Abstract 1733
Background
Melanoma brain metastases (MBM) are historically associated with poor prognosis. Radiotherapy (RT), mainly stereotactic, improves local control in pauci-metastatic disease. Targeted therapies (TT) and immunotherapies were recently allowed for a significant overall intracranial response that remains inferior and less durable than in extracranial metastases. This study investigates the role of concomitant RT (cRT) in real-life MBM patients (pts).
Methods
MelBase is a French multicentric biobank prospectively enrolling unresectable stage III or IV melanoma ( > 1400 pts) since Dec. 2013. Data from 262 MBM pts were collected (Dec. 2017) and compared between cRT (68% stereotactic) and no cRT (demography, treatment, overall survival (OS), progression-free survival (PFS), safety). We used inverse propensity score weighting (IPW) to correct for indication bias.
Results
Overall, 93 pts were treated by cRT (g1), 169 were not (g2). Mean age in g1 was 58 years, 95% of g1 pts were PS 0-1, 42% had elevated LDH, 29% had less than 3 MBM, 14% were leptomeningeal, 58% were asymptomatic; 31% received TT, 56% anti-PD1, 13% ipilimumab. Mean age in g2 was 61 years, 85% of g2 pts were PS 0-1, 37% had elevated LDH, 47% had less than 3 MBM, 7% were leptomeningeal, 60% were asymptomatic; 40% received TT, 23% anti-PD1, 21% ipilimumab. Median FU was 6.9 months (3.3-15.9). Median OS was respectively 16.8 (g1; 95%CI: 11.8-27.9) and 6.9 (g2; 95%CI: 5.4-9.4) months; median PFS was respectively 3.9 (g1; 95%CI: 3.3-5.2) and 3.6 (g2; 95%CI: 3.2-4.9) months with a low toxicity profile (g1: 20% grade 3-4; g2: 23% grade 3-4). IPW was successful in balancing prognostic variables between g1 and g2. In the weighted sample, cRT prolonged OS (HR 0.62; 95%CI: 0.44-0.79; p = 0.008).
Conclusions
To our knowledge, this study is the first to confirm the impact on survival of cRT in combination with systemic therapies in real-life MBM pts using the propensity score matching to mimic particular characteristics of a randomized trial and reduce or eliminate the effects of confounding in observational data. This method will be applied to take into account the effect of each systemic therapy associated with cRT.
Clinical trial identification
Legal entity responsible for the study
AP-HP DRCI.
Funding
French National Cancer Institute (INCa), BMS, MSD, Novartis, Roche.
Editorial Acknowledgement
Disclosure
C. Allayous: Meeting, travels, accomodations: Amgen, BMS, Roche. S. Dalle: Research funding: Roche, BMS; Travel, accomodations, expenses: BMS, MSD. L. Mortier: Travel, accomodations, expenses: Roche, BMS, Novartis. G. Jeudy: Consulting or advisory role: Roche, MSD. C. Dutriaux: Consulting or advisory role: Novartis, Roche, BMS, MSD. J-P. Lacour: Honoraria: BMS; Research funding: Roche, Novartis, BMS, MSD. P. Saiag: Honoraria: Roche, Novartis, Array BioPharma, Pierre Fabre, BMS, MSD; Consulting or advisory role: Roche, Novartis, Array BioPharma, Pierre Fabre, BMS, MSD; Research funding: Roche; Travel, accomodations, expenses: Roche, Novartis, BMS, MSD. J. De Quatrebarbes: Consulting or advisory role: BMS, Janssen; Travel, accomodations, expenses: Abbvie, BMS, MSD, Janssen. P-E. Stoebner: Travel, accomodations, expenses: Novartis, Janssen. D. Legoupil: Honoraria: BMS, Consulting or advisory role: BMS; Travel, accomodations, expenses: BMS. M. Beylot-Barry: Consulting or advisory role: Roche, BMS, MSD; Speakers' bureau: Novartis; Research funding: Roche; Travel, accomodations, expenses: Roche. T. Lesimple: Consulting or advisory role: Roche, Novartis, Incyte, MSD; Research funding: Roche; Travel, accomodations, expenses: Roche, BMS, MSD. F. Aubin: Consulting or advisory role: Roche, Novartis, Celgene, BMS, MSD; Travel, accomodations, expenses: Novartis, Abbvie. C. Lebbe: Honoraria: Roche, Novartis, Amgen, BMS, MSD; Consulting or advisory role: Roche, Novartis, Amgen, BMS, MSD; Speakers' bureau: Roche, Amgen, Novartis, BMS; Research funding: Roche, BMS; Travel, accomodations, expenses: Roche, Amgen, BMS. All other authors have declared no conflicts of interest.