Cytogenetic guided therapy using blinatumomab and inotuzumab ozogamicin in a patient with relapse/refractory acute...

Acute Lymphoblastic Leukemia (ALL) is an aggressive cancer that requires intense chemotherapy and has a high rate of recurrence. Treatments of Relapse/Refractory (R/R) B-cell ALL are limited. Blinatumomab, a bispecific T-cell engager (CD19/CD3) monocolonal antibody, and Inotuzumab Ozogamicin, an anti-CD22 antibody conjugate, are current recommended options.

To describe a R/R B-cell ALL patient who failed blinatumomab therapy. Subsequently she received inotuzumab ozogamicin achieving a complete response.

Our patient was initially treated with CALGB 10403 regimen but did not achieve a complete response. Blinatumomab was given for relapse/refractory disease however she had an incomplete response despite having 100% expression in CD19 markers. Consequently, she received inotuzumab ozogamicin attributable to 70% expression of CD22. She responded with a complete response and transitioned to a successful hematopoietic stem cell transplant.

There is limited clinical guidance on the preferred treatment of adult R/R B-Cell ALL. Currently, there are no randomized head-to-head trials comparing efficacy of blinatumomab and inotuzumab ozogamicin. Clinical patterns of blinatumomab resistance has been reported. Our case study remains unclear of why our patient had unsuccessful outcomes with blinatumomab regardless of having CD19 positivity of 100%. Future prospective analysis and comparative studies are needed to determine proper sequencing of these therapies.