The U.S. Food and Drug Administration (FDA) has approved the drug Keytruda® for patients with recurrent or metastatic head and neck squamous cell carcinoma (HNSCC) with disease progression on or after platinum-containing chemotherapy.
Keytruda® is an immunotherapy drug that works as a programmed death receptor, blocking monoclonal antibody that works by targeting the PD-1/PD-L1 pathway. This blockade mechanism is believed to stimulate the body’s immune system response against cancer cells, which may prove to be promising treatment for certain types of cancers.
The study that led to the approval was comprised of 174 patients who received intravenous pembrolizumab (Keytruda®) 10 mg/kg every two weeks or 200 mg every three weeks, which measured durable objective response rate (ORR).
The ORR was 16% and the range of duration of response was 2.4 months to 27.7 months. Twenty-three of the 28 responding patients had responses of six months or longer.
The most common negative reactions were fatigue, loss of appetite, and dyspnea. The most common serious effects included pneumonia, dyspnea, confusional state, vomiting, pleural effusion, and respiratory failure. Pneumonitis, colitis, hepatitis, adrenal insufficiency, diabetes mellitus, skin toxicity, mysoitis, and thyroid disorders were among the significant immune-mediated adverse reactions.
There have been clinical trials studying Keytruda® for mesothelioma cancer patients. Pulitzer Prize-winning journalist Gary Cohn wrote an article in June about a man named Paul Zygielbaum who was treated with the drug.
Zygielbaum had survived for 12 years after his original peritoneal mesothelioma diagnosis, but it seemed his time was up. Yet, ten months after he began infusions of Keytruda®, his tumors disappeared or shrunk, his appetite came back, and his blood tests were almost normal for the first time in a dozen years.
Per the most recent study, the recommended dose of Keytruda® is 200 mg in an intravenous infusion over 30 minutes every three weeks. This dosage is for HNSCC patients only.
Next steps are for Merck to conduct a multicenter, randomized trial proving Keytruda® superior to the standard therapy and describe the clinical benefits.