Abstract 5884
Background
The era of immunotherapy changed considerably prognosis of melanoma. Nonetheless, only around 40% can get benefit from this treatment, with no biomarkers identified for the therapeutic choice. On the basis of emerging clinical evidence, increased Tumor Mutational Burden (TMB) may be associated with higher sensitivity to immunotherapeutic agents.
Methods
The aim of this study was to analyze in advanced melanoma the relationship between the mutation load and: i) the histologic characteristics, ii) locations according to sun exposure and iii) response to PD-1 inhibitors, in advanced melanoma patients, in a retrospective multicentric analysis by sequencing using FoundationOne®. TMB was characterized as the number of somatic protein-coding base substitution or alterations mutations per megabase (Mb). DNA was extracted from paraffin embedded sections of primary tumor or metastasis. TMB was considered low between 1 and 5 muts/Mb, intermediate between 6 and 19, high if > 20 muts/Mb.
Results
In five centers in France, we included between October 2017 and March 2019 101 patients, aged from 16-year to 92-year-old, with metastatic melanomas. Results were available for 89 cases (12% DNA extraction failure). Acral (n = 6, 20%), mucosal (n = 5, 17%) and uveal melanoma (n = 4, 13%) had a lower TMB compared to sun-exposed melanomas. No melanoma of non-sun-exposed areas had high burden (n = 0); intermediate TMB was found in 21% (n = 8) and low TMB in 63% of cases (n = 19). Conversely, melanoma on chronic exposed areas (face and neck) had high TMB (5/7 cases; 71%). Complete and partial remission after 3 months of anti-PD-1 were more often observed in TMB high patients (n = 4;20%) whereas in low and intermediate mutational patients, progression was found in respectively 62% (n = 24) and 53% (n = 16).
Conclusions
TMB is affected by a variety of causes, including ultraviolet light in melanoma and smoking in lung cancer. Desmoplastic melanomas have been reported to have a high prevalence of somatic mutations whereas mucosal and acral have a 5-to 10-fold lower. Our study highlights the importance of TMB with higher response to PD-1 blockade. While it has to be confirmed, sun exposed areas or UV-signature may in be a valuable criterion in helping clinical decision-making.
Clinical trial identification
Editorial acknowledgement
Foundation One Medicine and Roche Laboratories.
Legal entity responsible for the study
French hospitals.
Funding
Has not received any funding.
Disclosure
C. Allayous: Travel / Accommodation / Expenses: BMS; Travel / Accommodation / Expenses: Roche; Travel / Accommodation / Expenses: Amgen. All other authors have declared no conflicts of interest.
Resources from the same session
3664 - Longitudinal changes in cell-free DNA (cfDNA) methylation levels identify early non-responders to treatment in advanced solid tumors
Presenter: Andrew Davis
Session: Poster Display session 3
Resources:
Abstract
3212 - Multigene panel testing results for hereditary breast cancer in 1325 individuals: implications for gene selection and considerations for guidelines.
Presenter: Georgios Tsaousis
Session: Poster Display session 3
Resources:
Abstract
2591 - PIK3R5 genetic predictors of hypertension induced by VEGF-pathway inhibitors
Presenter: Julia Quintanilha
Session: Poster Display session 3
Resources:
Abstract
4377 - ERBB2 mRNA as a predictor in HER2-positive (HER2+)/hormone receptor-positive (HR+) metastatic breast cancer (BC) treated with HER2 blockade in combination with endocrine therapy (ET): a retrospective analysis of the ALTERNATIVE and SOLTI-PAMELA trials.
Presenter: Nuria Chic
Session: Poster Display session 3
Resources:
Abstract
3439 - Early on-treatment vs pre-treatment tumor transcriptomes as predictors of response to neoadjuvant therapy for HER2-positive inflammatory breast cancer
Presenter: Sonia Pernas
Session: Poster Display session 3
Resources:
Abstract
2512 - AXL expression predicts poor prognosis and lack of efficacy of anti-angiogenic and anti-epidermal growth factor receptor (EGFR) agents in patients (pts) with RAS wild type (WT) metastatic colorectal cancer (mCRC)
Presenter: Claudia Cardone
Session: Poster Display session 3
Resources:
Abstract
4061 - Prevalence of EGFR mutations and its correlation with Egyptian patients’ human kinetics (PEEK Study)
Presenter: Adel Ibrahim
Session: Poster Display session 3
Resources:
Abstract
2547 - Evaluation of tumor microenvironment identifies immune correlates of response to combination immunotherapy with margetuximab (M) and pembrolizumab (P) in HER2+ gastroesophageal adenocarcinoma (GEA)
Presenter: Sergio Rutella
Session: Poster Display session 3
Resources:
Abstract
4671 - Clinicopathological and molecular criteria assessment for the screening of hypermutated proficient mismatch repair (pMMR) colorectal cancers (CRC) with exonucleasic domain POLE (edPOLE) mutations (mt).
Presenter: Benoit Rousseau
Session: Poster Display session 3
Resources:
Abstract
3862 - Tumor mutation burden and microsatellite instability in colorectal cancer
Presenter: Francesca Fenizia
Session: Poster Display session 3
Resources:
Abstract