Table 1 SCLC subtyping and therapeutic strategies

Subtype	Characteristic	Therapeutic strategies
SCLC-A	High DLL3 level [40] Amplifications of BCL2 [44] or EZH2 [ 45, 46] Decrease of CREBBP [47]	DLL3 inhibitor (Rova-T) [ 40– 43]
SCLC-N	Upregulation of C-MYC [30]	Aurora A/B kinase, CHK1, IMPDH1/2 inhibitors, arginine deprivation [ 48‒ 56]
SCLC-P	Activation of IGF-1R or PARP signaling [ 44, 57] High MCL1 level [58]	MCL1 inhibitor (S63845) [58]
SCLC-Y	Inflamed tumor microenvironment [59]	Immunotherapy [59]
SCLC-I a	Low expression of ASCL1, NEUROD1 and POU2F3 [44]	Combined chemotherapy and immunotherapy [44]
SCLC-I b	Immunosuppressive feature and high genomic instability, high POU2F3 level [60]	Combined chemotherapy and immunotherapy [60]