Safety and Preliminary Efficacy of Sabestomig (AZD7789), an Anti-PD-1 and Anti-TIM-3 Bispecific Antibody, in Patients with Relapsed or Refractory Classical Hodgkin Lymphoma Previously Treated with Anti-PD-(L)1 Therapy

Background Immunotherapies targeting the PD-1/PD-L1 pathway have been shown to induce high response rates in patients with relapsed/refractory (r/r) classical Hodgkin lymphoma (cHL). However, most responses are partial and not durable. T cell immunoglobulin and mucin domain-containing protein-3 (TIM-3) is implicated as a resistance mechanism following anti-PD-1 therapy, and increased TIM-3 expression has been observed on T cells of patients with cHL post anti-PD-1 therapy. Therefore, we hypothesized that dual targeting of PD-1 and TIM-3 may reinvigorate immune responses and lead to more durable antitumor activity. Sabestomig is a monovalent, bispecific, humanized IgG1 monoclonal antibody that binds PD-1 and a unique epitope in the TIM-3 IgV domain without blocking phosphatidylserine binding, eliciting differential functionality. In preclinical mouse models, sabestomig was more effective at inhibiting growth of solid tumors than treatment targeting only PD-1, and sequential sabestomig after anti-PD-1 therapy increased antitumor responses. Here we report preliminary data from the ongoing dose escalation portion of a Phase I/II, open-label, multicenter study to assess the safety and preliminary efficacy of sabestomig in patients with r/r cHL (NCT05216835). Methods Eligible patients are aged ≥16 years with r/r cHL, an Eastern Cooperative Oncology Group performance status 0-1, at least one positron emission tomography-avid measurable lesion according to modified Lugano Criteria, and exposure to at least 2 prior lines of systemic therapy including a minimum of 3 cycles of an anti-PD-(L)1-based therapy. Sabestomig is intravenously infused over 1 hour following pretreatment with diphenhydramine and acetaminophen every 3 weeks, with planned doses ranging from 2 to 2000 mg across 8 cohorts (A1-A8); cohorts A1 to A4 (2, 7, 22.5 or 75 mg) follow an accelerated titration design with a single patient treated at each dose level, while cohorts A5 to A8 (225-2000 mg) follow a modified toxicity probability interval-2 algorithm. The primary endpoint of the dose escalation part of the study is safety, including dose-limiting toxicities (DLTs). Secondary endpoints include efficacy, pharmacokinetics, and immunogenicity. Data cutoffs were May 17, 2023 for safety and June 20, 2023 for efficacy. Results As of May 17, 2023, 14 patients were treated across the first 6 cohorts (A1-A6; 2-750 mg). They were predominantly male (64.3%) with Stage IV disease (85.7%) and a median age of 41.5 years (range, 25-77). Patients received a median of 6 prior lines of therapy (range, 3-13). Baseline disease characteristics are summarized in Table 1. Four patients received sabestomig 2-75 mg in cohorts A1-A4 (n=1 each), 5 patients received 225 mg in cohort A5, and 5 patients received 750 mg in cohort A6. Median duration of exposure to sabestomig was 8.9 weeks (range, 3.0-34.3) with a median of 3 cycles received (range 1-12). Sabestomig was well tolerated with no Grade ≥3 treatment-related adverse events (AEs) (Table 2). One Grade ≥3 AE occurred, which was fatal (sepsis secondary to gastric ulcer rupture, not related to sabestomig but deemed a DLT by the safety review committee). No immune-mediated AEs were reported, and no AEs led to treatment discontinuation. At the safety data cutoff, treatment was ongoing for 6 patients (42.9%). As of June 20, 2023, 11 patients had their first disease assessment and 4/11 had an objective response based on modified Lugano Criteria: 1 patient in cohort A3 (22.5 mg, a partial response [PR]) and all 3 patients who had their first disease assessment in cohort A6 (750 mg, 2 CRs and 1 PR). Two of these 4 responders (both in cohort A6) had experienced a best overall response of progressive disease during prior anti-PD-1 therapy; the other two initially had a response (1 CR [cohort A6] and 1 PR [cohort A3]) but subsequently progressed on anti-PD-1 therapy. Sustained PD-1 receptor occupancy (≥90%) was observed in peripheral blood at doses ≥225 mg. Conclusions Sabestomig was well tolerated with a manageable safety profile. Early efficacy data at 750 mg is encouraging with objective responses in 3/3 patients who had their first disease assessment, including those who were anti-PD-1 refractory or who relapsed on treatment. Updated data will be presented from ongoing and subsequent patients treated during dose escalation with doses of up to 2000 mg.

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