On March 17, 2020 OncoSec Medical Incorporated (NASDAQ:ONCS) (the "Company" or "OncoSec"), a company developing late-stage intratumoral cancer immunotherapies, reported the publication of positive TAVO monotherapy data in patients with metastatic melanoma in the Annals of Oncology (Press release, OncoSec Medical, MAR 17, 2020, View Source [SID1234555651]). The publication titled, "Intratumoral Delivery of Tavokinogene Telseplasmid Yields Systemic Immune Responses in Metastatic Melanoma Patients," features data previously highlighted at both American Association of Cancer Research (AACR) (Free AACR Whitepaper) and the Melanoma Bridge annual meetings. Annals of Oncology is the official publication of the European Society for Medical Oncology.
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The complete publication in Annals of Oncology is linked here and available on OncoSec’s website at View Source
The publication describes OncoSec’s study of patients with Stage III/IV melanoma who were treated intratumorally with plasmid encoding IL-12 (tavokinogene telseplasmid or TAVO), followed by electroporation on days 1, 5, and 8 every 90 days in the main study with additional patients treated in two exploration cohorts with alternative schedules. Correlative analyses for programmed death-ligand 1 (PD-L1), flow cytometry to assess changes in immune cell subsets and analysis of intratumoral immune-related gene expression were carried out on pre-and post-treatment samples from study patients, as well as from additional patients treated during exploration of additional dosing schedules beyond the pre-specified protocol dosing schedule. Response was measured by study-specific criteria to maximize detection of latent and potentially transient immune responses in patients with multiple skin lesions. Toxicities were graded by the Common Terminology Criteria for Adverse Events version 4.0 (CTCAE v4.0).
The objective overall response rate (ORR) was 35.7% in the main study, with a complete response (CR) rate of 17.9%. The median progression-free survival in the main study was 3.7 months while the median overall survival was not reached at a median follow up of 29.7 months. A total of 46% of patients in all cohorts having both injected and uninjected lesions experienced regression of at least one of these uninjected lesions and 25% had a net regression of all untreated lesions. Transient procedural pain (n = 24, 80%) and injection site reactions were the most commonly experienced adverse events.
Transcriptomic and immunohistochemistry analysis showed that immune activation and co-stimulatory transcripts were up-regulated, with an increase of adaptive immune resistance.
The publication concluded that intratumoral TAVO was well-tolerated and led to systemic immune responses in advanced melanoma patients. While tumor regression and increased immune infiltration were observed in treated as well as untreated/distal lesions, adaptive immune resistance limited the response.
"TAVO treatment appears to drive a change in the immune microenvironment, which results in an immune response to melanoma with minimal systemic toxicity. These data demonstrate that this in situ tumor vaccination strategy may be a safe and effective approach to inducing multiple sustained, productive changes in the immune microenvironment that would be too toxic using similar systemic agents and drive significant clinical results," concluded study co-author Adil Daud, M.D., Department of Medicine, University of California, San Francisco. "We look forward to continued evaluation of the TAVO approach as a monotherapy in future clinical trials."
TAVO is currently being evaluated as a combination therapy in multiple clinical trials, including KEYNOTE-695, a pivotal trial in late-stage anti-PD-1 checkpoint refractory metastatic melanoma, and two phase 2 trials, one for triple negative breast cancer (TNBC) and a second for head and neck cancer. TAVO enables the intratumoral delivery of DNA-based IL-12, a naturally occurring protein with immune-stimulating functions. OncoSec’s technology, which employs electroporation, is designed to produce a controlled, localized expression of IL-12 in the tumor microenvironment, enabling the immune system to target and attack tumors throughout the body. Results from recently completed clinical studies of TAVO have demonstrated a local immune response, and subsequently, a systemic effect as either a monotherapy or combination treatment approach.
"While our ongoing pivotal KEYNOTE-695 study is evaluating TAVO and KEYTRUDA combination therapy in late-stage checkpoint refractory metastatic melanoma patients and has begun to yield positive results, publication of monotherapy data with TAVO demonstrates its utility as a standalone treatment in this patient population," stated Christopher Twitty, Ph.D., OncoSec’s Chief Science Officer and a co-author of the publication. "The increase in adaptive resistance observed in the tumor microenvironment, in particular PD-L1, makes TAVO a particularly well-suited partner with anti-PD-1 checkpoint therapies. We are encouraged to see such a high response rate and will continue to evaluate TAVO’s utility as a monotherapy for metastatic melanoma."
Annals of Oncology is the latest among a presently growing volume of peer-reviewed journals to highlight the potential of TAVO as a novel immunotherapy. A recent publication in Cancer Immunology Research, linked here, also explored the mechanism of activation of systemic immunity in patients from the TAVO monotherapy study in metastatic melanoma patients. Additionally, Clinical Cancer Research featured TAVO monotherapy data in Merkel cell carcinoma on the cover of its February 2020 issue, linked here. You can find a list of all TAVO publications and scientific presentations at View Source