Pembrolizumab Shows Antitumor Activity in Advanced SCLC

Because treatment options for patients with small cell lung cancer (SCLC) that progress on platinum-based chemotherapy are limited, researchers are looking for new treatments.

Pembrolizumab (Keytruda), an anti–PD-1 monoclonal antibody designed to block the interaction between PD-1 and its ligands PD-L1 and PD-L2, has shown antitumor activity in multiple advanced malignancies. Researchers are now looking at the use of pembrolizumab in patients with SCLC who have progressed on prior platinum-based therapy.

Researchers from the Dana-Farber Cancer Institute in Boston, and several other prominent cancer centers worldwide screened 135 patients with SCLC. Of those screened, 37 (27%) had PD-L1-positive tumors. Sixteen patients were enrolled in the KEYNOTE-028 clinical trial from March 2014 through January 2015. Of those 16 patients enrolled, there were varying degrees of response and drug-related adverse events that they experienced. Sixteen patients received prior platinum drug treatment and etoposide.

Nine patients (53%) experienced a drug-related adverse event; only one patient had a grade ≥ 3 adverse event. There were no treatment-related deaths or discontinuations due to adverse events. Four of 16 (25%) evaluable patients experienced a partial response. One patient had stable disease, resulting in a disease control rate of 31%. Six (37%) patients had progressive disease as their best response, and five patients had no assessment at the time of analysis. According to Patrick Alexander Ott, MD, Clinical Director, Center for Immuno-Oncology at Dana-Farber, Assistant Professor of Medicine, Harvard Medical School, and colleagues, responses are durable as all patients responded favorably on treatment for more than 16 weeks with ongoing response.

Dr. Ott presented his team's findings on the clinical trial KEYNOTE-028 (abstract 7502) at the 2015 American Society of Clinical Oncology (ASCO) Annual Meeting, held May 29-June 2, 2015 in Chicago. The findings can also be found in the May 2015 online issue of the Journal of Clinical Oncology.

This ongoing clinical trial is looking promising for pretreated patients who are in great need of another treatment option. Future trials will determine how safe and effective this treatment is for patients, but a larger accrual rate may be necessary to make this determination.