On March 31, 2021 Provectus (OTCQB: PVCT) reported that Melanoma Research had published results from an investigator-led, single-center study of Australian in-transit melanoma (ITM) patients who received intralesional (aka intratumoral) PV-10 under a Provectus-sponsored expanded access (aka compassionate use) program (EAP) (Press release, Provectus Biopharmaceuticals, MAR 31, 2021, View Source [SID1234577446]).
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The Melanoma Research article, entitled "Treatment of in-transit melanoma metastases using intralesional PV-10," detailed the experience of investigators at Melanoma Institute Australia (MIA; formerly the Sydney Melanoma Unit) in Sydney, Australia who treated 48 patients from 2008 to 2016.
The article may be accessed at: View Source (subscription required).
Key highlights of the Melanoma Research publication:
Baseline characteristics: 58% women; median age of 75.1 years (range 21.5-93.5),
Median of 5 lesions treated with PV-10 (interquartile range [IQR] 2-7),
Median of 1 PV-10 treatment (IQR 1-2),
46% complete response (CR) and 86% overall response rate (ORR) in patients, and
12- and 24-month overall survival (OS) rates of 77% and 56%, respectively.
This is the third publication about single-agent PV-10 treatment of ITM lesions under Provectus’ EAP (which has treated about 200 patients to date) and the fifth publication overall. Previous publications describing EAPs led by other major Australian medical institutions and the Company’s Phase 1 and 2 clinical trials at Australian and U.S. sites include:
"Intralesional PV-10 for the treatment of in-transit melanoma metastases – Results of a prospective, non-randomized, single center study" (Read et al. J Surg Oncol 2018), which describes the EAP at Princess Alexandra Hospital in Brisbane: 45 patients treated from 2008 to 2015; 42% patient CR (86% ORR); median of 1 PV-10 treatment (range 1-4),
"Intralesional PV-10 for in-transit melanoma – A single-center experience" (Lippey et al. J Surg Oncol 2016; subscription required), which describes the EAP at Peter MacCallum Cancer Centre in Melbourne: 19 patients treated from 2010 to 2014; 26% patient CR (52% ORR); most patients received 1 PV-10 treatment,
"Phase 2 Study of Intralesional PV-10 in Refractory Metastatic Melanoma" (Thompson et al. Ann Surg Oncol 2015): 28 (out of 80) patients with all known lesions treated; median of 1 PV-10 treatment (range 1-4); 50% patient CR (71% ORR), and
"Chemoablation of metastatic melanoma using intralesional Rose Bengal" (Thompson et al. Mel Res 2008; subscription required): 11 (out of 20) patients treated in the Phase 1 trial; 1 PV-10 treatment; 27% patient CR (54% ORR).
Dominic Rodrigues, Vice Chair of the Company’s Board of Directors, said, "Patients who present with in-transit melanoma lesions suffer from a rare disease that is a serious, life-threatening condition with no approved therapies. No drug therapies provide the rapid, sustained reduction of tumor burden, with low toxicity, that investigational drug product PV-10 does. Injection of lesions with PV-10 is globally recognized as a treatment option for in-transit melanoma patients in clinical practice guidelines, including those for Australiaa, Canadab, Europec, and the U.S.d"
Mr. Rodrigues added "Given the high percentage of in-transit melanoma lesions that achieve complete response from typically one or two PV-10 injections, and its established safety profile, we believe there is a role for PV-10 in the treatment of in-transit melanoma lesions for those patients who are not candidates for systemic drug therapies."
About PV-10
Intralesional (IL) administration of PV-10 for the treatment of solid tumor cancers can yield immunogenic cell death within hours of tumor injection, and induce tumor-specific reactivity in circulating T cells within days.1,2,3 This IL PV-10-induced functional T cell response may be enhanced and boosted in combination with immune checkpoint blockade (CB).4 In CB-refractory advanced cutaneous melanoma, IL PV-10 may restore disease-specific T cell function, which may also be prognostic of clinical response. IL PV-10 has been administered to over 450 patients with cancers of the skin and of the liver. It is administered under visual, tactile or ultrasound guidance to superficial malignancies, and under CT or ultrasound guidance to tumors of the liver.
About Rose Bengal Disodium
RBD is 4,5,6,7-tetrachloro-2′,4′,5′,7′-tetraiodofluorescein disodium, a halogenated xanthene and Provectus’ proprietary lead molecule. Provectus’ current Good Manufacturing Practices (cGMP) RBD is a proprietary pharmaceutical-grade drug substance produced by the Company’s quality-by-design (QbD) manufacturing process to exacting regulatory standards that avoids the formation of uncontrolled impurities currently present in commercial-grade rose bengal. Provectus’ RBD and cGMP RBD manufacturing process are protected by composition of matter and manufacturing patents as well as trade secrets.
An IL formulation (i.e., by direct injection) of cGMP RBD drug substance, cGMP PV-10, is being developed as an autolytic immunotherapy drug product for solid tumor cancers.
