number of T cells than what could be obtained by vaccination alone.  The tumor specific T cells are then infused into patients with cancer in an attempt to give their immune system the ability to overwhelm remaining tumor via T cells which can attack and kill cancer.  There are many forms of adoptive T cell therapy being used for cancer treatment; culturing tumor infiltrating lymphocytes or TIL, isolating and expanding one particular T cell or clone, and even using T cells that have been engineered to potently recognize and attack tumors" (Source: Tumor Vaccine Group, UW Medicine). The current approaches for ACT seem to focus on ex vivo (out of the tumor/body) improvements to T-cells; that is, endeavoring to make more of them better external to the patient.

But, as Moffitt first introduced in the February Cancer Watch article, per Dr. Sarnaik, PV-10 appears to improve the quality of T lymphocytes (cytotoxic?). It does this in vivo (in the tumor/body), of course. Perhaps Moffitt's novel approach is to utilize T-cells taken directly from the patient’s blood after they have received a PV-10 injection, which primes the tumor antigen specific T-cells first. Then, with active immunization already established by PV-10, they expand the number of those T-cells in the lab to greater numbers for therapeutic infusion, and thus even greater response success.

March (abstract), April (presentation), May (abstract(s)?), June (presentation(s)?)...

Explaining @MoffittNews' #AACR2013's Abstract for $PVCT's PV-10

A blog reader sent me the following "translation" of Moffitt's AACR abstract. Thank you.

Presentation Title: Intralesional injection with PV-10 induces a systemic anti-tumor immune response in murine models of breast cancer and melanoma

Abstract Body: PV-10 is a 10% solution of Rose Bengal that is currently being examined as a novel cancer therapeutic. In melanoma patients, intralesional injection (IL) of PV-10 has led to regression of injected lesions as well as distant metastases.

Injecting PV-10 into cancers makes them go away (Provectus' clinical trials and studies in mice and its previous studies). Also, PV-10 makes untreated remote tumors go away (bystander effect as Provectus has called it). 

In this study, we examined the efficacy and potential immune mechanism of PV-10 treatment in murine models of breast cancer and melanoma.

Moffitt studied how well PV-10 works (efficacy) in multiple types of tumors. Confirms Provectus' previous observations and conclusions that PV-10 works on more than just melanoma.

In BALB/c mice bearing MT-901 breast cancer, injection of PV-10 led to regression of injected and untreated contralateral subcutaneous lesions (p<0.05 compared to IL-PBS-treated mice).

PV-10 causes breast cancers to regress and control injections of salt water (in what PV-10 is dissolved) did not. PV-10 is doing it, and not the injection or salt water. This shows PV-10 works on breast cancer and demonstrates the bystander effect on breast tumors. Confirms what Provectus has claimed that PV-10 works on multiple tumor types.

A significant increase in survival was observed in mice treated with PV-10.

This is the hallmark of cancer treatment. The FDA only recognizes increases in life span. Treated mice with PV-10 live longer.

To examine immune response, MT901-specific IFN-gamma production and cytotoxicity were measured in splenocytes collected from mice treated with IL-PBS or IL-PV-10. MT901-bearing mice treated with IL-PV-10 demonstrated enhanced IFN-gamma production (992 ± 453 pg/ml) compared to splenocytes from PBS-treated mice (174 ± 105, p<0.05).

Moffitt took spleen cells from mice who were treated with tumors on the skin. Tumors were treated with PV-10 or an injection control (the solvent, which is salt water, alone). The immune cells from the spleen are making a large amount of a chemical made by immune cells (gamma interferon) compared to ones with salt water. PV-10 is activating the cells. Shows specific system wide activation, and not some generic irritation of the immune system. Confirms the same claim by Provectus using a different method in live animals.

In addition, a significant increase in lysis of MT-901 cells by T cells after PV-10 treatment was observed (p<0.01 compared to PBS-treated mice). No lysis of irrelevant CT-26 cells was detected.

Moffitt took T cells and showed they could kill cancer cells and it was very, very specific to the type of cancer that had been treated with PV-10. Demonstrates T cells are involved. Killing is very specific. Confirms Provectus' claims in studies in mice with no T cells that T cells are part of the killing of the cancer and it's very specific.

