denotes an abstract that is clinically relevant.
denotes that this is a recommended PHD Trainee Session.
denotes that this is a ticketed session.Session: 613. Acute Lymphoblastic Leukemias: Therapies Excluding Allogeneic Transplantation: Poster III
Hematology Disease Topics & Pathways:
Lymphoid Leukemias, ALL, Clinical Practice (Health Services and Quality), Diseases, Lymphoid Malignancies, Measurable Residual Disease
T-cell acute lymphoblastic leukemia (T-ALL) is a high-risk disease without good therapeutic options thus far. 50%~70% patients can only achieve complete remission (CR) with positive minimal residual disease (MRD) after intensive therapy, whereas MRD positivity often predicts an ultimate disease relapse. The BCL-2 inhibitor venetoclax has been reported to induce high remission rate in relapsed/refractory T-ALL (R/R T-ALL). CD38 was reported to be constantly expressed on T-ALL blasts even after chemotherapy. Daratumumab (DARA), as a CD38-targeted IgG1κ human monoclonal antibody, has demonstrated efficacy in both preclinical studies of patient-derived xenograft models and clinical cases of T-ALL. Herein, we speculate that the combination of venetoclax and DARA may improve the quality of remission by increasing the rate of MRD negativity.
Objective
In this study, venetoclax combined with DARA regimen was used to treat MRD positive T-ALL. The efficacy and safety profiles were evaluated.
Methods
From December 2022 to November 2023, T-ALL patients（n=7）with MRD positive during first CR (CR1) were analyzed. The median age was 22 (15~33) years old. Venetoclax was given at a dose of 100mg on day1, 200mg on day2, 400mg on day3~14 for the first cycle, then 400mg daily on day1~14 for the proceeding cycles. DARA was administrated at a dose of 16mg/kg on day 1 and day 8. Low-intensity CAG regimen was given as concurrent chemotherapy (Cytarabine 25mg/q12h day1~7, Aclarubicin 20mg/d day1~4, G-CSF 300μg/d day1~7). Every 4 weeks defined as a cycle. Once MRD turned negative, the patient will be scheduled for allogeneic hematopoietic stem cell transplantation (allo-HSCT) as soon as possible.
Multiparameter flow cytometry was employed for MRD monitoring, MRD negativity was defined as less than 0.01%. The expression of CD38 antigen was detected by flow cytometry. Safety assessments included the evaluation of adverse events, which were graded according to CTCAE (version 5.0).
Results
Between 12/2022 and 11/2023, seven patients have been treated by the combination of venetoclax and DARA. The median age was 22 yrs (range, 15~33). At baseline, all patients were remained in CR1, but with positive MRD, and the median MRD level was 0.2% (range, 0.01%~1.36%). All of them had undergone intensive multi-drug chemotherapy (median 2 cycles) as frontline treatment. CD38 expression were positively detected on the surface of leukemia cells in these patients. Five patients received one cycle of venetoclax and DARA, two patients received two cycles of venetoclax and DARA.
In total, 6 out of 7 (85.7%) patients achieved MRD negativity, with 4 of these 7 (57.1%) cases attained MRD negativity soon after one cycle. Subsequently, 5 out of 6 (83.3%) MRD negative patients underwent allo-HSCT. The median time from MRD negative to allo-HSCT was 72.5 days (range, 26~108 days). The rest one with MRD negative is planning to receive allo-HSCT. MRD retention was observed in 1 patient (1/7, 14.3%) after 2 cycles. This case showed partial benefit from this regimen with MRD decreased from 1.36% to 0.07%. After continuing venetoclax contained chemotherapy for 6 months, this patient also successfully bridged to allo-HSCT despite persistent low level MRD (0.01%~0.1%). With a median follow up of 8.6 months (range, 2.7~15.0), all 7 patients remained MRD negative survival. Both overall survival rate and progression free survival rate are 100%.
The most common adverse events of grade 3 or 4 associated with the regimen were leukocytopenia (3/7, 42.9%) and thrombocytopenia (1/7, 14.3%). Infusion-related reactions (IRR) to DARA (grade 1~2) were observed in 5 patients (71.4%) during the first infusion, all ameliorated after symptomatic treatment. No grade 3/4 IRRs were observed. None of the patients in this series developed tumor lysis syndrome related to venetoclax treatment. No life-threatening complications (grade 4) or death were noted. No treatment discontinuation occurred.
Conclusion
The combination of venetoclax and DARA plus CAG regimen is effective and safe in inducing rapid eradication of MRD in T-ALL. Our results suggest that comprehensive management, consisting of small molecular targeted drug, immunotherapy and low intensive chemotherapy followed by allo-HSCT, could be promising curative strategy in high-risk T-ALL. Nevertheless, this warrants further validation on a larger scale of T-ALL.
Disclosures: No relevant conflicts of interest to declare.
OffLabel Disclosure: Daratumumab is a CD38-targeted IgG1κ human monoclonal antibody that is used in the treatment of newly diagnosed and relapse/refractory multiple myeloma. As CD38 has been reported to be uniformly expressed on T-ALL blasts and remains persistently expressed after chemotherapy treatment. Also, both preclinical studies in patient-derived xenograft models and clinical case reports have demonstrated efficacy of daratumumab in inducing disease remission in T-ALL. Its effectiveness in newly diagnosed T-ALL remains to be studied