IL PV-10 is also undergoing preclinical study for relapsed and refractory pediatric solid tumor cancers, such as neuroblastoma, Ewing sarcoma, rhabdomyosarcoma, and osteosarcoma.5,6
A topical formulation of cGMP RBD drug substance, PH-10, is being developed as a clinical-stage immuno-dermatology drug product for inflammatory dermatoses, such as atopic dermatitis and psoriasis. RBD can modulate multiple interleukin and interferon pathways and key cytokine disease drivers.7
Oral formulations of cGMP RBD are undergoing preclinical study for relapsed and refractory pediatric blood cancers, such as acute lymphocytic leukemia and acute myelomonocytic leukemia.8,9
Oral formulations of cGMP RBD are also undergoing preclinical study as prophylactic and therapeutic treatments for high-risk adult solid tumor cancers, such as head and neck, breast, pancreatic, liver, and colorectal cancers.
Different formulations of cGMP RBD are also undergoing preclinical study as potential treatments for multi-drug resistant (MDR) bacteria, such as Gram-negative bacteria.
Topical formulations of cGMP RBD are also undergoing preclinical study as potential treatments for diseases of the eye, such as infectious keratitis
Tumor Cell Lysosomes as the Seminal Cancer Drug Target
Lysosomes are the central organelles for intracellular degradation of biological materials, and nearly all types of eukaryotic cells have them. Discovered by Christian de Duve, MD in 1955, lysosomes are linked to several biological processes, including cell death and immune response. In 1959, de Duve described them as ‘suicide bags’ because their rupture causes cell death and tissue autolysis. He was awarded the Nobel Prize in 1974 for discovering and characterizing lysosomes, which are also linked to each of the three primary cell death pathways: apoptosis, autophagy, and necrosis.
Building on the Discovery, Exploration, and Characterization of Lysosomes
Cancer cells, particularly advanced cancer cells, are very dependent on effective lysosomal functioning.10 Cancer progression and metastasis are associated with lysosomal compartment changes11,12, which are closely correlated (among other things) with invasive growth, angiogenesis, and drug resistance13.
RBD selectively accumulates in the lysosomes of cancer cells upon contact, disrupting the lysosomes and causing the cells to die. Provectus2,14, external collaborators5, and other researchers15,16,17 have independently shown that RBD triggers each of the three primary cell death pathways: apoptosis, autophagy, and necrosis.
Cancer Cell Autolytic Death via RBD: RBD-induced autolytic cell death, or death by self-digestion, in Hepa1-6 murine hepatocellular carcinoma (HCC) cells can be viewed in this Provectus video of the process (ethidium homodimer 1 [ED-1] stains DNA, but is excluded from intact nuclei; lysosensor green [LSG] stains intact lysosomes; the video is provided in 30-second frames, with a duration of approximately one hour). Exposure to RBD triggers the disruption of lysosomes, followed by nucleus failure and autolytic cell death. Identical responses have been shown by the Company in HTB-133 human breast carcinoma (which can be viewed in this Provectus video of the process, with a duration of approximately two hours) and H69Ar human multidrug-resistant small cell lung carcinoma. Cancer cell autolytic cell death was reproduced by research collaborators in neuroblastoma cells to show that lysosomes are disrupted upon exposure to RBD.5
Tumor Autolytic Death via RBD: RBD causes acute autolytic destruction of injected tumors (via autolytic cell death), mediating the release of danger-associated molecular pattern molecules (DAMPs) and tumor antigens; release of these signaling factors may initiate an immunologic cascade where local response by the innate immune system may facilitate systemic anti-tumor immunity by the adaptive immune system. The DAMP release-mediated adaptive immune response activates lymphocytes, including CD8+ T cells, CD4+ T cells, and NKT cells, based on clinical and preclinical experience in multiple tumor types. Mediated immune signaling pathways may include an effect on STING, which plays an important role in innate immunity.9
Orphan Drug Designations (ODDs)
ODD status has been granted to RBD by the U.S. Food and Drug Administration for metastatic melanoma in 2006, hepatocellular carcinoma in 2011, neuroblastoma in 2018, and ocular melanoma (including uveal melanoma) in 2019.
Intellectual Property
Provectus’ IP includes a family of US and international (a number of countries in Asia, Europe, and North America) patents that protect the process by which cGMP RBD and related halogenated xanthenes are produced, avoiding the formation of previously unknown impurities that exist in commercial-grade rose bengal in uncontrolled amounts. The requirement to control these impurities is in accordance with International Council on Harmonisation (ICH) guidelines for the manufacturing of an injectable pharmaceutical. US patent numbers are 8,530,675, 9,273,022, and 9,422,260, with expirations ranging from 2030 to 2031.
The Company’s IP also includes a family of US and international (a number of countries in Asia, Europe, and North America) patents that protect the combination of RBD and CB (e.g., anti-CTLA-4, anti-PD-1, and anti-PD-L1 agents) for the treatment of a range of solid tumor cancers. US patent numbers are 9,107,887, 9,808,524, 9,839,688, and 10,471,144, with expirations ranging from 2032 to 2035; US patent application numbers include 20200138942 (i.e., 16/678,133), which has been allowed.