In a murine model of melanoma, B16-F10 cells were injected into C57BL/6 mice to establish one subcutaneous tumor and multiple lung lesions. Treatment of the subcutaneous lesion with a single injection of IL-PV-10 led to regression of the injected lesion as well as distant B16 melanoma lung metastases.

Moffitt treated mice with a melanoma in their flank using PV-10. Treated tumors go away, as do remote tumors in lungs. Tumors in lungs go away (bystander effect). This is an extremely harsh model. Nobody has ever seen anything like this before. Provectus can confirm and repeat Moffitt's results.

In B16-bearing mice, treatment with IL-PV-10 led to the induction of T cells that produced IFN-gamma in response to B16 tumors but not irrelevant tumor (p<0.05) and demonstrated specific lysis of B16 (p<0.01 compared to T cells isolated from PBS-treated mice).

Same interferon induction if the tumor is melanoma or breast cancer. PV-10's very specific anti-tumor immunity is creating the bystander effect. Works on multiple cancers, as Provectus previously has claimed. Also, T cells can lyse (explode) melanoma cells. This “killing” activity has been induced remote from the treated tumor. It's why the bystander effect works.

In total, these studies support the induction of tumor-specific T cell-mediated immunity after single treatment with IL-PV-10 in multiple histologic subtypes. The immune mechanism of PV-10 ablation in cutaneous melanoma patients is currently under investigation at our institution.

Using PV-10 injected into a tumor makes the mice produce immunity with different cancers, it's very specific, and T cells are involved in doing it.


Takeaways

• Everything Provectus previously claimed has been confirmed using similar studies and different experimental designs.
• Conclusions advanced by Provectus previously are confirmed, even in harsher models. T cells are involved. Induction of system wide immunity. PV-10 works on multiple types of cancer.
• Provectus can confirm the results from Moffitt's mouse lung metastasis model.

Everything is reproducible. Conclusions reached independently by Provectus and Moffitt. 

A small molecule drug delivered directly into tumors kills them, and induces remote immunity that kills remote metastases in an incredible harsh model.

$PVCT: Post-AACR...

What now? AACR is finished. Two posters displayed: Moffitt and Provectus. Moffit's poster presentation displayed definitive data on PV-10's tumor-specific immunity (i.e., how PV-10 harnesses the immune system). Provectus' showed PV-10's orthogonality (i.e., how PV-10-based combination therapy can be efficacious for inaccessible tumor burden).

There are key questions to explore over the near-term. Among them:

• The FDA. Was the FDA convinced this local regional treatment can provide a systemic benefit to cancer patients? As the first intralesionally-injected compound that leads to the induction of tumor-specific immunity, does the FDA now understand the systemic benefit component of PV-10?

• Big Pharma. By providing not only anti-tumor immunity, but also inducing tumor-specific immunity, does Big Pharma now understand the systemic potential of PV-10?

My students competed well in London, but Wroclaw University of Economics are CFA Institute Research Challenge Global Final champions. "The CFA Institute Research Challenge is an annual global competition that provides university students with hands-on mentoring and intensive training in financial analysis and professional ethics. Students are tested on their analytic, valuation, report writing and presentation skills, and gain real-world experience as they assume the role of an equity research analyst. More than 3,500 students from over 755 universities in 55 countries participated in the 2012-2013 Research Challenge." To be that close will sting them (and me) for a while, but I think they'll harness this experience and success as they embark on their careers.

$PVCT: And Dr. Eric Wachter commented...

Eric's responsibility at Provectus comprises clinical development (e.g., trials, biostats, regulatory affairs, etc.), manufacturing and intellectual property (IP). In Provectus' PR about company research results at AACR, management inserted a quote attributable to Eric of "PV-10 is currently entering pivotal Phase 3 testing as a monotherapy for locoregional control of cutaneous metastatic melanoma." In the company's October 2012 ESMO PR, management wrote "The study duration is estimated to be approximately 30 months, with commencement expected in late 2012 or early 2013 following completion of review for SPA." The above describes Provectus' pursuit of the SPA since it first received guidance from the FDA to submit its Phase 3 protocol for review, either via standard review or a request for SPA in January 2012.

