Safety and efficacy of retreatment with immune checkpoint inhibitors in non-small cell lung cancer: a systematic review and meta-analysis

BACKGROUND: Retreatment with immune checkpoint inhibitors (ICIs) might be a subsequent therapeutic option for patients with non-small cell lung cancer (NSCLC) who discontinued initial ICIs treatment because of disease progression, immune-related adverse events (irAEs) or completion of a fixed course, yet little evidence exists on the safety and efficacy of ICIs retreatment to support this strategy. METHODS: We searched PubMed, Web of Science, Embase, Cochrane and major meeting libraries for articles about ICIs retreatment in NSCLC for systematic review and meta-analysis. The outcomes included objective response rate (ORR) and disease control rate (DCR) for efficacy and the incidence of all-grade and high-grade irAEs for safety. ICIs rechallenge implies retreatment that can be applied to patients who progressed, while ICIs resumption refers to retreatment for patients who discontinued prior treatment due to an irAE or completion of a fixed course of immunotherapy. RESULTS: Eighteen studies were enrolled in our analysis. The pooled ORR and DCR of ICIs retreatment were respectively 20% and 54%. ICIs retreatment was associated with a decrease in ORR and DCR compared to prior ICIs treatment (ORR: OR, 0.29, 95% CI: 0.14, 0.63, P=0.002; DCR: OR, 0.53, 95% CI: 0.28–0.99, P=0.05). The pooled ORR and DCR of ICIs rechallenge were 8% and 39%. ICIs rechallenge showed a lower ORR compared with initial ICIs treatment (P<0.05). ICIs resumption presented an ORR of 34% and a DCR of 71%, showing no significant difference in ORR and DCR compared with initial ICIs treatment (P>0.05). Retreated with the same type of ICIs as before showed no difference in ORR and DCR (P>0.05), while with different ICIs was associated with a decrease in ORR and DCR in contrast to initial treatment (P<0.05). The pooled incidence of all-grade and high-grade irAEs after ICIs retreatment in patients with NSCLC were separately 41% and 13% which showed a similar incidence compared with initial ICIs treatment (P>0.05). DISCUSSION: Retreatment with ICIs is feasible for patients with NSCLC in consideration of its encouraging efficacy and tolerable safety, especially in resumption with ICIs. When it comes to ICIs rechallenge, it is necessary to accurately identify the potential targeted beneficiary population. More large-scale prospective studies are warranted to confirm our discoveries. More attention could be paid to further exploring the efficacy and safety of retreatment concurrently with ICIs and chemotherapy.