Additional Relevant Details Advaxis and Merck have completed the first two dose-escalation cohorts and launched the third dose-escalation cohort in their KEYNOTE-046 clinical trial. The Phase 1/2 study is evaluating the combination of ADXS-PSA (ADXS31-142) and KEYTRUDA (pembrolizumab), the first anti-PD-1 (programmed death receptor-1) therapy approved in the United States, in patients with previously treated, metastatic castration-resistant prostate cancer (mCRPC).The KEYNOTE-046 trial is the first-in-human study of Advaxis' Lm immunotherapy candidate for prostate cancer. It is the second study initiated to evaluate the use of KEYTRUDA in the treatment of advanced prostate cancer.