Eric and Provectus are pursuing paths to regulatory clarity with the FDA via the SPA and breakthrough therapy designation (whether that is fast track review, a more precise SPA or accelerated approval). I imagine Eric wants to make sure PV-10 is approved, which should include working hand-in-hand with the FDA to determine the best path for this.

The company has long said its primary customers are the FDA and Big Pharma. One would presume the FDA wanted to see Moffitt AACR data (presumably in the context of the fundamental local versus systemic paradigm shift). Now that they have, or when they do, the remaining clarity for shareholders is how and where the FDA directs Provectus to the eventual regulatory path.

$PVCT: London Calling (where else, @starbucks)

My students are doing what they need to do, effectively telling me they don't need me or need me around. I have more time on my hands then I thought...

Some thoughts on the AACR PRs:

• Per management's approach in the past, the audience for which the PRs were meant was the pharmaceutical industry, domestically and abroad (e.g., potential Chinese, Japanese, Indian and European partners).

• The PRs certainly weren't designed to inform retail investors. And, I doubt management is expending slightly more than perfunctory effort engaging life sciences fund money on this, other than revisiting the conversation post-AACR. I think the focus, rightly, is on getting regional and/or global license deals done.

• The PR for Moffitt's data (via Dr. Pilon-Thomas's quote) highlighted a key feature of PV-10's mechanism. For the tumor-specific immunity PV-10 generates, the drug's ablative process is critical for this in situ stimulation of the immune system, which I think is helpful for Big Pharma to better understand. Additionally, the PR reinforces the role T cells play in this response and PV-10's systemic capability, with Moffitt saying they would do more research into the processes that PV-10 induces, stimulates, creates, etc.

• The essence of the PR from Provectus' data was combination therapy (i.e., PV-10 plus something else, which in this case was anti-CTLA-4 antibody 9H10 (see below).

Provectus' work on combination therapy had several facets to it.

There does not appear to be disagreement that PV-10, as a monotherapy, utilized for locoregional control of cutaneous metastatic melanoma in Stage III patients is singularly dramatically effective. Adjusting for a treatment protocol that allows unlimited frequent injections of the drug for this stage of diseased patient, it's probably not unreasonable to believe efficacy could be near-100%.

Provectus extends this effectiveness by demonstrating themselves and through Moffitt's work that tumor-specific immunity is harnessed, and distant untreated metastases are suppressed  reduced or eliminated because of it. PV-10 successfully battles tumor heterogeneity of accessible injected lesions (tumors).

"...[A]dvanced melanoma patients, particularly those with stage IV disease, have substantial tumor burden in areas that are often non-accessible to injection with PV-10..." (Provectus' AACR PR) How does PV-10 deal with tumor heterogeneity in tumors into which it has not been injected or visceral metastases for these very late stage diseased patients?

Provectus hypothesized combining anti-CTLA-4 agents (like already approved Yervoy (ipilimumab) with PV-10. The thought was to leverage the incremental benefit of the additional systemic agent (i.e., ipi), while ensuring (demonstrating) there were no incremental safety issues or adverse event features resulting from the combination. "...Provectus aimed to ensure that any systemic treatment was potentially safe in combination with PV-10, and that efficacy signals from the combination therapy could be differentiated from those of PV-10 alone." (Provectus' AACR PR) 

The poster and PR showed that "..., as hypothesized, addition of the immunologic effects of an anti-CTLA-4 agent augments the benefits of PV-10." This allows two proofs to be made, in my view. First, the proof of orthogonality -- combination allows for benefit, but no added risk or no greater "un-safety." Second, allowing for the benefit of the combined therapy, in this case the anti-CTLA-4 antibody, to be utilized but at [apparently] lower doses and thus at lower toxicities.

Provectus' work suggests treatment options for very late stage patients can increase markedly by combining a host of other systemic therapies (in potentially less toxic doses) with PV-10 to more effectively defeat tumor burden in inaccessible regions of the body (where injection of PV-10 cannot be done) and visceral metastases (where tumor heterogeneity is more heterogeneous than what PV-10 previously conquered).

Furthermore, management's work suggests

• Yervoy could (would) be more effective and more safe for very late stage diseased patients when combined with PV-10 in doses lower than currently used, and
• PV-10 could potentially salvage Pfizer's tremelimumab, a close relative of Yervoy/ipilimumab, by turning the combination of PV-10 and treme into an alternative to Yervoy?

