Tagraxofusp, the first CD123-targeted therapy and first targeted treatment for blastic plasmacytoid dendritic cell neoplasm

Low-dose venetoclax combined with azacitidine for blastic plasmacytoid dendritic cell neoplasm: a case report and literature review

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare hematologic malignancy that is highly aggressive with a poor prognosis. There is no standard treatment for BPDCN. Although conventional chemotherapies are usually sensitive in the initial therapy, relapse and drug resistance are inevitable within a short duration. Targeted therapies have enlightened new prospects for the treatment of BPDCN, especially for those in a frail state and intolerable to standard chemotherapies or hematopoietic stem cell transplantation. Here, we report an 82-year-old man diagnosed with cutaneous-limited BPDCN. Considering the old age and limited involvement of the tumor, we reduced the dosage of venetoclax. His skin lesions subsided significantly after 1 cycle of azacytidine (100 mg d1-7) combined with reduced doses of venetoclax (200 mg d1-14). The reduction in the dose of venetoclax avoided severe myelosuppression while achieving satisfactory outcomes. The patient received 2 cycles of therapy with no skin lesions re-occurred for 7 months before relapsing.

Cancer Nano-Immunotherapy: The Novel and Promising Weapon to Fight Cancer

Cancer is a complex disease that, despite advances in treatment and the greater understanding of the tumor biology until today, continues to be a prevalent and lethal disease. Chemotherapy, radiotherapy, and surgery are the conventional treatments, which have increased the survival for cancer patients. However, the complexity of this disease together with the persistent problems due to tumor progression and recurrence, drug resistance, or side effects of therapy make it necessary to explore new strategies that address the challenges to obtain a positive response. One important point is that tumor cells can interact with the microenvironment, promoting proliferation, dissemination, and immune evasion. Therefore, immunotherapy has emerged as a novel therapy based on the modulation of the immune system for combating cancer, as reflected in the promising results both in preclinical studies and clinical trials obtained. In order to enhance the immune response, the combination of immunotherapy with nanoparticles has been conducted, improving the access of immune cells to the tumor, antigen presentation, as well as the induction of persistent immune responses. Therefore, nanomedicine holds an enormous potential to enhance the efficacy of cancer immunotherapy. Here, we review the most recent advances in specific molecular and cellular immunotherapy and in nano-immunotherapy against cancer in the light of the latest published preclinical studies and clinical trials.

IRF8 may be a useful marker for blastic plasmacytoid dendritic cell neoplasm, especially with weak CD123 expression

We highlight the utility of interferon regulatory factor 8 (IRF8), a novel marker of monocytic and dendritic cell lineages, in the diagnosis of a case of blastic plasmacytoid dendritic cell neoplasm (BPDCN) presenting initially in the skin. A 60-year-old male with a previous history of myelodysplastic syndrome presented with cutaneous nodules on chest and scalp. A punch biopsy specimen of a skin nodule showed a diffuse dermal infiltrate of atypical mononuclear cells. The neoplastic cells expressed CD4, CD56, CD43, and TdT but showed minimal reaction for TCL-1 and CD123, and were negative for CD34, CD117, and MPO, confounding the diagnosis. IRF8 performed in retrospect was strongly positive. A new punch biopsy specimen of a chest nodule showed the blastoid tumor cells were positive for TCL-1, CD4, and CD56, but dim CD123. Subsequent bone marrow involvement showed blastoid tumor cells with intense positivity for CD123, CD4, and CD56, which was supportive of the BPDCN diagnosis. BPDCN cases with weak or variable CD123 and TCL-1 expression represent a potential diagnostic pitfall. In a recent study, 15 cases of BPDCN showed uniformly strong staining for IRF8, while CD123 was dim or negative in 4 of these 15 cases. We suggest IRF8 may be a useful marker for BPDCN, especially in cases with weak or variable expression of CD123 and TCL1.

Chimeric antigen receptor T-cell therapy in acute myeloid leukemia

PURPOSE OF REVIEW

Treatment outcome of relapsed or refractory AML patients remains dismal and new treatment options are needed. Adoptive cell therapy using CAR-T cells is a potentially interesting approach in this.

