Officials with the FDA granted accelerated approval to pembrolizumab (Keytruda, Merck) for patients with metastatic small cell lung cancer (SCLC), marking the first indication for pembrolizumab in SCLC, according to a press release.
 
Pembrolizumab is already an established treatment option for non-small cell lung cancer, with several approved indications for its use in the disease. With this approval, pembrolizumab is now indicated for patients with metastatic SCLC with disease progression on or after platinum-based chemotherapy and at least 1 other prior line of therapy.
 
This approval is based on tumor response rate and durability of response (DOR) as demonstrated in the KEYNOTE-158 and KEYNOTE-28 clinical trials. Patients in the trials evaluated for efficacy received either pembrolizumab 200 mg intravenously every 3 weeks or 10 mg/kg intravenously every 2 weeks. Among the 83 patients enrolled in the trials, 64% received 2 prior lines of therapy and 36% received 3 or more lines of therapy. Additionally, 60% received prior thoracic radiation therapy and 51% received prior radiation therapy to the brain.
 
Overall, patients treated with pembrolizumab demonstrated an overall response rate (ORR) of 19% (95% CI, 11-29), with a complete response rate of 2% and a partial response rate of 17%. Of the 16 responding patients, 94% had a DOR of 6 months or longer, 63% had a DOR of 12 months or longer, and 56% had a DOR of 18 months or longer.
 
In the safety analysis, adverse reactions that occurred were similar to those observed in patients with other solid tumors who received pembrolizumab as a single agent. 
 
“Small cell lung cancer, which accounts for 10% to 15% of all lung cancers, is often diagnosed at an advanced stage where the prognosis is very poor and there have historically been limited treatment options,” Patrick Ott, MD, PhD, clinical director for the Center for Immuno-Oncology at Dana-Farber Cancer Institute, said in the press release. “The approval of Keytruda in small cell lung cancer provides an additional treatment option for patients based on the clinical response rates from KEYNOTE-158 and KEYNOTE-028.”
 
In SCLC, the recommended dose of pembrolizumab is 200 mg administered as an intravenous infusion over 30 minutes every 3 weeks until disease progression, unacceptable toxicity, or up to 24 months in patients without disease progression, according to the press release.
 
Continued approval for this indication may be contingent upon verification and description of clinical benefit in the confirmatory trials.
 
Reference
 
FDA Approves Merck’s Keytruda (pembrolizumab) as Monotherapy for Patients with Metastatic Small Cell Lung Cancer (SCLC) with Disease Progression on or After Platinum-Based Chemotherapy and at Least One Other Prior Line of Therapy [news release]. https://www.mrknewsroom.com/news-release/prescription-medicine-news/fda-approves-mercks-keytruda-pembrolizumab-monotherapy-patie. Accessed June 18, 2019.