Sequential CAR T-Cell Therapy and Autologous Stem Cell Transplant Shows 97% Survival Rate in Ph-Negative B-ALL
核心洞察
A phase 2 trial of sequential CD22/CD19 CAR T-cell therapy (搜索) combined with autologous stem cell transplant achieved a 97% two-year overall survival rate in 37 patients with Philadelphia chromosome-negative B-cell acute lymphoblastic leukemia (搜索).
The "sandwich" strategy demonstrated progressive deepening of remissions, with 100% of patients achieving complete remission after the first CAR T-cell infusion and 93% maintaining molecular remission after the second infusion.
The treatment showed a favorable safety profile with no severe cytokine release syndrome or neurotoxicity, positioning it as a potential alternative to allogeneic stem cell transplant.
A novel "sandwich" treatment strategy combining sequential CD22/CD19 CAR T-cell therapy (搜索) with autologous hematopoietic stem cell transplantation (搜索) has demonstrated exceptional efficacy in patients with Philadelphia chromosome-negative B-cell acute lymphoblastic leukemia (搜索) (Ph-negative B-ALL (搜索)), according to results from a phase 2 clinical trial published in Cancer.
The study of 37 newly diagnosed adolescent, young adult, and adult patients achieved a remarkable 97% two-year overall survival rate (95% CI, 90%–100%) and 72% two-year leukemia-free survival rate (95% CI, 58%–90%) at a median follow-up of 28 months. Notably, all 35 patients who completed the full treatment regimen survived.
Progressive Remission Deepening
The sandwich strategy induced progressively deeper remissions at each treatment stage. Following standard induction chemotherapy, 92% of patients achieved complete remission (CR), with 54% achieving measurable residual disease (MRD)-negativity by multiparameter flow cytometry. After consolidation chemotherapy, 80% of evaluable patients remained in CR, with 71% maintaining MFC-MRD-negative status.
The first CD22 (搜索)/CD19 (搜索) CAR T-cell infusion proved particularly effective, with 100% of patients achieving MFC-MRD-negative CR and 68% achieving the more sensitive next-generation sequencing (NGS) MRD-negative status. Following autologous stem cell transplant and the second CAR T-cell infusion, all patients remained in MFC-MRD-negative CR, and 93% of evaluable patients achieved NGS-MRD-negative status.
The durability of these remissions was striking, with 80% of patients maintaining continuous MFC-MRD-negative CR after the second CAR T-cell infusion, and 72% maintaining continuous NGS-MRD-negative CR.
Relapse Management and Risk Factors
Of the 35 patients who completed the sandwich strategy, 20% experienced relapse at a median time of 5 months. All relapses were CD19 (搜索)-positive, and a high white blood cell count at initial diagnosis was identified as a potential risk factor. Importantly, all patients who relapsed achieved complete remission again after salvage therapy with blinatumomab or chemotherapy.
The strategy proved effective regardless of genetic risk stratification. There was no significant difference in overall survival or leukemia-free survival between patients in the poor-risk and standard-risk genetic groups, suggesting the sandwich strategy may overcome poor genetic risk factors.
Safety Profile
The treatment demonstrated a favorable safety profile with no instances of severe (grade ≥3) cytokine release syndrome (CRS) or immune effector cell-associated neurotoxicity syndrome. Mild (grade 1-2) CRS occurred in 22% of patients after the first CAR T-cell infusion and 34% after the second infusion.
All patients experienced expected grade 3-4 hematologic toxicities, with median neutropenia duration of 11 days and thrombocytopenia lasting 15 days after the second infusion. B-cell aplasia occurred in all patients, persisting for a median of 170 days. Four patients experienced manageable infections, and no severe organ toxicity or non-relapse mortality was reported.
Comparison to Allogeneic Transplant
An exploratory analysis comparing the 37 patients with an external control group of 52 patients who underwent allogeneic HSCT showed significant advantages for the sandwich strategy. Overall survival was significantly longer in the sandwich strategy group (P = 0.021), while leukemia-free survival was comparable between groups (P = 0.576). Crucially, the sandwich strategy achieved a non-relapse mortality rate of 0%, compared to 15% in the allogeneic HSCT group.
Study Design
This phase 2, open-label, single-center study enrolled newly diagnosed patients with Ph-negative B-ALL (搜索) who were unable to undergo or declined allogeneic HSCT. The median patient age was 28 years, with 57% presenting high-risk genetic features. The treatment protocol involved standard induction and consolidation chemotherapy, followed by sequential CD22 (搜索) and CD19 (搜索) CAR T-cell infusions at 5 × 10⁶ cells/kg, autologous stem cell transplant with modified BuCy conditioning, and a second CAR T-cell infusion.
"The CD22 (搜索)/CD19 (搜索) CAR T-cells and auto-HSCT sandwich strategy is a promising approach for treating Ph-negative B-ALL (搜索) in adolescent, young adult and adult patients, offering high efficacy with a favorable safety profile," concluded study authors Qian et al. "Future studies with larger sample sizes and longer follow-up are warranted to further validate these findings and further explore allo-HSCT-free strategies."