Person:

Nardi, Valentina

The last decade in oncology has witnessed impressive response rates with targeted therapies, largely because of collaborative efforts at understanding tumor biology and careful patient selection based on molecular fingerprinting of the tumor. Consequently, there has been a push toward routine molecular genotyping of tumors, and large precision medicine-based clinical trials have been launched to match therapy to the molecular alteration seen in a tumor. However, selecting the “right drug” for an individual patient in clinic is a complex decision-making process, including analytical interpretation of the report, consideration of the importance of the molecular alteration in driving growth of the tumor, tumor heterogeneity, the availability of a matched targeted therapy, efficacy and toxicity considerations of the targeted therapy (compared with standard therapy), and reimbursement issues. In this article, we review the key considerations involved in clinical decision making while reviewing a molecular genotyping report. We present the case of a 67-year-old postmenopausal female with metastatic estrogen receptor-positive (ER+) breast cancer, whose tumor progressed on multiple endocrine therapies. Molecular genotyping of the metastatic lesion revealed the presence of an ESR1 mutation (encoding p.Tyr537Asn), which was absent in the primary tumor. The same ESR1 mutation was also detected in circulating tumor DNA (ctDNA) extracted from her blood. The general approach for interpretation of genotyping results, the clinical significance of the specific mutation in the particular cancer, potential strategies to target the pathway, and implications for clinical practice are reviewed in this article. Key Points ER+ breast tumors are known to undergo genomic evolution during treatment with the acquisition of new mutations that confer resistance to treatment. ESR1 mutations in the ligand-binding domain of ER can lead to a ligand-independent, constitutively active form of ER and mediate resistance to aromatase inhibitors. ESR1 mutations may be detected by genomic sequencing of tissue biopsies of the metastatic tumor or by sequencing the circulating tumor cells or tumor DNA (ctDNA). Sequencing results may lead to a therapeutic “match” with an existing FDA-approved drug or match with an experimental agent that fits the clinical setting.

T- and NK-cell lymphomas (TCL) are a heterogenous group of lymphoid malignancies with poor prognosis. In contrast to B-cell and myeloid malignancies, there are few preclinical models of TCLs, which has hampered the development of effective therapeutics. Here we establish and characterize preclinical models of TCL. We identify multiple vulnerabilities that are targetable with currently available agents (e.g., inhibitors of JAK2 or IKZF1) and demonstrate proof-of-principle for biomarker-driven therapies using patient-derived xenografts (PDXs). We show that MDM2 and MDMX are targetable vulnerabilities within TP53-wild-type TCLs. ALRN-6924, a stapled peptide that blocks interactions between p53 and both MDM2 and MDMX has potent in vitro activity and superior in vivo activity across 8 different PDX models compared to the standard-of-care agent romidepsin. ALRN-6924 induced a complete remission in a patient with TP53-wild-type angioimmunoblastic T-cell lymphoma, demonstrating the potential for rapid translation of discoveries from subtype-specific preclinical models.

GNAS mutations have been described in mucinous and non-mucinous epithelial neoplasms of the appendix, pancreas, and colon, with hotspot GNAS mutations found in up to two-thirds of pancreatic intraductal papillary mucinous neoplasms. Additionally, many GNAS-mutated tumors have concurrent mutations in the Ras/Raf pathway. The clinicopathologic features of GNAS-mutated lung carcinomas, however, have not yet been characterized. Primary lung carcinomas from Brigham and Women's Hospital (n=1282) or Massachusetts General Hospital (n=1070) were genotyped on a targeted massively parallel sequencing panel of oncogenes and tumor suppressor genes including GNAS. Clinical and pathological features were reviewed, and TTF-1 immunohistochemistry was performed when material was available. Nineteen lung adenocarcinomas with hotspot GNAS mutations were identified (19/2352, 0.8%) including 14 at codon 201 and 5 at codon 227. GNAS-mutated lung adenocarcinomas occurred predominantly in female patients (16/19, 84%). Ten (10) were classified as invasive mucinous adenocarcinomas (IMA), and nine (9) were non-mucinous adenocarcinomas. All IMAs had GNAS codon 201 mutations and concurrent Ras/Raf pathway mutations (9 KRAS, 1 BRAF). No tumors with GNAS codon 227 mutations had mucinous histological features. 86% of GNAS-mutated non-mucinous adenocarcinomas (6/7) were positive for TTF-1 immunohistochemistry, while only 25% of GNAS-mutated IMAs (1/4) were positive for TTF-1. Patients with GNAS-mutated non-mucinous adenocarcinomas were more likely to have a history of smoking (9/9, 100%) compared to patients with GNAS-mutated IMAs (2/10, 20%) (P<0.001). Hotspot GNAS mutations can occur in primary lung adenocarcinomas. When associated with concurrent mutations in the Ras/Raf pathway, these neoplasms often present as IMAs. GNAS mutations are not specific to neoplasms of the gastrointestinal tract, and clinicopathologic correlation is necessary in GNAS-mutated adenocarcinomas in the lung to determine the primary site of origin.