Abstract 1054P
Background
We have shown that 75% of patients (pts) with metastatic melanoma treated with PD1 who have not progressed by 1-year on RECIST or clinical grounds have complete metabolic response (CMR) on PET imaging, including two-thirds of pts with partial response (PR) on CT. CMR pts have excellent medium-term survival, with progression seldom seen in 2 years. We now report 5-year outcomes.
Methods
Retrospective analysis of 104 pts with baseline and 1-year PET and CT. 1-year response was determined using RECIST for CT and EORTC criteria for PET, coded as CMR, PMR, stable disease (SMD) or progressive disease (PMD). Progression-free survival (PFS) and overall survival (OS) were determined from 1-year landmark.
Results
At median follow-up of 61 months (range 58-64) from 1-year PET, 94.2% of pts remained alive and all but one had discontinued treatment after a median of 23 months (range 1-59). Disease progression occurred in 19 pts (18%), compared to 14 (13%) at 24 months; 7 (37%) with CMR, 10 (53%) while on PD1 and 12 (63%) in solitary sites for which 8 (67%) received local treatment. RECIST PFS 5-years after PET was superior in pts with CR compared to PR/SD, CMR compared to non-CMR, and in pts with PR on CT, PFS was superior in PR + CMR compared to PR + non-CMR (Table). 34 (33%) pts (13 in CR, 30 CMR) discontinued treatment within 12 months either electively or due to toxicity with no impact on PFS compared to those that discontinued beyond 12 months (p=0.41). Despite progression events, OS at 5-years was excellent and similar in pts with CR & PR/SD, CMR & non-CMR, and within those with PR by PET response. Table: 1054P
| Response category at 1 year | 2-year | 5-year | |||||
| 2-year survival (%)* | 2-year HR (95% CI) | 2-year p-value | 5-year survival (%)* | 5-year HR (95% CI) | 5-year p-value | ||
| PFS | CR | 100 | 0.18 (0.06-0.56) | 0.06 | 93 | 0.27 (0.06-1.15) | 0.06 |
| PR/SD | 79 | 76 | |||||
| CMR | 95 | 0.06 (0.02-0.23) | <0.06 | 90 | 0.13 (0.05-0.33) | <0.01 | |
| Non-CMR | 54 | 54 | |||||
| PR + CMR | 93 | 0.07 (0.02-0.27) | <0.01 | 88 | 0.18 (0.06-0.55) | <0.01 | |
| PR + non-CMR | 48 | 59 | |||||
| OS | CR | - | - | - | 100 | - | 0.12 |
| PR/SD | - | 95 | |||||
| CMR | - | - | - | 97 | - | 0.14 | |
| Non-CMR | - | 94 | |||||
| PR + CMR | - | - | - | 96 | - | 0.64 | |
| PR + non-CMR | - | 95 |
Conclusions
5-years after PET imaging, sustained responses are observed in the vast majority of pts with CMR on PET and PET continues to predict outcome better than CT. In the minority of patients that progress, often in solitary sites and managed locally, OS remains excellent. PET is effective in evaluating residual lesions on CT and has an important role in predicting long-term benefit and potential early treatment cessation.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
A.C. Tan: Non-Financial Interests, Personal, Other: Amgen; Non-Financial Interests, Personal, Other: Thermo Fisher. M. Carlino: Non-Financial Interests, Personal, Advisory Role: Amgen, Bristol-Myers Squibb, Eisai, IDEAYA Biosciences, Merck and Co, Merck Sharp & Dohme, Nektar, Novartis, Pierre Fabre, Roche, Sanofi, QBiotics; Non-Financial Interests, Personal, Other: Bristol-Myers Squibb, Merck Sharp & Dohme, Novartis. G.V. Long: Non-Financial Interests, Personal, Advisory Role: Aduro Biotech Inc, Amgen Inc, Array Biopharma inc, Boehringer Ingelheim International GmbH, Bristol-Myers Squibb, Hexel AG, Highlight Therapeutics S.L., Merck Sharpe & Dohme, Novartis Pharma AG, OncoSec, Pierre Fabre, QBiotics Group Limited, Regeneron Pha. A.M. Menzies: Non-Financial Interests, Personal, Advisory Role: BMS, MSD, Novartis, Roche, Pierre-Fabre, QBiotics. All other authors have declared no conflicts of interest.