Dr. Richardson on Results of the HORIZON Trial in Relapsed/Refractory Multiple Myeloma

Paul G. Richardson, MD, clinical program leader and director of clinical research, Jerome Lipper Multiple Myeloma Center, and institute physician, Dana-Farber Cancer Institute, discusses interim results of the phase II HORIZON trial in relapsed/refractory multiple myeloma.

At the 17th International Myeloma Workshop, Richardson presented data on 136 evaluable patients who were enrolled in the HORIZON trial. The majority of patients were refractory to 3 therapeutic classes: immunomodulatory drugs, proteasome inhibitors, and CD38-directed monoclonal antibodies. Moreover, some patients had penta-refractory disease. Patients were treated with melflufen and dexamethasone monthly until progression or unacceptable toxicity.

The regimen was safe and effective, says Richardson. Investigators reported manageable myelosuppression, no hair loss, minimal mucositis, and no evidence of peripheral neuropathy. In terms of efficacy, Richardson reported a 27% objective response rate (ORR). Among patients with extramedullary disease (EMD), the ORR was 23%. Notably, patients with EMD that arose from the bone had a higher response rate compared with those whose disease arose only from soft tissue, says Richardson. For a single agent to show responses in approximately one-third of heavily pretreated patients is unprecedented, states Richardson.