Acalabrutinib and Rituximab in Previously Untreated Mantle Cell Lymphoma

This is a Phase II, multicentre, single arm, open label pilot study to assess the safety and efficacy of acalabrutinib in combination with rituximab for previously untreated elderly frail mantle cell lymphoma patients. 48 patients will be recruited from 12 UK centres over 30 months. Patients will receive acalabrutinib and rituximab for up to six cycles. The cycle length is 28 days. Specifically, patients will receive acalabrutinib, orally, at a dose of 100 mg twice daily for 28 days and rituximab 375 mg/m2 intravenously on day 1 (+/-3) of each cycle.\* Patients with any degree of response at the Week 12 (end of cycle 3) and Week 24 assessments (end of cycle 6) will continue with acalabrutinib monotherapy at a dose of 100 mg twice daily until disease progression, the development of unacceptable toxicity or any other reason (whichever occurs sooner). \* Note: Acalabrutinib may be administered at a dose of 100 mg od po for cycle 1 day 1-7 at the local investigator's discretion. The dose should be escalated to full dose (100 mg bd) by day 8, cycle 1 if no toxicity is seen (see dose modification section). If a patient experiences toxicity during cycle 1 day 1-7 100 mg od po, the case must be discussed with the TMG to decide if acalabrutinib should continue. The CTC CARAMEL team should be contacted as soon as possible to arrange discussions with the TMG. Rituximab may be administered subcutaneously at a flat dose of 1400 mg from cycle 2 onwards following an intravenous dose of 375 mg/m2 in cycle 1. Consider splitting the first dose of rituximab at cycle 1 in the minority of MCL patients presenting with a white cell count of \>25 x 109/L. Consider splitting 25-50 mg/m2 on D1 and 325-350 mg/m2 on D2 of cycle 1 (to a total of 375 mg/m2 over D1/D2) according to investigator and site preference. Full dose 375 mg/m2 IV (or s/c equivalent) should be given in all patients from cycle 2 as a single dose. All patients will be followed up for a minimum of 2 years following being registered into the trial. For patients that have been in follow-up for more than 2 years, annual survival and disease status follow-up will continue until the end of the trial.