Purpose: Older patients with ALL receiving conventional chemotherapy have poor survival due to toxic death and relapse. We hypothesized that a chemotherapy-free, targeted regimen using the anti-CD22 antibody-calicheamicin conjugate inotuzumab ozogamicin followed by the bispecific anti-CD19/CD3 T-cell engager blinatumomab would reduce toxic death and yield high rates of prolonged remission and survival.
Methods: Eligible patients were age 60 years and older with untreated, Philadelphia chromosome (Ph)-negative, CD22-positive, B-cell ALL. Patients received up to two cycles of inotuzumab ozogamicin followed by four or five cycles of blinatumomab with intrathecal methotrexate CNS prophylaxis. The primary end point was 1-year event-free survival (EFS).
Results: The 33 eligible patients had a median age of 71 years (range, 60-84) and a median CD22 expression of 92% (range, 21%-100%). Eight (24%) had previous chemotherapy or radiation for other cancers, six for multiple myeloma. The composite complete remission rate was 85% after two cycles of inotuzumab ozogamicin and 97% by the end of two cycles of blinatumomab. At a median follow-up of 30 months, the 1-year EFS and overall survival were 75% (95% CI, 61 to 92) and 85% (95% CI, 73 to 98), respectively. EFS was shorter with lower CD22 expression or detectable measurable residual disease at any time point.
Conclusion: Inotuzumab ozogamicin then blinatumomab without maintenance chemotherapy in older patients with untreated, Ph-negative, CD22-positive, B-cell ALL yields a high remission rate and excellent EFS. Given the lack of standard, safe, and effective therapies in this population, the regimen should be considered a standard treatment option.
Trial registration: ClinicalTrials.gov NCT03739814.