P49-9 Atezolizumab in combination with carboplatin and etoposide (CE) for small-cell lung cancer after failure to CE

Abstract

Atezolizumab was introduced as a first-line treatment option for extensive-stage small-cell lung cancer (ES-SCLC), in combination with carboplatin and etoposide (CE) chemotherapy. However, SCLC treatment options after progression to first-line chemotherapy are scarce and limited, which sometimes leads to warranting the readministration of previously used drugs in heavily treated patients. CE readministration could theoretically be effective in combination with atezolizumab, which is based on two tentative mechanisms: its additive and synergistic effects of atezolizumab on cytotoxic chemotherapy. The additive effect of atezolizumab was based on the IFCT-1603 trial, in which the Kaplan-Meier estimates of both progression-free survival (PFS) and overall survival in the atezolizumab group exhibited a tail plateau in the selected population. Conversely, anti-PD-L1 antibody synergistic effect on platinum compounds was assessed in a preclinical study. Therefore, atezolizumab in combination with CE could be a treatment option in heavily treated patients, especially in patients who have never exposed to atezolizumab. We describe the first case of a heavily treated ES-SCLC patient treated with chemoimmunotherapy, resulting in a partial response and a durable PFS as long as 6 months.