Pharmacokinetics/pharmacodynamics of ivosidenib in advanced IDH1-mutant cholangiocarcinoma: findings from the phase III ClarIDHy study

PURPOSE

Report pharmacokinetic (PK)/pharmacodynamic (PD) findings from the phase III ClarIDHy study and any association between PK/PD parameters and treatment outcomes in this population.

METHODS

Patients with mutant isocitrate dehydrogenase 1 (mIDH1) advanced cholangiocarcinoma were randomized at a 2:1 ratio to receive ivosidenib or matched placebo. Crossover from placebo to ivosidenib was permitted at radiographic disease progression. Blood samples for PK/PD analyses, a secondary endpoint, were collected pre-dose and up to 4 h post-dose on day (D) 1 of cycles (C) 1 - 2, pre-dose and 2 h post-dose on D15 of C1 - 2, and pre-dose on D1 from C3 onwards. Plasma ivosidenib and D-2-hydroxyglutarate (2-HG) were measured using liquid chromatography-tandem mass spectrometry. All clinical responses were centrally reviewed previously.

RESULTS

PK/PD analysis was available for samples from 156 ivosidenib-treated patients. Ivosidenib was absorbed rapidly following single and multiple oral doses (time of maximum observed plasma concentration [Tmax] of 2.63 and 2.07 h, respectively). Ivosidenib exposure was higher at C2D1 than after a single dose, with low accumulation. In ivosidenib-treated patients, mean plasma 2-HG concentration was reduced from 1108 ng/mL at baseline to 97.7 ng/mL at C2D1, close to levels previously observed in healthy individuals. An average 2-HG inhibition of 75.0% was observed at steady state. No plasma 2-HG decreases were seen with placebo. Plasma 2-HG reductions were observed in ivosidenib-treated patients irrespective of best overall response (progressive disease, or partial response and stable disease).

CONCLUSION

Once-daily ivosidenib 500 mg has a favorable PK/PD profile, attesting the 2-HG reduction mechanism of action and, thus, positive outcomes in treated patients with advanced mIDH1 cholangiocarcinoma.

CLINICAL TRIAL REGISTRATION

NCT02989857 Registered February 20, 2017.

Longitudinal trends in health-related quality of life (HRQoL) among patients treated with ivosidenib (IVO) for IDH1-mutated cholangiocarcinoma (CCA) in the ClarIDHy study

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Background: IVO—a first-in-class, oral, targeted inhibitor of the mutant IDH1 (mIDH1) protein, found mainly in intrahepatic CCAs (̃13% of patients globally)—is an FDA-approved therapy for the treatment of previously treated, locally advanced or metastatic mIDH1 CCA based on the results of the randomized, double-blind, phase 3 ClarIDHy study (NCT02989857). In this study, IVO significantly improved progression-free survival vs placebo (PBO) (HR = 0.37, p < 0.0001), resulted in a favorable overall survival trend vs PBO, and was well tolerated (Zhu JAMA Oncol 2021; Abou-Alfa Lancet Oncol 2020). Herein we describe the longitudinal assessment of HRQoL. Methods: A total of 126 and 61 patients were randomized to IVO 500 mg daily or PBO, respectively, with crossover to IVO permitted at radiographic disease progression. HRQoL was a secondary endpoint based on assessments with the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire Core 30 (EORTC QLQ-C30) and the Cholangiocarcinoma and Gallbladder Cancer module (QLQ-BIL21). Three domains of interest were prespecified: physical functioning (PF), pain, and appetite loss. After a protocol amendment, HRQoL was assessed predose on Cycle (C) 1 Day (D) 1, every 4 weeks on the first day of subsequent cycles until end of treatment (EOT), and every 12 weeks thereafter until start of new anticancer therapy (vs every 6 weeks between C1D1 and EOT in the original protocol). Mixed-effect models with repeated measurements were conducted on subscale score changes from baseline (BL). Results: At BL, EORTC QLQ-C30 and QLQ-BIL21 scores were available for 114 and 108 IVO patients and 53 and 52 PBO patients, respectively. Sample sizes for HRQoL analyses decreased in both arms over time, in part due to rapid disease progression, which is typical of CCA. No HRQoL assessments were available for PBO after C8 (Week 28), while change scores were available for some IVO patients beyond Week 52 (QLQ-C30 n = 17 at Week 52). From BL to C27D1, patients remaining on IVO tended to maintain their HRQoL, with no QLQ-C30 PF subscale change scores exceeding the threshold for clinically meaningful decline estimated from study data (12-13 points). For the small number of PBO patients with post-BL HRQoL assessments, clinically meaningful PF deterioration was observed at multiple cycles (C2D1, C3D1, C4D1, C5D1, C8D1). Similar preservation for IVO patients was observed on other prespecified subscales based on the published threshold of 10 points, indicating clinically meaningful change (ClarIDHy-based thresholds not estimable due to sample sizes). Conclusions: In ClarIDHy, patients with advanced mIDH1 CCA treated with IVO were likely to maintain their HRQoL over the duration of treatment, including those treated for relatively long periods of time (eg, 1 year). Clinical trial information: NCT02989857.

Final Overall Survival Efficacy Results of Ivosidenib for Patients With Advanced Cholangiocarcinoma With IDH1 Mutation: The Phase 3 Randomized Clinical ClarIDHy Trial

Question

Does ivosidenib treatment improve overall survival outcomes vs placebo among patients with chemotherapy-refractory cholangiocarcinoma with IDH1 mutation?

Findings

In this phase 3 randomized clinical trial including 187 previously treated patients with advanced cholangiocarcinoma with IDH1 mutation, ivosidenib treatment resulted in numerically improved overall survival benefits vs placebo, despite a high rate of crossover. Ivosidenib preserved certain quality of life subscales and was well tolerated.

Meaning

The combined efficacy data and tolerable safety profile, as well as corroborating quality of life data, support the clinical benefit of ivosidenib relative to placebo in cholangiocarcinoma with IDH1 mutation, which has an unmet need for new treatments.

Importance

Isocitrate dehydrogenase 1 (IDH1) variations occur in up to approximately 20% of patients with intrahepatic cholangiocarcinoma. In the ClarIDHy trial, progression-free survival as determined by central review was significantly improved with ivosidenib vs placebo.

Objective

To report the final overall survival (OS) results from the ClarIDHy trial, which aimed to demonstrate the efficacy of ivosidenib (AG-120)—a first-in-class, oral, small-molecule inhibitor of mutant IDH1—vs placebo for patients with unresectable or metastatic cholangiocarcinoma with IDH1 mutation.

