Use of a sequential “sandwich” strategy using CD22/CD19 chimeric antigen receptor (CAR) T-cell therapy followed by autologous stem cell transplant (ASCT) resulted in deep and durable remissions in patients with newly diagnosed Philadelphia chromosome (Ph)–negative B-cell acute lymphoblastic leukemia (B-ALL) who were unable to undergo or declined allogeneic hematopoietic stem cell transplant (allo-HSCT), according to findings from a phase 2 single-center study (NCT05470777).1
Findings published in Cancer demonstrated that at a median follow-up of 28 months (range, 10-50), evaluable patients (n = 37) achieved a median overall survival (OS) and leukemia-free survival (LFS) that had not yet been reached. The 2-year OS rate was 97% (95% CI, 90%-100%), and the 2-year LFS rate was 72% (95% CI, 58%-90%). MRD clearance deepened throughout treatment.
Following induction chemotherapy, 92% of patients experienced a complete remission (CR), 54% had a multiparameter flow cytometry minimal residual disease (MFC-MRD)–negative CR, and no patients achieved next-generation sequencing (NGS) MRD–negative CR. After consolidation chemotherapy, 80% of evaluable patients (n = 35) remained in CR, 71% had an MFC-MRD–negative CR, and 23% (n = 5 of 22) had an NGS-MRD–negative CR. After the first CD22/CD19 CAR T-cell therapy infusion, all patients achieved MFC-MRD–negative CR, and 68% achieved NGS-MRD–negative CR. Following ASCT and a second CAR T-cell infusion, all patients remained in MFC-MRD–negative CR, and 93% achieved NGS-MRD–negative CR (n = 25 of 27).
Among the 35 patients who completed the full treatment sequence, all remained alive at the last follow-up, and most sustained durable MRD-negative remissions beyond 1 and 2 years. Survival outcomes were comparable across standard- and high-risk genetic subgroups, and although patients with residual NGS-detectable disease prior to transplantation were associated with a trend toward shorter LFS, this difference was not statistically significant.
“The CD22/CD19 CAR T-cells and [ASCT] sandwich strategy is a promising approach for treating Ph-negative B-ALL in adolescent/young adult [AYA] and adult patients, offering high efficacy with a favorable safety profile,” lead study author Chong-Sheng Qian, MD, PhD, of the Research Center for Hematologic Diseases at the Jiangsu Institute of Hematology, The First Affiliated Hospital of Soochow University, in Suzhou, China, and colleagues wrote in the publication. “Future studies with larger sample sizes and longer follow-up are warranted to further validate these findings and further explore allo-HSCT–free strategies.”
What was the design of the study?
This investigation was a phase 2, single-arm, open-label study conducted at a single center and approved by the institutional review board of the First Affiliated Hospital of Soochow University.1,2 The study enrolled newly diagnosed AYA and adult patients with Ph-negative B-ALL who had CD19 and CD22 expression by MFC. Eligible patients were either unable to undergo allo-HSCT or declined transplantation.
The primary end point was overall survival, measured from the first day of the initial CAR T-cell infusion. Secondary end points included LFS, MRD-negativity rate and duration, incidence of adverse effects (AEs) following first CAR T-cell therapy infusion, and non-relapse mortality.1 Exploratory analyses assessed survival outcomes of the studied “sandwich” CAR T-based strategy in comparison with an external cohort of patients who received allo-HSCT.
According to the study protocol, patients received induction and consolidation therapy prior to CAR T-cell sequencing. After induction and lymphocyte recovery, peripheral blood lymphocytes were collected via leukapheresis to manufacture CAR T cells. CD22- and CD19-directed CAR T cells were infused sequentially at a dose of 5 × 106 cells/kg as the first infusion. Autologous stem cell mobilization and collection occurred 6 to 8 weeks later, followed by conditioning with a modified BuCy26 regimen and ASCT. A second course of CD22/CD19 CAR T cells was administered 2 days after ASCT. No maintenance therapy was used following the second CAR T-cell therapy infusion, except tyrosine kinase inhibitors for patients with Ph-like ALL harboring ABL-class fusions.
Per protocol, patients with MRD progression after the first CAR T-cell therapy infusion discontinued the sandwich approach and were considered for allo-HSCT or individualized salvage therapy.
What were the baseline patient characteristics of those patients enrolled?
A total of 38 patients were screened for eligibility, of whom 37 were enrolled; one patient was excluded due to active hepatitis B. The median age at enrollment was 28 years (range, 15-60 years), and 35% of the cohort were older than 35 years of age. Elevated baseline disease burden was observed in a subset of patients, with 6 individuals (16%) presenting with a white blood cell count of more than 30 × 109/L at diagnosis. Most patients (89%) had Ph-negative B-ALL, and 4 patients (11%) were classified as having Ph-like B-ALL, including 2 with ABL-class alterations and 2 with JAK-STAT pathway abnormalities. Based on National Comprehensive Cancer Network genetic risk stratification criteria, 21 patients (57%) were categorized as high-risk, including those with adverse genetic features such as TP53 mutations, complex karyotypes, or ZNF384 rearrangements.
Of the 37 enrolled patients, 35 successfully completed the full sandwich strategy. One patient with Ph-like B-ALL in the ABL class did not receive the protocol-specified TKI, representing a protocol deviation. Two patients experienced relapse following the first CAR T-cell therapy infusion and therefore did not proceed with the remainder of the sandwich approach; both subsequently underwent allo-HSCT.
What was the safety profile observed in the study?
The safety profile of the sequential CD22/CD19 CAR T-cell therapy and ASCT was consistent with expected toxicities of CAR T-cell therapy and high-intensity chemotherapy, with no unexpected signals. All patients experienced grade 3/4 hematologic toxicities, which reflected the treatment intensity; after the second CAR T-cell infusion, the median duration of neutropenia was 11 days, and thrombocytopenia lasted a median of 15 days.
Cytokine release syndrome (CRS) was generally mild: grade 1/2 CRS occurred in 22% of patients following the first CAR T-cell therapy infusion and in 34% of patients following the second infusion; no cases of grade 3 or higher CRS or immune effector cell–associated neurotoxicity syndrome were reported. No patients experienced severe organ toxicity. B-cell aplasia, a pharmacodynamic marker of CAR T-cell activity, was observed in all patients and persisted for a median of 170 days after the second infusion. Infectious complications included 2 cases of sepsis and 2 pulmonary infections, all of which were managed clinically. Importantly, no non-relapse mortality occurred.
References
- Qian, C, Wang Z, Li Z, et al. A phase 2 trial of a “sandwich” strategy: sequential CD22/CD19 chimeric antigen receptor T‐cells therapy combined with autologous hematopoietic stem cell transplantation in patients with Philadelphia chromosome–negative B‐cell acute lymphoblastic leukemia. Cancer. 2025;131(22):e70168-e70168. doi10.1002/cncr.70168
- CD22/CD19 CAR-T and auto-HSCT sandwich strategy as consolidation therapy for B-ALL. ClinicalTrials.gov Updated June 5, 2025. Accessed November 11, 2025. https://clinicaltrials.gov/study/NCT05470777