The purpose of this study is primarily designed to evaluate the safety and tolerability of CCS1477 in patients with relapsed or refractory acute myeloid leukaemia (AML)/high-risk myelodysplastic syndrome (MDS), multiple myeloma (MM) and non-Hodgkin lymphoma (NHL; B or T-cell).
CCS1477 is a potent, selective and orally bioavailable inhibitor of the bromodomain of p300 and CBP, critical transcriptional co-activators of genes that drive cell proliferation and survival. The compound causes G1 cell cycle arrest and is anti-proliferative across a broad range of haematological cell models, representative of AML, MM and lymphomas. This is also accompanied by an increase in myeloid differentiation in AML cells. CCS1477 has significant anti-tumour activity as a monotherapy in xenograft models of AML and multiple myeloma.
Additionally, there are molecular features of certain haematological malignancies that are likely to increase the sensitivity to p300/CBP inhibition with CCS1477. For example, in B-cell lymphomas there are frequent loss of function mutations in CBP. These tumours become dependent on the non-mutated p300 paralogue (twin) protein for their continued growth. When p300 is inhibited, this drives synthetic lethality leading to apoptosis/cell death.
This study will determine the maximum tolerated dose (MTD) and/or recommended Phase II dose (RP2D) and schedule(s) of CCS1477 and investigate clinical activity of CCS1477 monotherapy in patients with haematological malignancies.