Immunomodulatory and clinical effects of daratumumab in T-cell acute lymphoblastic leukaemia

Two novel assays demonstrate persistent daratumumab exposure in a pediatric patient with delayed engraftment following allogeneic hematopoietic stem cell transplantation

BACKGROUND AIMS

Daratumumab, a human IgG monoclonal antibody targeting CD38, is a promising treatment for pediatric patients with relapsed or refractory T-cell acute lymphoblastic leukemia (T-ALL). We describe a case of delayed engraftment following a mismatched, unrelated donor hematopoietic stem cell transplant (HSCT) in a 14-year-old female with relapsed T-ALL, treated with daratumumab and chemotherapy. By Day 28 post-HSCT, the patient had no neutrophil engraftment but full donor myeloid chimerism.

METHODS

We developed two novel, semi-quantitative, antibody-based assays to measure the patient's bound and plasma daratumumab levels to determine if prolonged drug exposure may have contributed to her slow engraftment.

RESULTS

Daratumumab levels were significantly elevated more than 30 days after the patient's final infusion, and levels inversely correlated with her white blood cell counts. To clear daratumumab, the patient underwent several rounds of plasmapheresis and subsequently engrafted.

CONCLUSIONS

This is the first report of both delayed daratumumab clearance and delayed stem cell engraftment following daratumumab treatment in a pediatric patient. Further investigation is needed to elucidate the optimal dosing of daratumumab for treatment of acute leukemias in pediatric populations as well as daratumumab's potential effects on hematopoietic stem cells and stem cell engraftment following allogenic HSCT.

Daratumumab and venetoclax combined with CAGE for late R/R T-ALL/LBL patients: Single-arm, open-label, phase I study

The prognosis of patients diagnosed with relapsed or refractory (R/R) T-lymphoblastic leukemia/lymphoma (T-ALL/LBL) has consistently been unsatisfactory, with limited treatment options. As reports, the CAG regimen can serve as a salvage treatment for R/R T-ALL/LBL, but there remains a subset of patients who do not benefit from it. Recent studies have indicated that daratumumab (Dara) and venetoclax (Ven) may offer promising therapeutic benefits for T-ALL/LBL. In light of these findings, we conducted a safety and efficacy evaluation of the enhanced treatment regimen, combining Dara and Ven with aclarubicin, cytarabine, granulocyte colony-stimulating factor, and etoposide (CAGE), in patients suffering from R/R T-ALL/LBL. The participants in this phase I trial were patients with R/R T-ALL/LBL who fail to standard treatment regimens. During each 28-day cycle, the patients were treated by Dara, Ven, cytarabine, aclarubicin, granulocyte colony-stimulating factor, etoposide. The primary endpoint of this study was the rate of remission. This report presents the prospective outcomes of 21 patients who received the salvage therapy of Dara and Ven combined with the CAGE regimen (Dara + Ven + CAGE). The objective remission rate (ORR) was determined to be 57.1%, while the complete remission (CR) rate was 47.6%. Notably, patients with the early T-cell precursor (ETP) subtype exhibited a significantly higher remission rate in the bone marrow compared to non-ETP patients (100% vs. 44.4%, p = 0.044). The Dara + Ven + CAGE regimen demonstrated a favorable remission rate in patients with R/R T-ALL/LBL. Moreover, the treatment was well-tolerated.

Targeted therapy and immunotherapy for T cell acute lymphoblastic leukemia/lymphoma

T cell acute lymphoblastic leukemia/lymphoma (T-ALL/LBL) is an aggressive malignancy of progenitor T cells. Despite significant improvements in survival of T-ALL/LBL over the past decades, treatment of relapsed and refractory T-ALL (R/R T-ALL/LBL) remains extremely challenging. The prognosis of R/R T-ALL/LBL patients who are intolerant to intensive chemotherapy remains poor. Therefore, innovative approaches are needed to further improve the survival of R/R T-ALL/LBL patients. With the widespread use of next-generation sequencing in T-ALL/LBL, a range of new therapeutic targets such as NOTCH1 inhibitors, JAK-STAT inhibitors, and tyrosine kinase inhibitors have been identified. These findings led to pre-clinical studies and clinical trials of molecular targeted therapy in T-ALL/LBL. Furthermore, immunotherapies such as CD7 CAR T cell therapy and CD5 CAR T cell therapy have shown profound response rate in R/R T-ALL/LBL. Here, we review the progress of targeted therapies and immunotherapies for T-ALL/LBL, and look at the future directions and challenges for the further use of these therapies in T-ALL/LBL.

