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Trial Testing Targeted Solid Tumor Immunotherapy

Alligator head


7 May 2019. A clinical trial is underway testing the safety of a cancer therapy that harnesses the immune system, but also works only in the tumor to reduce adverse side effects. The study, which enrolled its first participant, is sponsored by Alligator Bioscience AB in Lund, Sweden, developer of the therapy candidate code-named ATOR-1015.

Alligator Bioscience is a biotechnology enterprise creating synthetic antibodies that invoke the immune system to treat solid tumor cancers, such as breast, lung, and skin cancer. While a number of cancer immunotherapy drugs are already on the market and being developed, Alligator Bioscience says its approach designs therapies to localize the treatments in the tumors, making the therapies safer for patients. The company says it concentrates on early-stage drug development, through mid-stage clinical trials.

The new trial is testing the safety and tolerability of ATOR-1015, designed to treat a range of solid tumor cancers. ATOR-1015 is a product of Alligator’s antibody library that the company says has some 60 billion unique antibody fragments. The company says the fragments represent six distinct regions covering the antibody surface that bind to target molecules, but can be designed to look and act like natural antibodies in the human immune system.

ATOR-1015 is a bi-specific antibody that binds to cytotoxic T-lymphocyte–associated antigen 4, or CTLA-4, receptors, aiming to block this protein’s actions. At the same time, ATOR-1015 stimulates activity of OX40 proteins that together with CTLA-4, deplete regulatory T-cells in the immune system that normally limit the therapeutic T-cells attacking a tumor. In addition, ATOR-1015 is activated only in the presence of high levels of both target proteins, found only in the tumors, not in healthy cells or tissue. As a result, ATOR-1015 aims for and accumulates only in tumors, not affecting other cells and tissue, which the company says it found in preclinical studies.

The early-stage clinical trial is recruiting 53 participants with advanced or stubborn solid tumor cancers, at 5 sites in Denmark and Sweden. Participants will receive infusions of ATOR-1015 every 2 weeks until the participant shows signs of the cancer continuing to progress, unacceptable toxicity levels, or the participant leaves the study. The study team is looking primarily for signs of adverse effects, but is also tracking participants’ overall health conditions such as vital signs and results of clinical lab tests. The researchers are also tracking activity of ATOR-1015 in the body, including concentration of ATOR-1015 and antibody levels in participants’ blood, and effects on participants’ tumors, as indicated by computed tomography, or CT, scans.

Per Norlén, Alligator’s CEO, says in a company statement that “ATOR-1015 is the first investigational tumor-localizing bispecific CTLA-4 antibody ever being tested in the clinic.” Norlén adds, “While immune activation through CTLA-4 has shown impressive efficacy in multiple cancers, it is coupled with severe toxicity,” and will be at least as effective as other synthetic antibodies already on the market targeting CTLA-4, with fewer side effects.

Results of the trial are expected to be published in the second half of 2020.

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