Telaglenastat is an oral glutaminase inhibitor and this is the first time it has been administered to humans. Glutaminase is a key enzyme that controls the glutamine pathway that is prominent in renal cell carcinoma (RCC) and important for the tumour to thrive in the body.
In pre-clinical models, telaglenastat was found to synergise with cabozantinib, a VEGFR2/MET/AXL inhibitor. Telaglenastat (CB-839) plus cabozantinib (Cabometyx) showed encouraging clinical activity and tolerability in heavily pretreated patients with metastatic RCC.
The results of this phase I study were presented at the 2019 Genitourinary Cancers Symposium. Of the 12 patients who where evaluable, there was an objective response rate of 42%. In the 10 patients with clear cell metastatic RCC, the objective response rate was was 50%; 5 patients had a partial response and 5 patients demonstrated stable disease with the treatment.
A randomised phase II trial comparing telaglenastat plus cabozantinib with cabozantinib plus placebo is ongoing.