Delivery of PEGylated liposomal doxorubicin by bispecific antibodies improves treatment in models of high-risk childhood leukemia

High-risk childhood leukemia has a poor prognosis because of treatment failure and toxic side effects of therapy. Drug encapsulation into liposomal nanocarriers has shown clinical success at improving biodistribution and tolerability of chemotherapy. However, enhancements in drug efficacy have been limited because of a lack of selectivity of the liposomal formulations for the cancer cells. Here, we report on the generation of bispecific antibodies (BsAbs) with dual binding to a leukemic cell receptor, such as CD19, CD20, CD22, or CD38, and methoxy polyethylene glycol (PEG) for the targeted delivery of PEGylated liposomal drugs to leukemia cells. This liposome targeting system follows a "mix-and-match" principle where BsAbs were selected on the specific receptors expressed on leukemia cells. BsAbs improved the targeting and cytotoxic activity of a clinically approved and low-toxic PEGylated liposomal formulation of doxorubicin (Caelyx) toward leukemia cell lines and patient-derived samples that are immunophenotypically heterogeneous and representative of high-risk subtypes of childhood leukemia. BsAb-assisted improvements in leukemia cell targeting and cytotoxic potency of Caelyx correlated with receptor expression and were minimally detrimental in vitro and in vivo toward expansion and functionality of normal peripheral blood mononuclear cells and hematopoietic progenitors. Targeted delivery of Caelyx using BsAbs further enhanced leukemia suppression while reducing drug accumulation in the heart and kidneys and extended overall survival in patient-derived xenograft models of high-risk childhood leukemia. Our methodology using BsAbs therefore represents an attractive targeting platform to potentiate the therapeutic efficacy and safety of liposomal drugs for improved treatment of high-risk leukemia.

A Bright Horizon: Immunotherapy for Pediatric T-Cell Malignancies

Immunotherapy has transformed the treatment of hematologic malignancies in the past two decades. The treatment of acute lymphoblastic leukemia (ALL), in particular, has been highly impacted by multiple novel immunotherapies. For pediatric patients with T-cell malignancies, translating immunotherapies has proved more challenging due to the complexities of fratricide, risk of product contamination with malignant cells, and concerns over T-cell aplasia. Despite these hurdles, many creative and promising strategies are on the horizon. We review challenges in the development of immunotherapy for T-cell malignancies, strategies to overcome these challenges, as well as therapies currently being investigated and starting to reach the clinic. Immunotherapy will hopefully successfully treat patients with relapsed and refractory T-cell malignancies and may someday be incorporated in up-front protocols in order to prevent relapses.

Combining daratumumab with CD47 blockade prolongs survival in preclinical models of pediatric T-ALL

Acute lymphoblastic leukemia (ALL) is the most common malignant disease affecting children. Although therapy strategies improved, T-cell acute lymphoblastic leukemia (T-ALL) relapse is associated with chemoresistance and a poor prognosis. One strategy to overcome this obstacle is the application of monoclonal antibodies. Here, we show that leukemic cells from T-ALL patients express surface CD38 and CD47, both attractive targets for antibody therapy. We therefore investigated the commercially available CD38 antibody daratumumab (Dara) in combination with a proprietary modified CD47 antibody (Hu5F9-IgG2σ) in vitro and in vivo. Compared to single treatments, this combination significantly increased in vitro antibody-dependent cellular phagocytosis (ADCP) in T-ALL cell lines as well as in random de novo and in relapsed/refractory T-ALL patient derived xenograft (PDX) samples. Similarly, enhanced ADCP was observed when combining Dara with pharmacological inhibition of CD47 interactions using a glutaminyl cyclase inhibitor. Phase II-like preclinical in vivo trials using T-ALL PDX samples in experimental minimal residual disease like (MRD-like) and overt leukemia models revealed a high anti-leukemic efficacy of CD47 blockade alone. However, T-ALL xenograft mice subjected to chemotherapy first (post-chemo MRD) and subsequently co-treated with Dara and Hu5F9-IgG2σ displayed significantly reduced bone marrow infiltration as compared to single treatments. In relapsed and highly refractory T-ALL PDX combined treatment with Dara and Hu5F9-IgG2σ was required to substantially prolong survival as compared to single treatments. These findings suggest that combining CD47 blockade with Dara is a promising therapy for T-ALL, especially for relapsed/refractory disease harbouring a dismal prognosis in patients.

Daratumumab and venetoclax in combination with chemotherapy provide sustained molecular remission in relapsed/refractory CD19, CD20, and CD22 negative acute B lymphoblastic leukemia with KMT2A-AFF1 transcript

Relapsed/refractory (R/R) B-cell acute lymphoblastic leukemia (B-ALL) has a very poor prognosis with a median overall survival of four to nine months. Achieving a complete molecular response is most often required to obtain a sustained leukemia-free survival after allogeneic hematopoietic stem cell transplantation. Immunotherapies targeting CD19, CD20, or CD22 are very efficient in achieving this goal. However, in the absence of the expression of these immunotherapeutic targets by lymphoblasts, treatment options are extremely scarce. We report the successful treatment of a 26-year-old man who suffered R/R, CD19, CD20, and CD22 negative B-ALL targeting Bcl-2 and CD38 by combining venetoclax and daratumumab with chemotherapy.

