Patients suffering from relapsed or refractory multiple myeloma now have a new weapon against the disease: GlaxoSmithKline’s Blenrep (belantamab mafodotin-blmf). Recently approved by the FDA, the B-cell maturation antigen (BCMA) antibody-drug conjugate is indicated as a monotherapy treatment for patients who have typically failed therapy with four or more other agents. “This drug offers them a potential chance at survival,” says Asim Farooq, MD, assistant professor of ophthalmology and visual science, University of Chicago.

Blenrep does, however, have a side effect that brings ophthalmologists into the treatment picture: ocular toxicity.

Blenrep and ocular reactions

According to clinical trials, ocular adverse reactions — including keratopathy, changes in visual acuity, blurred vision and dry eye — occurred in 77% of the 218 patients in the pooled safety population. “Among patients with keratopathy (n = 165), 49% had ocular symptoms, 65% had clinically relevant visual acuity changes (decline of two or more lines on Snellen Visual Acuity in any eye) and 34% had both ocular symptoms and visual acuity changes,” according to the product prescribing information.

Dr. Farooq says the corneal toxicity that occurs with Blenrep is similar to what researchers have observed with other antibody drug conjugates. “Those of us who have been involved with clinical trials with other antibody drug conjugates have seen that these agents can cause what appear to be microcysts within the corneal epithelium.”

According to his research, these microcysts appear to be intracellular deposits. “While patients are undergoing therapy, they show up in the peripheral corneal epithelium first, then they appear to migrate toward the paracentral cornea, and sometimes into the central corneal epithelium,” he explains. When it does occur, though, those patients may experience vision loss. Still, he emphasizes, while lesions are quite common for patients on Blenrep (more than 70% of patients have some level of them), that does not necessarily mean those patients experience vision issues.

REMS to the rescue

To ensure physicians and patients are educated about the treatment and required monitoring, the drug is available only through the Blenrep Risk Evaluation and Management Strategy (REMS) program, a restricted distribution program in which an ophthalmologist is enlisted to monitor patients at regular intervals. The oncologist, who is certified for REMS, administers Blenrep in an IV infusion over an approximately 30-minute session every 3 weeks. The ophthalmologist performs a baseline ocular exam before the first treatment and subsequent examinations “at least a week after the patient receives an infusion but within 2 weeks of the next infusion” says Dr. Farooq. Thus, “every dose is monitored for ocular toxicity.”

Patients are seen approximately every 3 weeks. After each examination, the ophthalmologist sends a report to the oncologist to help guide any adjustments that might need to be made based on the corneal side effects. “Prior to the next IV infusion, the data from the form the ophthalmologist fills out is uploaded into an electronic system that allows the pharmacy to release the drug,” Dr. Farooq explains.

For more information on Blenrep, go to www.blenrephcp.com . OM