AF's newest hit piece...
@adamfeuerstein We're still waiting for you to explain to Dr. Weber why PV-10 is NOT the "perfect way to prime the immune system." Kenneth Dreesen (@Dreesenkl) June 11, 2014
Ken is referring to Provectus Pharmaceuticals (PVCT_) and its experimental intralesional melanoma therapy PV-10, also known as the dye Rose Bengal used commonly as a stain for eye exams. "Dr. Weber" is Dr. Jeffrey Weber of Moffitt Cancer Center. Weber is an investigator in a small clinical study of PV-10 in melanoma. Provectus and its beaten-down shareholders believe Moffitt's involvement with PV-10 is proof the drug works. That's silly, of course, but Provectus and its supporters tend to have a loose grip on reality.
The Weber quote Ken references in his tweet comes from an ecancernews.com story posted on June 10, referring to PV-10 data presented in a poster at the American Society of Clinical Oncology (ASCO) annual meeting. This is Weber's full quote regarding PV-10:
This [PV-10] data provides more and more evidence that you are altering both local and systemic immunity in a positive way. It also provides a rationale for combination trials of PV-10 with check point protein inhibitors, such as ipilimumab, pembrolizumab and nivolumab. PV-10 might offer the perfect way to prime the immune system.
That's a very nice, generous endorsement of PV-10 from Weber, but it also appeared to me contradictory to a more skeptical comment he made at an April melanoma meeting in New York City. There, Weber said intralesional therapy had "no role."
I was confused about what seems like two divergent opinions on intralesional therapies, including PV-10, so I emailed Weber for a clarification. He was kind enough to respond quickly Wednesday night:
My comment on 'no role' was in a debate from an academic perspective at the Melanoma Meeting in NYC in April, go look at the program; in fact as a stand-alone agent intralesional therapies in general are unlikely to have any more than a niche role in melanoma; their greatest potential is exactly as I said, as a priming maneuver with a checkpoint protein inhibitor.
Here's where the story goes bad for Provectus. At the ASCO meeting, Provectus announced plans for a phase III study in melanoma which will compare PV-10 to standard chemotherapies dacarabazine (DTIC) or temozolomide (TMZ). Provectus is holding a conference call next Thursday to discuss the study, but details were already disclosed on the company's PV-10 poster at ASCO.
Weber, the academic oncologist Provectus supporters point to as a PV-10 booster, believes intralesional therapies should be studied in combination with checkpoint inhibitors, yet Provectus management decides to conduct a study of PV-10 monotherapy against chemotherapy drugs no longer considered standard of care. Hmmm.
At the ASCO meeting, Dr. Axel Hauschild gave an oral presentation and review of intralesional therapies in which he described the response criteria used by Provectus in the PV-10 phase II study as "unusual." The PV-10 study also enrolled "highly selected" melanoma patients, Hauschild said.
Commenting on the future for intralesional therapies in melanoma, Hauschild, like Weber, recommended combination approaches with immunotherapies like PD-1s. He noted that Amgen (AMGN_) and Bristol-Myers Squibb (BMY_) are conducting a study of T-Vec combined with nivolumab. The challenge for therapies like PV-10, Hauschild added, was demonstrating a benefit for melanoma patients beyond what's been seen recently with PD-1s and combination therapy already. The just-completed ASCO meeting was buzzing with incredible immunotherapy data in melanoma, so finding a role for intralesional therapies will be difficult, Hauschild said.
Provectus completed the PV-10 phase II study in 2010 and has spent the following four years promising the start of a phase III study but never delivering. Instead, the company went on a quixotic quest to land Breakthrough Therapy Designation for PV-10, only to fail miserably. Now, Provectus is once again promising to run a phase III study of PV-10 but with a design that melanoma experts believe is clinically irrelevant.
Beyond the useless comparator arm, the rest of the PV-10 study design doesn't even make sense. According to Provectus' description of the study displayed at the ASCO meeting, to be eligible for enrollment, patients must have melanoma limited to cutaneous or subcutaneous sites. The patients must also have failed or be ineligible for systemic immunotherapy and have melanoma that is BRAF wild type.
The latter requirement crosses off about half melanoma patients with mutated BRAF who can be treated with BRAF inhibitors like Roche's (RHHBY_) Zelboraf. But how many patients with localized melanoma that have already failed systemic immunotherapy exist out there? Even if the eligibility requirements are loosened, it's hard to imagine any competent doctor steering a melanoma patient into a PV-10 monotherapy study instead of the huge number of checkpoint inhibitor studies already underway.
Provectus believes it can enroll 210 patients into the PV-10 phase III study in 18 months, starting in the third quarter. Good luck with that, unless Provectus' plan is to enroll melanoma patients in Turkmenistan.
The cynic in me believes Provectus executives have chosen to conduct an irrelevant trial of PV-10 on purpose so they can continue to soak shareholders for more paychecks. The painful truth is that PV-10 is a drug melanoma has already passed by. Provectus needs to find a willing partner with a checkpoint inhibitor in order to run a proper combination study. The company is dialing the phone, but no one, so far, is picking up on the other end.
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