Imugene sees positive early signs in VAXINIA trial; “may be potent anti-cancer drug”
Proactive Investors UK
Last updated: 11:28 06 Nov 2023, First published: 11:09 06 Nov 2023
Imugene Ltd (ASX:IMU, OTC:IUGNF) is seeing positive early signs from its phase 1 MAST (metastatic advanced solid tumours) clinical trial evaluating the safety and efficacy of VAXINIA — the novel cancer-killing virus CF33-hNIS, including one complete response in bile duct cancer and one partial response (PR) in melanoma.
The multicenter phase 1 MAST trial delivers 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 preclinical laboratory and animal models. The trial commenced in May 2022 and is anticipated to run for approximately 24 months while being funded from existing budgets and resources.
Imugene MD and CEO Leslie Chong said: “Phase 1 trials are generally designed to look for safety, tolerability and early response signals to determine the optimal dose for further development.
“The early positive response data we are seeing at the mid-dose level in hard-to-treat bile duct cancer suggests that VAXINIA may be a potent anti-cancer drug as we interrogate higher dose levels”. “With no adverse safety signals, thus allowing us to dose higher, VAXINIA will have a very high therapeutic window which is valuable in oncology drug development.”
High disease control rate
Imugene reports that a total of 34 heavily pre-treated patients had been dosed with VAXINIA during the continuing dose escalation phase, as of October 31, with all treatments determined safe and tolerable. This comprised 16 patients intratumorally and 18 patients intravenously, dosed with VAXINIA alone or in combination with checkpoint inhibitor drug pembrolizumab (KEYTRUDA).
Twenty-five patients were evaluable, having received at least their first scan at day 42, and seven patients have their first scan still pending.
Of those, the best overall response was one complete response (CR) in bile duct cancer in the mid dose on study for over 350 days; one partial response (PR) in melanoma in the mid dose; while 16 patients had stable disease (SD) showing patients had control and stability of their cancer. Eight had progressive disease (PD).
Early results from six patients with gastrointestinal cancers who received VAXINIA alone — including 2 colorectal cancer, 2 bile duct, 1 pancreatic and 1 liver cancer — showed positive treatment effects, with a disease control rate (all CR, PR and SD) of 75%.
Promising bile duct cancer results
Notably one patient with bile duct cancer, treated intratumorally with mid-dose level displayed “pseudoprogression” with a 49% increase in tumour burden after two cycles of therapy. But by the fourth cycle they achieved a complete response with no known recurrence in over 200 days.
A second patient with bile duct cancer, who previously progressed on prior drug therapies, achieved stable disease for more than four months upon receiving IV-administered VAXINIA.
Bile duct cancers are difficult to treat and typically respond poorly to immunotherapy drugs.
Pseudoprogression is a phenomenon in which the cancer initially appears to be growing, largely due to the cancer cells being infected by the virus then followed by infiltration of cancer fighting immune cells. However, it is usually followed by a decrease in tumour burden when the therapy takes effect. This phenomenon can benefit patients receiving immunotherapy but often leads to premature discontinuation of treatment owing to the false impression the cancer is growing.
Trial ongoing
The trial has now cleared cohort four of the intravenous arm of the monotherapy dose escalation study, as well as IV cohort 2 of the combination study where VAXINIA is administered with KEYTRUDA.
Cohort 5 of the intravenous arm for the monotherapy dose escalation is now open as is intravenous cohort 3 of the combination study.
The company says it intends to expand the trial for 10 patients with bile duct cancers.
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