Summit Therapeutics faces regulatory hurdles arising from divergent clinical trial outcomes with ivonescimab, a bispecific antibody targeting PD-1 and VEGF, in NSCLC treatment. Phase III data indicate patients in China experienced a 45% reduction in tumor progression risk with ivonescimab plus chemotherapy, whereas North American and European participants showed a non-significant 33% reduction with faster disease progression observed. This geographic discrepancy complicates approval strategies in Western markets. Summit’s full Phase 3 data release focused on Western cohorts reflects these challenges, underlining the importance of regional population responses in global oncology drug development.