Australia’s Prescient Therapeutics is getting its lead cancer program back after two of three trials were placed on clinical hold by the Food and Drug Administration.
In May, the FDA placed PTX-200 on hold after a patient in the study had developed liver failure and died, halting three trials of the Akt inhibitor for breast and ovarian cancer as well as acute myeloid leukemia. The patient was also taking paclitaxel, known to affect liver metabolism. In September the FDA allowed the company to resume phase 1b/2 AML trial. Authorization to resume the ovarian cancer study was granted this month, after the biotech changed the risk-management protocols in the studies. Yet, the phase 2 breast cancer trial remains halted, but the company is optimistic of continuation soon.
Analysts have estimated the halts have delayed the progress of the PTX-200 by more than a year, pushing back a prospective launch date to 2024 and a partnering agreement to 2020 instead of 2018. Assuming the drug is approved in the three target indications, potential sales could generate over $2 billion. Yet, the analysts believe the drug’s chance of approval at its current stage is only 15%.
Akt (PI3K) is an element of signaling pathways recognized for the promotion of cancer cell growth and its resistance to chemotherapy. Gilead’s drug, Zydelig, was the premier drug that pursued the pathway on the market, but withdrew due to toxicity issues. Bayer’s PI3K inhibitor, Aliqopa, has recently received accelerated approval from the FDA regarding follicular lymphoma. Numerous other drug candidates are also targeting this pathway in clinical testing from Eli Lilly and Array NioPharma/Roche.
With the PTX-200 program picking up where it left off, Prescient is making improvements with its second candidate PTX-100, a GGT1 inhibitor for rare lymphomas that may be taken through a key trial before outlicensing.