Inotuzumab Ozogamicin and Low-Intensity Chemotherapy in Older Patients With Newly Diagnosed CD22⁺ Philadelphia Chromosome–Negative B-Cell Precursor Acute Lymphoblastic Leukemia

Authors

Patrice Chevallier

¹Hematology Department, Nantes University Hospital, Nantes, France

Patrice Chevallier, Thibaut Leguay, Marc Delord, Cyril Salek, Rathana Kim, Françoise Huguet, Yosr Hicheri, Ulla Wartiovaara-Kautto, Emmanuel Raffoux, Thomas Cluzeau, Marie Balsat, Gabrielle Roth-Guepin, Emmanuelle Tavernier, Stephane Lepretre, Karin Bilger, Hugo Bergugnat, Ana Berceanu, Magda Alexis, Michael Doubek, Eolia Brissot, Mathilde Hunault-Berger, Delphine Lebon, Pascal Turlure, Sylvain Chantepie, Amine Belhabri, Stefan Wickenhauser, Jean-Noel Bastie, Victoria Cacheux, Chantal Himberlin, Anne Banos, Claude Gardin, Sarah Bonnet, Isabelle Plantier, Gian Matteo Pica, Martine Escoffre-Barbe, Nicolas Boissel, Herve Dombret, Emmanuelle Clappier, Philippe Rousselot,

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PURPOSE

The use of inotuzumab ozogamicin (InO), a conjugated anti-CD22 monoclonal antibody, is becoming a promising frontline treatment for older patients with ALL.

EWALL-INO is an open-label prospective multicenter phase II trial (ClinicalTrials.gov identifier: NCT03249870). Patients age 55 years and older with newly diagnosed CD22⁺ Philadelphia chromosome–negative (Ph–) B-cell precursor (BCP) ALL were eligible. After a prephase, a first induction consisting of vincristine, dexamethasone, and three injections of InO (0.8 mg/m² day 1, 0.5 mg/m² day 8/day 15) was followed by a second induction combining cyclophosphamide, dexamethasone, and two injections of InO (0.5 mg/m² day 1/day 8). Responders received up to six cycles of chemotherapy consolidation and 18-month chemotherapy maintenance. Allotransplant was allowed after three consolidations. The primary end point was 1-year overall survival (OS).

Between December 2017 and March 2022, 131 patients (median age 68 years) were included. Three patients died during induction 1 (n = 130), two from multiple organ failure and one from hemorrhage, and none during induction 2 (n = 120). After induction 2, 90% of the patients achieved complete remission (CR) or CR with incomplete platelet recovery (CRp) and 80% had measurable residual disease (MRD2) <10⁻⁴. Among responders (n = 119), 47 relapsed and 14 died in CR/CRp. One-year OS, relapse-free survival (RFS), and cumulative incidence of relapse (CIR) rates were 73.2%, 66%, and 25%, respectively. High-risk cytogenetics and lower CD22 expression (<70%) were associated with worse OS, while both high-risk cytogenetics and MRD2 ≥10⁻⁴ were associated with lower RFS and higher CIR. The 10 allotransplanted patients had very favorable outcomes (90% 2-year OS/RFS and no relapse). Only one nonfatal sinusoidal obstructive syndrome was documented during the study.

Our results support InO's use in first-line regimens for older patients with CD22⁺ Ph– BCP-ALL.