Real-World Efficacy of Midostaurin in Aggressive Systemic Mastocytosis

Pharmaco-phosphoproteomic analysis of cancer-associated KIT mutations D816V and V560G

The CD117 mast/stem cell growth factor receptor tyrosine kinase (KIT) is critical for haematopoiesis, melanogenesis and stem cell maintenance. KIT is commonly activated by mutation in cancers including acute myeloid leukaemia, melanoma and gastrointestinal stromal tumours (GISTs). The kinase and the juxtamembrane domains of KIT are mutation hotspots; with the kinase domain mutation D816V common in leukaemia and the juxtamembrane domain mutation V560G common in GISTs. Given the importance of mutant KIT signalling in cancer, we have conducted a proteomic and phosphoproteomic analysis of myeloid progenitor cells expressing D816V- and V560G-KIT mutants, using an FDCP1 isogenic cell line model. Proteomic analysis revealed increased abundance of proteases and growth signalling proteins in KIT-mutant cells compared to empty vector (EV) controls. Pathway analysis identified increased oxidative phosphorylation in D816V- and V560G-mutant KIT cells, which was targetable using the inhibitor IACS010759. Dysregulation of RNA metabolism and cytoskeleton/adhesion pathways was identified in both the proteome and phosphoproteome of KIT-mutant cells. Phosphoproteome analysis further revealed active kinases such as EGFR, ERK and PKC, which were targetable using pharmacological inhibitors. This study provides a pharmaco-phosphoproteomic profile of D816V- and V560G-mutant KIT cells, which reveals novel therapeutic strategies that may be applicable to a range of cancers.

Potential role of immunotherapy and targeted therapy in the treatment of cancer: A contemporary nursing practice

Immunotherapy and targeted therapy have emerged as promising therapeutic options for cancer patients. Immunotherapies induce a host immune response that mediates long-lived tumor destruction, while targeted therapies suppress molecular mechanisms that are important for tumor maintenance and growth. In addition, cytotoxic agents and targeted therapies regulate immune responses, which increases the chances that these therapeutic approaches may be efficiently combined with immunotherapy to ameliorate clinical outcomes. Various studies have suggested that combinations of therapies that target different stages of anti-tumor immunity may be synergistic, which can lead to potent and more prolonged responses that can achieve long-lasting tumor destruction. Nurses associated with cancer patients should have a better understanding of the immunotherapies and targeted therapies, such as their efficacy profiles, mechanisms of action, as well as management and prophylaxis of adverse events. Indeed, this knowledge will be important in establishing care for cancer patients receiving immunotherapies and targeted therapies for cancer treatment. Moreover, nurses need a better understanding regarding targeted therapies and immunotherapies to ameliorate outcomes in patients receiving these therapies, as well as management and early detection of possible adverse effects, especially adverse events associated with checkpoint inhibitors and various other therapies that control T-cell activation causing autoimmune toxicity. Nurses practice in numerous settings, such as hospitals, home healthcare agencies, radiation therapy facilities, ambulatory care clinics, and community agencies. Therefore, as compared to other members of the healthcare team, nurses often have better opportunities to develop the essential rapport in providing effective nurse-led patient education, which is important for effective therapeutic outcomes and continuance of therapy. In this article, we have particularly focused on providing a detailed overview on targeted therapies and immunotherapies used in cancer treatment, management of their associated adverse events, and the impact as well as strategies of nurse-led patient education.

Aggressive systemic mastocytosis with multiple organ involvement: a case report

Systemic mastocytosis is a rare malignancy whose main diagnostic finding is the abnormal proliferation of clonal mast cells. In this report, a 63-year-old woman is presented who was referred to the emergency department with lower back pain. Due to the hypereosinophilia in blood tests, a bone marrow biopsy was performed, and except for the presence of a large number of mastocytes, no other pathologic findings were seen. Furthermore, the immunohistochemistry test showed positive CD117 and CD25 markers, and the patient's platelet-derived growth factor receptor alpha test was positive. Hence, the patient was diagnosed with aggressive systemic mastocytosis. Treatment was initiated with the Cladribine regimen, but unfortunately, in the third course, the patient experienced bradycardia and loss of consciousness and expired. Systemic mastocytosis can manifest itself with non-cutaneous symptoms. Non-cutaneous symptoms do not rule out systemic mastocytosis as a differential diagnosis in patients with hypereosinophilia.

