Daratumumab at the frontiers of post-transplant refractory T-acute lymphoblastic leukemia—a worthwhile strategy?

Targeting CD38 for acute leukemia

Acute leukemia (AL) is a hematological malignancy, and the prognosis of most AL patients hasn’t improved significantly, particularly for relapsed or refractory (R/R) AL. Therefore, new treatments for R/R adult acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL) are urgently necessary. Novel developments have been made in AL treatment, including target and immune therapies. CD38 is one of the targets due to its high expression in many hematological malignancies, including multiple myeloma, ALL and a subset of AML. Consequently, targeting CD38 therapies, including CD38 monoclonal antibodies (mAbs), bispecific antibodies, and CAR-T cell therapy, exhibit promising efficacy in treating multiple myeloma without significant toxicity and are being explored in other hematological malignancies and nonhematological diseases. Herein, this review focuses on targeting CD38 therapies in ALL and AML, which demonstrate sound antileukemic effects in acute leukemia and are expected to become effective treatment methods.

Chimeric Antigen Receptor Based Cellular Therapy for Treatment Of T-Cell Malignancies

T-cell malignancies can be divided into precursor (T-acute lymphoblastic leukemia/lymphoblastic lymphoma, T-ALL/LBL) and mature T-cell neoplasms, which are comprised of 28 different entities. Most of these malignancies are aggressive with rather poor prognosis. Prognosis of relapsed/refractory (R/R) disease is especially dismal, with an expected survival only several months after progression. Targeted therapies, such as antiCD30 immunotoxin brentuximab vedotin, antiCD38 antibody daratumumab, and anti-CCR4 antibody mogamulizumab are effective only in subsets of patients with T-cell neoplasms. T-cells equipped with chimeric antigen receptor (CAR-Ts) are routinely used for treatment of R/R B-cell malignancies, however, there are specific obstacles for their use in T-cell leukemias and lymphomas which are fratricide killing, risk of transfection of malignant cells, and T-cell aplasia. The solution for these problems relies on target antigen selection, CRISPR/Cas9 or TALEN gene editing, posttranslational regulation of CAR-T surface antigen expression, and safety switches. Structural chromosomal changes and global changes in gene expression were observed with gene-edited products. We identified 49 studies of CAR-based therapies registered on www.clinicaltrials.gov. Most of them target CD30 or CD7 antigen. Results are available only for a minority of these studies. In general, clinical responses are above 50% but reported follow-up is very short. Specific toxicities of CAR-based therapies, namely cytokine release syndrome (CRS), seem to be connected with the antigen of interest and source of cells for manufacturing. CRS is more frequent in antiCD7 CAR-T cells than in antiCD30 cells, but it is mild in most patients. More severe CRS was observed after gene-edited allogeneic CAR-T cells. Immune effector cell associated neurotoxicity (ICANS) was mild and infrequent. Graft-versus-host disease (GvHD) after allogeneic CAR-T cells from previous hematopoietic stem cell donor was also observed. Most frequent toxicities, similarly to antiCD19 CAR-T cells, are cytopenias. CAR-based cellular therapy seems feasible and effective for T-cell malignancies, however, the optimal design of CAR-based products is still unknown and long-term follow-up is needed for evaluation of their true potential.

Controversial Flow Cytometry Monitoring of a Relapse Case of Pediatric T Cell Acute Lymphoblastic Leukemia: A Case Report

Acute lymphoblastic leukemia (ALL) is the most frequent childhood cancer, with 80-85% represented by B cell ALL and only 15% by T cell ALL. T Cell ALL (T-ALL) carries a more reserved prognosis compared to B Cell ALL (B-ALL) with regard to response to treatment, risk of relapse, and overall survival. Progress made in current monitoring protocols such as via flow cytometry immunophenotyping (FCM) and by PCR-based amplification of antigen-receptor genes led to improved management of patients with ALL and superior rates of survival. Nevertheless, challenges remain in some clinical cases. This manuscript describes a unique case of T-ALL and raises awareness of such clinical challenges. The article presents an overview of the flow cytometry immunophenotyping at diagnosis and during treatment of a pediatric patient with T-ALL from Fundeni Clinical Institute. In this case, in spite of various therapeutic measures such as first-line chemotherapy for high risk group, salvage chemotherapy (FLAG), conditioning regimen (FLU-BU-TT-ATG), and stem cell transplant, a chemoresistance clone continued to be present.

