IMM-101 is a suspension of heat-killed whole cell Mycobacterium obuense, which enhances the innate immune response and dendritic cell maturation. IMM-101 has shown to induce a protective CD8+ response in clinically relevant models of pancreatic cancer. In animal model IMM-101 have shown to activate dendritic cells in a dose-dependent manner, enabling these cells to induce IFNγ production by a variety of immune cells in vitro and in vivo and in vitro experiments with human blood cells showed similar results. It has been also shown that direct intradermal injection of IMM-101 initiates a Th1/Th17 adaptive immune response both locally and systemically.
In a randomised Phase II study in combination with gemcitabine, it showed improvement in progression free survival and overall survival without additional toxicity in metastatic pancreatic cancer patients compared to gemcitabine alone.
The purpose of this analysis presented at the Society for Melanoma Research Meeting in 2019 was to explore the long-term safety, tolerability and clinical course of IMM-101 in patients who were previously enrolled in the Phase I safety and tolerability study IMM-101-001, a first-in-human, open label, dose escalation, intra-patient, placebo controlled study, in adult Stage III or Stage IV melanoma patients, with the main objectives to evaluate safety and tolerability with respect to incidence of adverse events and local tolerability at the site of intradermal injection. Between March and September 2010, 18 patients with Stage III/IV melanoma completed a first-in-human (FIH) study to evaluate the safety and tolerability of IMM-101.
Treatment with IMM-101 then continued, initially on a compassionate use program and then in an open label long term follow up study, which closed in Dec 2018. Of the 18 patients (12 Stage IV, 3 Stage IIIB and 3 Stage IIIC) who completed the FIH study, 13 received subsequent treatment on a the compassionate program and 10 were enrolled in the long term follow up study.
Patients on the IMM-101-001 received a single dose of placebo followed by three doses of IMM-101. There were no safety concerns, the adverse event profile was in line with expectations and was manageable. There were no dose limiting toxicities or treatment related serious adverse events . Injection site reactions, as would be expected from exposure to a preparation of mycobacterial antigens, were consistent for this class of product and were mainly mild.
At time of the long term follow up study closure, six of the 10 patients enrolled were alive with 4 of them still receiving treatment with IMM-101. The median time on treatment from first dose in the FIH study was 5.2 years.
Two patients on the LTF study received immunotherapeutic agents other than IMM-101: one patient received IL-2 and one patient IL-2 and ipilimumab.
Other treatments included surgery (4 patients), radiotherapy (2 patients) and chemotherapy which was the standard of care of the time (4 patients).
Two patients did not enter the long term follow-up study but were regularly followed up in clinic and known to be alive and disease free in Dec 2018. One of these patients received further IMM-101 followed by ipilimumab at progression.
Overall, IMM-101 was safe and well-tolerated and local reactions at the injection site were the most frequently reported adverse events.