Monitoring of kinetics and exhaustion markers of circulating CAR-T cells as early predictive factors in patients with B-cell malignancies.

Purpose: CAR-T cell therapy has proven to be a disruptive treatment in the hematology field, however, less than 50% of patients maintain long-term response and early predictors of outcome are still inconsistently defined. Here, we aimed to optimize the detection of CD19 CAR-T cells in blood and to identify phenotypic features as early biomarkers associated with toxicity and outcomes. Experimental design: In this study, monitoring by flow cytometry and digital PCR (dPCR), and immunophenotypic characterization of circulating CAR-T cells from 48 patients treated with Tisa-cel or Axi-cel was performed. Results: Validation of the flow cytometry reagent for the detection of CAR-T cells in blood revealed CD19 protein conjugated with streptavidin as the optimal detection method. Kinetics of CAR-T cell expansion in blood confirmed median day of peak expansion at seven days post-infusion by both flow cytometry and digital PCR. Circulating CAR-T cells showed an activated, proliferative, and exhausted phenotype at the time of peak expansion. Patients with increased expansion showed more severe CRS and ICANs. Immunophenotypic characterization of CAR-T cells at the peak expansion identified the increased expression of co-inhibitory molecules PD1 and LAG3 and reduced levels of the cytotoxicity marker CD107a as predictors of a better long-term disease control. Conclusions: These data show the importance of CAR-T cells in vivo monitoring and identify the expression of PD1LAG3 and CD107a as early biomarkers of long-term disease control after CAR-T cell therapy.

Prognostic Value of Measurable Residual Disease in Patients with AML Undergoing HSCT: A Multicenter Study.

Allogeneic hematopoietic stem cell transplantation (HSCT) represents the best therapeutic option for many patients with acute myeloid leukemia (AML). However, relapse remains the main cause of mortality after transplantation. The detection of measurable residual disease (MRD) by multiparameter flow cytometry (MFC) in AML, before and after HSCT, has been described as a powerful predictor of outcome. Nevertheless, multicenter and standardized studies are lacking. A retrospective analysis was performed, including 295 AML patients undergoing HSCT in 4 centers that worked according to recommendations from the Euroflow consortium. Among patients in complete remission (CR), MRD levels prior to transplantation significantly influenced outcomes, with overall (OS) and leukemia free survival (LFS) at 2 years of 76.7% and 67.6% for MRD-negative patients, 68.5% and 49.7% for MRD-low patients (MRD < 0.1), and 50.5% and 36.6% for MRD-high patients (MRD ≥ 0.1) (p < 0.001), respectively. MRD level did influence the outcome, irrespective of the conditioning regimen. In our patient cohort, positive MRD on day +100 after transplantation was associated with an extremely poor prognosis, with a cumulative incidence of relapse of 93.3%. In conclusion, our multicenter study confirms the prognostic value of MRD performed in accordance with standardized recommendations.

Phase II Trial of Allogeneic Transplantation Plus Novel Drugs in Multiple Myeloma: Effect of Intensifying Reduced-Intensity Conditioning with Bortezomib and Adding Maintenance Treatment.

The use of reduced-intensity conditioning (RIC) regimens has decreased the risk of nonrelapse mortality (NRM) after allogeneic stem cell transplantation (alloSCT). In contrast, disease relapse remains the most frequent cause of treatment failure and death. Owing to both their antimyeloma effect and immunomodulatory properties, novel drugs could improve outcomes after alloSCT. This phase II European Myeloma Network trial was designed to evaluate the combination of alloSCT with novel agents. The study was conducted to evaluate the toxicity and efficacy of RIC intensified with bortezomib (Bz) prior to alloSCT for high-risk (HR) multiple myeloma (MM) patients, as well as the efficacy of post-transplantation maintenance with Bz and lenalidomide (Len). Patients received RIC with Bz on days -9 and -2, fludarabine on days -6 to -4, and melphalan on day -3. Patients who were in complete response (CR) or near CR at day +100 post-transplantation received 6 cycles of Bz every 56 days, and the remaining received Bz, Len, and dexamethasone. Len maintenance was started on day +180 at a dose of 5 mg and continued until relapse or toxicity occurred. Of the 24 patients included, 21 were evaluable on day +100, including 12 in CR, 4 in very good partial response, 3 in partial response, and 2 with relapse or progression. The cumulative incidence (CuI) of relapse was 13.6% (95% confidence interval [CI], 3.2% to 31.3%) at 1 year and 28.5% (95% CI, 11.1% to 48.9%) at 2 years. The CuI of NRM was 21.1% (95% CI, 7.4% to 39.4%) at 2 years. With a median follow-up of 39 months (range, 1 to 67 months), the median event-free survival (EFS) was 29 months, and median overall survival (OS) was not reached. EFS and OS at 3 years were 42.5% (95% CI, 21.9% to 61.7%) and 74.01% (95% CI, 50.9% to 87.5%), respectively. The use of Bz within an RIC regimen allows for a high response rate after alloSCT. Maintenance with Bz and Len is feasible and provides remarkable results in terms of EFS and OS in HR MM patients.