MRD in adult Ph/BCR-ABL-negative ALL: how best to eradicate?

Evaluation of minimal residual disease (MRD) during first-line treatment and after salvage therapy is part of the standard management of acute lymphoblastic leukemia (ALL). Persistent or recurrent MRD is one of the most relevant prognostic factors and identifies a group of patients with resistance to standard chemotherapy. These patients have a high risk of relapse despite continued first-line therapy. Although stem cell transplantation (SCT) is an appropriate strategy, patients with high MRD show an increased relapse rate even after SCT. Approximately one-quarter of adult ALL patients develop an MRD failure, defined as MRD above 0.01% after standard induction and consolidation. The best time point and level of MRD for treatment modification are matters of debate. In order to eradicate MRD and thereby improve chances for a cure, new targeted compounds with different mechanisms of action compared to chemotherapy are being utilized. These compounds include monoclonal antibodies, chimeric antigen receptor T cells, and molecular targeted compounds. Essential factors for decision-making, available compounds, and follow-up therapies are discussed.

MRD-Based Therapeutic Decisions in Genetically Defined Subsets of Adolescents and Young Adult Philadelphia-Negative ALL

Simple Summary

In acute lymphoblastic leukemia (ALL), once a complete remission is achieved following induction chemotherapy, the study of submicroscopic minimal residual disease (MRD) represents a highly sensitive tool to assess the efficacy of early chemotherapy courses and predict outcome. Because of the significant therapeutic progress occurred in adolescent and young adult (AYA) ALL, the importance of MRD in this peculiar age setting has grown considerably, to refine individual prognostic scores within different genetic subsets and support specific risk and MRD-oriented programs. The evidence coming from the most recent MRD-based studies and the new therapeutic directions for AYA ALL are critically reviewed according to ALL subset and risk category.

Abstract

In many clinical studies published over the past 20 years, adolescents and young adults (AYA) with Philadelphia chromosome negative acute lymphoblastic leukemia (Ph− ALL) were considered as a rather homogeneous clinico-prognostic group of patients suitable to receive intensive pediatric-like regimens with an improved outcome compared with the use of traditional adult ALL protocols. The AYA group was defined in most studies by an age range of 18–40 years, with some exceptions (up to 45 years). The experience collected in pediatric ALL with the study of post-induction minimal residual disease (MRD) was rapidly duplicated in AYA ALL, making MRD a widely accepted key factor for risk stratification and risk-oriented therapy with or without allogeneic stem cell transplantation and experimental new drugs for patients with MRD detectable after highly intensive chemotherapy. This combined strategy has resulted in long-term survival rates of AYA patients of 60–80%. The present review examines the evidence for MRD-guided therapies in AYA’s Ph− ALL, provides a critical appraisal of current treatment pitfalls and illustrates the ways of achieving further therapeutic improvement according to the massive knowledge recently generated in the field of ALL biology and MRD/risk/subset-specific therapy

Recent updates for antibody therapy for acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) is a hematologic malignancy arising from precursors of the lymphoid lineage. Conventional cytotoxic chemotherapies have resulted in high cure rates of up to 90% in pediatric ALL, but the outcomes for adult patients remain suboptimal with 5-year survival rates of only 30%-40%. Current immunotherapies exploit the performance of antibodies through several different mechanisms, including naked antibodies, antibodies linked to cytotoxic agents, and T-cell re-directing antibodies. Compared with chemotherapy, the application of an antibody-drug conjugates (ADC) called inotuzumab ozogamicin in relapsed or refractory (R/R) CD22+. ALL resulted in a complete remission (CR) rate of 81% and an overall median survival of 7.7 months with reduced toxicity. Similarly, blinatumomab, the first FDA-approved bispecific antibody (BsAb), produced a 44% complete response rate and an overall median survival of 7.7 months in a widely treated ALL population. In addition, approximately 80% of patients getting complete remission with evidence of minimal residual disease (MRD) achieved a complete MRD response with the use of blinatumomab. These results highlight the great promise of antibody-based therapy for ALL. How to reasonably determine the place of antibody drugs in the treatment of ALL remains a major problem to be solved for ongoing and future researches. Meanwhile the combination of antibody-based therapy with traditional standard of care (SOC) chemotherapy, chimeric antigen receptor (CAR) T-cell therapy and HSCT is also a challenge. Here, we will review some important milestones of antibody-based therapies, including combinational strategies, and antibodies under clinical development for ALL.