Available and emerging therapies for bona fide advanced systemic mastocytosis and primary eosinophilic neoplasms

The historically poor prognosis of patients with advanced systemic mastocytosis (AdvSM) and primary eosinophilic neoplasms has shifted to increasingly favorable outcomes with the discovery of druggable targets. The multikinase/KIT inhibitor midostaurin and the highly selective KIT D816V inhibitor avapritinib can elicit marked improvements in measures of mast cell (MC) burden as well as reversion of MC-mediated organ damage (C-findings) and disease symptoms. With avapritinib, the achievement of molecular remission of KIT D816V and improved survival compared with historical therapy suggests a potential to affect disease natural history. BLU-263 and bezuclastinib are KIT D816V inhibitors currently being tested in trials of AdvSM. In the new World Health Organization and International Consensus Classifications, the category of "myeloid/lymphoid neoplasms with eosinophilia and tyrosine kinase (TK) gene fusions" is inclusive of rearrangements involving PDGFRA, PDGFRB, FGFR1, JAK2, FLT3, and ETV6::ABL1. While the successful outcomes with imatinib in FIP1L1::PDGFRA-positive cases and PDGFRB-rearranged neoplasms have become the "poster children" of these disorders, the responses of the other TK-driven neoplasms to small-molecule inhibitors are more variable. The selective FGFR inhibitor pemigatinib, approved in August 2022, is a promising therapy in aggressive FGFR1-driven diseases and highlights the role of such agents in bridging patients to allogeneic transplantation. This review summarizes the data for these approved and investigational agents and discusses open questions and future priorities regarding the management of these rare diseases.

Midostaurin therapy for advanced systemic mastocytosis: Mayo Clinic experience in 33 consecutive cases

We retrospectively examined our experience with midostaurin therapy in 33 consecutive patients (median age 68 years; 58% females) with advanced systemic mastocytosis (adv-SM): aggressive SM (ASM; n = 17), SM associated with another hematologic neoplasm (SM-AHN; n = 14) and mast cell leukemia (MCL; n = 2). KITD816V mutation was detected in 84% of the patients and C findings in 91%. Eleven (33%) patients were previously treated with other cytoreductive drugs, including cladribine (n = 4) and imatinib (n = 3). Median time from diagnosis to initiation of midostaurin therapy was 2.2 months (range 0.3-41). Using modified valent criteria, overall response was 42% (53% ASM, 29% SM-AHN, 50% MCL; p = .22), all classified as being major. Responses included ≥50% reduction in bone marrow mast cells in 40% and normalization of serum tryptase in 29%, of evaluated cases. After a median follow-up of 14.6 months from initiation of midostaurin therapy, 7 (21%) deaths, 1 (3%) leukemic progression, and 18 (55%) treatment discontinuations were documented; median duration of midostaurin treatment was 7.9 months (range 0.5-123) and response duration 21.5 months (range 2.9-123). Most frequent side effect was gastrointestinal (51%) while grade 3/4 neutropenia or thrombocytopenia occurred in 12% of patients. Response to treatment was not predicted by KIT mutation (p = .67) or exposure to prior cytoreductive therapy (p = .44). Median survival was longer in midostaurin responders but not significantly (median 26.5 vs. 16 months; p = .15). Findings from the current study are broadly consistent with previously published clinical trial observations.

Systemic Mastocytosis Treatment with Midostaurin: [18F]FDG PET/CT as a Potential Monitoring Tool for Therapy Outcome

We report the case of a 68-year-old patient with diagnosed systemic mastocytosis and histopathologically confirmed manifestations in the stomach and intestinal tract who underwent 18F-Fluorodeoxyglucose ([18F]FDG) positron-emission tomography/computed tomography (PET/CT) pre- and post-6-month therapy with midostaurin, an established tyrosine kinase inhibitor. Post-therapeutic [18F]FDG PET/CT showed decreased multifocal tracer uptake in the known lesions in the gastrointestinal tract, which was consistent with relief of the patient’s symptoms and decrease in serum tryptase level. [18F]FDG PET/CT may thus be considered a potential method for monitoring the outcome of midostaurin therapy in systemic mastocytosis.

Precision Medicine in Systemic Mastocytosis

Mastocytosis is a rare hematological neoplasm characterized by the proliferation of abnormal clonal mast cells (MCs) in different cutaneous and extracutaneous organs. Its diagnosis is based on well-defined major and minor criteria, including the pathognomonic dense infiltrate of MCs detected in bone marrow (BM), elevated serum tryptase level, abnormal MCs CD25 expression, and the identification of KIT D816V mutation. The World Health Organization (WHO) classification subdivides mastocytosis into a cutaneous form (CM) and five systemic variants (SM), namely indolent/smoldering (ISM/SSM) and advanced SM (AdvSM) including aggressive SM (ASM), SM associated to hematological neoplasms (SM-AHN), and mast cell leukemia (MCL). More than 80% of patients with SM carry a somatic point mutation of KIT at codon 816, which may be targeted by kinase inhibitors. The presence of additional somatic mutations detected by next generation sequencing analysis may impact prognosis and drive treatment strategy, which ranges from symptomatic drugs in indolent forms to kinase-inhibitors active on KIT. Allogeneic stem cell transplant (SCT) may be considered in selected SM cases. Here, we review the clinical, diagnostic, and therapeutic issues of SM, with special emphasis on the translational implications of SM genetics for a precision medicine approach in clinical practice.