Salvage Therapy in Early Relapse of T-Lymphoblastic Leukemia/Lymphoma Using Daratumumab/Nelarabine Combination: Two Consecutive Cases

Treatment of early relapses of T lymphoblastic leukemia/lymphoma is often unsuccessful. We tested an experimental regimen containing daratumumab and nelarabine in two young patients with early relapses of T lymphoblastic lymphoma and T-ALL, respectively. Both patients achieved a deep complete remission. Combining daratumumab with chemotherapy may have a role in relapsing T lymphoblastic leukemia/lymphoma.

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.

Emerging Monoclonal Antibody Therapy for the Treatment of Acute Lymphoblastic Leukemia

The treatment of adults with ALL has undergone tremendous progress over the past 15 years. The advances have been particularly marked with B-lineage ALL. The development of bispecific antibodies directed against CD19 ushered in a new era in overcoming persistent minimal disease in newly diagnosed ALL patients as well as successfully treating those with relapsed disease. The immune-conjugates targeting CD22 have also had a similarly impressive role in improving the outcome in such patients. These advances are now being extended to frontline regimens for B-lineage ALL, including the Philadelphia-chromosome-positive subtype. Over the past decade, the development of chimeric antigen receptor T-cell therapy (CAR-T) has ushered in a new era, opening up hope when none was available for patients with particularly advanced disease. Such advances come at a considerable price for toxicity, which, however, are lessening with experience and the development of new agents to ameliorate some of the toxicities. Unfortunately, the progress for T-cell in ALL has lagged behind that of B-lineage ALL. Of late, however, there are preliminary results of potentially exciting data using monoclonal antibodies against CD38, in the form of daratumumab, and it is hoped that these will lead to an equally successful advance in the treatment of T-ALL. Despite all these advances, ALL in adults remains a formidable disease. While ongoing progress is being made, also in the therapy of older patients, we are still lagging behind the almost totally curative potential of current therapy for childhood ALL.

Antibody and cellular immunotherapies for acute lymphoblastic leukemia in adults

Despite improvements in the outcomes of patients with acute lymphoblastic leukemia (ALL), traditional therapies (including hematopoietic stem cell transplant) often still fail. Antigen-specific immunotherapies for the treatment of ALL such as monoclonal antibodies, antibody-drug conjugates, bispecific T-cell engagers (BiTEs), and chimeric antigen receptor (CAR) T-cells have demonstrated remarkable clinical efficacy and are rapidly evolving. With indisputable activity in patients with relapsed or refractory ALL, efforts now hope to integrate these agents into earlier phases of treatment. In this review, we will discuss the available antibody and cellular-based immunotherapies for the treatment of patients with ALL and provide a clinical and biologic framework with which to inform treatment approaches.

Targeted Therapy in Acute Lymphoblastic Leukaemia

The last decade has seen a significant leap in our understanding of the wide range of genetic lesions underpinning acute lymphoblastic leukaemia (ALL). Next generation sequencing has led to the identification of driver mutations with significant implications on prognosis and has defined entities such as BCR-ABL-like ALL, where targeted therapies such as tyrosine kinase inhibitors (TKIs) and JAK inhibitors may play a role in its treatment. In Philadelphia positive ALL, the introduction of TKIs into frontline treatment regimens has already transformed patient outcomes. In B-ALL, agents targeting surface receptors CD19, CD20 and CD22, including monoclonal antibodies, bispecific T cell engagers, antibody drug conjugates and chimeric antigen receptor (CAR) T cells, have shown significant activity but come with unique toxicities and have implications for how treatment is sequenced. Advances in T-ALL have lagged behind those seen in B-ALL. However, agents such as nelarabine, bortezomib and CAR T cell therapy targeting T cell antigens have been examined with promising results seen. As our understanding of disease biology in ALL grows, as does our ability to target pathways such as apoptosis, through BH3 mimetics, chemokines and epigenetic regulators. This review aims to highlight a range of available and emerging targeted therapeutics in ALL, to explore their mechanisms of action and to discuss the current evidence for their use.

