Assuntos
Antineoplásicos , Epigênese Genética , Segunda Neoplasia Primária , Neoplasias Ovarianas , Leucemia-Linfoma Linfoblástico de Células T Precursoras , Doenças Raras , Adulto , Feminino , Humanos , DNA Helicases/genética , Metilação de DNA , Epigênese Genética/efeitos dos fármacos , Proteínas Nucleares/genética , Neoplasias Ovarianas/diagnóstico , Neoplasias Ovarianas/genética , Neoplasias Ovarianas/terapia , Ovariectomia , Ovário/patologia , Ovário/cirurgia , Doenças Raras/diagnóstico , Doenças Raras/genética , Doenças Raras/terapia , Fatores de Transcrição/genética , Proteína Potenciadora do Homólogo 2 de Zeste/antagonistas & inibidores , Antineoplásicos/administração & dosagem , Antineoplásicos/efeitos adversos , Mutações Sintéticas Letais/efeitos dos fármacos , Leucemia-Linfoma Linfoblástico de Células T Precursoras/diagnóstico , Leucemia-Linfoma Linfoblástico de Células T Precursoras/genética , Segunda Neoplasia Primária/diagnóstico , Segunda Neoplasia Primária/genéticaRESUMO
Despite the potential of targeted epigenetic therapies, most cancers do not respond to current epigenetic drugs. The Polycomb repressive complex EZH2 inhibitor tazemetostat was recently approved for the treatment of SMARCB1-deficient epithelioid sarcomas, based on the functional antagonism between PRC2 and loss of SMARCB1. Through the analysis of tazemetostat-treated patient tumors, we recently defined key principles of their response and resistance to EZH2 epigenetic therapy. Here, using transcriptomic inference from SMARCB1-deficient tumor cells, we nominate the DNA damage repair kinase ATR as a target for rational combination EZH2 epigenetic therapy. We show that EZH2 inhibition promotes DNA damage in epithelioid and rhabdoid tumor cells, at least in part via its induction of the transposase-derived PGBD5. We leverage this collateral synthetic lethal dependency to target PGBD5-dependent DNA damage by inhibition of ATR but not CHK1 using elimusertib. Consequently, combined EZH2 and ATR inhibition improves therapeutic responses in diverse patient-derived epithelioid and rhabdoid tumors in vivo. This advances a combination epigenetic therapy based on EZH2-PGBD5 synthetic lethal dependency suitable for immediate translation to clinical trials for patients.
RESUMO
Epigenetic dependencies have become evident in many cancers. On the basis of antagonism between BAF/SWI-SNF and PRC2 in SMARCB1-deficient sarcomas, we recently completed the clinical trial of the EZH2 inhibitor tazemetostat. However, the principles of tumor response to epigenetic therapy in general, and tazemetostat in particular, remain unknown. Using functional genomics and diverse experimental models, we define molecular mechanisms of tazemetostat resistance in SMARCB1-deficient tumors. We found distinct acquired mutations that converge on the RB1/E2F axis and decouple EZH2-dependent differentiation and cell-cycle control. This allows tumor cells to escape tazemetostat-induced G1 arrest, suggests a general mechanism for effective therapy, and provides prospective biomarkers for therapy stratification, including PRICKLE1. On the basis of this, we develop a combination strategy to circumvent tazemetostat resistance using bypass targeting of AURKB. This offers a paradigm for rational epigenetic combination therapy suitable for translation to clinical trials for epithelioid sarcomas, rhabdoid tumors, and other epigenetically dysregulated cancers. SIGNIFICANCE: Genomic studies of patient epithelioid sarcomas and rhabdoid tumors identify mutations converging on a common pathway for response to EZH2 inhibition. Resistance mutations decouple drug-induced differentiation from cell-cycle control. We identify an epigenetic combination strategy to overcome resistance and improve durability of response, supporting its investigation in clinical trials. See related commentary by Paolini and Souroullas, p. 903. This article is featured in Selected Articles from This Issue, p. 897.