Big deal for small cells.
The Trial: Sometimes it seems like the invite for small cell lung cancer (SCLC) to the immunotherapy party got lost in the mail. Well, Genentech found it. In the IMpower133 trial, patients with extensive stage SCLC (including those with previously treated asymptomatic brain mets) were randomized to receive standard carboplatin / etoposide x 4 cycles +/- concurrent and maintenance atezolizumab. During the maintenance phase, patients could receive prophylactic cranial irradiation but not thoracic consolidation. The addition of atezo prolonged median progression free survival from 4 to 5 months and overall survival from 10 to 12 months. Looked at another way, atezo increased the rate of overall survival at one year from 38 to 52%. Unlike nivo for NSCLC, patients with all ranges of tumor mutational burden appeared to benefit. Diving in deeper, the overall response rates were similar between groups, but those responses appeared to be more durable with immunotherapy. Interestingly, patients over 65 derived the greatest benefit from immunotherapy (ugh, millennials).
The Takeaway: In one of the first headways this disease has seen in decades, adding atezolizumab to carbo / etoposide for extensive stage SCLC prolongs progression free and overall survival. | Horn, N Engl J Med 2018