On May 31, 2022 Alligator Bioscience (Nasdaq Stockholm: ATORX) reported that it it will present a poster on the 4-1BB conditional agonist antibody ATOR-1017 at the 2022 ASCO (Free ASCO Whitepaper) (American Society of Clinical Oncology) Annual Meeting, being held in Chicago June 3-7 (Press release, Alligator Bioscience, MAY 31, 2022, View Source [SID1234615246]).

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The poster, entitled "Initial findings from a first-in-human, multicenter, open-label study of ATOR-1017, a 4-1BB antibody, in patients with advanced solid malignancies", outlines results from Alligator’s first-in-human clinical trial with ATOR-1017, which is being developed as a tumor-directed therapy for advanced/metastatic solid cancers.

The results, to be presented at ASCO (Free ASCO Whitepaper), demonstrate an excellent safety profile. Five (22.7%) of the 22 patients treated with ATOR-1017 experienced grade 3-4 treatment-related adverse events (TRAEs). None of the TRAEs resulted in treatment discontinuation. No dose-limiting toxicity was observed, and thus the maximum tolerated dose (MTD) of ATOR-1017 has not been reached. ATOR-1017 exhibits a dose dependent and favorable pharmacokinetic profile. Activation of peripheral T cells and increased levels of soluble 4-1BB was observed across active dose levels of ATOR-1017, demonstrating biological activity and proof of mechanism.

Stable disease was achieved as best objective response in 10 (45%) of patients, with the longest treatment duration being 16 months.

Overall, the data showed that ATOR-1017 is safe and well-tolerated at doses up to 600 mg and has shown signs of clinical benefit. Dose escalation continues at the 900 mg dose and data from this cohort is expected to be reported in 2022.

"We are excited to be able to present these very promising data at ASCO (Free ASCO Whitepaper), outlining the strong safety profile and signs of efficacy of our ATOR-1017 drug candidate," said Søren Bregenholt, PhD, CEO of Alligator Bioscience. "4-1BB antibodies have been plagued with poor efficacy or unacceptable safety profile, but ATOR-1017 is distinct from other 4-1BB antibodies, partly because of its unique binding profile but also because its immunostimulating function is dependent on cross-linking to Fc-gamma receptors on immune cells. This localizes the immunostimulation to the tumor region, where both 4-1BB and Fc-gamma receptors are expressed at high levels. This means that ATOR-1017 has the potential to address a significant unmet medical need, and we look forward to finalizing this study and selecting a recommended dose for the upcoming Phase 2 study."

The Phase I study with ATOR-1017 is an open-label, dose-escalation study in patients with histologically confirmed, advanced, and/or refractory solid cancer (NCT04144842). The primary objective of the study is to investigate the safety and tolerability of ATOR-1017 and to determine the recommended dose for subsequent Phase 2 studies.