-Author name in bold denotes the presenting author
-Asterisk * with author name denotes a Non-ASH member
Clinically Relevant Abstract denotes an abstract that is clinically relevant.

PhD Trainee denotes that this is a recommended PHD Trainee Session.

Ticketed Session denotes that this is a ticketed session.

311 Updated Safety and Efficacy Results of Phase 1 Study of Olverembatinib (HQP1351), a Novel Third-Generation BCR-ABL Tyrosine Kinase Inhibitor (TKI), in Patients with TKI-Resistant Chronic Myeloid Leukemia (CML)Clinically Relevant Abstract

Program: Oral and Poster Abstracts
Type: Oral
Session: 632. Chronic Myeloid Leukemia: Clinical and Epidemiological: Mechanisms of resistance and expanded therapies
Hematology Disease Topics & Pathways:
Clinical Trials, Clinical Research, Clinically Relevant, Diseases, Myeloid Malignancies
Saturday, December 11, 2021: 5:00 PM

Jiang Qian, MD1, Dayu Shi2*, Zongru Li2*, Yazhen Qin2*, Ting Zhao2*, Bingcheng Liu3*, Zi Chen4,5*, Qian Niu4,5*, Lichuang Men4,5*, Hengbang Wang4,6*, Dajun Yang4,7*, Yifan Zhai4,5,8 and Xiaojun Huang9

1Peking University Institute of Hematology, Peking University People's Hospital, Beijing, Beijing, China
2Peking University Institute of Hematology, Peking University People’s Hospital, Beijing, China
3Institute of Hematology and Blood Diseases Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin, China
4Ascentage Pharma (Suzhou) Co., Ltd., Suzhou, China
5Guangzhou Healthquest Pharma Co. Ltd., Guangzhou, China
6HealthQuest Pharma Inc., Guangzhou, China
7Collaborative Innovation Center for Cancer Medicine, State Key Laboratory of Oncology in South China, Guangzhou, China
8Ascentage Pharma Group Inc., Rockville, MD
9Research Unit of Key Technique for Diagnosis and Treatments of Hematologic Malignancies, Chinese Academy of Medical Sciences, 2019RU029, Beijing China, Beijing, China

Background: Management of CML using TKIs is often constrained by treatment resistance, which portends a poor prognosis. Treatment failure may be due to therapeutic resistance (BCR-ABL1 mutation-dependent or independent), intolerance, and/or suboptimal adherence. The BCR-ABL1T315I (“gatekeeper”) genotype is insensitive to first- and second-generation TKIs, while compound mutations complicate management with all TKIs (including third-generation TKI ponatinib). HQP1351 (olverembatinib) is a novel, third-generation, orally active BCR-ABL1 TKI with evidence of antitumor activity against CML regardless of genotype (Ren X et al. Med Chem 2013;56:879-94) and a preliminary favorable safety profile in clinical trials (Jiang Q et al. Blood 2020;136:50-1).

Methods: This Chinese, open label, multicenter, phase 1 trial evaluated the safety and efficacy of olverembatinib in adults with CML in chronic phase (CML-CP) or accelerated phase (CML-AP). Eligible patients have CML-CP or CML-AP that is resistant or intolerant to first- or second-generation TKIs. Patients with severe cardiovascular diseases, hypertension, and pulmonary arterial hypertension were excluded. Olverembatinib is orally administered once every other day in 28-day cycles at 11 dose cohorts ranging from 1 to 60 mg. This study reports data on patients with long-term follow-up.

Results: From October 26, 2016, through February 2, 2021 (data cutoff date), 101 patients with CP-CML (n = 86) and AP-CML (n = 15) were enrolled and treated with olverembatinib. Seventy-one (70.3%) patients were male, the median age was 40 (range, 20-64) years, and median (range) interval from diagnosis to initial olverembatinib treatment was 6.0 (0.3-15.2) years. Eighty-four (83.2%) patients received ≥ 2 prior lines of TKI-therapy, and 63 (62.4%) harbored T315I mutation. At baseline, compound mutations were detected in 11 (10.9%) patients, of whom 7 (63.6%) had the BCR-ABL1T315I genotype. A total of 20 (19.8%) patients had 2 (n = 13) or ≥ 3 (n = 7) mutations. The median follow-up was 30.8 (1.2-51.8) months. As of the data cutoff date, 81 (80.2%) of 101 patients continued on treatment and 20 (14 CP-CML and 6 AP-CML) discontinued because of disease progression, intolerance, or occurrence of a secondary cancer. The cumulative median (range) drug exposure was 13,635 (1,650-20,975) mg. Of 101 patients, 18 (17.8%) were treated for > 3 years and 5 (5%) for > 4 years. Of evaluable patients without baseline responses, 97.0% had complete hematologic responses (CHR), 62.1% complete cytogenetic responses (CCyR), and 51.0% major molecular responses (MMR). Most evaluable patients with T315I mutations experienced 100% for CHR, 83.7% for MCyR, and 71.2% for MMR among patients in CP-CML, as well as 80.0% for CHR and 54.5% each for MCyR and MMR in AP-CML. At 36 months, the PFS rate (95% CI) was 96.3% (89.1%-98.8%) in patients with CP-CML and 71.4% (40.6%‒88.2%) in those with AP-CML. Treatment responses were durable and unaffected by baseline BCR-ABL1 mutational status. Corresponding values in patients with > 4 years of treatment were 100% (CHR), 80% (CCyR), and 60% (MMR). The mean (95% confidence interval) PFS rate was 100% (100%-100%) at 36 months, 100% at 48 months, and not reached (NR-NR) at 60 months. Most treatment-related adverse events were grade 1 or 2. The most frequent nonhematologic adverse event was (mostly grade 1 or 2) skin hyperpigmentation (86.1%). Grade ≥ 3 nonhematologic AEs included hypertriglyceridemia (10.9%), pyrexia (6.9%), and proteinuria (5.0%). The most common hematologic treatment-related adverse event was thrombocytopenia in 78 (77.2%) patients, including 52 (51.5% of total population) with grade ≥ 3 and 6 (5.9%) with serious adverse events. Leukopenia was grade ≥ 3 in 21 (20.8%) patients but not serious, while anemia was grade 3 or higher in 16 (15.8%) patients and serious in 4 (4.0%).

Conclusions: In patients with TKI-resistant CML-CP or CML-AP and long-term treatment, olverembatinib was efficacious and well tolerated. Internal study identifier HQP1351-SJ002.

Disclosures: Chen: Ascentage Pharma (Suzhou) Co., Ltd: Current Employment, Current equity holder in publicly-traded company. Niu: Ascentage Pharma (Suzhou) Co., Ltd: Current Employment, Current equity holder in publicly-traded company. Men: Ascentage Pharma (Suzhou) Co., Ltd.: Current Employment, Current equity holder in publicly-traded company. Wang: Ascentage Pharma (Suzhou) Co., Ltd: Current Employment, Current equity holder in publicly-traded company. Yang: Ascentage Pharma (Suzhou) Co., Ltd: Current Employment, Current equity holder in publicly-traded company, Other: Leadership and other ownership interests, Patents & Royalties, Research Funding. Zhai: Ascentage Pharma Group Inc.: Current Employment, Current equity holder in publicly-traded company, Other: Leadership and other ownership interests, Patents & Royalties, Research Funding; Ascentage Pharma (Suzhou) Co., Ltd.: Current Employment, Current equity holder in publicly-traded company, Other: Leadership and other ownership interests, Patents & Royalties, Research Funding.

*signifies non-member of ASH