$PVCT: PV-10 Data Presented by Moffitt Cancer Center Researchers Examines Induction of Systemic Immune Response in Multiple Tumor Types

Provectus issued a PR to circulate Moffitt's AACR poster. The poster is here. It is worthwhile to focus on Moffitt's Dr. Pilon-Thomas' quote in the PR.

"The findings of this study confirmed not only that PV-10 induces tumor-specific immunity after a single treatment with IL-PV-10 in multiple tumor types, but that the ablative process is critical for this in situ stimulation of the immune system. The data also show that T cells play a critical role in this response."

$PVCT Should Provide Moffitt Poster Once AACR ends

I would imagine because of AACR conference stipulations or regulations, Moffitt's poster will be made available when or after the conference ends (either Wednesday or Thursday). I have friends at the conference (smartphones anyone), but will wait until Provectus issues a proper poster copy to post and discuss.

@MoffittNews & $PVCT at #AACR: PV-10 Immunology Data Presented by Moffit Cancer Center Researchers at the American Association for Cancer Research Annual Meeting

Provectus issued a PR today about Moffitt's poster presentation.

Dr. Pilon-Thomas commented, “We believe our findings are meaningful because they confirm the induction of tumor-specific immunity after single treatment with IL-PV-10 in multiple tumor types. Our data show that T cells play a crucial roll in this response, and we are continuing our work to further elucidate the mechanisms that occur following PV-10 treatment.”

Dr. Amod Sarnaik observed, “The systemic response to intralesional PV-10 treatment observed in murine models was sufficiently compelling to warrant further clinical investigation. We look forward to additional insights from our current investigational study of the immune mechanism of PV-10 ablation in cutaneous melanoma patients.”

More Serious #Pharma Interest in $PVCT

At his presentation in New York in March, Craig noted Provectus was in the due diligence process of a pharmaceutical company for a global license. This is different from Pfizer's "interest" because, as far as we know, Dr. Eagle merely hangs out on Provectus' corporate advisory board. Of course, and as I written about copiously, Pfizer is in the pole position, and merely has to respond to some other competitor moving first by simply paying more. No guarantees of course, but that's the basic gist.

Management has not expressed elsewhere to which I can point other serious global pharmaceutical company interest.

I independently confirmed [what I think is] serious interest by another global player.

Provectus would not comment on the information (which did not originate from the pharma interested in PV-10) underlying my thought/belief/speculation. I want to dig further before naming the pharmaceutical company.

As Provectus approaches AACR week, things might be heating up.

$PVCT at #AACR

Provectus' approach to AACR PR will be to focus awareness of PV-10 from both investigator and advocate perspectives.

$PVCT & Breakthrough Therapy Designation (update)

It appears management will indeed consider submitting a request for breakthrough therapy designation to the FDA for PV-10, starting with metastatic melanoma.

$PVCT & Breakthrough Therapy Designation

A friend of the blog provided this link from the FDA's website: FAQs about the designation. Thank you. Updated statistics about application numbers, receipts and denials can be found here (as the FDA website is updated as of 12/31/12, and will be updated quarterly). I selected portions of the FAQs and provided them below in italics (bold emphasis is mine).

"Breakthrough therapy designation is intended to expedite the development and review of drugs for serious or life-threatening conditions."

"A breakthrough therapy designation conveys all of the fast track program features..., as well as more intensive FDA guidance on an efficient drug development program."

"A breakthrough therapy program is for a drug that treats a serious or life-threatening condition and preliminary clinical evidence indicates that the drug may demonstrate substantial improvement on a clinically significant endpoint(s) over available therapies. In contrast, a fast track program is for a drug that treats a serious or life-threatening condition, and nonclinical or clinical data demonstrate the potential to address unmet medical need."

"After a development program is designated as a breakthrough therapy, the FDA will work closely with the sponsor to ensure that the design of the clinical trials is as efficient as practicable, when scientifically appropriate. An efficient trial design typically would help minimize the number of patients exposed to a potentially less efficacious treatment, which could translate to fewer patients enrolled in clinical trials that support marketing approval. Regulatory standards to demonstrate safety and efficacy must still be met."

