Inotuzumab ozogamicin demonstrated robust activity in heavily pretreated patients with indolent B-cell non-Hodgkin lymphoma, but treatment duration was limited by hematologic toxicities, a study published in the British Journal of Haematology has shown.1

Inotuzumab ozogamicin is an investigational antibody-drug conjugate composed of an anti-CD22 monoclonal antibody, which is expressed in about 90% of B-cell malignancies, linked to a cytotoxic agent.

Therefore, researchers sought to evaluate its efficacy and safety in patients with refractory indolent B-cell non-Hodgkin lymphoma.

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For the phase 2 trial, researchers enrolled 81 patients refractory to rituximab alone, rituximab plus chemotherapy, or anti-CD20 radioimmunotherapy.

All participants received inotuzumab ozogamicin 1.8 mg/m2 intravenously for 4 to 8 28-day cycles. Those who achieved a complete response were eligible to receive 2 additional cycles.

RELATED: Inotuzumab Ozogamicin Granted Breakthrough Therapy Designation for Acute Leukemia

Results showed that 59% of patients received 3 or more cycles of inotuzumab ozogamicin and only 16% completed the treatment phase.

Researchers found that the overall response rate was 67%, with 31% achieving a complete response. Median progression-free survival was 12.7 months (95% CI, 8.9 – 26.9) and median overall survival had not yet been reached.

In regard to safety, hematologic adverse events were frequently reported, especially thrombocytopenia and neutropenia, which occurred in 74% and 56% of patients, respectively, and resulted in treatment discontinuation in 37% and 11%, respectively. A total of 58% of patients discontinued inotuzumab ozogamicin due to treatment-related toxicities.

Inotuzumab ozogamicin has also received Breakthrough Therapy Designation from the U.S. Food and Drug Administration for the treatment of patients with relapsed or refractory CD22-positive acute lymphoblastic leukemia. The decision was based on findings from the phase 3 INO-VATE ALL trial, which compared inotuzumab ozogamicin to standard of care chemotherapy.


  1. Goy A, Forero A, Wagner-Johnston N, et al. A phase 2 study of inotuzumab ozogamicin in patients with indolent B-cell non-Hodgkin lymphoma refractory to rituximab alone, rituximab and chemotherapy, or radioimmunotherapy [published online ahead of print April 22, 2016]. Br J Haematol. doi: 10.1111/bjh.14094.