ASCO 2019 — Acalabrutinib+obinutuzumab delivers high response in CLL

  • David Reilly
  • Oncology Conference reports
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  • Acalabrutinib+obinutuzumab demonstrated high-level response with minimal grade 3-4 adverse events (AEs) at 3-year follow-up in patients with treatment-naive or relapsed/refractory chronic lymphocytic leukemia (CLL).

Why this matters

  • Acalabrutinib monotherapy has previously demonstrated >93% objective response rate (ORR) in CLL.

Study design

  • 3-year follow-up of a phase 1b/2 study to investigate acalabrutinib+obinutuzumab in treatment-naive (n=19) and relapsed/refractory (n=26) CLL.
  • Median patient age, 61 (range, 42-76) years.
  • 53% of treatment-naive patients and 50% of those with relapsed/refractory disease had bulky disease.
  • Funding: Acerta Pharma.

Key results

  • Responses:
    • Treatment-naive group: 95% ORR; 31.6% complete response (CR); 63.2% partial response (PR).
    • Relapsed/refractory group: 92% ORR; 7.7% CR; 84.6% PR.
  • PFS:
    • Treatment-naive group at 39 months: 94.4% (95% CI, 66.6-99.2).
    • Relapsed/refractory group at 42 months: 72.7% (95% CI, 43.8-88.4).
  • Minimal residual disease (MRD) in bone marrow:
    • Treatment-naive group: 26%.
    • Relapsed/refractory group: 15%.
  • MRD negativity in peripheral blood was durable.
  • Incidence of grade 3-4 adverse events was minimal, with a 2% discontinuation rate. 


  • Bone marrow biopsies were only performed to confirm CR in patients with MRD negativity in peripheral blood; some CRs may have therefore have been classed as PRs.  

Expert comment

  • Matthew S. Davids, MD, associate director of the CLL Center at Dana-Farber Cancer Institute and assistant professor of medicine at Harvard Medical School, Boston, Massachusetts, noted that the acalabrutinib regimen described requires continuous therapy to maintain response and mentioned a study in which he is involved that aims to find whether the addition of venetoclax to the regimen may enable a fixed-duration regimen.