Design, Setting, and Participants

This multicenter, randomized, double-blind, placebo-controlled, clinical phase 3 trial was conducted from February 20, 2017, to May 31, 2020, at 49 hospitals across 6 countries among patients aged 18 years or older with cholangiocarcinoma with IDH1 mutation whose disease progressed with prior therapy.

Interventions

Patients were randomized 2:1 to receive ivosidenib, 500 mg, once daily or matched placebo. Crossover from placebo to ivosidenib was permitted if patients had disease progression as determined by radiographic findings.

Main Outcomes and Measures

The primary end point was progression-free survival as determined by blinded independent radiology center (reported previously). Overall survival was a key secondary end point. The primary analysis of OS followed the intent-to-treat principle. Other secondary end points included objective response rate, safety and tolerability, and quality of life.

Results

Overall, 187 patients (median age, 62 years [range, 33-83 years]) were randomly assigned to receive ivosidenib (n = 126; 82 women [65%]; median age, 61 years [range, 33-80 years]) or placebo (n = 61; 37 women [61%]; median age, 63 years [range, 40-83 years]); 43 patients crossed over from placebo to ivosidenib. The primary end point of progression-free survival was reported elsewhere. Median OS was 10.3 months (95% CI, 7.8-12.4 months) with ivosidenib vs 7.5 months (95% CI, 4.8-11.1 months) with placebo (hazard ratio, 0.79 [95% CI, 0.56-1.12]; 1-sided P = .09). When adjusted for crossover, median OS with placebo was 5.1 months (95% CI, 3.8-7.6 months; hazard ratio, 0.49 [95% CI, 0.34-0.70]; 1-sided P < .001). The most common grade 3 or higher treatment-emergent adverse event (≥5%) reported in both groups was ascites (11 patients [9%] receiving ivosidenib and 4 patients [7%] receiving placebo). Serious treatment-emergent adverse events considered ivosidenib related were reported in 3 patients (2%). There were no treatment-related deaths. Patients receiving ivosidenib reported no apparent decline in quality of life compared with placebo.

Conclusions and Relevance

This randomized clinical trial found that ivosidenib was well tolerated and resulted in a favorable OS benefit vs placebo, despite a high rate of crossover. These data, coupled with supportive quality of life data and a tolerable safety profile, demonstrate the clinical benefit of ivosidenib for patients with advanced cholangiocarcinoma with IDH1 mutation.

Trial Registration

ClinicalTrials.gov Identifier: NCT02989857

Final results from ClarIDHy, a global, phase 3, randomized, double-blind study of ivosidenib (IVO) versus placebo (PBO) in patients (pts) with previously treated cholangiocarcinoma (CCA) and an isocitrate dehydrogenase 1 (IDH1) mutation

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Background: CCA is a rare cancer for which there are limited effective therapies. IDH1 mutations occur in ̃20% of intrahepatic CCAs, resulting in production of the oncometabolite D-2-hydroxyglutarate, which promotes oncogenesis. IVO (AG-120) is a first-in-class, oral, small-molecule inhibitor of mutant IDH1 (mIDH1). ClarIDHy aimed to demonstrate the efficacy of IVO vs PBO in pts with unresectable or metastatic m IDH1 CCA. The primary endpoint was met with significant improvement in progression-free survival (PFS) by independent radiology center (IRC) with IVO vs PBO (hazard ratio [HR] = 0.37, p < 0.0001). Objective response rate (ORR) and stable disease for IVO were 2.4% (3 partial responses) and 50.8% (n = 63) vs 0% and 27.9% (n = 17) for PBO. IVO pts experienced significantly less decline in physical and emotional functioning domains of quality of life at cycle 2 day 1 vs PBO pts (nominal p < 0.05). Methods: Pts with m IDH1 CCA were randomized 2:1 to IVO (500 mg PO QD) or matched PBO and stratified by prior systemic therapies (1 or 2). Key eligibility: unresectable or metastatic m IDH1 CCA based on central testing; ECOG PS 0–1; measurable disease (RECIST v1.1). Crossover from PBO to IVO was permitted at radiographic progression. Primary endpoint: PFS by IRC. Secondary endpoints included overall survival (OS; by intent-to-treat), ORR, PFS (by investigator), safety, and quality of life. The planned crossover-adjusted OS was derived using the rank-preserving structural failure time (RPSFT) model. Results: As of 31 May 2020, ̃780 pts were prescreened for an IDH1 mutation and 187 were randomized to IVO (n = 126) or PBO (n = 61); 13 remain on IVO. Median age 62 y; M/F 68/119; 91% intrahepatic CCA; 93% metastatic disease; 47% had 2 prior therapies. 70% of PBO pts crossed over to IVO. OS data were mature, with 79% OS events in IVO arm and 82% in PBO. Median OS (mOS) was 10.3 months for IVO and 7.5 months for PBO (HR = 0.79; 95% CI 0.56–1.12; one-sided p = 0.093). The RPSFT-adjusted mOS was 5.1 months for PBO (HR = 0.49; 95% CI 0.34–0.70; p < 0.0001). Common all-grade treatment emergent adverse events (TEAEs, ≥ 15%) in the IVO arm: nausea 41%, diarrhea 35%, fatigue 31%, cough 25%, abdominal pain 24%, decreased appetite 24%, ascites 23%, vomiting 23%, anemia 18%, and constipation 15%. Grade ≥ 3 TEAEs were reported in 50% of IVO pts vs 37% of PBO pts, with grade ≥ 3 treatment-related AEs in 7% of IVO pts vs 0% in PBO. 7% of IVO pts experienced an AE leading to treatment discontinuation vs 9% of PBO pts. There were no treatment-related deaths. Conclusions: IVO was well tolerated and resulted in a favorable OS trend vs PBO despite a high rate of crossover. These data – coupled with statistical improvement in PFS, supportive quality of life data, and favorable safety profile – demonstrate the clinical benefit of IVO in advanced m IDH1 CCA. Clinical trial information: NCT02989857.

