Prescient Therapeutics Limited announced the opening of enrolment in the expansion cohort of the Phase 1b trial of PTX-100 to treat T-cell lymphomas, a group of aggressive and rare blood cancers with significant unmet clinical need. The expansion cohort is an open-label, non-randomised study that will enrol eight to 12 patients with relapsed and refractory T-cell lymphoma. It will be led by world-renowned hematologist, Professor H. Miles Prince at Epworth Hospital in Melbourne, Australia.

Excellent safety data and encouraging preliminary evidence of clinical efficacy in patients with T-cell lymphomas in the Phase 1b study prompted clinical investigators to recommend expanding the study and to focus on enrolling patients with peripheral T-cell lymphomas (PTCL). PTCL is a blood cancer with substantial unmet need for new therapies and represents an exciting clinical and commercial opportunity for PTX-100. Prescient plans to include several patients with cutaneous T-cell lymphoma (CTCL) as well.

CTCL clinical samples will bolster insights on drug activity in T-cell lymphomas overall. Prescient reported that drug shipment has arrived in Australia to support the trials. As previously reported, there were unforeseen delays in manufacturing of additional PTX-100 due to worldwide supply chain and logistics challenges that impacted so many sectors, including drug manufacturers and their suppliers.

This drug supply is sufficient for the dosing of the planned expansion cohort. Despite the delayed start, Prescient is still aiming to complete recruitment of the expansion cohort by the end of 2022. One PTCL patient from the Phase 1b escalation cohort has now undergone 37 cycles of therapy and continues to receive PTX-100.

This patient had particularly aggressive disease that had failed five prior therapies, none of which were able to control the disease for more than a few months before the disease progressed further. When treated with PTX-100, this patient experienced a partial response (reduction in cancer burden), and this response has endured for 24 months so far. Another patient with cutaneous T cell lymphoma (CTCL) also had aggressive disease and had failed three prior treatments.

This patient had a partial response on the study, with reduced cancerous lesions and symptomatic relief. The patient was on therapy for 12 months, receiving 19 cycles of therapy. In both cases, such patients with refractory T-cell lymphomas on standard treatments would typically be expected to have disease progression within 4 months.

This highlights the encouraging nature of the responses to PTX-100. Peripheral T-Cell Lymphoma (PTCL) PTCL encompasses a group of uncommon and aggressive cancers resulting from a patient's T-cells becoming cancerous. T-cells are an important part of the immune system which help the body fight infection.

In cases when some T-cells start to grow too quickly and out of control, they can accumulate in the body. There are several sub-types of PTCL, but usually present in a similar way. PTCL generally affects people aged 60 years and older, although it can occur at any time throughout adulthood.

Current treatments for PTCL include combination chemotherapy regimens, localised radiotherapy, stem cell transplants and steroid therapy. PTX-100 PTX-100 is a first-in-class targeted therapy that blocks an important cancer growth enzyme called GGT-1. It was co-invented by Prescient's Scientific Founder, Professor Said Sebti, and is exclusively licensed by Prescient from Yale University. In the prior Phase 1b basket study, a total of 10 patients were enrolled - five with solid tumours (pancreatic and colorectal cancers) and five with haematological malignancies (multiple myeloma and T-cell lymphomas).

Patients had received a median of three prior lines of therapy and up to five prior lines of therapy. PTX-100 was administered at doses ranging from 500 mg/m2 to 2,000 mg/m2. No serious adverse events related to PTX-100 were observed, and a clinical signal was seen in T-cell lymphomas.