Immunotherapy in adult acute lymphoblastic leukemia: the role of monoclonal antibodies

Contribution of the TIME in BCP-ALL: the basis for novel approaches therapeutics

The bone marrow (BM) niche is a microenvironment where both immune and non-immune cells functionally interact with hematopoietic stem cells (HSC) and more differentiated progenitors, contributing to the regulation of hematopoiesis. It is regulated by various signaling molecules such as cytokines, chemokines, and adhesion molecules in its microenvironment. However, despite the strict regulation of BM signals to maintain their steady state, accumulating evidence in B-cell precursor acute lymphoblastic leukemia (BCP-ALL) indicates that leukemic cells can disrupt the physiological hematopoietic niche in the BM, creating a new leukemia-supportive microenvironment. This environment favors immunological evasion mechanisms and the interaction of these cells with the development and progression of BCP-ALL. With a growing understanding of the tumor immune microenvironment (TIME) in the development and progression of BCP-ALL, current strategies focused on "re-editing" TIME to promote antitumor immunity have been developed. In this review, we summarize how TIME cells are disrupted by the presence of leukemic cells, evading immunosurveillance mechanisms in the BCP-ALL model. We also explore the crosstalk between TIME and leukemic cells that leads to treatment resistance, along with the most promising immuno-therapy strategies. Understanding and further research into the role of the BM microenvironment in leukemia progression and relapse are crucial for developing more effective treatments and reducing patient mortality.

Mechanisms of Immune Evasion in Acute Lymphoblastic Leukemia

Acute lymphoblastic leukemia (ALL) results from a clonal expansion of abnormal lymphoid progenitors of B cell (BCP-ALL) or T cell (T-ALL) origin that invade bone marrow, peripheral blood, and extramedullary sites. Leukemic cells, apart from their oncogene-driven ability to proliferate and avoid differentiation, also change the phenotype and function of innate and adaptive immune cells, leading to escape from the immune surveillance. In this review, we provide an overview of the genetic heterogeneity and treatment of BCP- and T-ALL. We outline the interactions of leukemic cells in the bone marrow microenvironment, mainly with mesenchymal stem cells and immune cells. We describe the mechanisms by which ALL cells escape from immune recognition and elimination by the immune system. We focus on the alterations in ALL cells, such as overexpression of ligands for various inhibitory receptors, including anti-phagocytic receptors on macrophages, NK cell inhibitory receptors, as well as T cell immune checkpoints. In addition, we describe how developing leukemia shapes the bone marrow microenvironment and alters the function of immune cells. Finally, we emphasize that an immunosuppressive microenvironment can reduce the efficacy of chemo- and immunotherapy and provide examples of preclinical studies showing strategies for improving ALL treatment by targeting these immunosuppressive interactions.

An overview of antibody-drug conjugates in oncological practice

Antibody–drug conjugates (ADCs) are designed to manipulate the toxic efficacy of specific chemotherapeutic compounds, employing the high affinity of antibody-mediated delivery so as to drive them selectively to target cancer cells. These immunoconjugates encompass the general tendency towards precision medicine and avert the systemic toxicities of conventional chemotherapy, accomplishing an improved therapeutic index. Cumulative experience acquired from first-generation ADCs offers new perspectives to these promising therapeutic modalities for various hematological and solid cancers and propels their clinical development in a faster-than-ever pace, as indicated by the approval of four novel ADCs during the last year. This paper aims to provide an up-to-date overview of the eight ADCs approved by the US Food and Drug Administration and their current indications in oncological practice. Starting from their bio-pharmaceutical background, we track their clinical evolution, with an emphasis on the pivotal trials that led to their commercial release. Late-stage studies examining these eight ADCs in other-than-approved settings as well as the investigation of potential new candidates are also reviewed. In the close future, more data are expected to expand ADCs’ oncological utility and to further reshape their role in cancer therapeutics.

Advances in biology of acute lymphoblastic leukemia (ALL) and therapeutic implications

Acute lymphoblastic leukemia (ALL) is the most common pediatric cancer and also occurs in adults. Although the outcomes of multi-agent chemotherapy regimens have greatly improved, high toxicity and relapses in many patients necessitate the development of novel therapeutic approaches. Advances in molecular profiling and cytogenetics have identified a broad range of genetic abnormalities, including gene mutations, chromosome translocations and aneuploidy, which has provided a more comprehensive understanding of the biology and pathogenesis of ALL. This understanding has also led to new targeted therapeutic approaches, including the use of selective small molecule inhibitors, nucleic acid-based therapies and immune-based therapies mediated by specific monoclonal antibodies and cellular immunotherapy, which are poised to revolutionize the treatment of various ALL subtypes. The main focus of this review is to highlight the latest advances in ALL biology, including the identification of prognostic factors and putative therapeutic targets. We also review the current status of, and ongoing progress in, the development of targeted therapies for ALL.

An observational study of Chinese adults with relapsed/refractory Philadelphia-negative acute lymphoblastic leukemia

Aim:

Chinese adults with relapsed/refractory Philadelphia chromosome-negative B-cell precursor acute lymphoblastic leukemia (Ph- ALL) have poor outcomes.

Patients & methods:

We conducted a nationwide, retrospective, observational study to assess outcomes in this patient population.

Results:

Of the 270 enrolled patients, 31% of patients at last salvage achieved complete remission (CR) or CR with partial hematologic recovery (CRh), with median time to CR/CRh of 30 days and median CR/CRh duration of 2.7 months. The CR/CRh rate was more favorable with earlier versus later lines of salvage (41, 24 and 17% at first, second and third or later salvages, respectively).

Conclusion:

This dataset serves as an important reference of real-world outcomes using currently available chemotherapy regimens for high-risk Chinese adults with relapsed/refractory Ph- ALL.