Molecular and morphological changes induced by ivosidenib correlate with efficacy in mutant-IDH1 cholangiocarcinoma

Background: IDH1 mutations occur in approximately 13% of intrahepatic cholangiocarcinomas (IHCCs). The oral, targeted, mutant IDH1 (mIDH1) inhibitor ivosidenib (AG-120) suppresses production of the oncometabolite D-2-hydroxyglutarate, promoting disease stabilization and improved progression-free survival (PFS) in mIDH1 IHCC. Materials & methods: Harnessing matched baseline and on-treatment biopsies, we investigate the potential mechanisms underlying ivosidenib's efficacy. Results: mIDH1 inhibition leads to decreased cytoplasm and expression of hepatocyte lineage markers in patients with prolonged PFS. These findings are accompanied by downregulation of biliary fate, cell cycle progression and AKT pathway activity. Conclusion: Ivosidenib stimulates a hepatocyte differentiation program in mIDH1 IHCC, a phenotype associated with clinical benefit. mIDH1 inhibition could be a paradigm for differentiation-based therapy in solid tumors. Clinical trial registration: NCT02073994 (ClinicalTrials.gov).

Final results from ClarIDHy, a global, phase III, randomized, double-blind study of ivosidenib (IVO) versus placebo (PBO) in patients (pts) with previously treated cholangiocarcinoma (CCA) and an isocitrate dehydrogenase 1 (IDH1) mutation

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Background: CCA is a rare cancer for which there are limited effective therapies. IDH1 mutations occur in ~20% of intrahepatic CCAs, resulting in production of the oncometabolite D-2-hydroxyglutarate, which promotes oncogenesis. IVO (AG-120) is a first-in-class, oral, small-molecule inhibitor of mutant IDH1 (m IDH1). ClarIDHy aimed to demonstrate the efficacy of IVO vs PBO in pts with unresectable or metastatic m IDH1 CCA. The primary endpoint was met with significant improvement in progression-free survival (PFS) by independent radiology center (IRC) with IVO vs PBO (hazard ratio [HR] = 0.37, p < 0.0001). Objective response rate (ORR) and stable disease for IVO were 2.4% (3 partial responses) and 50.8% (n = 63) vs 0% and 27.9% (n = 17) for PBO. IVO pts experienced significantly less decline in physical and emotional functioning domains of quality of life at cycle 2 day 1 vs PBO pts (nominal p < 0.05). Methods: Pts with m IDH1 CCA were randomized 2:1 to IVO (500 mg PO QD) or matched PBO and stratified by prior systemic therapies (1 or 2). Key eligibility: unresectable or metastatic m IDH1 CCA based on central testing; ECOG PS 0–1; measurable disease (RECIST v1.1). Crossover from PBO to IVO was permitted at radiographic progression. Primary endpoint: PFS by IRC. Secondary endpoints included overall survival (OS; by intent-to-treat), ORR, PFS (by investigator), safety, and quality of life. The planned crossover-adjusted OS was derived using the rank-preserving structural failure time (RPSFT) model. Results: As of 31 May 2020, ~780 pts were prescreened for an IDH1 mutation and 187 were randomized to IVO (n = 126) or PBO (n = 61); 13 remain on IVO. Median age 62 y; M/F 68/119; 91% intrahepatic CCA; 93% metastatic disease; 47% had 2 prior therapies. 70% of PBO pts crossed over to IVO. OS data were mature, with 79% OS events in IVO arm and 82% in PBO. Median OS (mOS) was 10.3 months for IVO and 7.5 months for PBO (HR = 0.79; 95% CI 0.56–1.12; one-sided p = 0.093). The RPSFT-adjusted mOS was 5.1 months for PBO (HR = 0.49; 95% CI 0.34–0.70; p < 0.0001). Common all-grade treatment emergent adverse events (TEAEs, ≥ 15%) in the IVO arm: nausea 41%, diarrhea 35%, fatigue 31%, cough 25%, abdominal pain 24%, decreased appetite 24%, ascites 23%, vomiting 23%, anemia 18%, and constipation 15%. Grade ≥ 3 TEAEs were reported in 50% of IVO pts vs 37% of PBO pts, with grade ≥ 3 treatment-related AEs in 7% of IVO pts vs 0% in PBO. 7% of IVO pts experienced an AE leading to treatment discontinuation vs 9% of PBO pts. There were no treatment-related deaths. Conclusions: IVO was well tolerated and resulted in a favorable OS trend vs PBO despite a high rate of crossover. These data – coupled with statistical improvement in PFS, supportive quality of life data, and favorable safety profile – demonstrate the clinical benefit of IVO in advanced m IDH1 CCA. Clinical trial information: NCT02989857.

Ivosidenib in IDH1-mutant, chemotherapy-refractory cholangiocarcinoma (ClarIDHy): a multicentre, randomised, double-blind, placebo-controlled, phase 3 study

BACKGROUND

Isocitrate dehydrogenase 1 (IDH1) mutations occur in approximately 13% of patients with intrahepatic cholangiocarcinoma, a relatively uncommon cancer with a poor clinical outcome. The aim of this international phase 3 study was to assess the efficacy and safety of ivosidenib (AG-120)-a small-molecule targeted inhibitor of mutated IDH1-in patients with previously treated IDH1-mutant cholangiocarcinoma.

METHODS

This multicentre, randomised, double-blind, placebo-controlled, phase 3 study included patients from 49 hospitals in six countries aged at least 18 years with histologically confirmed, advanced, IDH1-mutant cholangiocarcinoma who had progressed on previous therapy, and had up to two previous treatment regimens for advanced disease, an Eastern Cooperative Oncology Group performance status score of 0 or 1, and a measurable lesion as defined by Response Evaluation Criteria in Solid Tumors version 1.1. Patients were randomly assigned (2:1) with a block size of 6 and stratified by number of previous systemic treatment regimens for advanced disease to oral ivosidenib 500 mg or matched placebo once daily in continuous 28-day cycles, by means of an interactive web-based response system. Placebo to ivosidenib crossover was permitted on radiological progression per investigator assessment. The primary endpoint was progression-free survival by independent central review. The intention-to-treat population was used for the primary efficacy analyses. Safety was assessed in all patients who had received at least one dose of ivosidenib or placebo. Enrolment is complete; this study is registered with ClinicalTrials.gov, NCT02989857.

FINDINGS

Between Feb 20, 2017, and Jan 31, 2019, 230 patients were assessed for eligibility, and as of the Jan 31, 2019 data cutoff date, 185 patients were randomly assigned to ivosidenib (n=124) or placebo (n=61). Median follow-up for progression-free survival was 6·9 months (IQR 2·8-10·9). Progression-free survival was significantly improved with ivosidenib compared with placebo (median 2·7 months [95% CI 1·6-4·2] vs 1·4 months [1·4-1·6]; hazard ratio 0·37; 95% CI 0·25-0·54; one-sided p<0·0001). The most common grade 3 or worse adverse event in both treatment groups was ascites (four [7%] of 59 patients receiving placebo and nine [7%] of 121 patients receiving ivosidenib). Serious adverse events were reported in 36 (30%) of 121 patients receiving ivosidenib and 13 (22%) of 59 patients receiving placebo. There were no treatment-related deaths.