Current and emerging therapeutic approaches for T-cell acute lymphoblastic leukaemia

T-cell ALL (T-ALL) is an aggressive malignancy of T-cell progenitors. Although survival outcomes in T-ALL have greatly improved over the past 50 years, relapsed and refractory cases remain extremely challenging to treat and those who cannot tolerate intensive treatment continue to have poor outcomes. Furthermore, T-ALL has proven a more challenging immunotherapeutic target than B-ALL. In this review we explore our expanding knowledge of the basic biology of T-ALL and how this is paving the way for repurposing established treatments and the development of novel therapeutic approaches.

Flow cytometric evaluation of CD38 expression levels in the newly diagnosed T-cell acute lymphoblastic leukemia and the effect of chemotherapy on its expression in measurable residual disease, refractory disease and relapsed disease: an implication for anti-CD38 immunotherapy

Background

Recently, anti-CD38 monoclonal antibody (Mab) therapy has become a focus of attention as an additional/alternative option for many hematological neoplasms including T-cell acute lymphoblastic leukemia (T-ALL). It has been shown that antitumor efficacy of anti-CD38-Mab depends on the level of CD38 expression on tumor cells. Reports on CD38 expression in T-ALL are scarce, and data on the effect of cytotoxic chemotherapy on CD38 expression are limited to very few samples. Moreover, it lacks entirely in refractory disease and in adult T-ALL. We report the flow cytometric evaluation of CD38 expression in T-ALL blasts at diagnosis and the effect of cytotoxic chemotherapy on its expression in measurable residual disease (MRD), refractory disease (MRD≥5%), and relapsed disease in a large cohort of T-ALL.

Methods

The study included 347 samples (188 diagnostic, 100 MRD, 24 refractory and 35 relapse samples) from 196 (children: 85; adolescents/adults: 111) patients with T-ALL. CD38-positive blasts percentages (CD38-PBPs) and expression-intensity (mean fluorescent intensity, CD38-MFI) were studied using multicolor flow cytometry (MFC). MFC-based MRD was performed at the end-of-induction (EOI-MRD, day 30–35) and end-of-consolidation (EOC-MRD, day 78–85) subsequent follow-up (SFU-MRD) points.

Results

Patients were classified into early thymic precursor subtype of T-ALL (ETPALL, 54/188, 28.7%), and non-ETPALL (134/188, 71.3%). Of 188, EOI-MRD assessment was available in 152, EOC-MRD was available in 96 and SFU-MRD was available in 14 patients. CD38 was found positive in 97.9% (184/188) of diagnostic, 88.7% (110/124) MRD (including 24-refractory) and 82.9% (29/35) relapsed samples. Median (95% CI) of CD38-PBPs/MFI in diagnostic, MRD, refractory, and relapsed T-ALL samples were, respectively, 85.9% (82.10%–89.91%)/4.2 (3.88–4.47), 74.0% (58.87%–83.88%)/4.6 (3.67–6.81), 79.6% (65.25%–96.11%)/4.6 (3.33–8.47) and 85.2% (74.48%–93.01%)/5.6 (4.14–8.99). No significant difference was noted in CD38 expression between pediatric versus adult and patients with ETPALL versus non-ETPALL. No change was observed in CD38-MFI between diagnostic versus MRD and diagnostic versus relapsed paired samples. However, we noticed a mild drop in the CD38-PBPs in MRD samples compared with the diagnostic samples (p=0.016).

Conclusion

We report an in-depth analysis of CD38 expression in a large cohort of T-ALL at diagnosis, during chemotherapy, and at relapse. Our data demonstrated that CD38 is robustly expressed in T-ALL blasts with a little effect of cytotoxic chemotherapy making it a potentially effective target for antiCD38-Mab 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.

Early precursor T-cell acute lymphoblastic leukemia: current paradigms and evolving concepts

Early precursor T cell-acute lymphoblastic leukemia (ETP-ALL) is a rare entity characterized by chemo-resistance and a paucity of data regarding optimal management. We review here the literature regarding the management of ETP-ALL and focus on the recent, emerging data, regarding the potential role of molecularly targeted approaches with a focus on venetoclax.

