Progenics Pharmaceuticals, Inc.’s (PGNX) shares nosedived 27.4% after safety issues related to its prostate-specific membrane antigen antibody drug conjugate (PSMA ADC) were revealed in a meeting abstract ahead of the American Society of Clinical Oncology's 2014 Genitourinary Cancers Symposium Meeting.
Progenics is conducting a phase II trial (n = 70) to evaluate the use of PSMA ADC for taxane-refractory metastatic castrate resistant prostate cancer (mCRPC). Two doses of PSMA ADC: 2.5 mg/kg and 2.3 mg/kg are being evaluated in the study.
Several adverse events were found to be associated with the use of both doses of PSMA ADC. While patients experiencing neutropenia was higher for the 2.5 mg/kg dose (11.4%) compared to the 2.3 mg/kg dose (6.7%), peripheral neuropathy was noticed in more patients receiving the 2.3 mg/kg dose (6.7%) versus the 2.5 mg/kg dose (5.7%).
Two instances of death due to sepsis (a fatal whole-body inflammation) were reported in patients receiving the 2.5 mg/kg dose of PSMA ADC.
From an efficacy point of view, anti-tumor activity and reduction in prostate-specific antigen (PSA) and circulating tumor cells (CTC) was observed for both dosages.
We find the safety issues found to be associated with PSMA ADC concerning. We believe that the company will find it challenging to further develop and gain approval for this candidate given the safety issues.
Currently several products including Sanofi’s (SNY) Taxotere and Jevtana and Johnson & Johnson’s (JNJ) Zytiga are approved for mCRPC.
Further details on PSMA ADC will be provided by the company shortly. Progenics plans to present data on 1404, its prostate cancer imaging agent and PSMA ADC at the afore-mentioned meeting.
Progenics carries a Zacks Rank #3 (Hold). Some better-ranked stocks include Actelion Ltd. (ALIOF) carrying a Zacks Rank #1 (Strong Buy).