"A breakthrough therapy designation and SPA are two independent regulatory pathways. Therefore, a drug designated as a breakthrough therapy is eligible for SPA, if the protocol meets the criteria for SPA. Conversely, a drug for which an SPA is under review may be considered for breakthrough therapy designation, if the breakthrough therapy designation criteria are met."

"[T]he FDA may suggest that the sponsor consider submitting a request for breakthrough therapy designation if: (1) after reviewing submitted data and information (including preliminary clinical evidence), the Agency thinks the drug development program may meet the criteria for breakthrough therapy designation and (2) the remaining drug development program can benefit from the designation."

The FDA knows Provectus always wanted an expedited regulatory path for PV-10. The company's MM Phase 2 trial was designed for accelerated approval. How does the regulatory path potential get clarified? Moffitt data at the annual meeting of the American Association for Cancer Research in April.

Management has long spoken of a very collaborative relationship with the FDA. Did the Agency suggest to them that Provectus submit a request for breakthrough therapy designation for PV-10...?

$PVCT #AACR2013 Thoughts...

Two summary thoughts from today's release of the AACR abstracts, one by Moffitt and one by Provectus, follow.

Moffitt
The first one derives from the second to last sentence of Moffitt's abstract: "In total, these studies support the induction of tumor-specific T cell-mediated immunity after single treatment with IL-PV-10 in multiple histologic subtypes."

"Multiple histologic subtypes," an extremely comprehensive statement, refers to all cancer indications tested by Moffitt: breast, melanoma, ... Tumor specific immunity was achieved in multiple indications.

Chemoablation via PV-10 ablation causes antigenization, and antigenization causes immunization.

Wachter et al.
The second thought comes from the last sentence of the company's abstract: "The rapid reduction in tumor burden and tumor specific immunologic stimulation provided by PV-10 may complement the immune stimulation of anti-CTLA-4 antibodies such as ipilimumab without increased toxicity."

You will recall I wrote earlier:

The crux of the matter is that PV-10, as a local agent, needs to show systemic potential for life science investors, Big Pharma and the FDA to view the drug as clinically relevant. This is the local agent "burden of proof." There must be systemic potential to be relevant for treating cancer after surgery, where cancer is viewed by definition as a systemic disease. PV-10 is an drug with tremendous local efficacy and before unseen systemic benefit (even more so than systemic agents). 

But PV-10 still is a local agent. 

The mindset of the industry -- medical oncologists and hematologist-oncologists, but not surgeons -- is that a local agent has to be combined with a systemic agent to be relevant.  The industry does not yet realize how much of an impact PV-10 will be just as a local agent. All it can currently understand is that PV-10 works, and harnesses the immune system in novel manner. It is obvious to industry PV-10 will get even better systemic results when combined with other agents, or, other agents will get better results when combined with PV-10.

"PV-10 may complement the immune stimulation of anti-CTLA-4 antibodies...without increased toxicity:" Provectus further elucidates the concept of PV-10 orthogonality to systemic therapies; in this case, systemic immunotherapy in the form of anti-CTLA4 agents like Bristol Myers' ipilimumab (Yervoy) in murine model work. Ipilimumab gets better results when combined with PV-10, with no increased toxicity.

Orthogonality: In geometry, two lines (vectors) are orthogonal if they are perpendicular; that is, they form a right angle. Our three dimensions -- the x-, y- and z-axes -- are orthogonal because each is at right angles with the others: non-overlapping, uncorrelated, or independent of each other. In computer science, orthogonality is "a system design property which guarantees that modifying the technical effect produced by a component of a system neither creates nor propagates side effects to other components of the system." (Source: Wikipedia).

Previously, the company demonstrated orthogonality (in pre-clinical work that led up to the upcoming human trial) with systemic chemotherapy agent sorafenib (in the case of liver cancer/HCC). Sorafenib gets better results when combined with PV-10, with no increased toxicity.

Later, Provectus provided results of orthogonality with [inexpensive] systemic chemotherapy agent 5-fluorouracil ("5-FU") in murine model work. 5-FU gets better results when combined with PV-10, with no increased toxicity.

