A phase 2a, single-arm, open-label study of tafasitamab, a humanized, Fc-modified, anti-CD19 antibody, in patients with relapsed/refractory B-precursor cell acute lymphoblastic leukemia

Cancer. 2021 Nov 15;127(22):4190-4197. doi: 10.1002/cncr.33796. Epub 2021 Aug 3.


Background: B-precursor cell acute lymphoblastic leukemia (B-ALL) in adults is an aggressive and challenging condition, and patients with relapsed/refractory (R/R) disease after allogeneic stem cell transplantation (SCT), or noncandidates for SCT, have a particularly poor prognosis. The authors investigated the activity of the Fc-modified anti-CD19 antibody tafasitamab in adults with R/R B-ALL (NCT01685021).

Methods: Adults with R/R B-ALL received single-agent tafasitamab 12 mg/kg weekly for up to four 28-day cycles. Patients with complete remission (with or without neutrophil/platelet recovery; complete remission [CR] or complete remission with incomplete count recovery [CRi]) after cycles 2, 3, or 4 could continue tafasitamab every 2 weeks for up to 3 further months. The primary end point was overall response rate (ORR).

Results: Twenty-two patients were treated (median, 2 prior lines of therapy; range, 1-8). Six patients completed 2 cycles, and 2 of these patients responded for an ORR of 9%; 16 patients (73%) progressed before their first response assessment. Responses lasted 8 and 4 weeks in the 2 patients with CR and minimal residual disease (MRD)-negative CRi, respectively. Tafasitamab produced rapid B-cell/blast depletion in 21 of 22 patients within 1 to 2 weeks of first administration. Tafasitamab was well tolerated, with the most frequent adverse events being infusion-related reactions (59.1%) and fatigue (40.9%). Grade 3 to 4 febrile neutropenia (22.7%) was the most common hematologic adverse event.

Conclusions: Tafasitamab monotherapy was associated with clinical activity in a subset of patients with R/R B-ALL, including short-lasting CR and MRD-negative CRi. Given its favorable tolerability profile, further development of tafasitamab in chemoimmunotherapy combinations and MRD settings should be explored.

Keywords: B-lymphocytes; CD19; MOR208; Xmab5574; acute lymphoblastic leukemia; antineoplastic monoclonal antibody.

Publication types

  • Clinical Trial, Phase II
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Antibodies, Monoclonal, Humanized
  • Antigens, CD19
  • Hematopoietic Stem Cell Transplantation*
  • Humans
  • Lymphoma, B-Cell*
  • Precursor Cell Lymphoblastic Leukemia-Lymphoma* / drug therapy


  • Antibodies, Monoclonal, Humanized
  • Antigens, CD19
  • tafasitamab

Associated data

  • ClinicalTrials.gov/NCT01685021

Grant support