Starpharma’s DEP irinotecan shows promising efficacy in Phase 2 advanced cancer trials

Starpharma (ASX: SPL) has announced positive anti-tumour efficacy results from a Phase 2 clinical trial of its lead candidate DEP irinotecan in heavily pre-treated patients with a range of difficult-to-treat advanced and metastatic cancers.

DEP irinotecan is a novel patented nanoparticle formulation of SN38, the active metabolite of the widely-used anti-cancer drug irinotecan (marketed as Camptosar).

Developed using Starpharma’s proprietary DEP dendrimer technology, the drug is designed to solubilise and directly deliver SN38 to cancer tissue, eliminating the need for liver metabolism and thereby avoiding the production of toxic metabolites.

The 114 patients enrolled in the trial ranged in age from 31 to 78 years of age and had exhausted all standard-of-care treatment options for colorectal cancer and platinum-resistant ovarian cancer prior to commencing therapy with DEP irinotecan.

Results included significant and sustained tumour shrinkage and disease control.

Favourable comparison

The Phase 2 results showed that patients with advanced colorectal cancer who used DEP irinotecan in combination with 5-fluorouracil (5-FU) and leucovorin (LV) achieved a median progression-free survival (mPFS) of 4.2 months, approximately 68% longer than published data.

The disease control rate (DCR) in these patients was 86% and the objective response rate (ORR) was 14%, which also compares favourably with the published ORR of 4% for conventional irinotecan plus 5-FU/LV.

Key efficacy results were similarly positive in heavily pre-treated patients with advanced platinum-resistant/refractory ovarian cancer.

DEP irinotecan monotherapy used once a fortnight achieved an mPFS rate of 9.3 months, approximately three times longer than published data on standard-of-care (SoC) single-agent therapies including paclitaxel.

These patients had a DCR of 100% and an ORR of 43%, which also compares favourably to published ORRs of up to 12% for SoC single-agent therapies.

Well-tolerated

DEP irinotecan, administered as a monotherapy or in combination with 5-FU/LV, was confirmed to be well-tolerated by the patient group with a notable lack of severe gastrointestinal adverse events and no instances of cholinergic syndrome, in contrast to standard irinotecan.

Importantly, no immune-mediated adverse events were reported from the trial, making the drug suitable for combination with immuno-oncology agents.

Commercial opportunities

“This data demonstrates clinically meaningful anti-tumour efficacy and a favourable safety and tolerability profile in multiple hard-to-treat cancers,” Starpharma chief executive officer Cheryl Maley said.

“We are confident that DEP irinotecan presents significant commercial opportunities in colorectal and ovarian cancer indications as a monotherapy and in a range of potential combination regimens.”

“[It could] potentially address unmet medical needs in these challenging-to-treat cancers.”

Ms Maley said the company had commenced seeking a partner to further develop DEP irinotecan for patients in need.