RECENT FINDINGS

Several potentially interesting AML targets are being investigated with CAR-T therapy with over 60 clinical trials listed on clinicaltrials.gov. The first clinical data are only just emerging with mixed results, once more proving that further research is needed.

SUMMARY

Adoptive cell therapy using chimeric antigen receptor T cells is being investigated in AML through many clinical trials. So far, no AML-specific antigen has been identified, requiring additional strategies to mitigate on-target off-tumor toxicity and to increase efficacy. Focus point is to acquire control over the CAR T cells once administered. Strategies to do so include biodegradable CARs, inducible CARs, suicide-switch containing CARs and two-component modular CARs. Limited and mixed results are available, confirming the risk of lasting toxicity for nonswitchable CARs. Initial results of modular CARs suggest toxicity can be mitigated whilst maintaining CAR activity by the use of modular CAR concepts that allows for 'ON' and 'OFF' switching.

Targeting CD123 in BPDCN: an emerging field

INTRODUCTION

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare and aggressive hematologic malignancy with historically poor outcomes for patients, often refractory to traditional chemotherapy. Recent research has focused on targeted therapy to improve responses and limit potential toxicity.

AREAS COVERED

CD123 (also known as IL-3 Rα) is a cell surface marker and attractive therapeutic target for many myeloid malignancies, particularly BPDCN, whose cells ubiquitously overexpress CD123. We review the history of CD123 research regarding BPDCN, recent advances including FDA approval of tagraxofusp (formerly SL-401) for BPDCN, and ongoing clinical studies utilizing novel therapeutic strategies to target CD123.

EXPERT OPINION

The approval of tagraxofusp for the treatment of BPDCN in December 2018 drastically changed the treatment landscape for patients with this rare neoplasm. While tagraxofusp is better tolerated than traditional multi-agent chemotherapy regimens, it requires close monitoring and sound clinical judgment by providers to prevent and mitigate severe treatment-related complications with special attention to the recognition and management of capillary leak syndrome (CLS). Several other promising strategies for targeting CD123 in BPDCN are currently under investigation, including antibody-drug conjugates, T-cell engagers, and CAR-T cellular therapeutics. These CD123 targeted approaches may soon become standard of care for patients with this difficult to treat malignancy.

Blastic Plasmacytoid Dendritic Cell Neoplasm without Cutaneous Manifestation: A Case Report

Patient: Male, 85-year-old

Final Diagnosis: Blastic plasmacytoid dendritic cell neoplasm

Symptoms: Dizziness • leg pain • malaise • weakness

Medication: —

Clinical Procedure: Bone marrow biopsy • lumbar puncture

Specialty: Hematology • Oncology

CD123-targeted therapy in acute myeloid leukemia

INTRODUCTION

Acute myeloid leukemia (AML) results from the neoplastic transformation of a hematopoietic stem cell. While therapeutic progress has stagnated for several decades, recent progress in the genomic classification of AML has paved the way for multiple new drug approvals. These long-awaited achievements represent a paradigm shift in the approach to a disease that has largely been managed with conventional chemotherapy since the 1970s. With the evolution of targeted AML therapies, novel agents continue to be developed with the goal to improve efficacy while minimizing toxicity. Monoclonal antibodies targeting AML-specific surface markers have emerged as promising candidates to improve outcomes. CD123, interleukin-3 receptor alpha chain [IL-3 Rα], is highly expressed in AML, particularly within the AML stem cell compartment. Several CD123-targeted strategies are currently being evaluated in clinical trials.

AREAS COVERED

The authors herein discuss recent clinical data in CD123-directed therapy in AML. A computerized PubMed search was conducted using key words relevant to the various sections of this article. Relevant abstracts presented at the American Society of Hematology, the European Hematology Association, and the American Society of Clinical Oncology were also reviewed.

EXPERT OPINION

CD123 represents a suitable therapeutic target that has the potential to improve AML patient outcomes.

