The following article features coverage from the American Society of Hematology 2019 meeting. Click here to read more of Cancer Therapy Advisor‘s conference coverage.

Inotuzumab ozogamicin (InO) exhibits clinical efficacy against heavily pretreated, relapsed CD22-positive pediatric B-cell acute lymphoblastic leukemia (B-ALL), according to findings from a single-arm phase 2 clinical trial. The findings of this single-arm phase 2 trial were presented in during the 61st American Society of Hematology (ASH) Annual Meeting and Exposition in Orlando, Florida.

“InO demonstrated a CR/CRi [complete response/CR with incomplete count recovery] rate of 58% in these heavily pretreated children and young adults with R/R CD22-positive B-ALL,” reported lead author Maureen M. O’Brien, MD, of the Cancer and Blood Diseases Institute, Cincinnati Children’s Hospital Medical Center, Ohio, and coauthors.

“In responders, 65% achieved MRD <0.01%,” they reported. “Minimal hepatic toxicity was observed during InO therapy. SOS occurred in 26% of patients who underwent subsequent HSCT, and it was “manageable with supportive care including defibrotide.”

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InO is a CD22-targeted, calicheamicin-linked antibody-drug conjugate approved by the US Food and Drug Administration for adults with relapsed and refractory B-ALL. While InO is approved for adults with relapsed/refractory B-ALL, there has not been prospective data on its safety and clinical efficacy in children.


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The study authors enrolled 48 evaluable patients with a median age of 9 years, who received InO (1.8 mg/m2; 0.8 mg/m2 on day 1, 0.5 mg/m2 on days 8 and 15). Eligibility included at least 5% marrow blasts and direct bilirubin equal to or less than 1.5 times upper limit of normal, the authors noted.

“This single-arm phase 2 trial enrolled patients age 1-21 years with CD22-positive B-ALL in >2nd relapse, refractory to 2 prior induction regimens, any relapse after HSCT, or 1st relapse with Down syndrome (DS),” they reported.

The CR/CRi rate was 58%.

Three patients experienced partial responses (PR) and 9 stable disease. Eight patients experienced disease progressive (PD) despite treatment, two of whom had marrow CR (minimal residual disease [MRD] 0.02% and <0.01%).

The most common adverse events (AEs) in cycle 1 were febrile neutropenia and infection, the authors reported. “No treatment-related toxic deaths were reported.” The most common dose-limiting toxicity was prolonged marrow aplasia.

“Given the observed efficacy, InO will be incorporated into a randomized phase 3 trial for newly diagnosed pediatric patients with high-risk B-ALL,” the authors reported.

Read more of Cancer Therapy Advisor‘s coverage of ASH’s annual meeting by visiting the conference page.

Reference

O’Brien MM, Ji L, Shah NN, et al. A phase 2 trial of inotuzumab ozogamicin (InO) in children and young adults with relapsed or refractory (R/R) CD22+ B-acute lymphoblastic leukemia (ALL) results from Children’s Oncology Group Protocol AALL1621. Presented at: 61st American Society of Hematology (ASH) Annual Meeting and Exposition; December 7-10, 2019; Orlando, FL. Abstract 741.