Abstract 4836
Background
Lung cancer patients with activating EGFR mutations tend to respond poorly to IO, but this is not true for all activating mutation driven lung cancers. Recent data show that patients with BRAF mutations tend to respond better to IO. Our study estimated the tumor neoantigen burden in these tumors, and the likelihood of their presentation to cytotoxic T cells by estimating their binding affinity to major histocompatibility complex (MHC).
Methods
Whole exome data for 68 patients with EGFR mutant lung adenocarcinoma and 33 with BRAF mutations were extracted from the Cancer Genome Atlas. MAFTOOLs was used to determine the tumor mutational load. Nonamers were estimated by simulating possible nonamer neoantigens from MAF files. The neoantigen (MT) and wildtype (WT) binding affinities to MHC-I were calculated using the NetMHC 4.0 server. The differential binding affinity of the neoantigens in comparison to wildtype was calculated as mean differential agretopicity index (DAI) = WT - MT. Patient survival was estimated by the Kaplan-Meier method.
Results
Patients with mutated BRAF had higher median mutational burden (445, range 165-776) than those with EGFR mutations (90.5, range 60.5-219.5, p = 0.001). The median number of simulated neoantigens was higher in the BRAF (9536.5, range 3839.5-14626.0) vs the EGFR group (1895.5, range 1148.5-4766.5, p < 0.001). Mean DAI for BRAF and EGFR patients were 1046 and 1033, respectively, p = 0.86. In the BRAF mutant group, patients with DAI < 1,000 had significantly better 5-year survival (80% vs 40%, p = 0.022) compared to patients with DAI > 1,000. No such survival benefit was identified in the EGFR mutant group (56% vs 58%, p = 0.81).
Conclusions
BRAF mutant lung cancers are characterized by higher neoantigen burden, but their neoantigen differential binding affinity to MHC-I complex was not different from EGFR mutant lung cancers. Our analysis suggests that the improved response to IO in the BRAF mutant population is due to increased quantity in neoantigen burden and not a qualitative difference in MHC-I binding. Further, DAI had a prognostic impact in the BRAF population suggesting that it may be a measure of tumor neoantigen immunogenicity.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
J. Subramanian: Advisory / Consultancy, Speaker Bureau / Expert testimony: AstraZeneca; Advisory / Consultancy: Pfizer; Advisory / Consultancy, Speaker Bureau / Expert testimony: Boehringer Ingelheim; Advisory / Consultancy, Research grant / Funding (institution): Paradigm; Speaker Bureau / Expert testimony: Lilly; Research grant / Funding (institution): Biocept. All other authors have declared no conflicts of interest.
Resources from the same session
1885 - Factors associated with disease progression in patients treated with trametinib in combination with dabrafenib for unresectable advanced BRAFV600-mutant melanoma: an open label, non randomized study
Presenter: Philippe Saiag
Session: Poster Display session 3
Resources:
Abstract
5259 - Integrative RNAseq and Target panel sequencing reveals common and distinct innate and adaptive resistance mechanisms to BRAF inhibitors
Presenter: Phil Cheng
Session: Poster Display session 3
Resources:
Abstract
5619 - Effective treatment with T-VEC monotherapy in Stage IIIB/C-IVM1a Melanoma of the Head & Neck Region
Presenter: Viola Franke
Session: Poster Display session 3
Resources:
Abstract
5666 - Re-introduction of T-VEC Monotherapy in Recurrent Stage IIIB/C-IVM1a melanoma is effective
Presenter: Viola Franke
Session: Poster Display session 3
Resources:
Abstract
4117 - Efficacy of talimogene laherparepvec (T-VEC) in melanoma patients (pts) with locoregional (LR) recurrence, including in-transit metastases (ITM): subgroup analysis of the phase 3 OPTiM study
Presenter: Mark Middleton
Session: Poster Display session 3
Resources:
Abstract
5303 - Real Life Use of Talimogene Laherparepvec in Melanoma in Centers in Austria and Switzeland
Presenter: Christoph Hoeller
Session: Poster Display session 3
Resources:
Abstract
4130 - Outcomes of advanced melanoma patients who discontinued pembrolizumab (pembro) after complete response (CR) in the French early access program (EAP)
Presenter: Philippe Saiag
Session: Poster Display session 3
Resources:
Abstract
2050 - Outcome of patients with elevated LDH treated with first-line targeted therapy (TT) or PD-1 based immune checkpoint inhibitors (ICI)
Presenter: Sarah Knispel
Session: Poster Display session 3
Resources:
Abstract
1618 - Comparative-Effectiveness of Pembrolizumab vs. Nivolumab for Patients with Metastatic Melanoma
Presenter: Justin Moser
Session: Poster Display session 3
Resources:
Abstract
3556 - Long-term efficacy of combination nivolumab and ipilimumab for first-line treatment of advanced melanoma: a network meta-analysis
Presenter: Peter Mohr
Session: Poster Display session 3
Resources:
Abstract