Promising interim update from Evgen's STEM breast cancer trial

Clinical stage drug development company Evgen Pharma announced an encouraging interim update on STEM, its Phase II clinical trial in advanced breast cancer, on Monday.

The AIM-traded firm said the update, which it was able to provide as the trial design was open label, comprised the first 20 patients to have completed the trial.

It said patients recruited in STEM had previously responded to hormone therapy (tamoxifen, aromatase inhibitors or fulvestrant) for at least six months, but had then been diagnosed with progressive disease, indicating secondary resistance to the hormone therapy.

Patients in STEM continued on their hormone therapy, but also received SFX-01.

They had six-weekly scans and were discontinued from the study as soon as a scan showed progressive disease or progress was evident on symptomatic grounds.

The maximum period on the trial was 24 weeks, with patients who responded to the drug able to access SFX-01 after that time via a compassionate use programme.

“At this interim stage, in the opinion of the principal investigator, Dr Sacha Howell, and of the company's Chief Medical Advisor, SFX-01 is proving to be well tolerated with no safety concerns arising, [and] SFX-01 shows encouraging early signs of anti-tumour activity,” Evgen’s board said in its statement.

“Four patients had their disease stabilised - that is, having joined the trial with progressive disease their tumours stopped progressing - for the full duration of the study through to, and including, a favourable final scan result at week 24.

“Of these four patients, one also had a partial response which is a reduction in tumour size of at least 30% on one scan.”

In addition to those four patients, the company said a further two patients had their disease stabilised through to, and including, the week 18 scan but then showed disease progression at the final week 24 scan.

“One of these two patients also demonstrated a partial response on one scan before disease progression was recorded at the final scan.”

All patients that have a favourable week 18 scan were registered in the compassionate use programme to ensure continuity of drug between the final week 24 scan and the scan result, which could be some time later, Evgen explained.

It said those that have a favourable week 24 scan continued on the programme.

“STEM, which will include up to 60 patients, remains on track to report around the end of 2018 with 14 sites having already recruited a total of 44 patients across the UK, Belgium, Spain and France.

“The 44 patients include the 20 patients in this interim update.”

Evgen said the primary endpoints of the study were safety and tolerability, and clinical benefit rate at 24 weeks - i.e. the proportion of patients with no disease progression after 24 weeks of therapy, including stable disease, partial response and complete response.

“The design of the STEM study, adding the drug to endocrine therapy on which a patient's cancer was progressing, sets a high bar for SFX-01,” said principal investigator Dr Sacha Howell of the Christie Hospital, Manchester.

“In light of this, these interim results are highly encouraging.

“Objective responses indicate activity in this setting, and disease stabilisation for 6-12+ months represents clinically meaningful prolongation of response.”

Dr Howell said SFX-01 was generally well tolerated and the results together, should they look similar in the final analysis, suggested further investigation of SFX-01 in advanced breast cancer would be warranted.