Pratilas, Christine A.

Aneuploidy is a hallmark of cancer often associated with inferior prognosis. Copy number gains of chromosome 8 (chr8) are recurrent in multiple cancers, including breast, prostate, colorectal cancers, and sarcomas such as malignant peripheral nerve sheath tumors (MPNSTs). MPNSTs are aggressive, hard-to-treat sarcomas frequently linked to the Neurofibromatosis type 1 (NF1) cancer predisposition syndrome. To investigate the role of chr8 gain in MPNST pathogenesis, we performed a CRISPR knockout screen and identified 58 essential genes on chr8, including PTK2, which encodes focal adhesion kinase (FAK). We evaluated FAK as a therapeutic target and tested small-molecule FAK inhibitors (FAKi) alone or combined with RAF/MEK inhibitors (RAF/MEKi), a class of agents relevant to NF1-deficient tumors with ERK pathway hyperactivation. Both pharmacological and genetic inhibition of FAK reduced MPNST cell proliferation in vitro and tumor growth in vivo. Combined FAKi and RAF/MEKi treatment further suppressed phosphorylation of FAK, STAT3, and AKT while increasing cleaved caspase-3 and PARP-1, indicating enhanced apoptosis. In MPNST patient-derived xenograft (PDX) models, combination therapy significantly reduced tumor growth, showing superior efficacy, particularly in chr8 gain MPNST-PDX. These results support FAK/RAF/MEK co-targeting as a promising therapeutic strategy for chr8 gain MPNST and related tumors.

Abstract Purpose: Combined mTOR and MEK inhibition, critical components of the RAS effector pathway underlying the pathogenesis of neurofibromatosis type 1 (NF1)–related tumors, caused regression in a malignant peripheral nerve sheath tumor (MPNST) transgenic mouse model. The primary objective was to determine the clinical benefit rate in patients with unresectable/metastatic MPNST. Patients and Methods: The study design was a multi-institutional, open-label, Simon two-stage, phase II study of the MEK inhibitor selumetinib and mTOR inhibitor sirolimus. Patients ≥12 years with histologically confirmed MPNST received selumetinib 50 mg twice daily and sirolimus 4 mg once daily, in continuous 28-day cycles. Correlative studies evaluated patient-reported pain, immune signature in peripheral blood, and cell-free DNA (cfDNA). Results: A total of 21 heavily pretreated patients [seven females; median age, 41 years (range, 16–72); and 14 with NF1] with advanced disease enrolled at five participating sites. Clinical benefit was observed in only one of seven in stage 1 and one of 14 patients in stage 2. The median number of cycles was two (range, 1–6). Most common adverse events (AE) were grade ≤2 gastrointestinal toxicity, acneiform rash, hypertriglyceridemia, mucositis, and transaminase elevation. Unlike the preclinical model, early 18F-fluorodeoxyglucose PET scan performed during cycle 1 demonstrated partial metabolic responses in five patients (24%), but these did not correlate with objective responses after cycle 2. cfDNA was able to detect MPNST with the potential to be a biomarker of response. Conclusions: The combination was safe, with manageable and expected AEs, but did not meet study parameters for further evaluation in MPNST. Correlative studies were informative and may guide future therapeutic trials of MPNST.

Abstract Purpose: Early detection of neurofibromatosis type 1 (NF1)–associated peripheral nerve sheath tumors (PNST) informs clinical decision-making, enabling early definitive treatment and potentially averting deadly outcomes. In this study, we describe a cell-free DNA (cfDNA) fragmentomic approach that distinguishes nonmalignant, premalignant, and malignant forms of PNST in the cancer predisposition syndrome, NF1. Experimental Design: cfDNA was isolated from plasma samples of a novel cohort of 101 patients with NF1 and 21 healthy controls and underwent whole-genome sequencing. We investigated diagnosis-specific signatures of copy-number alterations with in silico size selection as well as fragment profiles. Fragmentomics were analyzed using complementary feature types: bin-wise fragment size ratios, end motifs, and fragment non-negative matrix factorization signatures. Results: The novel cohort of patients with NF1 validated that our previous cfDNA copy-number alteration–based approach identifies malignant PNST (MPNST) but cannot distinguish between benign and premalignant states. Fragmentomic methods were able to differentiate premalignant states including atypical neurofibromas (AN). Fragmentomics also adjudicated AN cases suspicious for MPNST, correctly diagnosing samples noninvasively, which could have informed clinical management. Conclusions: Novel cfDNA fragmentomic signatures distinguish AN from benign plexiform neurofibromas and MPNST, enabling more precise clinical diagnosis and management. This study pioneers the early detection of malignant and premalignant PNST in NF1 and provides a blueprint for decentralizing noninvasive cancer surveillance in hereditary cancer predisposition syndromes.

This selection from the NCCN Guidelines for Adolescent and Young Adult (AYA) Oncology focuses on considerations for the comprehensive care of AYA patients with cancer. Compared with older adults with cancer, AYA patients have unique needs regarding treatment, fertility counseling, psychosocial and behavioral issues, and supportive care services. The complete version of the NCCN Guidelines for Adolescent and Young Adult (AYA) Oncology addresses additional aspects of caring for AYA patients, including risk factors, screening, diagnosis, and survivorship.