KIT D816V

After Course 2 consolidation, the KIT_H patients with >3-log reduction in the RUNX1::RUNX1T1 transcript levels (11/45; 24.4%) had similar RFS as that of patients with <3-log reduction in the RUNX1::RUNX1T1 transcript levels. The combination of KITmut and RUNX1::RUNX1T1 transcript levels after Course 2 consolidation may improve risk stratification in t (8; 21) AML patient with KIT mutation.

The patient rapidly evolved towards SM-AHN, characterized by the persistence of the PRKG2::PDGFRB chimera, due to the presence of an extra copy of the der(5)t(4;5)(q24;q34) chromosome and an increase in the RUNX1 mutation allelic frequency. The results indicated that the transcriptional landscape and the mutational profile of SM deserve attention to predict the evolution and prognosis of this complex disease, whose classification criteria are still a matter of debate.

Flow cytometric immunophenotyping is a quick, sensitive, high-yield tool for evaluating the immunophenotype of mast cells. An abnormal FCI finding should prompt careful histologic evaluation and sensitive KIT D816V mutation testing to address the possibility of SM. CD2, CD25, and CD30 are important markers for the detection of immunophenotypic aberrancy of mast cells, and their frequencies of aberrancy differ across SM subtypes.

The KITneg. SM-AHN phenotype was dominated by the heterogeneous AHN (low mast cell burden, presence of additional mutations) with a better median OS of 4.5 years. We conclude that (i) in MCL, negativity for D816V is a relevant prognostic factor and (ii) PSS fail to correctly classify D816Vneg. patients.

Pathway analysis identified increased oxidative phosphorylation in D816V- and V560G-mutant KIT cells, which was targetable using the inhibitor IACS010759...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.

Whereas in typical cases the diagnosis of CM may be uncomplicated, less typical manifestations may require specific investigations for making the diagnosis and predicting its course.

The patient's severe symptoms were likely the result of organ damage from mast cell infiltration. Despite the use of intensive acute myeloid leukemia (AML)-like polychemotherapy, the patient died during the course of post-induction myelosuppression due to bleeding complications.

For all patients in our cohort, age > 60 years, KITD816 mutations and BCOR mutations were showed to be independent unfavorable predictors for OS and EFS. Our results revealed that SM-t(8;21) AML shared more similar clinical characteristics, molecular features and clinical outcomes with KITD816 t(8;21) AML.

We here characterized TNF as a KIT D816V-dependent cytokine that promotes clonal dominance. We propose TNF and apoptosis-associated proteins as potential therapeutic targets in SM.

ASH 2022). These data highlight the importance of close monitoring for signs of progression and warrant further research to identify subsets of ISM patients who may have a higher underlying risk of progression.

Key exclusion criteria include a diagnosis of acute myeloid leukemia, history of intracranial hemorrhage or risk of major hemorrhage, prior treatment with avapritinib or decitabine with documented progression in SM or AHN component, respectively, or history of treatment with alternative KIT inhibitor or azacitidine within 4 weeks of study treatment initiation. Patients with platelet count ≥ 25 x 10 9/L and < 75 x 10 9/L, will receive lead-in dosing with decitabine or decitabine/cedazuridine with the ability to add avapritinib if sufficient platelet thresholds are achieved. This study will open at 7 sites in the United States and is anticipated to open in January 2024.

Involvement of additional Italian labs is already planned, and further implementation within the ECNM will be proposed. Definition of common SOPs, uniform sample requirements and web-based reporting following the GIMEMA LabNet model will be pursued.

While SM can have a variety of clinical manifestations, including elevated tryptase level and mediator release symptoms, the presence of KIT D816V in the peripheral blood is a strong predictor of SM diagnosis. Persistently elevated serum tryptase without the KIT D816V mutation may suggest the likelihood of HaT, while only mediator release symptoms with normal serum tryptase and without the KIT mutation is a strong negative predictor of SM and HaT.

When reactions did occur, she treated them at one point with a cocktail of an histamine-2 blocker (ranitidine), histamine-1 blocker (diphenhydramine), and a mast cell stabilizer (cromolyn) and without requiring the use of epinephrine...After the most recent BMB the patient altered her daily regimen due to gastric upset and found she could take of her histamine-1 blocker (diphenhydramine) once daily along with a twice daily regimen of her imatinib (split into two smaller daily doses), histamine-1 antagonist (cetirizine), her histamine-2 antagonist (famotidine), and citalopram (selective serotonin reuptake inhibitor or SSRI) with improved symptomatic control to this day. This case serves to illustrate the diagnostic and therapeutic challenges associated with SM, as well as the potential therapeutic use of imatinib in patients with D816V outside of its original FDA indication. Further characterization of the effect of imatinib on D816V mutated SM may warrant the consideration of expanding the FDA indications for imatinib as its role and efficacy outside of solely D816V negative c-kit MS.

The patient started hematological follow up, treatment with hydroxyurea and transfusion support for LMMC diagnosis. Midostaurin is a TKI effective against KITD816V with an ORR of 60% in aggressive SM. Although midostaurin represents the most potent agent available for SM patients, other medications are under investigation to overcome resistance due to D816V-mutated variant of KIT.

Despite the limitations of retrospective data analysis, the data from this large multicenter cohort of patients with HES due to a chronic myeloid neoplasm suggest that routine demographic, clinical and laboratory features vary depending on the underlying molecular abnormality. This approach could ultimately help guide empiric therapy when molecular studies are negative or unavailable.

Patients with a history of prior TKI therapy (e.g., avapritinib, midostaurin) are permitted in the trial. Enrollment in Part 1 of the Apex trial is complete. Patients enrolled in Part 1 of the Apex trial are generally representative of the population of patients with AdvSM based on patient characteristics and markers of disease. Part 1 includes a small subset of patients with prior use of TKIs.

