- The Food and Drug Administration on Wednesday approved a new drug to treat the blood cancer multiple myeloma, clearing GlaxoSmithKline's Blenrep for patients whose disease has evaded other treatments.
- Blenrep is the seventh drug since 2015 to pass FDA review for use in multiple myeloma, a treatable cancer that's nonetheless characterized by drug resistance and frequent disease relapses. Blenrep, though, is notable for the way it works: the therapy is the first to target a protein called BCMA that's almost universally found on malignant cells.
- Approval for Blenrep is conditional, based on early data showing treatment with the drug led to tumor responses in roughly a third of patients who had previously received a median of seven other drugs for their cancer. But frequent side effects, most notably in the eye, led the FDA to require a black box warning for the drug.
Blenrep is the first of what could soon be several multiple myeloma treatments that target BCMA, short for B-cell maturation antigen.
BCMA is well-suited as a drug target, overexpressed on cancerous cells but, critically, few others. That profile has drawn the attention of several other drugmakers, including Bristol Myers Squibb, Bluebird bio, Johnson & Johnson, Amgen and Regeneron.
The companies are taking different approaches to targeting BCMA, however. In the case of Blenrep, GSK designed the drug by pairing a BCMA-targeting antibody with a cell-killing toxin — a combination known most often as an antibody-drug conjugate.
Others are using engineered T cells or a type of antibody known as a bispecific. Bristol-Myers and Bluebird, for instance, recently resubmitted to the FDA their cell therapy ide-cel, which they hope to win approval for by March of next year after a hitting an unexpected regulatory delay. J&J could soon follow with a similar, rival treatment it expects to file with the agency later this year.
Developing new drug types for multiple myeloma is an important task, even after a spate of approvals over the past decade has greatly expanded the number of available treatment options.
Patients regularly cycle through different drugs, or combinations of several. For the trial supporting Blenrep's approval, GSK enrolled individuals whose cancer was judged to be relapsed or refractory, and who had previously been given three or more other treatments.
Thirty of the 97 patients who received the lower of two tested doses of Blenrep responded to treatment. A similar number responded to a higher dose, but the side effects were correspondingly more severe.
Even at the lower dose, treatment with Blenrep led to frequent adverse events, most notably changes in the eye known as keratopathy. Because of the risks, the FDA approved Blenrep with a black box warning, its strictest, and requires patients to undergo eye exams before each dose of the drug.
The drug's safety profile was the focus of questions raised by FDA staff for an advisory committee panel convened by the agency in July. Despite the regulator's apparent concerns, the panel unanimously agreed the drug's benefits outweigh its risks.
GSK has set high expectations for Blenrep, rolling out an ambitious clinical trial program spanning 11 studies in different multiple myeloma treatment settings.
The drugmaker set a list price of $8,277 per vial for Blenrep. Based on an average patient weight of roughly 175 pounds, GSK estimates the monthly cost of treatment to be $23,900. Depending on insurance coverage, patient out-of-pocket costs would likely be lower.
Other multiple myeloma drugs recently approved by the FDA include Sanofi's Sarclisa and Karyopharm's Xpovio.