Prescient Therapeutics receives encouraging efficacy results for leading cancer drug candidate PTX-200

Prescient Therapeutics breast cancer women PTX ASX Phase 2 HER2 negative
PTX-200 achieved a 91% response rate in phase 2 clinical trials in women with locally advanced HER2 negative breast cancer.

Oncology company Prescient Therapeutics (ASX: PTX) has unveiled news of a high response rate to its PTX-200 leading drug candidate from a phase 2 breast cancer trial.

The news comes less than two weeks since Prescient announced positive interim data from a phase 1b safety study of its lead drug PTX-200 in women with recurrent or persistent platinum-resistant ovarian cancer.

In a statement to the market, Prescient said that it had received “encouraging efficacy results” in a clinical trial being conducted by Professor Joseph Sparano and Dr Heather Tan at the Montefiore Medical Center, Albert Einstein College of Medicine in New York.

In this phase 2a study, eleven patients were enrolled with locally advanced, HER2-negative breast cancer and receiving 35mg of PTX-200, together with 80mg per week of paclitaxel, followed by standard AC therapy and surgery.

According to Prescient, results obtained from the 11 women that participated in the trial exhibited an overall response rate of 91% with two patients experiencing a complete eradication of disease.

All patients that could be evaluated responded to therapy and all experienced varying degrees of response to Prescient’s lead drug candidate.

The success rate achieved compares well with typical expectations within the medical healthcare sector of around 16%, for women with locally advanced ER-positive and HER2 negative breast cancer.

As part of the company’s commentary of the published results, one aspect highlighted by Prescient has been durability of response.

Following the trial, patients will continue to be evaluated to monitor disease progression with Prescient confirming that nine out of the 10 patients currently being monitored have remained cancer-free to date.

“These promising results are an important clinical milestone in our work to find better treatments for breast cancer,” said Prescient chief executive officer and managing director Steven Yatomi-Clarke.

“Results indicate that the most responsive patient population to our therapy in breast cancer is patients with ER-positive disease and that we should focus on this subset of patients for PTX-200,” he said.

Pipeline progress

Oncology researchers published an article in Lancet Oncology in 2014 which asserted that, typically, up to 60% of women with locally advanced HER2 negative breast cancer experience disease recurrence five years after successful treatment, but many of these cases end up progressing within the first 24 months.

Furthermore, Prescient declared that developmental progress with PTX-200 is “tracking favourably against expectations” because since the completion of this portion of the trial, patients continue to exhibit robust durability of response, with progression-free survival averaging between 22-40 months.

Breast cancer continues to affect millions of people globally with around 12% of women expected to develop breast cancer in their lifetime.

In the past year alone, around 300,000 new cases of breast cancer were diagnosed in the US with similarly high rates prevalent in all Western countries.

Improving outcomes

According to Mr Yatomi-Clarke, the status-quo shows that there is currently a poorly met clinical need for effective breast cancer medication globally.

Global demand for HER2-negative breast cancer therapies is expected to grow to as much as US$10.6 billion (A$15.4 billion) by 2025 and to continue growing thereafter on the back of unhealthy lifestyle choices.

Given the rapid growth of various cancers in Western countries (as well as amongst lower age groups), the launch of new breast cancer drugs in the pre-operative setting is expected to be a major driver of future demand for pharmaceutical treatments.

Prescient says it wants to help address this unmet clinical need by progressing PTX-200 and eventually making it available on a commercial basis to thousands of patients.

Having received optimistic results at phase 2, Prescient said that it now plans to initiate a new trial focusing specifically on patients with estrogen-receptor-positive disease, which appears to be the most responsive patient population.

“We will now seek to switch this study to a new trial combining PTX-200 and hormone therapy, which is the standard of care for locally advanced ER-positive breast cancer,” said Mr Yatomi-Clarke.

“Furthermore, our investigators also expect this combination to have a superior safety profile to the current combination with chemotherapies paclitaxel and AC. To mitigate rising costs of conducting clinical studies in the US, Prescient will seek to conduct this study in Australia and/or as an investigator-sponsored study backed by non-dilutive funding,” he added.