Mithra announced plans to support the clinical development of its CSF-1R kinase inhibitor, as a monotherapy, and in combination with immune checkpoint inhibitors, following positive results in three different preclinical models.

Mithra is developing the CSF-1R kinase inhibitor with BCI Pharma for the treatment of endometriosis, oncology, and inflammatory disorders. The collaboration was first announced in 2021, and Mithra has the option to acquire the rights to the series of CSF-1R inhibitors, in addition to other rights and intellectual property related to this class of drugs.

Colony-stimulating factor 1 receptor (CSF-1R) is a cell-surface tyrosine kinase receptor and a key regulator of macrophage biology and homeostasis.

chief scientific officer of the Belgium-based company, Graham Dixon, said the data from preclinical models support further development of CSF-1R inhibitors in combination with immune checkpoint inhibitors.

GlobalData has identified immune checkpoint inhibitors and modulators as the most utilised class of immuno-oncology drugs in clinical trials. However, their high price tag has led to increased reimbursement issues reported by the prescribers.

GlobalData is the parent company of Clinical Trials Arena.

CSF-1R’s preclinical data

According to Mithra, a decrease in tumour-infiltrating macrophages, and repolarisation of the tumour-supportive M2 macrophage to the tumour-suppressive M1 macrophage was observed when the lead drug was evaluated in a preclinical study model.

The CSF-1R inhibitor was more effective when administered twice a day in comparison to a once-daily administration in the preclinical model.

Furthermore, upon assessing the CSF-1R inhibitor’s efficacy in combination with the anti-PD1 therapeutic antibodies additional tumour growth inhibition was observed, with 50% of the animals in the triple-negative breast model achieving complete tumour regression with the combination.