Novel Therapeutic Approaches in Blastic Plasmacytoid Dendritic Cell Neoplasm (BPDCN): Era of Targeted Therapy

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare hematologic malignancy arising from the aberrant transformation of plasmacytoid dendritic cells (pDCs) and involving skin, bone marrow, lymph nodes, and central nervous system. Characteristically unique from other myeloid neoplasms, BPDCN cells express CD4, CD56, and CD123 as well as TCL-1 and TCF4 in almost all cases. Historically, this malignancy has exhibited a poor prognosis, with median survival of less than 2 years. Traditional treatment approaches have involved conventional cytotoxic chemotherapy followed by hematopoietic stem cell transplantation; however, patients frequently relapse with chemotherapy-resistant disease. We have recently entered a modern era of therapy with targeting of CD123, with first-in-class agent tagraxofusp, a CD123- targeted agent approved by the US Food and Drug Administration for therapy of patients with BPDCN ages 2 and older. Relapsed and refractory BPDCN remains an elusive therapeutic challenge, but better understanding of the underlying pathophysiology has led to the development of other CD123-targeted agents and combination therapy, as well as agents targeting beyond CD123. Specifically, the use of venetoclax in targeting BCL2 has been promising in BPDCN treatment. This review will focus on the underlying diagnostic markers of BPDCN which have led to novel targeted treatment strategies, as well as future directions in therapy we can expect in coming years.

Recent development and optimization of pseudomonas aeruginosa exotoxin immunotoxins in cancer therapeutic applications

Recombinant immunotoxins are fusion proteins composed of a peptide toxin and a specific targeting domain through genetic recombination. They are engineered to recognize disease-specific target receptors and kill the cell upon internalization. Full-sized monoclonal antibodies, smaller antibody fragments and ligands, such as a cytokine or a growth factor, have been commonly used as the targeting domain, while bacterial Pseudomonas aeruginosa exotoxin (PE) is the usual toxin fusion partner, due to its natural cytotoxicity and other unique advantages. PE-based recombinant immunotoxins have shown remarkable efficacy in the treatment of tumors and autoimmune diseases. At the same time, efforts are underway to address major challenges, including immunogenicity, nonspecific cytotoxicity and poor penetration, which limit their clinical applications. Recent strategies for structural optimization of PE-based immunotoxins, combined with mutagenesis approaches, have reduced the immunogenicity and non-specific cytotoxicity, thus increasing both their safety and efficacy. This review highlights novel insights and design concepts that were used to advance immunotoxins for the treatment of hematological and solid tumors and also presents future development prospect of PE-based recombinant immunotoxins that are expected to play an important role in cancer therapy.

A misdiagnosed case of blastic plasmacytoid dendritic cell neoplasm experiencing multiple recurrences who underwent allogeneic stem cell transplantation: a case report

BACKGROUND

Blastic plasmacytoid dendritic cell neoplasm represents a rare type of hematologic malignancy that often manifests itself through various skin lesions. It commonly affects the elderly male population. Lymph nodes, peripheral blood, and bone marrow involvement are the typical findings that justify its aggressive nature and dismal prognosis. On histopathological assessment, malignant cells share some similarities with blastic cells from the myeloid lineage that make immunohistochemistry staining mandatory for blastic plasmacytoid dendritic cell neoplasm diagnosis.

CASE PRESENTATION

A 35-year-old Asian man presented with cervical lymphadenopathy followed by an erythematous lesion on his left upper back. At first, the lesion was misdiagnosed as an infectious disease and made the patient receive two ineffective courses of azithromycin and clarithromycin. Six months later, besides persistent skin manifestations, he felt a cervical mass, which was misdiagnosed as follicular center cell lymphoma. Tumor recurrence following the chemoradiation questioned the diagnosis, and further pathologic assessments confirmed blastic plasmacytoid dendritic cell neoplasm. The second recurrence occurred 3 months after chemotherapy. Eventually, he received a bone marrow transplant after complete remission. However, the patient expired 3 months after transplant owing to the third recurrence and gastrointestinal graft versus host disease complications.

CONCLUSIONS

Early clinical suspicion and true pathologic diagnosis play a crucial role in patients' prognosis. Moreover, allogenic bone marrow transplant should be performed with more caution in aggressive forms of blastic plasmacytoid dendritic cell neoplasm because of transplant side effects and high risk of cancer recurrence.