INTERPRETATION

Progression-free survival was significantly improved with ivosidenib compared with placebo, and ivosidenib was well tolerated. This study shows the clinical benefit of targeting IDH1 mutations in advanced, IDH1-mutant cholangiocarcinoma.

FUNDING

Agios Pharmaceuticals.

Phase I Study of the Mutant IDH1 Inhibitor Ivosidenib: Safety and Clinical Activity in Patients With Advanced Chondrosarcoma

PURPOSE

Surgery is the primary therapy for localized chondrosarcoma; for locally advanced and/or metastatic disease, no known effective systemic therapy exists. Mutations in the isocitrate dehydrogenase 1/2 (IDH1/2) enzymes occur in up to 65% of chondrosarcomas, resulting in accumulation of the oncometabolite D-2-hydroxyglutarate (2-HG). Ivosidenib (AG-120) is a selective inhibitor of mutant IDH1 approved in the United States for specific cases of acute myeloid leukemia. We report outcomes of patients with advanced chondrosarcoma in an ongoing study exploring ivosidenib treatment.

PATIENTS AND METHODS

This phase I multicenter open-label dose-escalation and expansion study of ivosidenib monotherapy enrolled patients with mutant IDH1 advanced solid tumors, including chondrosarcoma. Ivosidenib was administered orally (100 mg twice daily to 1,200 mg once daily) in continuous 28-day cycles. Responses were assessed every other cycle using RECIST (version 1.1).

RESULTS

Twenty-one patients (escalation, n = 12; expansion, n = 9) with advanced chondrosarcoma received ivosidenib (women, n = 8; median age, 55 years; range, 30-88 years; 11 had received prior systemic therapy). Treatment-emergent adverse events (AEs) were mostly grade 1 or 2. Twelve patients experienced grade ≥ 3 AEs; only one event was judged treatment related (hypophosphatemia, n = 1). Plasma 2-HG levels decreased substantially in all patients (range, 14%-94.2%), to levels seen in healthy individuals. Median progression-free survival (PFS) was 5.6 months (95% CI, 1.9 to 7.4 months); the PFS rate at 6 months was 39.5%. Eleven (52%) of 21 patients experienced stable disease.

CONCLUSION

In patients with chondrosarcoma, ivosidenib showed minimal toxicity, substantial 2-HG reduction, and durable disease control. Future studies of ivosidenib monotherapy or rational combination approaches should be considered in patients with advanced mutant IDH1 chondrosarcoma.

IDH1 mutation detection in plasma circulating tumor DNA (ctDNA) and association with clinical response in patients with advanced intrahepatic cholangiocarcinoma (IHC) from the phase III ClarIDHy study

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Background: Mutations in isocitrate dehydrogenase 1 ( IDH1) are detected in ~13% of IHCs. Ivosidenib (IVO) is a first-in-class, oral inhibitor of the mutant IDH1 (mIDH1) protein. In ClarIDHy, a global, phase 3, double-blind study in previously treated patients with advanced m IDH1 IHC (N = 186), IVO demonstrated an improvement in progression-free survival (PFS) vs placebo (hazard ratio 0.37, p < 0.001) (Abou-Alfa et al., Ann Oncol 2019; NCT02989857). Feasibility of m IDH1 detection in plasma ctDNA from patients with IHC was demonstrated and was highly concordant with mutation status in tumor tissue (Aguado-Fraile et al., Cancer Res 2019). This analysis was extended to the larger patient cohort from ClarIDHy, and longitudinal m IDH1 detection from ctDNA was assessed and correlated with clinical response. Methods: Baseline plasma and tumor tissue samples were obtained before randomization; longitudinal plasma samples were collected on day 1 of each treatment cycle. m IDH1 status in tissue was prospectively and centrally confirmed using Oncomine Focus Assay. A BEAMing digital PCR test was used for quantification of m IDH1 in plasma. IDH1 mutation clearance ( IDH1-MC) was achieved when plasma m IDH1 variant allele frequency was below the assay’s sensitivity (0.02% for R132C/L/S/G; 0.04% for R132H). Results: m IDH1 detection in plasma ctDNA and tissue was concordant in 92% (193/210) of samples screened. As of 31 Jan 2019, median PFS was 2.7 months for IVO vs 1.4 months for placebo. Longitudinal analysis with biomarker data available as of Jan 2020 demonstrated IDH1-MC in plasma from 10 IVO-treated patients with PFS ≥2.7 months (n = 36) vs 0 patients with PFS < 2.7 months (n = 40). No IDH1-MC was observed in patients treated with placebo, irrespective of response (n = 49). Conclusions: These results reinforce the feasibility of IDH1-R132 detection in plasma from patients with IHC, with a 92% concordance with detection in tumor tissue, supporting m IDH1 detection in liquid biopsy as a viable patient selection strategy where tissue exhaustion can limit conventional methods. Plasma IDH1-MC was also observed in a subset of IVO-treated patients who achieved disease control. Clinical trial information: NCT02989857 .

Pharmacokinetics/pharmacodynamics (PK/PD) of ivosidenib in patients with mutant IDH1 advanced cholangiocarcinoma from the phase III ClarIDHy study

