|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.”
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.
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.
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.