Abstract B040: NCI 10129: A Phase 2 Study of the PARP inhibitor Olaparib (AZD2281) in IDH1 and IDH2 mutant advanced solid tumors
Authors: Cecchini Michael , Pilat Mary Jo , Uboha Nataliya , Azad Nilofer S , Cho May , Davis Elizabeth J , Ahnert Jordi Rodon , Tinoco Gabriel , Shapiro Geoff I , Khagi Simon , Powers Benjamin , Groisberg Roman , Drappatz Jan , Chen Li , Das Biswajit , Bao Xun , Li Jing , Patel Abhijit , Niger Monica , Doroshow Deborah , Durecki Diane , Boerner Scott , Bindra Ranjit , Ivy Percy , Shyr Yu , LoRusso Patricia 
Published: December 2023

Introduction: Cholangiocarcinoma (CCA) is a highly aggressive malignancy with mutations in Isocitrate dehydrogenase (IDH) identified in approximately 15% of patients. Neomorphic mutations in IDH 1/2 result in accumulation of the oncometabolite 2-hydroxyglutarate (2G), which has been implicated in tumor progression via inhibitory effects on alpha ketoglutarate. Moreover, the mutant IDH dependent accumulation of 2HG results in homologous recombination deficiency (HRD) and renders these cells exquisitely sensitive to Poly (ADP-Ribose) polymerase (PARP) inhibitors. NCI 10129 evaluated the efficacy of olaparib for IDH mutated solid tumors, and here we present the CCA cohort.

Methods: NCI 10129 is a 3 arm, open label phase 2 clinical trial performed in the NCI National Clinical Trials Network evaluating olaparib 300 mg twice daily for IDH mutated solid tumors refractory to standard treatment. Patients with CCA were enrolled in 2 cohorts 1) IDHi pre-treated CCA and 2) IDHi untreated CCA. The primary endpoint was overall response rate (ORR) and secondary endpoints includes progression-free survival (PFS), and overall survival (OS). An exploratory analysis measured the impact of circulating 2HG levels, circulating tumor DNA, and tumor genomics on patient outcomes. 

Results: Thirty patients with CCA enrolled on NCI10129 (15 each IDHi pre-treated and IDHi treatment naïve), 18 patients received ≥ 2 prior systemic treatments, and 23 patients had IDH1 mutations and 7 patients IDH2 mutations. There were no objective responses seen in the first 15 CCA patients in either cohort and enrollment was closed. The median PFS was 2.4 months 95% CI (1.9 - 6.5) and median OS 12.9 months 95% CI (6.3 – not reached). The IDHi pre-treated cohort had improved median OS compared to IDHi treatment naïve (15.3 vs 7.3, P = 0.04). There were 8/30 (27%) patients with clinical benefit (CB) as defined by PFS &gt; 6 months. Patients with CB had lower baseline mean D-2HG levels compared to those without CB (1.4 umol/L vs 5.9 umol/L, p = 0.02). Whole exome sequencing revealed the study population to be enriched for HRD by sum scores and HRD mutational signatures without alternative HRD mutations other than IDH1/2. No improvement in survival was noted based on HRD status. RNA sequencing Gene Set Enrichment Analysis revealed that cell cycle and interferon alpha pathways were activated in patients with CB (p &lt; 0.01). Olaparib was tolerable with the majority of adverse events grade 1-2.

Conclusion: Olaparib did not result in objective responses in IDH mutated CCA. However, a subgroup of patients did demonstrate prolonged PFS comparable to historical controls for refractory CCA as well that seen with targeted agents such as IDHi. Exploratory analysis revealed this subgroup to be enriched for lower baseline 2HG levels. Serial ctDNA analysis is ongoing and will be presented. Given the CB subgroup and OS data, additional clinical trials leveraging the HRD properties of IDH mutations is warranted. Future studies may benefit from DNA damage combination therapies thereby enhancing potency.

Citation Format: Michael Cecchini, Mary Jo Pilat, Nataliya Uboha, Nilofer S Azad, May Cho, Elizabeth J Davis, Jordi Rodon Ahnert, Gabriel Tinoco, Geoff I Shapiro, Simon Khagi, Benjamin Powers, Roman Groisberg, Jan Drappatz, Li Chen, Biswajit Das, Xun Bao, Jing Li, Abhijit Patel, Monica Niger, Deborah Doroshow, Diane Durecki, Scott Boerner, Ranjit Bindra, Percy Ivy, Yu Shyr, Patricia LoRusso. NCI 10129: A Phase 2 Study of the PARP inhibitor Olaparib (AZD2281) in IDH1 and IDH2 mutant advanced solid tumors [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr B040.