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Background: Mutations in isocitrate dehydrogenase 1 (m IDH1) occur in up to 20% of intrahepatic cholangiocarcinomas (CC), leading to accumulation of 2-hydroxyglutarate (2-HG) and epigenetic dysregulation, promoting oncogenesis. Ivosidenib (IVO; AG-120), a first in-class, oral, targeted inhibitor of the mIDH1 enzyme, showed improved progression-free survival and a positive trend in overall survival versus placebo (PBO) in ClarIDHy, a global, phase 3, multicenter, double-blind study (Abou-Alfa et al. ESMO 2019 LBA10_PR; NCT02989857). Methods: Patients (pts) with unresectable or metastatic m IDH1 CC were randomized 2:1 to IVO (500 mg once daily in continuous 28-day cycles) or matched PBO, stratified by number of prior systemic therapies (1 or 2). Crossover from PBO to IVO was permitted at radiographic progressive disease. Blood samples for PK/PD analyses, a secondary endpoint, were collected predose, 0.5, 2, and 4 h postdose on day (D) 1 of cycles (C) 1–2, predose and 2 h postdose on D15 of C1–2, and predose on D1 from C3 onwards. Plasma IVO and 2-HG were measured using validated or qualified LC-MS/MS methods. Results: As of 31Jan2019, 185 pts were randomized to IVO (n = 124) or PBO (n = 61); 35 pts crossed over to IVO. PK/PD analysis was available from 156 pts receiving IVO. IVO was absorbed rapidly following single and multiple oral doses; exposure, as measured by Cmax and AUC, was higher at C2D1 than after a single dose, with low accumulation. Plasma IVO reached steady state within C1 of daily dosing. In pts receiving IVO, baseline mean plasma 2-HG concentration was reduced from 1108 ng/mL to 97.7 ng/mL at C2D1, close to levels in healthy subjects (72.6±21.8 ng/mL). 2-HG inhibition was robust and persistent up to Cycle 19. An average 2-HG inhibition of 75.0% (up to 97.3%) was observed at steady-state after multiple IVO administrations. No plasma 2-HG decreases were seen with PBO. Analyses of plasma 2-HG levels and association with clinical outcomes will be presented. Conclusions: In pts with advanced m IDH1 CC, oral IVO 500 mg once-daily demonstrated good exposure, and maintained the inhibition of 2-HG to levels observed in healthy subjects, whereas 2-HG remained elevated with PBO. Clinical trial information: NCT02989857.

Clinical pharmacokinetics and pharmacodynamics of ivosidenib, an oral, targeted inhibitor of mutant IDH1, in patients with advanced solid tumors

Background Mutant isocitrate dehydrogenase 1 and 2 (IDH1/IDH2) enzymes produce the oncometabolite D-2-hydroxyglutarate (2-HG). Ivosidenib (AG-120) is a targeted mutant IDH1 inhibitor under evaluation in a phase 1 dose escalation and expansion study of IDH1-mutant advanced solid tumors including cholangiocarcinoma, chondrosarcoma, and glioma. We explored the pharmacokinetic (PK) and pharmacodynamic (PD) profiles of ivosidenib in these populations. Methods Ivosidenib was administered orally once (QD) or twice (BID) daily in continuous 28-day cycles; 168 patients received ≥1 dose within the range 100 mg BID to 1200 mg QD. PK and PD were assessed using validated liquid chromatography-tandem mass spectrometry assays. Results Ivosidenib demonstrated good oral exposure after single and multiple doses, was rapidly absorbed, and had a long terminal half-life (mean 40–102 h after single dose). Exposure increased less than dose proportionally. Steady state was reached by day 15, with moderate accumulation across all tumors (1.5- to 1.7-fold for area-under-the-curve at 500 mg QD). None of the intrinsic and extrinsic factors assessed affected ivosidenib exposure, including patient/disease characteristics and concomitant administration of weak CYP3A4 inhibitors/inducers. After multiple doses in patients with cholangiocarcinoma or chondrosarcoma, plasma 2-HG was reduced by up to 98%, to levels seen in healthy subjects. Exposure-response relationships for safety and efficacy outcomes were flat across the doses tested. Conclusions Ivosidenib demonstrated good oral exposure and a long half-life. Robust, persistent plasma 2-HG inhibition was observed in IDH1-mutant cholangiocarcinoma and chondrosarcoma. Ivosidenib 500 mg QD is an appropriate dose irrespective of various intrinsic and extrinsic factors. Trial RegistrationClinicalTrials.gov (NCT02073994).

ClarIDHy: A phase 3 multicenter randomized double-blind study of AG-120 versus placebo in patients with non-resectable or metastatic cholangiocarcinoma with an IDH1 mutation

TPS545

Background: Advanced cholangiocarcinoma (CC) is a life-threatening disease with limited effective chemotherapy options. Mutations in isocitrate dehydrogenase 1 (mIDH1) occur in 13–15% of CC cases, and up to 25% of intrahepatic CC cases, leading to epigenetic and genetic changes that promote oncogenesis via production of the oncometabolite 2-hydroxyglutarate (2-HG). AG-120 (ivosidenib), a first-in-class oral mIDH1 inhibitor, displayed a favorable safety profile and clinical activity in a phase 1 study enrolling 73 mIDH1 CC patients who had received ≥1 prior systemic regimen. As of 10 Mar 2017, 4/73 (5%) had a partial response and 41/73 (56%) stable disease. Progression free survival (PFS) rates at 6 months and 12 months were 38.5% and 20.7%, respectively. The 500 mg once daily dose level of AG-120 was selected for further development in mIDH1 CC. Methods: ClarIDHy is a global, phase 3, multicenter, double-blind, randomized (2:1) study of AG-120 (500 mg once daily) vs. matched placebo in 186 mIDH1 CC patients (ClinicalTrials.gov NCT02989857). Key eligibility criteria: non-resectable or metastatic CC, documented mIDH1 by central laboratory testing, ECOG performance status 0–1, measurable disease (RECIST v1.1), documented disease progression after ≤2 prior systemic therapies in the advanced setting including at least 1 gemcitabine- or 5-fluorouracil-containing regimen, and no prior mIDH inhibitor therapy. Crossover from placebo to AG-120 will be allowed at time of radiographic disease progression. Primary endpoint: PFS assessed by independent radiologists. Secondary endpoints: safety, tolerability, overall response rate (RECIST 1.1), overall survival, pharmacokinetic/pharmacodynamic analyses, and quality of life (EORTC QLQ-C30 and QLQ-BIL21 scales). An independent data monitoring committee will monitor the data during study conduct. The ClarIDHy study is currently activated at participating sites in the US, UK, EU, and S. Korea. R eused with permission from the American Society of Clinical Oncology (ASCO). This abstract was accepted and previously presented at the 2017 ASCO Annual Meeting. All rights reserved. Clinical trial information: NCT02989857.

