Systemic therapy options following first-line chemoimmunotherapy in small-cell lung cancer

Nearly all patients with extensive-stage small-cell lung cancer (ES-SCLC) relapse following first-line etoposide plus platinum (EP) with or without immune checkpoint inhibition. Topotecan and amrubicin are chemotherapies approved for these patients. The toxicities of these chemotherapies are significant and survival when treated with these regimens is minimal. The programmed death-1 (PD-1) inhibitors nivolumab and pembrolizumab are unlikely to be effective for patients who develop progressive disease on first-line chemoimmunotherapy. Newer systemic therapies (e.g., lurbinectedin and temozolomide plus poly-ADP ribose polymerase inhibition) have demonstrated greater response rates than topotecan, amrubicin or PD-1 inhibitors. The data on these newer systemic therapies and other agents that may soon enter clinic are reviewed in this manuscript. Additionally, some of the key questions arising following clinical trials of these newer agents are highlighted.