$PVCT #AACR2013: Combination of PV-10 immuno-chemoablation and systemic anti-CTLA-4 antibody therapy in murine models of #melanoma

Presentation Title: Combination of PV-10 immuno-chemoablation and systemic anti-CTLA-4 antibody therapy in murine models of melanoma

Abstract Body: Rose bengal disodium (PV-10) is an investigational small molecule ablative agent currently entering pivotal phase 3 clinical testing as a monotherapy for locoregional control of cutaneous metastatic melanoma. Upon intralesional (IL) administration, PV-10 localizes to the injected tumor tissues while clearing rapidly from healthy tissue. Tumor infiltration with PV-10 leads to rapid necrosis of the injected lesion, with complete resolution common within 2-8 weeks. In phase 2 testing in 80 patients with Stage IIIB-IV(M1c) melanoma, IL PV-10 elicited an objective response in injected tumors in 51% of patients (CR:25%, PR:26%) after 1-4 treatment cycles. In addition to this direct ablative effect on injected tumors, some patients achieved an objective response in their monitored untreated tumors (CR:26%, PR:7% in 42 subjects with monitored untreated lesions) in an apparent immune-mediated bystander response that highly correlated with successful ablation of their injected tumors. Treatment was generally well tolerated, with adverse events confined mainly to the injection site and no grade 4 or 5 adverse events associated with use of PV-10. Recent nonclinical testing in the B16-F10 murine melanoma tumor line has confirmed that PV-10 ablation induces tumor-specific immunity, resulting in marked suppression of synchronous lung metastases upon ablation of a flank tumor and tumor-specific IFN-γ production. In this study we assess potential benefit of combination of PV-10 immuno-chemoablation with the hamster anti-murine CTLA-4 antibody 9H10 in bilateral flank and lung metastasis models (B16-F10 melanoma in C57BL/6 mice). Results from these models will be reported and could support clinical development of combination therapy in advanced melanoma patients, such as stage IV patients with substantial tumor burden in locations inaccessible to PV-10 injection. The rapid reduction in tumor burden and tumor specific immunologic stimulation provided by PV-10 may complement the immune stimulation of anti-CTLA-4 antibodies such as ipilimumab without increased toxicity.

$PVCT -- @MoffittNews #AACR2013: Intralesional injection with PV-10 induces a systemic anti-tumor immune response in murine models of #breast #cancer and #melanoma

Presentation Title: Intralesional injection with PV-10 induces a systemic anti-tumor immune response in murine models of breast cancer and melanoma

Abstract Body: PV-10 is a 10% solution of Rose Bengal that is currently being examined as a novel cancer therapeutic. In melanoma patients, intralesional injection (IL) of PV-10 has led to regression of injected lesions as well as distant metastases. In this study, we examined the efficacy and potential immune mechanism of PV-10 treatment in murine models of breast cancer and melanoma. In BALB/c mice bearing MT-901 breast cancer, injection of PV-10 led to regression of injected and untreated contralateral subcutaneous lesions (p<0.05 compared to IL-PBS-treated mice). A significant increase in survival was observed in mice treated with PV-10. To examine immune response, MT901-specific IFN-gamma production and cytotoxicity were measured in splenocytes collected from mice treated with IL-PBS or IL-PV-10. MT901-bearing mice treated with IL-PV-10 demonstrated enhanced IFN-gamma production (992 ± 453 pg/ml) compared to splenocytes from PBS-treated mice (174 ± 105, p<0.05). In addition, a significant increase in lysis of MT-901 cells by T cells after PV-10 treatment was observed (p<0.01 compared to PBS-treated mice). No lysis of irrelevant CT-26 cells was detected. In a murine model of melanoma, B16-F10 cells were injected into C57BL/6 mice to establish one subcutaneous tumor and multiple lung lesions. Treatment of the subcutaneous lesion with a single injection of IL-PV-10 led to regression of the injected lesion as well as distant B16 melanoma lung metastases. In B16-bearing mice, treatment with IL-PV-10 led to the induction of T cells that produced IFN-gamma in response to B16 tumors but not irrelevant tumor (p<0.05) and demonstrated specific lysis of B16 (p<0.01 compared to T cells isolated from PBS-treated mice). In total, these studies support the induction of tumor-specific T cell-mediated immunity after single treatment with IL-PV-10 in multiple histologic subtypes. The immune mechanism of PV-10 ablation in cutaneous melanoma patients is currently under investigation at our institution.