Abstract A071: AG-120 (ivosidenib), a first-in-class mutant IDH1 inhibitor, promotes morphologic changes and upregulates liver-specific genes in IDH1 mutant cholangiocarcinoma

Background: Somatic mutations in the isocitrate dehydrogenase 1 (IDH1) gene have been reported in ~25% of patients with intrahepatic cholangiocarcinoma (CC). The mutant IDH1 (mIDH1) enzyme has a gain-of-function activity, catalyzing the reduction of alpha-ketoglutarate to D-2-hydroxyglutarate (2-HG). Accumulation of 2-HG leads to epigenetic dysregulation, and potential silencing of genes that control cellular differentiation. In a preclinical model of liver development, IDH1 mutation resulted in HNF4A silencing and impaired hepatocyte differentiation. AG-120 (ivosidenib) is a first-in-class, oral, selective inhibitor of mIDH1 that has been shown to reduce 2-HG levels in plasma and tumor tissue in preclinical and clinical studies, and to induce differentiation of leukemic blasts in patients with acute myeloid leukemia. In solid tumors, the consequences of IDH1 mutations and the effects of inhibition are less understood. In AG120-C-002 (ClinicalTrials.gov NCT02073994), a phase 1 clinical trial in mIDH1 advanced solid tumors, 73 patients with CC were treated with AG-120 at doses ranging from 100 mg twice daily to 1200 mg once daily. Among the phase 1 CC subjects who underwent on-study biopsies, we assessed morphologic and gene expression profile changes to understand the relationship between these parameters. Methods: Biopsy samples were collected from patients with CC enrolled in AG120-C-002 at screening, Cycle 3 Day 1, and in some cases Cycle 7 Day 1, disease progression, and end of treatment. Fourteen pre- and post-dose formalin-fixed paraffin-embedded (FFPE) tumor sample pairs were evaluable for morphology assessment (from 27 FFPE pre- and post-dose pairs collected), and 19 pre- and post-dose fresh frozen tumor sample pairs underwent gene expression profiling (from 38 pre- and post-dose pairs collected). Both morphology and gene expression data were assessed in eight patients to elucidate their relationship. Hematoxylin and eosin stained sections were evaluated for a cholangiocellular growth pattern and cytoplasmic alterations by two gastrointestinal pathologists from independent institutions. Gene expression profiles were generated by RNA sequencing to relate to morphologic changes. Results: Morphologic assessment of 14 pre- and post-dose sample pairs showed that upon 8-24 weeks of AG-120 treatment, a subset of CCs exhibited change in two phenotypes: (a) an increase of 20% or more in the cholangiocellular growth pattern (n=5), and (b) a reduction in the volume of cytoplasm (n=8). Changes in both phenotypes (a) and (b) were seen in five cases. RNA sequence profiling in samples with increased cholangiolar histology also showed a trend toward increased liver-specific gene expression. Conclusions: This is the first demonstration that AG-120 treatment may induce morphologic and molecular changes in a subset of mIDH1 CCs. Correlation of changes in morphology and gene expression with specific clinical outcomes will be described. Further studies, such as methylation changes, protein change by immunohistochemistry, and preclinical studies, are warranted to understand the biology of these morphologic and gene expression changes.

Citation Format: Yuko Ishii, Carlie Sigel, Maeve A. Lowery, Lipika Goyal, Camelia Gliser, Liewen Jiang, Susan Pandya, Bin Wu, Sung Choe, Vikram Deshpande. AG-120 (ivosidenib), a first-in-class mutant IDH1 inhibitor, promotes morphologic changes and upregulates liver-specific genes in IDH1 mutant cholangiocarcinoma [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr A071.

Abstract B126: AG-881, a brain penetrant, potent, pan-mutant IDH (mIDH) inhibitor for use in mIDH solid and hematologic malignancies

AG-881 is an orally available, brain penetrant, potent, small-molecule inhibitor of isocitrate dehydrogenase (IDH) 1 and IDH2 mutant proteins. Small-molecule inhibition of the mutant IDH (mIDH) protein represents a targeted approach to cancer treatment for patients who harbor an IDH1 and/or an IDH2 mutation. Direct inhibition of the gain-of-function activity of the mIDH protein is intended to inhibit the production of the oncogenic metabolite D-2-hydroxyglutarate (2-HG) and induce tumor cell differentiation.

Biochemical studies of AG-881 demonstrate that it has low nanomolar potency inhibition (IC50) against multiple mIDH homodimer and heterodimer enzymes. It is a rapid-equilibrium inhibitor of mIDH1-R132H and mIDH2-R172K homodimer enzymes and is a slow-binding inhibitor of mIDH2-R140Q homodimer and wild type (wt) IDH1/mIDH1-R132H, wtIDH2/mIDH2-R140Q, and wtIDH2/mIDH2-R172K heterodimers.

The potency against mIDH1 and mIDH2 enzymes has also been shown in cell lines and primary human patient samples. The IC50 range for 2-HG inhibition by AG-881 was 0.04-22 nM in cells expressing mIDH1-R132C, mIDH1-R132G, mIDH1-R132H, or mIDH1-R132S mutations and was 7-14 nM and 130 nM in cells expressing mIDH2-R140Q and mIDH2-R172K mutations, respectively. The treatment of these mIDH cell lines or primary human acute myeloid leukemia samples with AG-881 led to the onset of cellular differentiation.

The pharmacokinetics of AG-881 are characterized by rapid oral absorption and low total body plasma clearance in mice (0.406 L/hr/kg) and rats (0.289 L/hr/kg). Because of these favorable properties, a series of in vivo pharmacology studies were conducted with AG-881 in mouse xenograft models. In these studies, dose-response relationships for the reduction in 2-HG in tumor by AG-881 were established. Twice-daily dosing of AG-881 in the HT1080 (mIDH1-R132C) and U87 (mIDH2-R140Q) mouse models reduced tumor 2-HG levels by &gt;96% at doses ≥30 mg/kg. In the orthotopic glioma model (mIDH1-R132H), brain tumor 2-HG levels were reduced by &gt;97% at doses ≥0.1 mg/kg. Based on in vivo exposure-response analyses, plasma AG-881 AUC0-24hr values of 402 hr•ng/mL and 45,200 hr•ng/mL are projected to result in sustained 97% reduction in tumor 2-HG levels in the glioma indication and the non-glioma solid and liquid tumor indications, respectively. AG-881 also exhibits excellent brain penetration, with brain-to-plasma ratios ranging from 0.62 to 1.96 in mice and 1.11 to 1.48 in rats (based on AUC0-24hr), and has an acceptable preclinical safety profile that supports clinical testing.

Taken together, these data show that AG-881 is a potent inhibitor of the mIDH1 and mIDH2 proteins and suppresses 2-HG production in enzymatic, cell-based, and in vivo systems. Pharmacology studies support that suppression of 2-HG levels by AG-881 results in alterations of cellular downstream markers, leading to a release from blockage of tumor cell differentiation. AG-881 is currently in phase 1 clinical development in patients with an IDH1 and/or IDH2-mutation who have advanced solid tumors including gliomas (ClinicalTrials.gov NCT02481154), and advanced hematologic malignancies (ClinicalTrials.gov NCT02492737).

