North American Blastic Plasmacytoid Dendritic Cell Neoplasm Consortium: position on standards of care and areas of need

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare hematologic malignancy with historically poor outcomes and no worldwide consensus treatment approach. Unique among most hematologic malignancies for its frequent cutaneous involvement, BPDCN can also invade other extramedullary compartments, including the central nervous system. Generally affecting older adults, many patients are unfit to receive intensive chemotherapy, and although hematopoietic stem cell transplantation is preferred for younger, fit individuals, not all are eligible. One recent therapeutic breakthrough is that all BPDCNs express CD123 (IL3Rα) and that this accessible surface marker can be pharmacologically targeted. The first-in-class agent for BPDCN, tagraxofusp, which targets CD123, was approved in December 2018 in the United States for patients with BPDCN aged ≥2 years. Despite favorable response rates in the frontline setting, many patients still relapse in the setting of monotherapy, and outcomes in patients with relapsed/refractory BPDCN remain dismal. Therefore, novel approaches targeting both CD123 and other targets are actively being investigated. To begin to formally address the state of the field, we formed a new collaborative initiative, the North American BPDCN Consortium (NABC). This group of experts, which includes a multidisciplinary panel of hematologists/oncologists, hematopoietic stem cell transplant physicians, pathologists, dermatologists, and pediatric oncologists, was tasked with defining the current standard of care in the field and identifying the most important research questions and future directions in BPDCN. The position findings of the NABC's inaugural meetings are presented herein.

Biological therapy in elderly patients with acute myeloid leukemia

INTRODUCTION

The introduction of target molecules and immunological therapies is changing the treatment landscape of acute myeloid leukemia (AML).

AREAS COVERED

We recapitulate the biological therapies that can be employed in the treatment of elderly patients with AML. Alongside small molecules inhibitors that target specific gene mutations, antibodies, tumor microenvironment modulators, and cellular therapies are being developed for the cure of the disease. Here, we report the biological activities, the efficacy and toxicities of humanized antibodies and antibody-drug conjugates that targets surface antigens as CD33 (gemtuzumab ozogamicine) or CD123 (pivekimab sunirine). We further explore mechanisms and effectiveness of medications that modify the microenvironment, such as glasdegib, or that harness the immune system against leukemia, such as CD47 antibody magrolimab, PD1/PDL1 inhibitors pembrolizumab and nivolumab, TIM3 inhibitor sabatolimab, T-cell and NK-cell engagers. Cellular therapies are considered, even if a large trial is still pending for the feasibility of the approach. In this scenario, a brief overview of the mechanism of action of target agents is provided, particularly with respect to their biological mechanisms.

EXPERT OPINION

Overall, this therapeutic armamentarium will constitute the basis for multimodal and personalized combinations that, in the idea of precision medicine, will enormously benefit elderly AML patients.

An Update on the Clinical Evaluation of Antibody-Based Therapeutics in Acute Myeloid Leukemia

PURPOSE OF REVIEW

The advent of several targeted agents has revolutionized the treatment of acute myeloid leukemia (AML) in recent times; however, majority of patients are still not cured. In the ongoing quest for rationally targeted treatment strategies in AML, scientific endeavors have focused on identifying new antigen targets on the leukemic cells for therapeutic exploitation including strategies to directly deliver toxins into the leukemic blasts as well as strategies that harness host immunity to favorably impact clinical outcomes. Gemtuzumab ozogamicin, a CD33 directed antibody-drug conjugate, has provided the proof of concept for the potential efficacy of monoclonal antibody-based therapies in AML. This article provides an overview of immunologically relevant antigen targets expressed on the leukemic cells and synopsizes the clinical results evaluating targeted antibody-based therapeutic approach in AML.

RECENT FINDINGS

AML blasts and leukemic stem cells express several antigens, including CD33, CD47, CD70, CD123, and CLEC12A. The past several years have seen the burgeoning of cell-specific immunotherapy concepts, including checkpoint inhibitors, antibody-toxin conjugates, and bispecific antibodies in the treatment of AML. The first-in-class anti-CD47 antibody magrolimab and anti-CD70 antibody cusatuzumab in combination with hypomethylating agent (HMA) azacitidine, in newly diagnosed AML, and flotetuzumab, a bispecific DART® (dual-affinity retargeting) antibody to CD3ε and CD123 as salvage option in relapsed/refractory AML appear promising. The development of antibody-based immunotherapeutic approach in AML has been encouraging. Ongoing research will define the choice of an appropriate complementary therapeutic agent in antibody-based combination therapy, and whether one or more than one antigen should be simultaneously targeted. Further studies will likely refine the role of antibody-based therapy in post hematopoietic cell transplant setting.

Current and Emerging Therapies for Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is predominantly a disease of older adults and the majority of affected patients succumb to the disease. After decades of slow progress, the last 5 years have witnessed remarkable progress in AML therapy with the approval of multiple highly active and well-tolerated novel therapies. Notable among these are agents targeting driver mutations including FLT3, IDH1/2 as well as the Bcl-2 inhibitor venetoclax. The combination of hypomethylating agents with venetoclax is highly active in AML and has become the standard of care for older patients as well as those with comorbidities. As a result of these advances, a larger proportion of AML patients now achieve complete remissions enabling them to undergo allogeneic hematopoietic cell transplantation with curative intent. Progress is also being made in the field of monoclonal antibodies targeting leukemia antigens and other immunotherapies and many such agents are currently under active investigation.