Advaxis (ADXS) Announces Updated Survival Data in Phase 1/2 ADXS-PSA Trial at ASCO

Advaxis, Inc. (Nasdaq: ADXS), a clinical-stage biotechnology company focused on the development and commercialization of immunotherapy products today announced updated results from the combination arm of KEYNOTE-46 (Part B), the Company’s ongoing Phase 1/2 study investigating ADXS-PSA with KEYTRUDA® (pembrolizumab) in patients with metastatic, castrate-resistant prostate cancer (mCRPC) at the ASCO Genitourinary Cancers Symposium in San Francisco, California. The KEYNOTE-46 trial was conducted in conjunction with Merck (known as MSD outside the U.S. and Canada) and evaluated ADXS-PSA, one of Advaxis’ Listeria monocytogenes (Lm)-based immunotherapies, alone and in combination with KEYTRUDA®, Merck’s anti-PD-1 therapy.

“The presented survival data in patients with visceral metastases strengthens our confidence that ADXS-PSA in combination with KEYTRUDA® has the potential to provide meaningful increases in median overall survival in patients with advanced, metastatic, castration-resistant prostate cancer,” said Kenneth A. Berlin, President and Chief Executive Officer of Advaxis. “Importantly, these demonstrated impacts on survival have not been previously observed with immunotherapy in this advanced patient population leading us to actively assess next steps for the program with the hope of providing a much-needed new treatment for these patients with limited options.”

Key findings presented by Mark N. Stein M.D., FACS, Associate Professor of Medical Oncology at Columbia University Medical Center and lead study investigator, titled, “KEYNOTE-046 (Part B): Effects of ADXS-PSA in combination with pembrolizumab on survival in metastatic, castration-resistant prostate cancer patients with or without prior exposure to docetaxel” include:

• Median overall survival (95% CI) of 33.7 months (15.4-NR) for patients treated with ADXS-PSA in combination with KEYTRUDA® (n=37)
• Median overall survival (95% CI) of 16.0 months (6.4-34.6) for patients with prior docetaxel (n=20)
• Median overall survival (95% CI) of 16.4 months (4.0-NR) for patients with prior visceral metastasis (n=11; 10 of who had prior docetaxel)
• 72.4% (21/29) of evaluable patients showed stable disease
• 38% of patients had PSA declines and 27% had >= 30% PSA decline from baseline
• The combination of ADXS-PSA and pembrolizumab appeared safe and tolerable in this heavily pretreated, unselected population of patients with MSI-High-negative mCRPC
• Treatment-related adverse events were mostly Grade 1-2, with no additive toxicity observed with combination therapy

Mark N. Stein M.D., FACS said, “These data are encouraging given the advanced nature of the patient population which includes those who have failed next generation hormonal agents and/or docetaxel, and now those with visceral metastasis.” He added, “I am particularly enthusiastic to see increases in median overall survival to 16.4 months as compared to standard of care, which tends to be closer to 11 months in patients with measurable disease/visceral metastasis. This improvement, delivered with a generally safe and well-tolerated treatment regimen, warrants additional evaluation in larger studies and I look forward seeing the potential of a continued evaluation of ADXS-PSA in combination with KEYTRUDA®.”

KEYNOTE-046 was an open-label, multicenter, dose-determining safety and tolerability Phase 1/2 trial of 50 heavily pretreated patients conducted in two parts (Part A and Part B), with a Phase 2 expansion cohort. The objective of the study was to evaluate ADXS-PSA alone (Part A) and in combination with KEYTRUDA® (Part B) for primary endpoints that include safety, tolerability and dosing. Secondary endpoints included anti-tumor activity, progression-free survival and overall survival, and exploratory endpoints that include associations between biomarkers of immunologic response (serum PSA) with clinical outcomes. Enrollment in the study has been completed and the database lock occurred on January 28, 2020. The majority of treatment-related adverse events consisted of transient and reversible Grade 1-2 chills/rigors, fever, hypotension, nausea and fatigue. The combination of ADXS-PSA and KEYTRUDA® has appeared to be well-tolerated, to date, with no additive toxicity observed.

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