A personalized medicine approach identifies enasidenib as an efficient treatment for IDH2 mutant chondrosarcoma

Abstract

BackgroundSarcomas represent an extensive group of malignant diseases affecting mesodermal tissues. Among sarcomas, the clinical management of chondrosarcomas remains a complex challenge, as high-grade tumors do not respond to current therapies. Mutations in the isocitrate dehydrogenase (IDH) 1 and 2 genes are among the most common mutations detected in chondrosarcomas and may represent a therapeutic opportunity. The presence of mutated IDH (mIDH) enzymes results in the accumulation of the oncometabolite 2-HG leading to molecular alterations that contribute to drive tumor growth. MethodsWe developed a personalized medicine strategy based on the targeted NGS/Sanger sequencing of sarcoma samples (n=6) and the use of matched patient-derived cell lines as a drug-testing platform. The anti-tumor potential of IDH mutations found in two chondrosarcoma cases was analyzed in vitro, in vivo and molecularly (transcriptomic and DNA methylation analyses). FindingsWe treated several chondrosarcoma models with specific mIDH1/2 inhibitors. Among these treatments, only the mIDH2 inhibitor enasidenib was able to decrease 2-HG levels and efficiently reduce the viability of mIDH2 chondrosarcoma cells. Importantly, oral administration of enasidenib in xenografted mice resulted in a complete abrogation of tumor growth. Enasidenib induced a profound remodeling of the transcriptomic landscape not associated to changes in the 5mC methylation levels and its anti-tumor effects were associated with the repression of proliferative pathways such as those controlled by E2F factors. InterpretationOverall, this work provides the first preclinical evidence for the use of enasidenib to treat mIDH2 chondrosarcomas. FundingSpanish Research Agency (grants PID2019-106666RB-I00; PI20CIII/00020; DTS18CIII/00005; CB16/12/00390; CB06/07/1009; CB19/07/00057). RESEARCH IN CONTEXTO_ST_ABSEvidence before this studyC_ST_ABSSarcomas represent an extensive group of malignant diseases affecting mesodermal tissues. The genomic nature of most sarcoma subtypes, displaying high inter- and intra-tumor heterogeneity with few recurrent driver mutations in a small portion of patients, makes these tumors especially indicated for personalized treatment approaches. For optimal development of these personalized protocols and a more efficient translation to the clinic, it is necessary to create patient-derived models suitable for testing the efficiency of candidate therapies. These strategies might be especially indicated for chondrosarcomas, a subtype of bone sarcoma that is inherently resistant to current therapies. Added value of this studyTo develop a personalized medicine strategy for sarcomas we have applied targeted sequencing protocols to detect druggable mutations in a collection of sarcomas cases with available patient-derived models. Among those potential druggable alterations detected in patient samples and avatar cell lines, we found IDH mutations in two chondrosarcomas. The presence of mutated IDH enzymes results in the accumulation of the oncometabolite 2-HG which contributes to driving tumor growth. In vitro and in vivo experiments evidenced the anti-tumor potential of the IDH mutant inhibitor enasidenib for the treatment of IDH2 mutant chondrosarcomas. Our transcriptomic and epigenomic analyses show that the mechanism of action of this drug is associated with the repression of proliferative pathways rather than with the promotion of tumor differentiation. Implications of all the available evidenceThis study suggests that enasidenib may represent an efficient therapeutic alternative for mutant IDH2 chondrosarcomas. This anti-proliferative mechanism of action of this drug may be especially relevant in dedifferentiated chondrosarcomas where reversal of this phenotype is not possible. In addition, this work provides support for the use of sarcoma patient-derived lines as avatar models capable of predicting (pre)-clinical responses in personalized medicine strategies.