LONDON (ShareCast) - (Sharecast News) - Clinical-stage drug development company Evgen Pharma announced new preclinical data on Monday, which showed 'SFX-01' could be of benefit to metastatic breast cancer (mBC) patients who had become resistant to CDK4/6 inhibitors.
The AIM-traded firm said that, since the 'STEM' open-label phase 2 trial of SFX-01 in mBC concluded, CDK4/6 inhibitors had become standard-of-care as the first line mBC treatment for the large group of patients who were estrogen receptor positive.

Those drugs provided an extended period of progression-free survival, but invariably patients' tumours became resistant to them.

Options for such patients were limited, the company explained, especially since drugs used in such a setting were poorly tolerated.

As a result, Evgen's collaborators at the Manchester Breast Centre, the University of Manchester, were conducting further in-vitro preclinical work to assess the impact of SFX-01 in CDK4/6 resistance models.

An increasing body of in vitro data from there showed that in those models, SFX-01 could suppress tumour growth and metastasis in patients who had become resistant to CDK4/6 inhibitors.

In particular, SFX-01 reduced the viability and mammosphere colony formation ability of palbociclib-resistant cells in vitro.

Palbociclib was described by Evgen as the "leading" CDK4/6 inhibitor, marketed by Pfizer, with sales of around $5bn in 2019.

Mammospheres are colonies of primary tumour cells which represent a disease-relevant model to study drug effectiveness, it added.

Should that data be reinforced with in-vivo work, the company said it would pursue a phase 2 placebo-controlled study in second line estrogen receptor positive mBC treatment of patients who had failed on CDK4/6 inhibitors, which could begin in 2022.

The company said its previous open-label STEM trial in patients who had not received CDK4/6 inhibitors demonstrated evidence of anti-cancer activity via objective responses of tumour shrinkage.

It said 24% of patients showed a "durable clinical benefit" for at least six months, despite the late stage of disease and patients' established resistance to hormone therapy.

Of those, five patients were still receiving SFX-01 at 12 months, and one patient remained on SFX-01 treatment for 18 months.

Evgen said it also had a "mild and favourable" side effect profile for an anti-cancer drug.

"It is exciting that the preliminary data set generated by our colleagues at the Manchester Breast Centre suggests SFX-01 may have a valuable role in the treatment of patients who have developed CDK4/6 resistance patients," said chief executive officer Dr Huw Jones.

"We will soon be proceeding with the in vivo work and we are working up the design of the next trial."

At 1453 BST, shares in Evgen Pharma were down 4.73% at 8.05p.

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