On June 4, 2021 Alligator Bioscience (Nasdaq Stockholm: ATORX) reported that 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 (Press release, Alligator Bioscience, JUN 4, 2021, View Source [SID1234583508]). The results, presented in a poster presentation at the 2021 ASCO (Free ASCO Whitepaper) 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.

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"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.

The ASCO (Free ASCO Whitepaper) poster presentation with the title "A first-in-human, multicenter, open-label, phase 1 study of ATOR-1017, a 4-1BB antibody, in patients with advanced solid malignancies" will be available at 03.00 p.m. CEST today, June 4, on the company website View Source

This information is such information as Alligator Bioscience AB (publ) is obliged to make public pursuant to the EU Market Abuse Regulation. The information was submitted for publication, through the agency of the contact person set out above, at 08:00 a.m. CEST on June 4, 2021.