Cachia, David

Acute myeloid leukemia (AML) pathogenesis is deeply rooted in the concept of clonal evolution, in which hematopoietic stem cells experience an initial genetic insult, followed by the sequential acquisition of mutations leading to various disease phenotypes. Through natural selection, a malignant clone can diversify and propagate with time. Aside from clonal evolution, a number of time-honored principles of molecular oncology account for the initiation and maintenance of AML. These principles include loss of heterozygosity, genomic instability, epigenomic disruption, deregulation of signaling pathways, anti-apoptotic mechanisms, and oncogene addiction. Such tenets of cancer biology not only explain AML cellular behavior but also may inform target validation in AML. Herein, we highlight the current state of targeted therapeutics, including the 14 novel agents (beyond 7+3 chemotherapy) approved by the Food and Drug Administration, in the context of these tenets and discuss future prospects by leveraging current knowledge of AML genomics. Such therapeutic concepts, including synthetic lethality, are especially relevant to TP53-mutant AML, as there are no unique therapies that have received regulatory approval for this subset to date. We emphasize the emerging role of single-cell genomics and multi-omics toward better understanding of AML biology and development of future successful AML therapies.

ABSTRACT Age‐related changes in human hematopoietic stem cells (HSCs) often form the basis for clonal hematopoiesis (CH), which presages the development of overt myeloid neoplasm with variable risk. CH can also arise after exposure to chemotherapy, radiotherapy, or immune interventions. In this study, we performed clinico‐genomic profiling of therapy‐related CH (t‐CH) ( n = 67) versus de novo CH ( n = 123) from a multidisciplinary CHIP Clinic. The most enriched mutations in t‐CH were TET2 (26.2%), DNMT3A (22.4%), and TP53 (8.4%). Median latency period from the time of initial exposure to the diagnosis of t‐CH was 6.96 ± 1.10 years. Patients with t‐CH had inferior event‐free survival compared to de novo CH (median 29.9 months versus 122.1 months, p = 0.0045). Overall survival was also shorter in t‐CH versus de novo CH (median 55.3 months vs. 129.2 months, p = 0.043). Genes that imparted significantly increased risk for progression from t‐CH to overt therapy‐related myeloid neoplasm (t‐MN) included JAK2 (relative risk (RR) 9.42, p = 0.0001), RUNX1 (RR 7.11, p = 0.001), EZH2 (RR 7.11, p = 0.001), and TET2 (RR 13.4, p = 0.01). Clonal dynamic modeling of patients with t‐CH who progressed to overt t‐MN showed an increase in the relative clonal fraction and new clonal outgrowth. In the t‐CH cohort, higher mean variant allele frequency was observed in progressors versus non‐progressors (77.1% vs. 30.6%, p = 0.017). This study sheds light onto outcomes for CH based on differing clinical ontogeny and has implications for previvorship for secondary malignancies.

PURPOSE Patients with progressive or recurrent meningiomas have limited systemic therapy options. Focal adhesion kinase (FAK) inhibition has a synthetic lethal relationship with NF2 loss. Given the predominance of NF2 mutations in meningiomas, we evaluated the efficacy of GSK2256098, a FAK inhibitor, as part of the first genomically driven phase II study in recurrent or progressive grade 1-3 meningiomas. PATIENTS AND METHODS Eligible patients whose tumors screened positively for NF2 mutations were treated with GSK2256098, 750 mg orally twice daily, until progressive disease. Efficacy was evaluated using two coprimary end points: progression-free survival at 6 months (PFS6) and response rate by Macdonald criteria, where PFS6 was evaluated separately within grade-based subgroups: grade 1 versus 2/3 meningiomas. Per study design, the FAK inhibitor would be considered promising in this patient population if either end point met the corresponding decision criteria for efficacy. RESULTS Of 322 patients screened for all mutation cohorts of the study, 36 eligible and evaluable patients with NF2 mutations were enrolled and treated: 12 grade 1 and 24 grade 2/3 patients. Across all grades, one patient had a partial response and 24 had stable disease as their best response to treatment. In grade 1 patients, the observed PFS6 rate was 83% (10/12 patients; 95% CI, 52 to 98). In grade 2/3 patients, the observed PFS6 rate was 33% (8/24 patients; 95% CI, 16 to 55). The study met the PFS6 efficacy end point both for the grade 1 and the grade 2/3 cohorts. Treatment was well tolerated; seven patients had a maximum grade 3 adverse event that was at least possibly related to treatment with no grade 4 or 5 events. CONCLUSION GSK2256098 was well tolerated and resulted in an improved PFS6 rate in patients with recurrent or progressive NF2-mutated meningiomas, compared with historical controls. The criteria for promising activity were met, and FAK inhibition warrants further evaluation for this patient population.

Abstract Ependymomas are rare primary central nervous system (CNS) tumors in adults. They occur most commonly in the spinal cord, and have classically been graded histologically into World Health Organization (WHO) grades I, II, or III based on the level of anaplasia. Recent data are showing that genetic heterogeneity occurs within the same histological subgroup and that ependymomas arising from different CNS locations have different molecular signatures. This has renewed interest in developing targeting therapies based on molecular profiles especially given the variable outcomes with radiation and the poor results with cytotoxic agents. In this paper, we present the case of a 46-year-old woman with a classic presentation of spinal cord ependymoma and discuss the current histopathological and molecular classification for ependymomas as well as current guidelines for patient management.