Retro will add two higher doses of RTR242 and expand the Phase 1 trial to 108 volunteers

Retro will add two higher doses of RTR242 and expand the Phase 1 trial to 108 volunteers

Healthy adults aged 18 to 65 are receiving RTR242 in Australia. The company will add 32 participants and two new groups receiving higher doses to select a dose for the next stages of the clinical program.

Phase 1 is the first stage of testing a drug in humans. Its main purposes are to assess tolerability and identify an appropriate dose. On August 26, Retro CEO Joe Betts-LaCroix told Business Insider that the RTR242 trial would enroll 108 participants, up from 76.

In May, Retro reported that the first participant had received RTR242. The company is now expanding enrollment and increasing the doses to define the program’s next step more precisely.

Betts-LaCroix said the trial was being expanded because the initial tolerability assessment had not yet identified an upper dose limit. The team needs to find a dose that participants can tolerate and that can be taken forward into subsequent trials.

“In some ways, this is both a curse and a blessing for us because it makes it a little harder to determine when we can say, ‘Great, the drug works,’” Betts-LaCroix said.

Retro describes RTR242 as a small-molecule drug designed to enhance autophagy, the process by which cells direct damaged proteins and cellular components for breakdown. At the end of this process, lysosomes, acidic compartments inside cells, break this material down into components that can be reused. The company expects RTR242 to restore lysosomal acidity and make this recycling process more efficient.

Paul Robbins, a biochemist at the University of Minnesota, described lysosomes as an interesting target. For Retro, the 32 additional participants will broaden the dose range from which the company can select a dose for further development of RTR242.