Alligator Bioscience, a clinical-stage biotechnology company, presents novel supportive data from the ongoing phase I clinical trial with the 4-1BB (CD137) drug candidate ATOR-1017 developed as tumor-directed therapy for metastatic cancer. The results, presented in at the 2021 ASCO Annual Meeting, validate the therapeutic potential of ATOR-1017 demonstrating a very favorable safety profile combined with clear signs of proof of mechanism, as activation of T cells in the circulation was observed across active dose levels of ATOR-1017.
"ATOR-1017 is the first of the second generation monospecific 4-1BB antibodies to report proof of mechanism by showing increase in number of activated T cells in the circulation. Safety data show that ATOR-1017 is safe and well tolerable at doses up to 200 mg and no dose limiting toxicity has occurred. We are encouraged by these data validating the potential of ATOR-1017 and we are now focused on completing the study and determining the dose for the subsequent phase II program," said Søren Bregenholt, CEO of Alligator Bioscience.
The phase I study with ATOR-1017 is a dose escalation study in patients with advanced solid cancer (NCT04144842). The primary endpoint of the study is to investigate the safety and tolerability of ATOR-1017 and to determine the recommended dose for subsequent phase II studies. The first patient was dosed in December 2019. As of data cut-off March 31, 2021, a total of 13 patients with varying advanced solid malignancies had been included. 4 patients (31%) remained on treatment, 3 (23%) of whom had confirmed stable disease for a period of 3.5-12.5 months.
The results from the evaluation of doses up to and including 200 mg demonstrate that ATOR-1017 has an encouraging safety profile as the drug related adverse events in the study have generally been mild and transient. No dose-limiting toxicity or severe immune-related adverse events have been reported. The results further demonstrate that ATOR-1017 exhibits a favorable pharmacokinetic profile with linear elimination and no accumulation. Activation of T cells in the circulation was observed across therapeutic dose levels of ATOR-1017 demonstrating biological activity and proof of mechanism.