Figure 4. .

A 72-year-old male with metastatic melanoma in a phase 1 trial of Pembrolizumab. Images a, b show case examples of baseline and follow-up 1 study (13 weeks later) assessed in irRC and irRECIST criteria, respectively. Patient had only 1 target lesion at baseline\, but developed several new lesions (retroperitoneal lymph nodes) on follow-up. In irRC criteria (a), a total of 10 new lesions (5 per organ) can be assessed as “new target lesions”. Hence, all three new retroperitoneal lymph nodes were assessed as “new lesions” and total tumour burden was calculated from SPD of old and new target lesions. In irRECIST criteria (b), a total of 5 new lesions (2 per organ) can be assessed as “new target lesions”. Hence, only 2 new retroperitoneal lymph nodes (from among 3 new lesions) were assessed as “new lesions” and total tumour burden was calculated from SLD (or short-axis for lymph nodes) of old and new target lesions. irRC, immune-related response criteria; irRECIST, immune-related Response Evaluation Criteria in Solid Tumours; SLD, sum of long axis diameters; SPD, sum of product of diameters.