Conclusion This study presents updated clinicopathologic data from a large, pooled cohort of patients with MstCL. It identifies age, anemia, thrombocytopenia, leukemic presentation, complex cytogenetics, type of therapy, and quality of response to treatment as critical determinants of OS.

The development of these KitJak cell lines greatly facilitates the production of cRBCs and will pave the way to large-scale erythroid cell production for transfusion and other translational applications. As a first application, we show that the RBCs produced are fully compatible with the Immucor red blood cell typing system and can be used as reagent red blood cells.

For these patients, (poly)chemotherapy, antibody-based therapies, and allogeneic hematopoietic stem cell transplantation may be viable treatment alternatives. In this article, we discuss treatment options for patients with drug-resistant advanced SM, including novel KIT-targeting drugs, antibody-based drugs, and stem cell-eradicating therapies.

P2/3, N=443, Recruiting, Blueprint Medicines Corporation | Trial primary completion date: Aug 2023 --> Jun 2028

P1/2, N=67, Recruiting, Blueprint Medicines Corporation | Initiation date: Apr 2023 --> Sep 2023

Currently, the techniques recommended to detect the KIT D816V mutation and quantify the mutational burden in peripheral blood, bone marrow, or other organs/tissues are allele specific-quantitative PCR or droplet digital PCR. These techniques are useful for diagnosis, prognostication, follow-up and monitoring of therapeutic efficacy of cytoreductive agents in patients with SM.

The results of gene expression profiling indicate the increased expression of genes belonging to the integral component of the membrane in mastocytosis patients (GRM2 and KRTCAP3). Further work is warranted, especially in relation to the disease subvariants, to identify links between the methylation status and the symptoms and novel therapeutic targets.

A high KIT D816V VAF in PB and/or presence of HRM unveil a substantial proportion of pts with ‘masked’ SM-AMN. Clustering of HRM with other HRM frequently occurs and adversely impacts OS.

Here, we describe a new mouse model for systemic mastocytosis, which involves crossing an existing KitD814Vflox line with a tamoxifen-inducible SclCreER-driver line... Our findings show that our animal model might be used for studies of advanced systemic mastocytosis. More mice are currently being analyzed to assess the hematopoietic stem and progenitor cell compartment in more detail.

A gain-of-function KIT D816 V mutation is the primary oncogenic driver found in about 90% of all patients with AdvSM. Midostaurin, an oral multikinase inhibitor with activity against KIT D816V, and avapritinib, an oral selective KIT D816V inhibitor are approved for AdvSM.

Next-generation sequencing of the sarcoma showed a KIT D816V mutation. In our case, MCS with a KIT D816V mutation is a unique finding in the setting of concurrent SM, highlighting the potential relatedness of these 2 entities and the progression from SM to MCS, a currently poorly understood phenomenon.

Although mast cell lesions frequently demonstrate atypical cytology, many pathologists think of spindle cell and hypogranular features when considering this disease. This case highlights the importance of considering the myriad appearances atypical mast cells can demonstrate, including forms having kidney-shaped or bilobed nuclei (promastocytes).

KITv CAR T cells have equivalent or better in vivo efficacy than second-generation CAR T cells and are susceptible to tyrosine kinase inhibitors (safety switch). When combined with CD28 co-stimulation, KITv co-stimulation functions as a third signal, enhancing efficacy and providing a potent approach to treat solid tumors.

This patient, being young and presenting with multiple invasive melanomas in a short space of time, and with no other known risk factors for melanoma (apart from Type 2 Fitzpatrick skin) highlights the link between mastocytosis and melanomas. This suggests the need for careful and regular skin surveillence in patients with known mastocytosis

We report three patients with AdvSM-AHN on avapritinib who achieved complete remission (CR) of SM and were successfully bridged to allogeneic haematopoietic cell transplant (allo-HCT). Two cases additionally highlight the risk of clonal evolution within the AHN component and requirement for close monitoring while on targeted therapy.

We characterize the clonal architecture of KIT MT -CMML with/without SM, noting distinct patterns of KIT MT origination and propagation. KIT mutations were always detected in apical HSCs, accompanied by CHIP mutations: contrasting with sporadic SM, in which KIT is typically the sole mutation. The fraction of KIT MT cells was much lower in SM-CMML, indicating SM as a subclonal branch of a broader disease complex.

Although the multi tyrosine kinase inhibitors (TKI) Midostaurin and Avapritinib are approved for the treatment of SM with overall response rates (ORR) of 75% for Avapritinib, the median overall survival ranges from 3.5 years (aggressive SM: ASM) to less than six months (mast cell leukemia: MCL). In conclusion, we demonstrate in preclinical SM models the efficient targeting and killing in vitro and in vivo by CAR T-cells directed against human CD117. Given that CD117 is expressed on healthy hematopoietic stem and progenitor cells (HSPCs) on a substantially lower level, there might be a therapeutic window for anti-CD117 immunotherapy in advanced forms ofmastocytosis. However, as CAR T-cells are highly efficient, collateral damage on healthy HSPCs will likely need to be compensated by subsequent HSC transplantation.

In patients with AdvSM, avapritinib continues to provide robust efficacy with a favorable benefit-risk profile, regardless of prior therapy or disease subtype. Tyrosine kinase inhibitor, c-kit, Systemic mastocytosis

Small-molecule kinase inhibitors targeting the KIT-downstream and KIT-independent pathways were recently approved for treating advanced SM. I describe recent advances in diagnosis of SM, and review the currently available and emerging therapeutic options for SM management.

P1/2, N=67, Recruiting, Blueprint Medicines Corporation | Not yet recruiting --> Recruiting