$PVCT -- @MoffittNews #AACR2013: Intralesional injection with PV-10 induces a systemic anti-tumor immune response in murine models of #breast #cancer and #melanoma

A Moffitt poster presentation at AACR in April: Intralesional injection with PV-10 induces a systemic anti-tumor immune response in murine models of breast cancer and melanoma

Author Block: Shari A. Pilon-Thomas, Amy Weber, Krithika Kodumudi, Lisa Kuhn, Paul Toomey, Amod Sarnaik. Lee Moffitt Cancer Ctr. & Res. Inst., Tampa, FL; University of South Florida, Tampa, FL

$PVCT: The #Holy #Grail of #Cancer Treatment is...

It was interesting to read about Moffitt's work in the February edition of Cancer Watch.

Some believe Provectus has the most unusual opportunity in the history of drug development thus far, and that no one has ever seen a drug work like Rose Bengal in PV-10 and PH-10.

[Emphasis below all mine.]

The Cancer Watch article establishes context with historical PV-10 clinical trial success: Back in October, 2012, Phase 2 metastatic melanoma data on use of intralesional PV-10 presented at ESMO (European Society for Medical Oncol- ogy) 2012 Congress in Vienna, Austria, showed an objective response rate (ORR) of 51%, and a disease control rate of 69% in target melanoma lesions. The other finding, which lies behind some of the intensifying interest in PV-10, was a 61% ORR in bystander (uninjected) lesions among patients who had complete or partial responses in their target lesions. The bystander lesion ORR in patients with non responsive target lesions was 18%. Of deep interest, as well, were case studies showing potential stasis or regression of untreated visceral lesions in patients following PV-10 treatment of their cutaneous lesions.

The author further establishes governing thought: A bystander effect was clearly apparent in the first study in that PV-10-treated mice had 3 or fewer lung metastases as compared with more than 250 in each of the untreated mice.

In further elucidating the work at the cancer center, the author wrote: 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. Is Dr. Sarnaik implying PV-10 is the Holy Grail?

In response to the weakness of cancer vaccines: The strategy of adoptive cell transfer potentially overcomes the weak vaccine response...While adoptive cell transfer offers the advantage that enough T cells can be obtained for infusion in all patients, the T-cell receptors transfected into the T cells have a limited antigen specificity.

PV-10, however: ...Shari Pilon-Thomas, PhD, also a Moffitt researcher, demonstrated that T-lymphocytes recovered from mice treated with PV-10 do appear to be of a higher quality, as evidenced by stronger tumor reactivity...

Sarnaik's study will test Pilon-Thomas' conclusions in humans: "This is a straightforward study that will give a yes or no answer," Dr. Sarnaik said.

The Cancer Watch article about Moffitt may be the information/PR prelude to the cancer center's long-awaited high profile conference presentation and contemporaneous publication of its work on the immunological MOA characterization of PV-10 work.

When I think of appropriate "high profile" conferences, two come to mind: the annual meetings of the American Association for Cancer Research ("AACR") and the American Society of Clinical Oncology ("ASCO"). The former runs April 6-10, while the latter runs May 31-June 4. While research is presented at both conferences, ASCO is more focused on clinical trial results and updates. As such, and since Moffitt's work to date (excluding the recently initiated human trial) has been murine research, I'd guess the target conference for Moffitt is AACR. If AACR is indeed where Moffitt presents, then I'd also guess the target peer-reviewed publication is Cancer Research.

$PVCT: Provectus to Present Data on PV-10 at the American Association for Cancer Research Annual Meeting in April 2013

Provectus issued a PR yesterday announcing the acceptance of Craig et al.'s poster presentation -- Combination of PV-10 immuno-chemoablation and systemic anti-CTLA-4 antibody therapy in murine models of melanoma -- at the American Association for Cancer Research (AACR) Annual Meeting in April 2013 in Washington, D.C.

Management checked with AACR to see what they could and could not say about the abstract and work in the PR. Provectus, at this point, is allowed to say (i) the abstract is accepted and (ii) the title. They cannot release data until the embargo is lifted, which will be in stages and does not start until sometime in March.

