MCL1 and esophageal cancer: Despite the challengesassociated with inhibition of Mcl-1, potentsmall molecule Mcl-1 inhibitors (S64315 (1),49,50 AZD5991 (2),51,52 AMG176 (3),53−57 AMG397 (4),58,59 ABBV-467 (5),60−64 PRT1419 (6),65,66 GS9716 (7)67−69) have entered clinical trials within the last six years and havetargeted not only hematological malignancies but also solid tumors,including breast, non-small cell lung cancer (NSCLC), small cell lungcancer (SCLC), cervical, and esophageal cancer (Figure 1).