Prima BioMed (ASX: PRR) has announced a new clinical trial of IMP321, to be called ‘TACTI-mel’, short for ‘Two ACTive Immunotherapeutics in melanoma’.
In the safety and dose finding study IMP321 will be combined with an approved checkpoint inhibitor in patients with metastatic melanoma.
The Human Research Ethics Committee at the Greenslopes Private Hospital in Brisbane has approved Prima’s Phase I clinical trial protocol, and it is expected that the first patient in the TACTI-mel study will be dosed in the first half of 2016.
According to the company, the trial will represent one of the first clinical occasions in which an Antigen Presenting Cell (APC) activator has been combined with a checkpoint inhibitor.
Prima CSO and CMO, Dr Frederic Triebel, said: “The TACTI-mel study represents a significant development for Prima BioMed because the future of immuno-oncology lies in combination therapies. If we can combine IMP321 synergistically with a checkpoint inhibitor, as the pre-clinical evidence has suggested, then we will be well positioned in this revolutionary field.”
The checkpoint inhibitors are monoclonal antibody drugs which target certain inhibitory ‘checkpoints’ on immune cells. The regular function of such checkpoints is to supress an immune response and cancer is able to exploit the checkpoints to prevent the immune system from attacking tumours. The checkpoint inhibitors, by foiling this tumour escape route, allow a more effective immune response, leading to significant beneficial outcomes for many patients.
The pre-clinical and clinical evidence to date has suggested that IMP321 can treat cancer by activating APCs to sustain an anti-cancer immune response.
This is a markedly different mechanism of action from the checkpoint inhibitors, and suggests that the two approaches can be used synergistically in combination, said the company.
Prima advised the market in May 2015 that it had filed a provisional patent application over the use of IMP321 in combination with immune checkpoint inhibitors, thereby potentially providing patent exclusivity for the product to 2035 or beyond if granted.