Imugene reports positive outcomes in novel virus trial against advanced cancers

Clinical stage immuno-oncology company Imugene (ASX: IMU) has obtained positive initial results from a clinical trial investigating its potential treatment of tumours with a unique cancer-killing virus.

The phase 1 MAST (metastatic advanced solid tumours) trial is currently evaluating the safety and efficacy of the novel cancer-killing virus CF33-hNIS (VAXINIA).

The multi-centre phase 1 MAST trial commenced by delivering a low dose of VAXINIA to patients with metastatic or advanced solid tumours who have had at least two prior lines of standard of care treatment.

The City of Hope-developed oncolytic virus has been shown to shrink colon, lung, breast, ovarian and pancreatic cancer tumours in pre-clinical laboratory and animal models.

Positive early results from phase 1 have included the eradication of lesions on a number of patients.

To date, 38 patients have been dosed with VAXINIA during the continuing dose escalation phase as either monotherapy or in combination with pembrolizumab, 31 of which were found to be at a suitable stage for evaluation for efficacy.

Testing found seven of 15 patients, (47%) had a reduction in tumour burden in injected lesions and three had lesions that were completely eradicated.

Three patients (21%) had an objective response, including one complete response in a patient with cholangiocarcinoma (a type of biliary tract cancer) and two partial responses in patients with melanoma (skin cancer) by RECIST.

In IV cohorts involving 17 patients, 53% achieved stable disease (SD) as their best response.

Clinical benefits derived

It was also found that patients who received prior checkpoint blockade therapy derived clinical benefit with and without pembrolizumab.

As planned, Imugene will now expand the trial for 10-20 patients with biliary tract cancers.

In early results presented at the annual ASCO-GI symposium in San Francisco, California this week, seven patients with gastrointestinal cancers who received CF33-hNIS alone – including three colorectal patients, two biliary tract, one pancreatic and one liver cancer – showed positive treatment effects with a disease control rate of 86%.

Imugene said that tumour burden in these patients correlated with systemic immunological changes known to promote anti-tumour immunity, a key development.

Positive responses

“This latest data reinforces the early positive responses we’ve seen in gastrointestinal cancers and in particular for cholangiocarcinoma,” Imugene managing director and chief executive officer Leslie Chong said.

“It provides an excellent platform to investigate the impact of VAXINIA at higher dose levels as we also expand the trial to additional patients with hard-to-treat biliary tract cancers.”

“It is a proud moment for us to be able to present these results at ASCO-GI and promote the potential of VAXINIA and CF33 more broadly.”

Ms Chong said it was notable that one patient with biliary tract cancer treated intratumourally with a mid-dosage level displayed pseudo-progression with a 49% increase in tumour burden after two cycles of therapy.

However, by the fourth cycle they achieved a complete response with no known recurrence in more than 430 days.

A second patient with bile duct cancer, who previously progressed on prior drug therapies, achieved SD for more than four months upon receiving intravenously-administered CF33-hNIS.

Overall, the MAST study aims to recruit cancer patients across approximately ten trial sites in the United States and Australia.