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GENEVA, SWITZERLAND-Treatment with the anti-PD1 antibody nivolumab did not improve response rates or survival over standard chemotherapy in patients with metastatic small-cell lung cancer (SCLC) who relapsed following first-line treatment, according to findings presented at the 2018 ESMO Immuno-Oncology Congress (Abstract LBA5).

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Martin Reck, MD, PhD, of the Lung Clinic Grosshansdorf, German Centre of Lung Research in Grosshansdorf in Germany noted that, although patients with SCLC often show high initial response rates, most patients will relapse soon after first-line treatment. These relapsing patients have few treatment options leaving them with a poor prognosis.


Reck and colleagues conducted the CheckMate 331 (NCT02481830) study evaluating nivolumab, which has been approved in the U.S. for treatment of patients with SCLC and progression after platinum-based chemotherapy and one or more other lines of treatment.


CheckMate 331 Details

CheckMate 331 was a global, open-label, phase III trial comparing nivolumab to chemotherapy. The trial enrolled 569 patients with limited or extensive relapsed metastatic SCLC who progressed after first-line platinum-based chemotherapy. The patients were randomly assigned 1:1, with 282 patients receiving nivolumab and 285 receiving chemotherapy with topotecan or amrubicin, according to local approval. The patients were stratified by platinum sensitivity (90 days) and the presence of CNS metastases. Both treatments were continued until progression, or clinical benefit was no longer observed with nivolumab, or until unacceptable toxicity occurred. Overall survival (OS) with nivolumab versus chemotherapy served as the primary endpoint.


After a minimum follow-up of 15.8 months, 225 (79%) OS events occurred with nivolumab compared to 245 (86%) with chemotherapy. No statistically significant improvement in OS was seen with nivolumab compared to chemotherapy; median OS was 7.5 months versus 8.4 months with nivolumab versus chemotherapy, respectively (HR 0.86; 95% CI, 0.72-1.04]). However, the OS curves showed delayed separation after month 12; the 1-year OS rates were 37 percent with nivolumab versus 34 percent with chemotherapy.


With the respective treatments, median progression-free survival (PFS) was median 1.5 versus 3.8 months (HR 1.41; 95% CI, 1.18-1.69) and the 1-year PFS rates were 11 percent versus 10 percent.


The objective response rates were 39 percent versus 47 percent, and the duration of response in responding patients was median 8.3 (95% CI 7.0-12.6) months versus 4.5 (95% CI 4.4-5.8) months with nivolumab versus chemotherapy, respectively.


In patients with platinum-resistant SCLC, the HR for OS with nivolumab versus chemotherapy was 0.71 (95% CI, 0.54-0.94).


The safety profile was improved with nivolumab compared to chemotherapy. All-grade treatment-related adverse events (TRAE) occurred in 55 percent versus 90 percent and grade 3-4 TRAE occurred in 4 percent versus 73 percent of nivolumab versus chemotherapy treated patients. Two treatment-related deaths occurred with nivolumab and three deaths occurred that were chemotherapy related.


The primary overall survival endpoint for second-line nivolumab versus chemotherapy was not met in CheckMate 331.


However, according to the authors, the late separation of curves and potential activity in the platinum-refractory setting suggests possible long-term benefit for some patients. There were no new safety signals, and lower adverse event rates were reported with nivolumab.