Solbec's Coramsine found safe and tolerable

Solbec Pharmaceuticals' (ASX:SBP) devil's apple-derived drug Coramsine (SBP002) has met the primary endpoint of safety and tolerability for the two-hour infusion cohort of its single agent phase I clinical trial for advanced solid tumours.

The investigator's final report showed that Coramsine was safe to use and well tolerated at a dose rate of 1 mg/kg/day infused over two hours daily for five days every two weeks.

The secondary endpoint was also achieved, with Coramsine showing a potentially therapeutic benefit in patients with advanced cancer.

"The patients in these phase I trials are patients who were non-respondent to current therapies. In other words, they had tumours which were resistant to all the chemicals they were throwing at them, so they were refractory tumours," said Solbec's CEO and managing director Stephen Carter. "To see a response in a patient that won't respond to any of the normal treatments, whose tumours have probably developed multi-drug resistance, is quite significant."

Six of the 11 patients enrolled in the two-hour infusion cohort completed six or more cycles of Coramsine therapy with two of these responding to the treatment. One of these responders, a patient with metastatic renal cell cancer, which had spread throughout his body, displayed a long-term durable response.

"What we saw in that patient was quite significant in tumour volume reduction. That patient should have died long ago. He's still alive and his tumours haven't started growing back to our knowledge. He was treated about 14-15 months ago," said Carter.

Other than dose limiting toxicities, identified by a transient reversible rise in liver enzymes, no serious adverse events were considered to be related to the study medication and adverse events related to Coramsine were mild and transient in nature.

Quality of life also improved for the patients in the trial, said Carter. "While the numbers are still low, it was extremely interesting to see the majority of patients reporting improvements in things such as cognition, emotional and social wellbeing, and about half that patients had reductions in pain," he said.

The results of this trial will assist Solbec's scientific advisory board in choosing which tumours to target in its phase II studies, said Carter. "It gives us a lot more confidence that our phase II directed on a larger scale will be successful," he said.

The principal investigator Prof Michael Millward, at Perth's Sir Charles Gairdner Hospital, recommended that Coramsine's anti-cancer activity be further explored in disease-directed phase II clinical trials.

"It is unusual to see radiological responses in a phase I study," said Millward. "The documentation of two [such] patients in this study suggests that SBP002 does have potential significant activity."

Four-hour infusion cohort

Recruitment for Solbec's four-hour infusion cohort trial for Coramsine has been completed and the final report is expected shortly. Preliminary results have highlighted a patient with non-small cell lung cancer who has shown a response to Coramsine treatment.