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In this phase I study, the safety, pharmacokinetics, and antitumour activity of the HER2-targeted antibody-drug conjugate A166 were evaluated in patients with HER2-expressing advanced solid tumours. Patients with advanced solid tumours refractory to standard therapies received A166 at doses of 0.1, 0.3, 0.6, 1.2, 2.4, 3.6, 4.8 or 6.0 mg/kg Q3W in a standard "3 + 3" design. Dose cohorts were expanded at 4.8 and 6.0 mg/kg Q3W. Primary endpoints were assessment of the safety and tolerability of A166 and identification of the maximum tolerated dose or recommended phase II dose. In total, 81 patients were enroled and received A166 (n = 1 for 0.1 mg/kg; n = 3 for each of 0.3, 0.6, 1.2, 2.4 and 3.6 mg/kg doses; n = 27 for 4.8 mg/kg; n = 38 for 6.0 mg/kg). No dose-limiting toxicity or drug-related deaths occurred. The most common treatment-related adverse events at grade 3 or higher were corneal epitheliopathy (30.9%), blurred vision (18.5%), dry eyes (7.4%), and peripheral sensory neuropathy (6.2%). The Cmax and area under the curve of Duo-5, its free payload, were approximately 0.1% and 0.2% of those of the ADC, respectively. For all assessable HER2-positive breast cancer patients enroled in the 4.8 mg/kg and 6.0 mg/kg cohorts, the corresponding ORRs were 73.9% (17/23) and 68.6% (24/35), respectively, and the median PFS was 12.3 and 9.4 months, respectively. A166 has a recommended phase II dose of 4.8 mg/kg Q3W, manageable toxicity, good stability in the circulation and promising antitumour activities in HER2-positive breast cancer patients.
RESUMO
Background: KL-A167 is a fully humanized monoclonal antibody targeting programmed cell death-ligand 1. This phase 2 study aimed to evaluate the efficacy and safety of KL-A167 in Chinese patients with previously treated recurrent or metastatic (R/M) nasopharyngeal carcinoma (NPC). Methods: This was a multicentre, single-arm, phase 2 study of KL-A167 in R/M NPC (KL167-2-05-CTP) (NCT03848286), conducted at 42 hospitals across the People's Republic of China. Eligible patients had histologically confirmed non-keratinising R/M NPC, and had failed at least two lines of chemotherapy. Patients received KL-A167 900mg intravenously once every 2 weeks until confirmed disease progression, intolerable toxicity, or withdrawal of informed consent. The primary endpoint was objective response rate (ORR) assessed by the independent review committee (IRC) according to RECIST v1.1. Findings: Between Feb 26th, 2019 and Jan 13th, 2021, 153 patients were treated. Totally, 132 patients entered full analysis set (FAS) and were evaluated for the efficacy. As of data cutoff date on Jul 13th, 2021, the median follow-up time was 21.7 months (95%CI 19.8-22.5). For FAS population, the IRC-assessed ORR was 26.5% (95%CI 19.2-34.9%), and disease control rate (DCR) was 56.8% (95%CI 47.9-65.4%). Median progression-free survival (PFS) was 2.8 months (95%CI 1.5-4.1) . Median duration of response was 12.4 months (95%CI 6.8-16.5), and median overall survival (OS) was 16.2 months (95%CI 13.4-21.3). When using the cutoff of 1000 copies/ml, 5000 copies/ml and 10,000 copies/ml for plasma EBV DNA titer, baseline low plasma EBV DNA was consistently related with better DCR, PFS and OS. Dynamic change of plasma EBV DNA was significantly associated with ORR and PFS. Among 153 patients, treatment related-adverse events (TRAEs) occurred in 73.2% of patients, and grade ≥3 TRAEs were in 15.0% of patients. No TRAE leading to death was reported. Conclusion: In this study, KL-A167 showed promising efficacy and an acceptable safety profile in patients with previously treated R/M NPC. Baseline plasma EBV DNA copy number might be a potentially useful prognostic biomarker for KL-A167 treatment, and post-treatment EBV DNA decrease might be correlated with better response to KL-A167. Funding: Sichuan Kelun-Biotech Biopharmaceutical Co., Ltd., China National Major Project for New Drug Innovation (2017ZX09304015).