Immunotherapy and Immunomodulation in Myeloproliferative Neoplasms

Myeloproliferative neoplasms are characterized by chronic inflammation. The discovery of constitutively active JAK-STAT signaling associated with driver mutations has led to clinical and translational breakthroughs. Insights into the other pathways and novel factors of potential importance are being actively investigated. Various classes of agents with immunomodulating or immunosuppressive properties have been used with varying degrees of success in treating myeloproliferative neoplasms. Early clinical trials are investigating the feasibility, effectiveness, and safety of immune checkpoint inhibitors, cell-based immunotherapies, and SMAC mimetics. The dynamic landscape of immunotherapy and immunomodulation in myeloproliferative neoplasms is the topic of the present review.

CD123 as a Biomarker in Hematolymphoid Malignancies: Principles of Detection and Targeted Therapies

Simple Summary

CD123 is overexpressed in multiple hematologic malignancies. Advances in CD123-targeted therapies over the past decade have positioned this molecule as an integral biomarker in current practice. This review provides an overview of CD123 biology and in-depth discussion of clinical laboratory techniques used to determine CD123 expression in various hematolymphoid neoplasms. In addition, we describe various pharmacologic strategies and agents that are available or under evaluation for targeting CD123.

Abstract

CD123, the α chain of the interleukin 3 receptor, is a cytokine receptor that is overexpressed in multiple hematolymphoid neoplasms, including acute myeloid leukemia, blastic plasmacytoid dendritic cell neoplasm, acute lymphoblastic leukemia, hairy cell leukemia, and systemic mastocytosis. Importantly, CD123 expression is upregulated in leukemic stem cells relative to non-neoplastic hematopoietic stem cells, which makes it a useful diagnostic and therapeutic biomarker in hematologic malignancies. Varying levels of evidence have shown that CD123-targeted therapy represents a promising therapeutic approach in several cancers. Tagraxofusp, an anti-CD123 antibody conjugated to a diphtheria toxin, has been approved for use in patients with blastic plasmacytoid dendritic cell neoplasm. Multiple clinical trials are investigating the use of various CD123-targeting agents, including chimeric antigen receptor-modified T cells (expressing CD123, monoclonal antibodies, combined CD3-CD123 dual-affinity retargeting antibody therapy, recombinant fusion proteins, and CD123-engager T cells. In this review, we provide an overview of laboratory techniques used to evaluate and monitor CD123 expression, describe the strengths and limitations of detecting this biomarker in guiding therapy decisions, and provide an overview of the pharmacologic principles and strategies used in CD123-targeted therapies.

Tagraxofusp as treatment for patients with blastic plasmacytoid dendritic cell neoplasm

INTRODUCTION

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare, aggressive hematologic malignancy that previously lacked standardized therapeutic approaches. CD123 (interleukin-3 receptor alpha unit) is highly expressed in many hematologic malignancies, including BPDCN. Tagraxofusp-ezrs (tagraxofusp from herein) is an agent that consists of interleukin-3 fused to a truncated diphtheria toxin, targeting CD123. The Food and Drug Administration recently approved tagraxofusp as therapy for BPDCN for adults and children aged 2 years and older.

AREAS COVERED

We discuss the history and clinical background of BPDCN along with tagraxofusp as its first-line therapy. We review the clinical efficacy and safety profile of tagraxofusp in adults including proposed sensitivity and resistance. Finally, we summarize tagraxofusp use in the pediatric population.

EXPERT OPINION

Tagraxofusp is a newly approved therapy for BPDCN, a hematologic malignancy that has overall historically poor outcomes. With its significant efficacy, many patients were successfully bridged to stem cell transplantation in the clinical trial leading to its ultimate approval. Clinical awareness for major toxicities, including capillary leak syndrome will be a critical aspect of using this novel agent. In the future, investigation of its use in other hematologic malignancies and expansion of clinical trials in pediatric populations with BPDCN are warranted.

Blastic Plasmacytoid Dendritic Cell Neoplasm: The European Perspective

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) has to be considered an orphan tumoral disease. BPDCN is a good model concerning the structuring and the organization of a concerted medical program on a nation-based, transnational, or international level. In 2019 in France the diagnosis process for BPDCN was clearly established. Two prospective clinical trials are ongoing. Because of the difficulties in diagnostic procedures and the rarity of the disease it is important that European countries collaborate to build a real European network to ensure the best and equitable medical care to all BPDCN patients.