As Craig mentioned during his presentation at the Noble Financial Capital Markets Ninth Annual Equity Conference (click the preceding link to view it) around about minute 14:00, there is very significant interest to see how PV-10 works with systemic treatments (e.g., chemotherapy, immunotherapy, etc.), because it has become clear these secondary treatments work better after an initial use or application of PV-10.

You may recall from my post Provectus Pharmaceuticals Announces H. Lee Moffitt Cancer Center Initiates Phase 1 Study of PV-10 to Elucidate Bystander Effect the notion of PV-10 making cancer treatment more effective in combination with other therapies also is important (very, actually); particularly for late stage patients (a group not targeted by Provectus' current registration pathway for PV-10, which is to facilitate the treatment of Stage III and early-Stage IV patients) and those with heavy tumor burden.

Craig et al.'s work announced today -- the combination of PV-10 and systemic anti-CTLA-4 antibody therapy -- clearly targets and is in response to serious interest from Big Pharma: Bristol-Myers Squibb & ipilimumab/Yervoy and Pfizer/MedImmune-AstraZeneca & tremelimumab (MedImmune in-licensed tremi from Pfizer in 2011 for global development rights to the drug while Pfizer retained rights to specified types of combination therapies).

PV-10 + systemic chemotherapy: Craig etl al.'s murine work -- Generation of an antitumor response and immunity using a small molecule drug (PV-10) -- at the Society for Immunotherapy of Cancer (SITC) 27th Annual Meeting on October 26 and 27, 2012 in North Bethesda, Maryland explored time to progression and tumor growth from PV-10 alone, 2 cycles of 5-FU, PV-10 and 2 cycles of 5-FU, and a saline control. Provectus concluded co-administration of PV-10 immuno-chemoablation with other systemic therapy, in this case, 5-FU, can yield potent synergy in uninjected tumors (Combination of PV-10 with systemic chemotherapy can yield synergistic benefit in untreated tumors supportive of ongoing clinical work; f/n: A study to assess PV-10 chemoablation of cancer of the liver; clinical trial NCT00986661). PV-10 did not interfere with the systemic chemotherapy agent, nor did it create or cause a toxic reaction. In fact, by boosting the immune system, PV-10 allowed the chemo agent to perform better.

PV-10 + radiotherapy: Foote et al.'s initial and ongoing work combining PV-10 and radiotherapy are showing dramatic improvement for patients with much later stage disease (Stage IV) and heavy tumor burden. At least 10 patients have been treated, a follow-up to the success of their initial work on 3 patients.

PV-10 + systemic immunotherapy: As I wrote earlier, there is very significant interest to see how PV-10 works with ipilimumab (an anti-CTLA-4 agent). Because ipi is human-specific, Craig used a mouse anti-CTLA-4 antibody. Craig et al.'s work is a necessary pre-cursor to human trials (one cannot simply run such experiments without sufficient data to show the FDA how the combination might work and that it is safe). This mouse study will be used to convince regulators that Provectus should be allowed to run a Phase 1 trial combining PV-10 and ipi (as Craig mentioned at the Noble conference).

Click to enlarge figure.

Other combinations: As a treatment PV-10 lies in the "sweet spot" of the addressable market of patients afflicted with melanoma that comprises the vast majority of patients. Patients with very late stage disease and/or very heavy tumor burden, depending on whose numbers you use, probably comprises 2-5%. Nevertheless, as with today's announcement that heralds the successful demonstration of PV-10 and a systemic immunotherapeutic agent (as with the company's SITC-presented earlier work that successfully demonstrated the combination of PV-10 and a systemic chemotherapeutic agent) Provectus is seeking further combinations to make very late stage disease patient treatment options better (e.g., intra-tumoral GM-CSF, systemic interleukin, anti-PD-1 antibodies/agents, etc.).

Today's PR is not related to the anticipated Moffitt immunological MOA characterization work (mouse & human) that will be presented later this year at a high profile conference like AACR. Moffitt presumably will notify Provectus if the cancer center's abstract(s) has (have) been accepted. Then, management will work with Moffitt to coordinate news flow.