On September 1, acalabrutinib was listed on the Pharmaceutical Benefits Scheme (PBS) for the treatment of relapsed or refractory chronic lymphocytic leukaemia (CLL) and small lymphocytic lymphoma (SLL). Acalabrutinib is an inhibitor of Bruton’s tyrosine kinase (BTK), an important enzyme in oncogenic signalling. Inhibition of BTK ultimately leads to reduced proliferation and survival of malignant B-cells.
The efficacy of acalabrutinib in the treatment of CLL was assessed in two randomised Phase III clinical trials. In the ASCEND trial, patients received acalabrutinib monotherapy or physician’s choice (rituximab plus idelalisib or bendamustine) with a median follow-up of 16.1 months. The median progression-free survival (PFS) was not reached in the acalabrutinib group, compared to 16.5 months for the control group. In the ELEVATE-TN trial, patients received acalabrutinib monotherapy, acalabrutinib with obinutuzumab, or obinutuzumab with chlorambucil. After a median follow-up of 28.3 months, the median PFS was not reached for patients taking acalabrutinib, compared to 22.6 months for the control group.
The most common adverse events reported during these clinical trials include anaemia, neutropenia, thrombocytopenia, upper respiratory tract infection, and diarrhoea. Bleeding events, such as bruising and petechiae, are very common; major haemorrhage was reported in 3.6% of patients. To minimise the risk of bleeding, physicians may consider withholding therapy in the three to seven days before and after surgery.
1. Calquence® (Acalabrutinib) Australian approved product information. Macquarie Park: AstraZeneca. Approved November 2019.
2. Ghia P, Pluta A, Wach M, Lysak D, Kozak T, Simkovic M, et al. ASCEND: Phase III, Randomized trial of acalabrutinib versus idelalisib plus rituximab or bendamustine plus rituximab in relapsed or refractory chronic lymphocytic leukemia. J Clin Oncol. 2020; 38(25): 2849-61.
3. Sharman JP, Egyed M, Jurczak W, Skarbnik A, Pagel JM, Finn IW, et al. Acalabrutinib with or without obinutuzumab versus chlorambucil and obinutuzumab for treatment-naive chronic lymphocytic leukaemia (ELEVATE-TN): a randomised, controlled, phase 3 trial. Lancet. 2020; 395(10232): P1278-91.
4. Singh SP, Dammeijer F, Hendriks RW. Role of Bruton’s tyrosine kinase in B cells and malignancies. Mol Cancer. 2018; 17: 57.