The PARP enzyme is highly expressed in SCLC.47 A randomized Phase 2 study of veliparib plus EP in treatment naïve SCLC patients demonstrated a slight improvement in PFS from 5.6 to 5.8 months without a corresponding benefit in overall survival.48 More encouraging was the identification of Schlafen 11 (SLFN11), an RNA/DNA helicase that serves as a potential predictive biomarker for sensitivity to PARP inhibition, since SLFN11 expression, which is high in SCLC, decreases significantly after treatment with veliparib.49 This evidence concerns the gene SLFN11 and small cell lung carcinoma.