On April 18 the FDA granted the immunotherapy pembrolizumab (Keytruda) the Breakthrough Therapy Designation for the treatment of patients with relapsed or refractory classical Hodgkin lymphoma (cHL). The Breakthrough Therapy Designation indicates that the FDA perceives the drug candidate may represent a substantial improvement over existing therapies and that it warrants additional resources to help expedite the approval process.
What is pembrolizumab?
Pembrolizumab is a humanized monoclonal antibody that binds to programmed death receptor-1 (PD-1). PD-1, also called programmed cell death protein-1, binds to programmed death ligand-1 (PD-L1), initiating inhibitory, immunosuppressive signals in T cells. Tumor cells, like Hodgkin lymphoma cells, often take advantage of this PD-1 by increasing expression of PD-L1, turning off the T cells and helping them to evade a potentially damaging immune response. Pembrolizumab acts by binding to PD-1, blocking its inhibitory actions, thereby activating the T-cell response against cancer cells, and initiating cell death. Pembrolizumab is already approved by the FDA for treatment of patients with unselectable or metastatic melanoma and for patients with non-small cell lung cancer whose tumors express PD-L1.
Why did the FDA grant pembrolizumab a Breakthrough Therapy Designation?
The new designation is based on preliminary date from the KEYNOTE-013 trial, which was last presented at the 2015 meeting of the American Society of Hematology, and the KEYNOTE-087 trial. In KEYNOTE-013, 64% of patients with brentuximab vedotin-refractory cHL responded, including 16% achieving a complete response. Results from the KEYNOTE-087 trial are not yet public but will likely be presented soon.
Were there any side effects?
Side effects were considered manageable and the most common included hypothyroidism, diarrhea, nausea, and pneumonitis.
How can you access pembrolizumab now?
Although the FDA has approved pembrolizumab for melanoma and lung cancer, it has not yet approved pembrolizumab for Hodgkin lymphoma. Patients interested in receiving immune checkpoint inhibitors are advised to seek out clinical trial options. Please visit our clinical trials website or contact our office (646-962-2064) for additional information.