STop and Restart Acalabrutinib In fRail Patients With Previously Untreated Chronic Lymphocytic Leukemia

The irreversible Bruton's Tyrosine Kinase (BTK) inhibitor acalabrutinib (ACA) has potent clinical activity as a single agent in patients with treatment naive and Relapsed/Refractory Chronic Lymphocytic Leukemia (CLL). However, a growing body of concerns is raising regarding the unlimited administration of targeted therapy as BTKi. First, long-term treatments expose the patients to increased risk of specific adverse events (infections, bleeding events or cardiovascular problems). Second, continuous administration might also increase the risk of clonal evolution and therapeutic resistance resulting from genetic alterations such as BTK or PLCG2 mutations. Discontinuation of therapy after a fixed period is expected to prevent these events. Rapid and deep responses yielded by ACA in elderly patients pave the way of investigating a limited 18-months period schedule. This study aims to investigate the 1-year PFS upon ACA discontinuation and efficacy of restarting ACA upon symptomatic relapse.

This multicenter, non comparative, randomized phase II trial aims at evaluating the impact of a stopping ACA strategy on PFS of CLL patients \>70 years or with coexisting comorbidities. Patients will receive continuous Acalabrutinib (ACA) at 100 mg bid for 18 months. Dose adaptations will be made according to labels. In case of first occurrence of grade ≥3 non-hematological toxicity, febrile grade ≥3 neutropenia or grade ≥4 hematological toxicity treatment must be stopped until recovering grade 1 or baseline state. * 1st and second occurrence : restart at 100 mg twice daily * 3rd occurrence : restart at 100 mg once daily * 4th occurrence : discontinue acalabrutinib At month 19 day 1, patients will be randomized (1:2) in two arms: * Arm 1 = Control arm (acalabrutinib) continuing acalabrutinib until disease progression or unacceptable toxicity or * Arm 2 = Experimental arm (watch and monitor) without ACA (see trial design). Upon progression in the experimental arm, all patients will be re-treated with ACA at the last received dose after central reviewing of treatment criteria. Upon progression in the control arm, patients will receive next line therapy at the discretion of their physicians and according to iwCLL 2018 criteria. Patients will be monitored every three months until M31 then every 6 months until M60 or progression for both response and toxicity according to CTCAE v.5. Minimal/Measurable Residual Disease (MRD) assessment will be done at month 19 day 1 in the peripheral blood. CT-scan will be performed at baseline, then at month 19 day 1 and every 6 months within the year after randomization.