Novel Approaches to Treatment of Acute Myeloid Leukemia Relapse Post Allogeneic Stem Cell Transplantation

[Preventing relapse of acute leukemias and myelodysplastic syndromes in post-allograft transplantation: Prophylactic and preemptive strategies (SFGM-TC)]

Disease relapse remains the first cause of mortality of hematological malignancies after allogeneic hematopoietic stem cell transplantation (allo-HCT) for acute myeloid and lymphoid leukemia (AML and ALL) and for myelodysplastic syndroms (MDS). More and more patients are eligible for allo-HCT over the years and for many of them, only reduced intensity conditioning is possible, which is associated with a higher risk of relapse. Knowledge and biotechnology allow us to better identify diseases at very high risk of relapse and to measure residual disease before allo-HCT. Planning post-transplant maintenance treatment as part of a prophylaxis strategy is now feasible. Monitoring biomarkers of residual disease and post-transplant chimerism after allo-HCT allows a preemptive strategy. Within the frame of the 14th annual workshops of the Francophone Society for Bone Marrow Transplantation and Cell Therapy, the working group reviewed the literature and discussed novel strategies and therapies used to prevent relapse post-allo-HCT. Innovative drugs have been developed recently. Their toxicity profile allows their use post-allo-HCT, albeit with precaution. We reviewed the use of FLT3 inhibitors for AML, BCR::ABL inhibitors for Philadelphia chromosome for ALL, hypomethylating agents and Bcl-2 inhibitors for AML and MDS. The indications of immunomodulation and infusion of donor lymphocytes have been reviewed. Finally, we outlined methods of follow-up and support for patients receiving these prophylactic treatments.

Optimizing maintenance therapy in acute myeloid leukemia: where do we stand in the year 2024?

INTRODUCTION

Despite the prognosis of patients affected by acute myeloid leukemia (AML) improved in the last decade, most patients relapse. Maintenance therapy after a chemotherapy approach with or without allogeneic stem cell transplantation could be a way to control the undetectable residual burden of leukemic cells. Several studies are being carried out as maintenance therapy in AML. Some critical points need to be defined, how the physician can choose among the various drugs available.

AREAS COVERED

This review discusses the advances and controversies surrounding maintenance therapy for AML patients.

EXPERT OPINION

Patients withFLT3-positive AML should receive midostaurin or quizartinib in the first-linesetting. For a patient initially receiving midostaurin, consider switching to sorafenib in the post-transplant setting. Because of the improved safety profile and potency, many experts will lean toward using a second-generation FLT3 inhibitor such as quizartinib or gilteritinib. Finally, no data indicate whether maintenance therapy should be prolonged until progression or for a defined period.

Donor Lymphocyte Infusion (DLI) post allogeneic stem cell transplant (allo-SCT) in Acute Myeloid Leukemia (AML) and High-Grade Myelodysplastic Syndrome (MDS). A longitudinal retrospective study using peripheral blood (PB) CD34+ and CD3+ donor chimerism (DC) monitoring

INTRODUCTION

This longitudinal study was based on the outcomes of Donor Lymphocyte Infusion (DLI) for falling peripheral blood (PB) CD34+ and CD3+ donor chimerism (DC).

METHODS

From 2012 to 2018, data was collected from the BMT database and electronic medical records (EMR). The primary objective was to compare the indication for DLI based on falling PB CD34+ or CD3+ DC in patients post allo-SCT for AML and MDS and their overall survival (OS).

RESULTS

18/70 patients met the inclusion criteria. Indications for DLI were i) falling PB CD34+ DC ≤ 80 % with morphological relapse, ii) falling PB CD34+ DC ≤ 80 % without morphological relapse and iii) falling PB CD3+ DC ≤ 80 % without falling PB CD34+ DC. Log rank analysis showed falling PB CD34+ DC and morphological relapse had significantly lower OS. Linear regression demonstrated better OS post DLI if there was PB CD34+ and CD3+ chimerism response at 30 days (p = 0.029), GVHD (p = 0.032) and tapering immunosuppression at the time of falling DC (p = 0.042).

CONCLUSION

DLI for PB CD34+ DC values ≤ 80 % and morphological relapse had the lowest OS. In this study, full DC was achieved after DLI even with a PB CD3+DC value as low as 13 %, provided the PB CD34+ DC remained > 80 %. Further research is vital in CD34+ DC as a biomarker for disease relapse and loss of engraftment.

Broadening the horizon: potential applications of CAR-T cells beyond current indications

Engineering immune cells to treat hematological malignancies has been a major focus of research since the first resounding successes of CAR-T-cell therapies in B-ALL. Several diseases can now be treated in highly therapy-refractory or relapsed conditions. Currently, a number of CD19- or BCMA-specific CAR-T-cell therapies are approved for acute lymphoblastic leukemia (ALL), diffuse large B-cell lymphoma (DLBCL), mantle cell lymphoma (MCL), multiple myeloma (MM), and follicular lymphoma (FL). The implementation of these therapies has significantly improved patient outcome and survival even in cases with previously very poor prognosis. In this comprehensive review, we present the current state of research, recent innovations, and the applications of CAR-T-cell therapy in a selected group of hematologic malignancies. We focus on B- and T-cell malignancies, including the entities of cutaneous and peripheral T-cell lymphoma (T-ALL, PTCL, CTCL), acute myeloid leukemia (AML), chronic myeloid leukemia (CML), chronic lymphocytic leukemia (CLL), classical Hodgkin-Lymphoma (HL), Burkitt-Lymphoma (BL), hairy cell leukemia (HCL), and Waldenström's macroglobulinemia (WM). While these diseases are highly heterogenous, we highlight several similarly used approaches (combination with established therapeutics, target depletion on healthy cells), targets used in multiple diseases (CD30, CD38, TRBC1/2), and unique features that require individualized approaches. Furthermore, we focus on current limitations of CAR-T-cell therapy in individual diseases and entities such as immunocompromising tumor microenvironment (TME), risk of on-target-off-tumor effects, and differences in the occurrence of adverse events. Finally, we present an outlook into novel innovations in CAR-T-cell engineering like the use of artificial intelligence and the future role of CAR-T cells in therapy regimens in everyday clinical practice.