Randomized phase 2 trial of consolidative thoracic radiotherapy with atezolizumab maintenance in extensive-stage small cell lung cancer

Chemoimmunotherapy followed by immunotherapy maintenance is the standard first-line treatment for extensive-stage small cell lung cancer (ES-SCLC). Data regarding efficacy and safety of consolidative thoracic radiotherapy (TRT) are lacking. The randomized phase 2 TREASURE trial in Germany and Austria investigated whether combining consolidative TRT with immunotherapy maintenance in ES-SCLC is safe and improves overall survival (OS) and progression-free survival (PFS). Eligible patients had ES-SCLC with at least stable disease after induction chemoimmunotherapy (carboplatin-etoposide-atezolizumab). Patients were randomized 1:1 to either atezolizumab maintenance combined with consolidative TRT (30 Gy in 10 fractions; n=34) or atezolizumab maintenance alone (n=34). The trial found that TRT plus immunotherapy unexpectedly resulted in significantly more frequent and severe toxic effects, particularly infections, without improving survival. Recruitment was halted prematurely. Persistent lymphocyte depletion after TRT suggested a potential contributor to the observed toxic effects. The authors conclude that these findings argue against routine use of consolidative TRT combined with immunotherapy maintenance in unselected patients with ES-SCLC (visual abstract).