A Phase 1/2 Study of STP938 (Dencatistat) for Adult Subjects With Relapsed/Refractory B-Cell and T-Cell Lymphomas

The drug STP938 is an inhibitor of an enzyme called cytidine triphosphate synthase 1 (CTPS1). CTPS1, and a very similar enzyme cytidine triphosphate synthase 2 (CTPS2), control the final step in the production of the cytidine triphosphate (CTP). CTP is an essential building block of deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). Studies of people with inherited mutations of the CTPS1 gene indicate that certain types of blood cells required CTPS1 in order to divide rapidly, whereas other cells in the body use the CTPS2 enzyme. Based on these observations, it is expected that blocking CTPS1, using the drug STP938, may be an effective treatment for certain types of cancer that arise from blood cells. The purpose of this study is to see if STP938 is effective at treating different types of lymphoma. STP938 will be given as a tablet. Blood samples will be taken during the study in order to understand the effects of STP938 on the lymphoma and on the rest of the body. The main outcome of the first part of the study is to see if STP938 can be given safely to patients with lymphoma, and to work out the best dose of STP938. The main outcome of the second part of the study is to see if ST938 is effective in treating different types of lymphoma.