The primary objective of a late-stage study intended to demonstrate that GSK’s blood cancer drug Blenrep was superior to an already available treatment on the market was not met, the company said on Monday.

As a standalone manufacturer of prescription drugs and vaccines, oncology is a major area of focus for GSK. Following its statement, which raised concerns that Blenrep’s regulatory approval may be revoked, its shares fell 3%.

In patients with relapsed or refractory multiple myeloma, Blenrep did not achieve the primary endpoint of “progression-free survival,” or the time that a person lives with the disease without it getting worse after treatment, according to GSK.

In order to gain access to its primary experimental medication for a rare blood cancer and complement GSK’s Blenrep, the company decided to purchase American pharmaceutical company Sierra Oncology in April.

The medication is currently indicated as a treatment for patients with relapsed or refractory multiple myeloma who received at least four prior therapies after receiving an accelerated approval from U.S. authorities in 2020.

In the trial, pomalidomide and low doses of the steroid dexamethasone were combined with Blenrep. Pomalidomide was created by Celgene, which is now a division of Bristol-Myers Squibb, and was authorized as a multiple myeloma treatment in 2013.

J.P. Morgan analysts stated in a note that data from the so-called superiority trial known as DREAMM-3 may call into question Blenrep’s current approval. They added that many regulatory scenarios now exist, including existing approvals being revoked or authorities waiting for more data.

“Overall, with this data calling into question Blenrep’s approvability in the existing setting and the chances of success in earlier treatment lines, we therefore expect the market to price in a risk that Blenrep approval is rescinded,” they said.

Data from the trial will be shared with the appropriate health authorities, according to GSK, and further discussions about Blenrep trials are currently taking place.

The medication is a member of an emerging class of therapies known as antibody drug conjugates, which are engineered antibodies that bind to tumor cells and then release chemicals that kill those cells.

(Adapted from FinancialPost.com)