9539 Background: PEMBRO improves survival of patients (pts) with advanced melanoma. Optimal duration of treatment in responding pts hasn’t been established. Methods: 12 European hospitals collected data from 509 pts treated with PEMBRO outside an interventional clinical trial. Outcome was evaluated for pts who discontinued PEMBRO in the absence of progressive disease [PD]. Results: After a median follow up of 56 wks [range 1-135], median PFS was 22 wks [95% CI 18-26] and median OS was 70 wks [95% CI 59-81] for the total population. PEMBRO is ongoing in 66 [13%] pts, 344 [68%] pts stopped PEMBRO because of PD, and 99 [19%] pts discontinued PEMBRO without evidence of PD (of which 65 [13%] pts upon pt/MD decision, 26 [5%] pts due to a PEMBRO-related AE of grade < 4 and 8 [2%] pts due to a grade 5 PEMBRO-unrelated AE). Pts discontinuing PEMBRO without PD had a significant [ P <.005] better ECOG PS, less advanced tumor stage, less frequent brain metastases and more often a normal LDH at baseline. There was no significant difference between pts stopping due to AE or upon pt/MD decision. The median time on treatment for the 65 pts who stopped PEMBRO upon pt/MD decision was 55 wks [range 9-112].Their best objective response rate [BORR] was 80% [31 [48%] CR, 21 [32%] PR, 12 [18%]SD, 1[2%]NE]. After a median follow-up of 26 wks [range 1-75] after the last PEMBRO dose, 3 [5%] pts progressed (after 9, 14 and 15 wks). PEMBRO was reintroduced in 1 patient resulting in a CR. The median time on treatment of the 26 pts who stopped PEMBRO due to an AE in the absence of PD was 27 wks [range 1-103]. Their BORR was 77% [9 [35%] CR, 11 [42%] PR, 5 [19%] SD, 1 [4 %] NE]. After a median follow-up of 50 wks [range 12-109] following the last PEMBRO dose, 9 [35 %] pts progressed. Median time to PD was 26 wks [range 7-108]. PD was not correlated with BOR. PEMBRO was reintroduced in 4 pts resulting in 1 CR, 1 PD, 1 SD and 1 NE. Conclusions: In this real life experience, advanced melanoma pts who discontinue PEMBRO treatment upon pt/MD decision, in the absence of PD or AE, were at low risk for short-term recurrence. Pts stopping PEMBRO due to an AE in the absence of PD (having a shorter exposure to PEMBRO and longer FU after discontinuing treatment) seem to have a higher risk for subsequent PD.
1119P Targeted treatment and immunotherapy in older patients with advanced melanoma: A single institution real-life experience