Indirect Treatment Comparison of Inotuzumab Ozogamicin Versus Blinatumomab for Relapsed or Refractory Acute Lymphoblastic Leukemia

INTRODUCTION: No head-to-head studies have compared inotuzumab ozogamicin (InO) and blinatumomab (Blina) for the treatment of adults with relapsed or refractory B cell precursor acute lymphoblastic leukemia (ALL). Indirect treatment comparisons (ITCs), namely network meta-analysis (NMA), anchored matching-adjusted indirect comparison (MAIC), and simulated treatment comparison (STC), were conducted to compare the relative efficacy of these therapies. METHODS: Patient-level data from a study that evaluated InO with standard of care (SoC) chemotherapy (INO-VATE-ALL) and published data from a study that evaluated Blina with SoC chemotherapy (TOWER) were used in the analyses. Endpoints evaluated included remission rate defined as complete remission or complete remission with incomplete hematologic recovery (CR/CRi), hematopoietic stem cell transplantation (HSCT), overall survival (OS), and event-free survival (EFS). For each outcome, treatment-effect modifiers were adjusted for in the anchored MAIC and STC analyses. RESULTS: Analyses showed statistically significant higher rates of remission and HSCT with InO compared to Blina irrespective of the ITC method used or measure of the effect (i.e., odds ratio [OR] or rate difference). The treatment effects derived from the MAIC and STC analyses were consistent and stronger than those estimated from the NMA. A trend favoring InO was detected for EFS. The ITC results for OS suggest no difference between InO and Blina. CONCLUSION: Results from these ITCs indicated a statistically significant advantage for InO over Blina for rates of remission and HSCT in adults with relapsed or refractory B cell precursor ALL. It was not possible to fully adjust for all treatment-effect modifiers, and the similarity in chemotherapy regimens used in the SoC comparator arms of the INO-VATE-ALL and TOWER studies is worthy of further exploration. Both studies, however, used chemotherapy regimens that have a low response rate; therefore, no significant differences in efficacy outcomes are expected between SoC arms. FUNDING: Pfizer Inc, New York, NY. PLAIN LANGUAGE SUMMARY: Plain language summary available for this article. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s12325-019-00991-w) contains supplementary material, which is available to authorized users.