Imugene Limited announced that enrolment has opened for its expansion study in bile tract cancer (cholangiocarcinoma) patients, having completed the fifth, high dose cohort in the intratumoural (IT) arm of the monotherapy dose escalation study evaluating its cancer-killing virus CF33-hNIS (VAXINIA). The expansion of the MAST (Metastatic Advanced Solid Tumours) Phase 1 trial is planned for 10 patients with bile tract cancers, after early positive responses were observed in gastrointestinal cancers, particularly in cholangiocarcinoma. Cholangiocarcinoma is a rare disease in which malignant cancer cells form in the bile ducts.

It is difficult to treat and generally responds poorly to immunotherapy drugs. One patient with cholangiocarcinoma who had failed three prior lines of therapy received a mid-dose of IT-administered monotherapy VAXINIA achieved a complete response, meaning the disappearance of all signs of cancer in response to treatment, with no known recurrence in more than 430 days. A second patient with cholangiocarcinoma, who has also progressed on prior drug therapies, achieved stable disease for more than four months upon receiving IV-administered VAXINIA.

In November 2023, the FDA granted the VAXINIA MAST clinical program Fast Track Designation for the treatment of bile duct cancer (cholangiocarcinoma), which allows Imugene closer cooperation with the FDA to expedite the program and potential approval process. This designation followed the promising data detailing Phase 1 efficacy and tolerability. On Friday 12 April 2024, the Cohort Review Committee cleared the fifth cohort in the IT arm of the monotherapy dose escalation portion of the MAST trial, with no safety signals seen to date.

In addition to the patients dosed in the monotherapy dose escalation portion of the trial, enrolment is ongoing for the VAXINIA and pembrolizumab combination portion of the trial, with 16 patients dosed to date. The multicenter, 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. With no safety signals identified to date, the trial has since progressed through the monotherapy dose escalation cohorts as well as the combination study, whereby VAXINIA is administered with well-known checkpoint inhibitor pembrolizumab.

CF33 oncolytic virus, developed by City of Hope, has been shown to shrink colon, lung, breast, ovarian and pancreatic cancer tumours in preclinical laboratory and animal models. Further dose escalation to continue as long as no safety issues are observed.