Molecular profiling of melanoma brain metastases (MBM) compared to primary cutaneous melanoma (CM).

Authors

Gino In

Gino Kim In

USC Norris Comprehensive Cancer Center, Los Angeles, CA

Gino Kim In , Kelsey Anne Poorman , Michelle Saul , Steven O'Day , Jeffrey M. Farma , Steven Daveluy , Anthony J. Olszanski , Michael S. Gordon , Jacob Stephen Thomas , Burton Larry Eisenberg , Lawrence E. Flaherty , Geoffrey Thomas Gibney , Michael B. Atkins , Ari M. Vanderwalde

Organizations

USC Norris Comprehensive Cancer Center, Los Angeles, CA, Caris Life Sciences, Phoenix, AZ, John Wayne Cancer Institute, Santa Monica, CA, Fox Chase Cancer Center, Philadelphia, PA, Wayne State University, Dearborn, MI, Pinnacle Oncology Hematology, Arizona Center for Cancer Care, HonorHealth Research Institute Clinical Trials Program, Virginia G. Piper Cancer Center, Scottsdale, AZ, University of Southern California Norris Comprehensive Cancer Center, Los Angeles, CA, Hoag Family Cancer Institute, Newport Beach, CA, Karmanos Cancer Institute, Detroit, MI, Moffitt Cancer Center, Tampa, FL, Georgetown Lombardi Comprehensive Cancer Center, Washington, DC, Division of Hematology/Oncology, The University of Tennessee Health Science Center, West Cancer Center, Germantown, TN

Research Funding

Other

Background: Nearly 50% of metastatic melanoma patients develop brain metastases, warranting further investigation into the biology of this event. Methods: We analyzed 132 MBM and 745 CM submitted to Caris Life Sciences from 2015-2018, using next generation sequencing of a 44 or 592 cancer-related gene panel, tumor mutational burden (TMB), and PD-L1 expression by IHC. Genomic alterations (GA), including somatic mutations or CNA, were reported. High TMB (TMB-H) was defined as ≥17 mut/Mb. Comparison of molecular profiles, including cancer-related genes and recurrently altered pathways, between tumor sites and by genomic subgroup (BRAF, NRAS, KIT, NF1), was performed using Fisher’s exact test. Results: Among 132 MBM, 72.7% were male, with median age 62 yo (range 25-83). The most common GAs among MBM were: BRAF (52.4%), NRAS (26.6%), CDKN2A (23.3%), NF1 (18.9%), TP53 (18%), ARID2 (13.8%), SETD2 (11.9%), and PBRM1 (7.5%). Compared to CM, MBM were more often TMB-H (53.7% v 38%, p = .025), with higher PD-L1 expression, using both a ≥1% (54.4% v 35.6%, p = .002) and ≥5% cut-off (32.9% v 15.9%, p = .0006). MBM showed higher rates of GAs among: SETD2 (11.9% v 1.9%, p = .0008), BRAF (52.4% v 35.6%, p = .017), PBRM1 (7.5% v 1.6%, p = .018), KRAS (4% v 1%, p = .026), CCND1 (2.9% v 0%, p = .03), and DICER1 (4.4% v 0.6%, p = .04), compared to CM. Alterations of the MAPK (87.9% v 77.8%, p = .015) and SWI/SNF (22.1% v 11.6%, p = .036) pathway were more frequent in MBM, than CM. When analyzed by genomic subgroup, BRAF+ MBM had more GAs involving the PI3K pathway (20% v 5.1%, p = .027), compared to BRAF WT MBM. NRAS+ MBM had higher PD-L1 expression at the ≥1% cutoff (66.7% v 38.6%, p = .05), but not ≥5%, compared to NRAS WT MBM. NF1+ MBM had more GAs involving the SWI/SNF (60% v 11.6%, p = .003) pathway, as opposed to NF1 WT MBM. No significant associations were seen between KIT status, TMB, PD-L1 or other pathways among MBM. Conclusions: In this cross-sectional study, MBM demonstrated higher PD-L1 expression and were more often TMB-H, compared to CM. MBM also featured more GAs involving BRAF and the MAPK pathway. We identified two novel genes, PBRM1 and SETD2, as well as recurrent alterations of the SWI/SNF pathway, supporting future studies of chromatin remodeling pathways in MBM.

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Abstract Details

Meeting

2019 ASCO Annual Meeting

Session Type

Poster Session

Session Title

Melanoma/Skin Cancers

Track

Melanoma/Skin Cancers

Sub Track

Biologic Correlates

Citation

J Clin Oncol 37, 2019 (suppl; abstr 9565)

DOI

10.1200/JCO.2019.37.15_suppl.9565

Abstract #

9565

Poster Bd #

136

Abstract Disclosures

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