Clinical Cancer Research

2023
Mariño-Enríquez A, Philipp Novotny J, Gulhan DC, Klooster I, Tran AV, Kasbo M, Lundberg MZ, Ou W-B, Tao DL, Pilco-Janeta DF, Mao VY, Zenke FT, Leeper BA, Gokhale PC, Cowley GS, Baker LH, Ballman KV, Root DE, Albers J, Park PJ, George S, Fletcher JA. Hyper-Dependence on NHEJ Enables Synergy Between DNA-PK Inhibitors and Low-Dose Doxorubicin in Leiomyosarcoma. Clinical Cancer Research 2023;Abstract

Purpose: Leiomyosarcoma (LMS) is an aggressive sarcoma for which standard chemotherapies achieve response rates under 30%. There are no effective targeted therapies against LMS. Most LMS are characterized by chromosomal instability (CIN), resulting in part from TP53 and RB1 co-inactivation and DNA damage repair defects. We sought to identify therapeutic targets that could exacerbate intrinsic CIN and DNA damage in LMS, inducing lethal genotoxicity.

Experimental design: We performed clinical targeted sequencing in 287 LMS and genome-wide loss-of-function screens in 3 patient-derived LMS cell lines, to identify LMS-specific dependencies. We validated candidate targets by biochemical and cell-response assays in vitro and in 7 mouse models.

Results: Clinical targeted sequencing revealed a high burden of somatic copy number alterations (median fraction of the genome altered=0.62) and demonstrated homologous recombination deficiency signatures in 35% of LMS. Genome-wide shRNA screens demonstrated PRKDC (DNA-PKcs) and RPA2 essentiality, consistent with compensatory non-homologous end joining hyper-dependence. DNA-PK inhibitor combinations with unconventionally low-dose doxorubicin had synergistic activity in LMS in vitro models. Combination therapy with peposertib and low-dose doxorubicin (standard or liposomal formulations) inhibited growth of 5 of 7 LMS mouse models without toxicity.

Conclusion: Combinations of DNA-PK inhibitors with unconventionally low, sensitizing, doxorubicin dosing showed synergistic effects in LMS in vitro and in vivo models, without discernable toxicity. These findings underscore the relevance of DNA damage repair alterations in LMS pathogenesis and identify dependence on NHEJ as a clinically actionable vulnerability in LMS.

2022
Batalini F, Gulhan DC, Mao V, Tran A, Polak M, Xiong N, Tayob N, Tung NM, Winer EP, Mayer EL, Knappskog S, Lønning PE, Matulonis UA, Konstantinopoulos PA, Solit DB, Won H, Eikesdal HP, Park PJ, Wulf GM. Mutational Signature 3 Detected from Clinical Panel Sequencing is Associated with Responses to Olaparib in Breast and Ovarian Cancers. Clinical Cancer Research 2022;28(21):4714-4723.Abstract

Purpose: The identification of patients with homologous recombination deficiency (HRD) beyond BRCA1/2 mutations is an urgent task, as they may benefit from PARP inhibitors. We have previously developed a method to detect mutational signature 3 (Sig3), termed SigMA, associated with HRD from clinical panel sequencing data, that is able to reliably detect HRD from the limited sequencing data derived from gene-focused panel sequencing.

Experimental design: We apply this method to patients from two independent datasets: (i) high-grade serous ovarian cancer and triple-negative breast cancer (TNBC) from a phase Ib trial of the PARP inhibitor olaparib in combination with the PI3K inhibitor buparlisib (BKM120; NCT01623349), and (ii) TNBC patients who received neoadjuvant olaparib in the phase II PETREMAC trial (NCT02624973).

Results: We find that Sig3 as detected by SigMA is positively associated with improved progression-free survival and objective responses. In addition, comparison of Sig3 detection in panel and exome-sequencing data from the same patient samples demonstrated highly concordant results and superior performance in comparison with the genomic instability score.

Conclusions: Our analyses demonstrate that HRD can be detected reliably from panel-sequencing data that are obtained as part of routine clinical care, and that this approach can identify patients beyond those with germline BRCA1/2mut who might benefit from PARP inhibitors. Prospective clinical utility testing is warranted.

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2010
Goutagny S, Yang HW, Zucman-Rossi J, Chan J, Dreyfuss JM, Park PJ, Black PM, Giovannini M, Carroll RS, Kalamarides M. Genomic profiling reveals alternative genetic pathways of meningioma malignant progression dependent on the underlying NF2 status. Clin Cancer Res 2010;16(16):4155-64.Abstract

PURPOSE: Meningiomas are the most common central nervous system tumors in the population of age 35 and older. WHO defines three grades predictive of the risk of recurrence. Clinical data supporting histologic malignant progression of meningiomas are sparse and underlying molecular mechanisms are not clearly depicted. EXPERIMENTAL DESIGN: We identified genetic alterations associated with histologic progression of 36 paired meningioma samples in 18 patients using 500K SNP genotyping arrays and NF2 gene sequencing. RESULTS: The most frequent chromosome alterations observed in progressing meningioma samples are early alterations (i.e., present both in lower- and higher-grade samples of a single patient). In our series, NF2 gene inactivation was an early and frequent event in progressing meningioma samples (73%). Chromosome alterations acquired during progression from grade I to grade II meningioma were not recurrent. Progression to grade III was characterized by recurrent genomic alterations, the most frequent being CDKN2A/CDKN2B locus loss on 9p. CONCLUSION: Meningiomas displayed different patterns of genetic alterations during progression according to their NF2 status: NF2-mutated meningiomas showed higher chromosome instability during progression than NF2-nonmutated meningiomas, which had very few imbalanced chromosome segments. This pattern of alterations could thus be used as markers in clinical practice to identify tumors prone to progress among grade I meningiomas.

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