Pembrolizumab confers clinical benefit after previous treatments for small cell lung cancer
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Pembrolizumab induced encouraging antitumor activity among a cohort of patients with recurrent or metastatic small cell lung cancer, according to a pooled analysis of data from the KEYNOTE-028 and KEYNOTE-158 studies published in Journal of Thoracic Oncology.
The anti-PD-1 monoclonal antibody also appeared well-tolerated.
“Small cell lung cancer comprises approximately 13% to 15% of all lung cancers. It is characterized by rapid growth, early metastasis and initial response followed by resistance to chemotherapy and radiotherapy,” Min Hee Hong, MD, a sub-investigator of this trial and researcher in the division of medical oncology and the department of internal medicine at Yonsei Cancer Center of the Severance Hospital at Yonsei University College of Medicine in Seoul, Korea, told Healio. “For several decades, there had been a scarce improvement in the field of small cell lung cancer, in contrast to non-small cell lung cancer. In addition, recent guidelines had not provided options for patients who require third-line therapy with an expected survival of less than 6 months. Thus, there was a significant unmet need for patients who experience progression after first- and second-line treatment.”
Researchers conducted a pooled analysis to evaluate the safety and efficacy of pembrolizumab (Keytruda, Merck) among 83 patients (median age, 62 years; 63.9% men) in KEYNOTE-028 (n = 19) and KEYNOTE-158 (n = 64) who had received two or more lines of previous therapy for small cell lung cancer. Sixty-four percent of patients had two prior lines of therapy, 57% had PD-L1-positive tumors and 80% had previously undergone radiation therapy.
Median follow-up was 7.7 months.
Results showed an overall response rate of 19.3% (95% CI, 11.4-29.4) and median PFS of 2 months (95% CI, 1.9-3.4). Median duration of response was not reached (range, 4.1-35.8+ months), with 61% of responses lasting at least 18 months. Two patients, one of whom had a PD-L1-positive tumor, achieved complete response, and 14 patients, including 13 with PD-L1-positive tumors, achieved partial response.
Researchers observed median OS of 7.7 months (95% CI, 5.2-10.1) and a 2-year OS rate of 20.7%.
“Considering that responses were rare and the duration of response was extremely short in many prior trials in heavily treated small cell lung cancer, these findings are quite promising and encouraging,” Hong told Healio. “Recently, the treatment landscape in the first-line setting in extensive-stage small cell lung cancer has shifted to the combination of cytotoxic chemotherapy and immune checkpoint inhibitors. In addition, our results indicated that for patients with small-cell lung cancer who have not been exposed to immune checkpoint inhibitors upfront, the use of pembrolizumab in the third-line setting is a standard of care.”
Treatment-related adverse effects occurred among 61.4% of patients, and 9.6% experienced grade 3 or higher adverse effects.
“The benefit of pembrolizumab is likely better demonstrated in earlier lines of therapy,” Hong told Healio. “The results for the global, randomized phase 3 study of chemotherapy with or without pembrolizumab in the first-line setting among patients with extensive-stage small-cell lung cancer (KEYNOTE-604) were recently disclosed and will be presented at an upcoming meeting.” – by Jennifer Southall
For more information:
Min Hee Hong, MD, can be reached at Yonsei University College of Medicine, 50-1 Yonsei-RO, Seodaemon-GU, Seoul, 03722, Korea; email: minhee_hong@yus.ac.
Disclosures: Hong reports no relevant financial disclosures. Please the study for all other authors’ relevant financial disclosures.
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