Poly(ADP-Ribose) Polymerase Inhibition in Small Cell Lung Cancer: A Review

Small cell lung cancer (SCLC) is a highly aggressive neuroendocrine malignancy with high and rapid relapse rates and poor outcomes. Treatment for SCLC has historically been limited by the lack of targetable driver genomic lesions, however recent developments in the underpinnings of genomic instability in SCLC and understanding of its transcriptional subtypes have led to increased interest in the use of poly(ADP-ribose) polymerase (PARP) inhibitors as a rationale therapy. Poly(ADP-ribose) polymerase inhibitors, historically designed to target BRCA1/2-mutated malignancies, capitalize on synthetic lethality in homologous recombination-deficient tumors. In this review, we outline the mechanistic rationale for the use of PARP inhibitors in treating SCLC and detail key clinical trials investigating their use in combination with chemotherapy and immunotherapy. We describe developments in the understanding of biomarkers for sensitivity to therapy and highlight further investigational directions for the use of PARP inhibitors in treating SCLC.