Citation Format: Katharine Yen, Zenon Konteatis, Zhihua Sui, Erin Artin, Lenny Dang, Kimberly Straley, Erica Tobin, Carl Campos, Hua Yang, Raj Nagaraja, Yue Chen, Hyeryun Kim, Camelia Gliser, Brandon Nicolay, Andrew Olaharski, Lee Silverman, Scott Biller, Shinsan M. Su, Ingo Mellinghoff, Janeta Popovici-Muller. AG-881, a brain penetrant, potent, pan-mutant IDH (mIDH) inhibitor for use in mIDH solid and hematologic malignancies [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr B126.

ClarIDHy: A phase 3, multicenter, randomized, double-blind study of AG-120 vs placebo in patients with an advanced cholangiocarcinoma with an IDH1 mutation

TPS4142

Background: Advanced cholangiocarcinoma (CC) is a life-threatening disease for which there are limited therapeutic options. Mutations in isocitrate dehydrogenase 1 (mIDH1) occur in up to 25% of intrahepatic CC cases. mIDH1 lead to epigenetic and genetic changes that promote oncogenesis via production of the oncometabolite, D-2-hydroxyglutarate (2-HG). AG-120 is a first-in-class oral inhibitor of the mIDH1 enzyme, and is being tested in a phase 1 study that enrolled 73 patients (pts) with mIDH1 CC who had received a median of 2 prior therapies (range 1–5). AG-120 has demonstrated a favorable safety profile and clinical activity in this study. Among the 72 efficacy evaluable pts (≥1 post-baseline response assessment or discontinued prematurely), 6% (n = 4) had a confirmed partial response and 56% (n = 40) had stable disease. Progression-free survival (PFS) rate at 6 months was 40% as of Dec 16, 2016. The 500 mg once daily (QD) dose of AG-120 was selected for the ongoing phase 3 study in mIDH1 CC described here. Methods: ClarIDHy is a global, phase 3, multicenter, double-blind study randomizing 186 pts with mIDH1 CC in a 2:1 ratio to AG-120 (500 mg QD) or matched placebo (NCT02989857). Key eligibility criteria: nonresectable or metastatic CC; documented mIDH1 based on central laboratory testing; ECOG 0–1; measurable disease (RECIST v1.1); documented disease progression following ≤2 prior systemic therapies in the advanced setting, including at least 1 gemcitabine- or 5-fluorouracil-containing regimen; and no prior mIDH inhibitor therapy. Crossover from the placebo arm to the AG-120 arm will be permitted. The primary endpoint is PFS as assessed by an independent review. Secondary endpoints include safety, tolerability, overall response rate, overall survival, pharmacokinetic and pharmacodynamic analyses on plasma, and quality of life as assessed by the EORTC QLQ-C30, EORTC QLQ-BIL21, and EQ-5D-5L instruments. An independent data monitoring committee will monitor the data throughout the study. The ClarIDHy study is currently activated at participating sites in the US and will be activated in centers throughout Europe and in South Korea. Clinical trial information: NCT02989857.

Phase I study of AG-120, an IDH1 mutant enzyme inhibitor: Results from the cholangiocarcinoma dose escalation and expansion cohorts

4015

Background: Mutations in the metabolic enzyme isocitrate dehydrogenase 1 (mIDH1) occur in patients (pts) with cholangiocarcinoma (CC) and are detected in up to 25% of intrahepatic CC. mIDH1 produce the oncometabolite, D-2-hydroxyglutarate (2-HG), resulting in epigenetic and genetic dysregulation and oncogenesis. AG-120 is a first-in-class, potent, oral inhibitor of mIDH1 tested in this phase I study in mIDH1 solid tumors, including CC. Methods: AG-120 was escalated in a 3+3 design from 100 mg twice daily to 1200 mg once daily (QD) in 28-day cycles (N = 60, mIDH1 advanced solid tumors). Key eligibility for CC: recurrence of progressive mIDH1 CC following standard therapy (dose escalation) or at least a prior gemcitabine-based regimen (expansion cohort). Response (RECIST 1.1) was assessed every 8 weeks. Plasma and tumor tissue were collected for exploratory analyses. Results: Based on the safety, pharmacokinetic, and pharmacodynamic data from dose escalation, the 500 mg QD dose was selected for expansion in mIDH1 CC and other mIDH1 solid tumors. As of Dec 16, 2016, 73 pts with mIDH1 CC had been dosed in the dose escalation (n = 24) and expansion (n = 49) cohorts. Demographics: M/F = 24/49, median number of prior therapies = 2 (range 1–5), ECOG 0–1 = 26/47. There were no dose-limiting toxicities. Treatment-related adverse events (AEs) in ≥5% pts: fatigue (21%), nausea (18%), vomiting (12%), diarrhea (10%), decreased appetite (8%), dysgeusia (5%), QT prolongation (5%). Two (3%) pts experienced related grade 3 AEs: fatigue and low phosphorus. There were no AG-120-related AEs leading to discontinuation. Among the 72 efficacy evaluable (≥1 post baseline response assessment or discontinued prematurely) mIDH1 CC pts (24 in escalation and 48 in expansion cohort), 6% (n = 4) had a confirmed partial response and 56% (n = 40) experienced stable disease. The progression-free survival rate at 6 months was 40%, and 8 pts have been treated with AG-120 for ≥1 year. Conclusions: In this pretreated mIDH1 CC population, AG-120 was associated with a favorable safety profile and prolonged stable disease. A global, phase III, randomized, placebo-controlled study of AG-120 in mIDH1 CC has been initiated (ClarIDHy). Clinical trial information: NCT02073994.

