US FDA pauses clinical trial of BLU-222 amid safety concerns

The US FDA have put a hold in place on the testing of an experimental breast cancer drug from Blueprint Medicines. 

The trial began in April last year, involving 366 participants, according to information from a US government database. The aim of the trial was to test which dosage of the drug was appropriate from 50 mg BID to 800 mg BID. 

While the trial was ongoing, some patients reported experiencing some adverse effects, in the form of periods of sensitivity to light and blurred vision. In light of this, the FDA has called a partial clinical hold on the trial, whilst they work with Blueprint Medicines to investigate the events further. They are hoping to be able to adjust the clinical trial protocol to better monitor the patients. 

"Patient safety is our first priority, and we are working closely with the FDA to investigate the reported visual adverse events as well as amend the VELA trial protocol to provide specific guidance to investigators on how to monitor for and manage these events should they occur," stated Becker Hewes, Chief Medical Officer at Blueprint Medicines. "We have confidence in the benefit-risk profile of BLU-222 based on the activity and safety data we have seen to date in the dose escalation study. In addition, we recognize the urgency to treat patients with CDK2-vulnerable cancers, many of whom have seen their disease progress after exhausting all other options, and we aim to resume enrollment as expeditiously and responsibly as possible."

Similar holding periods have been put in place in clinical trials in the past when adverse events have occurred. In this case David Nierengarten, an analyst from Wedbush Securities, stated he was optimistic about the continuation of the trial after a brief holding period as there had been no signs of eye inflammation – uveitis – on treatment with BLU-222. This had caused the abandonment of a similar clinical trial on a cancer drug from Nuvation Bio previously. 

"We note that uveitis occurrence is difficult to predict and remain vigilant around this safety update," Nierengarten added.

As some participants have experienced visual-related adverse events, experts are aware of the similarity between the two drugs, which are of the same drug class. 

Participants of the trail who have advanced solid tumours will continue their treatment with BLU-222, under careful supervision, but the enrolment of new participants will be stopped until the FDA and the drug maker are confident to resume.