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3139 A Phase I/II Study Evaluating the Safety, Tolerability, Pharmacokinetics, and Preliminary Antitumor Activity of BTK Inhibitor HZ-a-018 in Adult Patients with Relapsed and/or Refractory Central Nervous System Lymphoma

Program: Oral and Poster Abstracts
Session: 627. Aggressive Lymphomas: Clinical and Epidemiological: Poster II
Hematology Disease Topics & Pathways:
Research, clinical trials, Clinical Research
Sunday, December 10, 2023, 6:00 PM-8:00 PM

Wenbin Li1*, Zhuang Kang1*, Feng Chen1*, Shenglan Li1*, Xianggui Yuan2*, Xi Chen3*, Wenbin Qian2*, Haiyan Yang4, Miao Hu5 and Xinglu Zhou5*

1Department of Neuro-oncology, Cancer Center, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
2Department of Hematology, The Second Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China
3Department of Lymphatic Oncology, Zhejiang Cancer Hospital, Hangzhou, China
4Department of Lymphoma, Cancer Hospital of the University of Chinese Academy of Sciences (Zhejiang Cancer Hospital), Hangzhou, China
5HealZen Therapeutics Co., Ltd, Hangzhou, China

Background: HZ-A-018 is a highly selective and potent covalent BTK inhibitor with CNS-penetrating profile, which was previously reported (Abstract 5501, ASH 2022). Phase I/II study is ongoing in China, and here we present preliminary results of HZ-A-018 monotherapy of the phase I part in central nervous system lymphoma.

Methods: HZ-A-018-102 is an ongoing phase I/II study (CTR20210181) to evaluate the safety, tolerability, pharmacokinetics, and antitumor activity of HZ-A-018 in central nervous system lymphoma. The primary objective for phase I monotherapy was to determine the safety and tolerability and the recommended phase 2 dose (RP2D), and secondary objectives included preliminary antitumor activity and pharmacokinetics in patients with relapsed/refractory primary/secondary CNS lymphoma (R/R PCNSL/SCNSL) and primary vitreoretinal lymphoma (PVRL) who had received ≥1 prior therapy. HZ-A-018 was administered orally once daily in 28-day cycles until disease progression or unacceptable toxicity.

Results: At the data cutoff date of 30 May 2023, 21 pts from the phase I monotherapy were analyzed, including 18 R/R PCNSL and 3 R/R SCNSL. 3 pts received 300mg/d, 12 pts received 450mg/d and 6 pts received 600mg/d. 600mg was the highest dose pre-defined in the study and MTD was not reached. Pts were with a median age of 62 years (range: 36-80), median KPS 80 (range: 60-90) and a median of 2 prior systemic therapies (range: 1-5). 20 pts (95.2%) presented with brain parenchyma, and 1 pt (4.8%) presented with intraocular (IO) involvement. All patients had received HD-MTX based chemotherapy, 19 pts (90.5%) had received rituximab and 1 pt had received whole brain radiation therapy (WBRT). 16 of 21 pts (76.2%) experienced a treatment related adverse event (TRAE). The most common TRAEs (≥10%) were thrombocytopenia (42.9%), neutropenia (23.8%), leukopenia (23.8%), and hypokalemia (14.3%), majority of which were grade 1 to 2. DLTs occurred in 1 pt at 450 mg/d and 1 pt at 600 mg/d. 4 pts (19.0%) had dose interruption, no pts had dose reductions, and no pts discontinued from the study due to TRAEs. The plasma and cerebrospinal fluid (CSF) pharmacokinetics showed HZ-A-018 was rapidly absorbed and could cross the blood-brain barrier with CSF HZ-A-018 concentration ranged from 5.94 to 17.5 ng/mL two hours post-dose. Of 19 pts available for tumor assessment (16 PCNSL with brain parenchyma, 1 PCNSL with IO and 2 SCNSL with brain parenchyma) and 2 pts not evaluable (1 PCNSL with brain parenchyma, and 1 SCNSL with brain parenchyma), the overall response rate (ORR) was 52.4% (95%CI: 29.8, 74.3), including 23.8% (5 pts) complete response(CR)/unconfirmed complete response(CRu), 28.6% (6 pts) partial response (PR), and 19.0% (4 pts) stable disease (SD), contributing to an 71.4% (95%CI: 47.8, 88.7) disease control rate (DCR). At 600mg/d, all 6 pts had achieved high and deep responses, contributing to 100% ORR and 50% CRR, with the 3-month duration of response (DOR) rate not reached. Dose expansion was ongoing at 600mg QD.

Conclusions: These results demonstrated that HZ-A-018 was efficacious and well-tolerated in CNS lymphoma patients with high CNS penetrating profile. The monotherapy RP2D for R/R PCNSL was determined as 600 mg QD and a phase 2 R/R PCNSL registration study in China is currently planned.

Disclosures: No relevant conflicts of interest to declare.

*signifies non-member of ASH