Combination Targeted Therapy to Disrupt Aberrant Oncogenic Signaling and Reverse Epigenetic Dysfunction in IDH2- and TET2-Mutant Acute Myeloid Leukemia

Genomic studies in acute myeloid leukemias (AML) have identified mutations that drive altered DNA methylation, including TET2 and IDH2 Here, we show that models of AML resulting from TET2 or IDH2 mutations combined with FLT3^ITD mutations are sensitive to 5-azacytidine or to the IDH2 inhibitor AG-221, respectively. 5-azacytidine and AG-221 treatment induced an attenuation of aberrant DNA methylation and transcriptional output and resulted in a reduction in leukemic blasts consistent with antileukemic activity. These therapeutic benefits were associated with restoration of leukemic cell differentiation, and the normalization of hematopoiesis was derived from mutant cells. By contrast, combining AG-221 or 5-azacytidine with FLT3 inhibition resulted in a reduction in mutant allele burden, progressive recovery of normal hematopoiesis from non-mutant stem-progenitor cells, and reversal of dysregulated DNA methylation and transcriptional output. Together, our studies suggest combined targeting of signaling and epigenetic pathways can increase therapeutic response in AML.Significance: AMLs with mutations in TET2 or IDH2 are sensitive to epigenetic therapy through inhibition of DNA methyltransferase activity by 5-azacytidine or inhibition of mutant IDH2 through AG-221. These inhibitors induce a differentiation response and can be used to inform mechanism-based combination therapy. Cancer Discov; 7(5); 494-505. ©2017 AACR.See related commentary by Thomas and Majeti, p. 459See related article by Yen et al., p. 478This article is highlighted in the In This Issue feature, p. 443.

D-2-hydroxyglutarate produced by mutant IDH2 causes cardiomyopathy and neurodegeneration in mice

Mutations in isocitrate dehydrogenase 1 and 2 (IDH1/2) have been discovered in several cancers, and these mutant enzymes exhibit neomorphic activity resulting in production of D2-hydroxyglutaric acid (D-2HG). Akbay et al. find that adult transgenic mice with conditionally activated IDH2^R140Q and IDH2^R172K alleles exhibit dilated cardiomyopathy and muscular dystrophy. These phenotypes were even more pronounced in embryos. Cardiac hypertrophy was also observed in nude mice implanted with IDH2^R140Q-expressing xenografts. Silencing of IDH2^R140Q in mice with an inducible transgene restored heart function by lowering 2HG levels.

Mutations in isocitrate dehydrogenase 1 and 2 (IDH1/2) have been discovered in several cancer types and cause the neurometabolic syndrome D2-hydroxyglutaric aciduria (D2HGA). The mutant enzymes exhibit neomorphic activity resulting in production of D2-hydroxyglutaric acid (D-2HG). To study the pathophysiological consequences of the accumulation of D-2HG, we generated transgenic mice with conditionally activated IDH2^R140Q and IDH2^R172K alleles. Global induction of mutant IDH2 expression in adults resulted in dilated cardiomyopathy, white matter abnormalities throughout the central nervous system (CNS), and muscular dystrophy. Embryonic activation of mutant IDH2 resulted in more pronounced phenotypes, including runting, hydrocephalus, and shortened life span, recapitulating the abnormalities observed in D2HGA patients. The diseased hearts exhibited mitochondrial damage and glycogen accumulation with a concordant up-regulation of genes involved in glycogen biosynthesis. Notably, mild cardiac hypertrophy was also observed in nude mice implanted with IDH2^R140Q-expressing xenografts, suggesting that 2HG may potentially act in a paracrine fashion. Finally, we show that silencing of IDH2^R140Q in mice with an inducible transgene restores heart function by lowering 2HG levels. Together, these findings indicate that inhibitors of mutant IDH2 may be beneficial in the treatment of D2HGA and suggest that 2HG produced by IDH mutant tumors has the potential to provoke a paraneoplastic condition.

Abstract PL02-04: IDH mutations and tumorigenicity

Mutations in the isocitrate dehydrogenase 1 (IDH1) and 2 (IDH2) genes are present in ∼20% of acute myeloid leukemia, and cause a neomorphic enzyme activity that results in the production of 2-hydroxyglutarate (2HG). Mutational and epigenetic profiling of a large patient cohort of acute myeloid leukemia (AML) has revealed that IDH1/2-mutant AMLs display global DNA hypermethylation and impaired hematopoietic differentiation.

To further investigate the intrinsic effect of 2HG on hematopoietic proliferation and differentiation, we transfected an erythroleukemia cell line (TF-1) with either IDH1 or IDH2 mutant alleles. These cells overexpress the mutant enzyme, have high levels of 2HG, and exhibit GM-CSF independent growth. Consistent with clinical observations, overexpression of the IDH mutant proteins led to hypermethylation of both histones and DNA. These results suggest that mutations in IDH1/2 could lead to epigenetic rewiring of cells that could facilitate the gain of function phenotype. We are currently studying the global and specific effects of IDH1/2 mutant overexpression to gain a broader understanding of the biological consequence of the IDH1/2 gain of function mutations.

We have also generated mutation selective molecules that are capable of inhibiting IDHm enzymes. Upon compound treatment in vitro, we are able to reverse hypermethylation of both histones and DNA and induce cellular differentiation in IDHm cell lines and primary human IDHm AML patient samples(1, 2). These data suggest that an inhibitor of IDH1/2 mutations could correct the altered gene expression patterns seen in IDH1/2 mutant AML tumors leading to a profound effect on hematopoietic differentiation, proliferation and tumor growth.

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):PL02-04.

Citation Format: F. Wang, J. Travins, B. DeLaBarre, V. Penard-Lacronique, S. Schalm, E. Hansen, K. Straley, A. Kernytsky, W. Liu, C. Gliser, H. Yang, S. Gross, E. Artin, V Saada, E. Mylonas, C. Quivoron, J. Popovici-Muller, J. O. Saunders, F. G. Salituro, S. Yan, S. Murray, W. Wei, Y. Gao, L. Dang, M. Dorsch, S. Agresta, D. P. Schenkein, S. A. Biller, S. M. Su, S. de Botton, Katharine E. Yen. IDH mutations and tumorigenicity. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr PL02-04.

Targeted inhibition of mutant IDH2 in leukemia cells induces cellular differentiation

A number of human cancers harbor somatic point mutations in the genes encoding isocitrate dehydrogenases 1 and 2 (IDH1 and IDH2). These mutations alter residues in the enzyme active sites and confer a gain-of-function in cancer cells, resulting in the accumulation and secretion of the oncometabolite (R)-2-hydroxyglutarate (2HG). We developed a small molecule, AGI-6780, that potently and selectively inhibits the tumor-associated mutant IDH2/R140Q. A crystal structure of AGI-6780 complexed with IDH2/R140Q revealed that the inhibitor binds in an allosteric manner at the dimer interface. The results of steady-state enzymology analysis were consistent with allostery and slow-tight binding by AGI-6780. Treatment with AGI-6780 induced differentiation of TF-1 erythroleukemia and primary human acute myelogenous leukemia cells in vitro. These data provide proof-of-concept that inhibitors targeting mutant IDH2/R140Q could have potential applications as a differentiation therapy for cancer.