Prescient Therapeutics Limited provided an update on the PTX-100 Phase 1b expansion cohort in relapsed and refractory T cell lymphomas (TCL). PTX-100 continues to show encouraging clinical activity in this difficult-to-treat patient population, with several clinical responses that include two patients with relapsed and refractory peripheral TCL (PTCL) that have had complete responses (complete eradication of cancer) since the prior update in November 2022, which is not generally expected in this disease. PTX-100 also continues to exhibit an excellent safety profile at the highest dose of 2000 mg/m2.

The study is being led by globally renowned haematologist, Professor H. Miles Prince at Epworth Hospital in Melbourne, Australia. Phase 1b Enrolment A total of 13 TCL patients have been dosed with PTX-100: 8 patients with PTCL and 5 patients with cutaneous TCL (CTCL). Patients had received a median of 3 prior lines of therapy and up to 5 systemic prior lines of therapy.

PTX-100 was administered at doses up to 2,000 mg/m2. The expansion cohort has met its minimum enrolment schedule, and the study is ongoing as patients are responding for longer than expected. Four patients currently remain on therapy and additional patients are being recruited.

Safety: PTX-100 continues to exhibit an excellent safety profile on the study, with very few serious adverse events. Grade 3 (severe) adverse events observed as being possibly related to PTX-100 include cases of neutropenia, thrombocytopenia and anaemia. Several of these cases were observed in the same patient and the patients recovered/resolved these events.

Prescient believes that such side effects are not uncommon in treating this patient population and are likely manageable. Clinical activity: Although the primary goal of the study is to evaluate safety, PTX-100 continues to exhibit encouraging clinical activity in the difficult-to-treat patient population, especially when considered against responses expected from current standards of care. Next steps: Based on encouraging data so far, regulatory advisors have recommended enrolling seven additional patients in order to support a more robust data package for a meeting with the US FDA.

Prescient is planning a subsequent Phase 2 trial in TCL, which will be conducted subject to satisfactory Phase 1b outcomes. Prescient will seek to apply for this Phase 2 trial to be an Accelerated Approval trial with the FDA in an Orphan Indication. If this is granted, Accelerated Approval could pave the way for the Phase 2 trial to be the study enabling expedited regulatory approval of PTX-100.

If Accelerated Approval is not granted, the Phase 2 trial will proceed as per conventional drug development pathways, with a subsequent study likely required for approval. Prescient will also be seeking clarification on the dose optimisation and dose schedule considerations for the Phase 2 study pursuant to the FDA's Project Optimus, which seeks to maximizes not only the efficacy of a drug but also its the safety and tolerability. Prescient will be applying for a meeting the FDA later this year.

A favorable outcome would see the registrational Phase 2 study open within 12 months, subject to satisfactory results from the Phase 1b trial. A possible scenario may involve regulatory interactions taking place and/or a subsequent Phase 2 trial initiated before the current Phase 1b officially concludes, due to the long duration of responses being observed in this Phase 1b study. To facilitate further studies, Prescient will conduct another manufacturing campaign of PTX- 100, planning for this has already commenced.

Manufacturing will be conducted and documented at higher levels of rigour required to support later stage trials and regulatory submissions.