Pathos AI Inc., a biotechnology company focused on improving precision medicine in cancer by harnessing the power of machine learning to transform drug development, has announced the world-wide license of PRT811, a potent, selective, and orally bioavailable brain penetrant SAM-competitive PRMT5 inhibitor from Prelude Therapeutics.
 
PRT811 (renamed P-500) was developed by Prelude Therapeutics and completed a Phase 1 trial in March 2023.

Results from Prelude’s Phase 1 Study

The trial enrolled patients with solid tumors including high-grade glioma and uveal melanoma and has potential application in other indications with high unmet need. Out of 16 patients with high-grade glioma with isocitrate dehydrogenase mutations (IDH+) in the Phase 1 trial, two confirmed complete responses (CR) were observed. At last follow-up, 1 response is ongoing and has lasted 31.0 months while the duration of response for the second CR patient was 7.5 months. Additionally, 1 patient achieved an unconfirmed partial response (PR).
 
In addition, out of 23 uveal melanoma patients (10 patients with splicing factor 3B subunit 1 (SF3B1) splicing mutations and 13 without an SF3B1 mutation), one confirmed PR (duration of response of 10 months) and a second unconfirmed PR were observed, both in patients SF3B1 mutations.
 
In the entire safety population (N=86), the most common adverse events of any grade, with an incidence of >20% were nausea (60.5%), vomiting (46.5%) fatigue (36.0%), constipation (29.1%), and thrombocytopenia (24.4%), and were predominantly grade 1-2. The most common adverse events (grade ≥3), occurring >5% were thrombocytopenia (9.3%), anemia (9.3%), and fatigue (5.8%).
 
“These results from Prelude’s Phase 1 study are promising news for high-grade glioma patients and clinicians, who still have limited treatment options with chemotherapy and radiation that hasn’t changed in decades. With our AI Platform, we aim to increase the already encouraging response rate of P-500 through a novel biomarker-driven strategy, ultimately bringing this medicine to patients as efficiently as possible,” said Ryan Fukushima, Pathos CEO.