Harnessing immunotherapy for pediatric T-cell malignancies

Pediatric T-cell hematologic malignancies are a diverse group of rare cancers. The most common pediatric T-cell malignancies include T-cell acute lymphoblastic leukemia (T-ALL) and anaplastic large cell lymphoma (ALCL). Although the overall survival rates have improved markedly in recent years, children with relapsed T-ALL and ALCL have very low rates of cure and few salvage therapies exist. Current treatment regimens rely on toxic chemotherapies with significant short- and long-term morbidity. Immunotherapies, including antibodies and adoptive cellular therapies, have revolutionized the treatment of B-cell malignancies in pediatrics. The adaptation of these therapies to T-cell malignancies has been slower because of challenges implicit in the design and implementation of immunotherapies for T-cell malignancies, including the potential risks of fratricide, immunosuppression, and graft versus host disease (GVHD). We present a review of current challenges in the development of immunotherapies for T-cell hematologic malignancies, potential solutions and therapies under investigation. We include a particular focus on T-ALL and ALCL. Immunotherapies offer promising strategies to improve outcomes in children with T-cell malignancies, particularly in the setting of relapse. Optimizing efficacy, mitigating toxicity, and safely integrating with conventional therapies are key considerations as immunotherapies are translated into the clinic.

Approach to the Adult Acute Lymphoblastic Leukemia Patient

During recent decades, understanding of the molecular mechanisms of acute lymphoblastic leukemia (ALL) has improved considerably, resulting in better risk stratification of patients and increased survival rates. Age, white blood cell count (WBC), and specific genetic abnormalities are the most important factors that define risk groups for ALL. State-of-the-art diagnosis of ALL requires cytological and cytogenetical analyses, as well as flow cytometry and high-throughput sequencing assays. An important aspect in the diagnostic characterization of patients with ALL is the identification of the Philadelphia (Ph) chromosome, which warrants the addition of tyrosine kinase inhibitors (TKI) to the chemotherapy backbone. Data that support the benefit of hematopoietic stem cell transplantation (HSCT) in high risk patient subsets or in late relapse patients are still questioned and have yet to be determined conclusive. This article presents the newly published data in ALL workup and treatment, putting it into perspective for the attending physician in hematology and oncology.

Novel monoclonal antibody-based treatment strategies in adults with acute lymphoblastic leukemia

Adult acute lymphoblastic leukemia (ALL) has a poor overall survival compared with pediatric ALL where cure rates are observed in more than 90% of patients. The recent development of novel monoclonal antibodies targeting CD20, CD19, and CD22 has changed the long-term outcome of this disease, both in the frontline setting (e.g. rituximab) and for patients with relapsed/refractory disease (e.g. inotuzumab ozogamicin and blinatumomab). The CD3-CD19 bispecific T-cell-engaging antibody blinatumomab is also the first drug approved in ALL for patients with persistent or recurrent measurable residual disease, providing a new treatment paradigm for these patients. Several new agents are also in development that use novel constructs or target alternative surface epitopes such as CD123, CD25, and CD38. Herein, we review the role of monoclonal antibodies in adult ALL and summarize the current and future approaches in ALL, including novel combination therapies and the possibility of early incorporation of these agents into treatment regimens.

Novel targeted therapeutic agents for the treatment of childhood, adolescent and young adult non-Hodgkin lymphoma

Non-Hodgkin lymphomas (NHLs) are a heterogeneous group of malignancies. Most NHLs in children, adolescent and young adult patients are aggressive lymphomas that are generally treated with multi-agent chemotherapy or immunochemotherapy regimens. While overall survival is high, the treatment can lead to a high rate of acute and long-term toxicity. However, in the rarer instance of relapsed or refractory disease, outcomes are dismal. Novel therapeutic approaches to the treatment of both T-cell and B-cell NHLs are critical to improve outcomes while also minimising the associated toxicity of current treatment regimes. Potential therapeutic approaches in development include humoral and cellular immunotherapies, small molecule inhibitors of relevant signalling pathways and epigenetic modifying agents. In this review, we will highlight the current state of development of agents of interest with a focus on agents relevant to childhood, adolescent and young adult NHL.