Prescient Therapeutics maintains positive development for lead breast cancer drug candidate

Oncology company Prescient Therapeutics (ASX: PTX) has delivered some positive interim news relating to its study evaluating the impact of its lead drug candidate PTX-200 on locally advanced breast cancer.

The drug is said to be a novel PH domain inhibitor that impedes an important tumour survival pathway known as Akt, which plays a key role in the development of many cancers, including breast, ovarian, and leukaemia.

Prescient’s interim durability data on the PTX-200 study in HER2 negative, locally advanced breast cancer has revealed “none of the five responders in the Phase 2 component of the trial have had disease progression” to date.

The company’s chief executive officer Steven Yatomi-Clarke explained that another concurrent study being done by pharma giant Roche demonstrates several insights relevant to Prescient.

Roche’s Phase 3 Akt inhibitor, ‘ipatasertib’ has been shown to confirm that the Akt pathway is activated in response to chemotherapy in breast cancer patients.

Also, Akt inhibitors enhance the killing of breast cancer cells and most significantly, “this Akt inhibition results in clinical benefit for breast cancer patients,”  – an insight that could have developmental benefit for Prescient including accelerated approval by the US Food and Drug Administration, in addition to two cornerstone personnel additions to the oncology company’s roster.

“This demonstrates that Akt inhibition can make a clinical difference to breast cancer patients, which is what Prescient is seeking to demonstrate in these studies. Further, we believe that PTX-200’s unique mechanism of action as a PH domain inhibitor may have advantages over other Akt inhibitors,” said Mr Yatomi-Clarke.

“It is worth noting that two of the people involved in the discovery and development of ‘ipatasertib’ at Array BioPharma both now work in key roles with Prescient: our vice president of chemistry, manufacturing and controls, Dr Mike Preigh and our vice president for business development Dr Jim Winkler,” Mr Yatomi-Clarke noted.

Unlike other drug candidates that target Akt inhibition, PTX-200 is on course to prove that it has lower toxicity problems compared to other industry variants. According to Prescient, PTX-200 has a novel mechanism of action that specifically inhibits Akt while being comparatively safer.

This highly promising compound is now the focus of three separate clinical trials – two Phase 1b/2 and one Phase 2 trial, all carried out in the US.

Progressive development

In further good news, the company said that not only did patients with pathological complete responses (pCR) remain free of disease progression, but all patients with partial responses (PRs), also remain free of disease progression after more than two years.

Progression Free Survival (PFS), which is the time from the start of treatment until disease recurrence or progression, ranges from 22.8 months to 30.4 months so far, with an average of 27 months.

Prescient said that all its patients remain “progression-free” to date.

Meanwhile, overall survival (OS), which is the time from start of treatment until death, exhibits the same average duration of 27 months, given that none of the patients have passed away.

While PFS and OS are not formal endpoints to this study, “their analysis nevertheless fortifies the body of evidence for the study’s endpoint of pCR rates, which the US FDA recognises as an endpoint to accelerated approval”.

“Typically, women with locally advanced breast cancer will have disease recurrence five years after successful treatment, but many of these women will progress within the first two years,” said Terrence Chew, chief medical officer of Prescient.

“The observation that our patients have not experienced any cancer progression beyond two years on average is therefore encouraging and supports the response rates we have seen so far,” he added.