Avapritinib for Systemic Mastocytosis

An Update on the Nitrogen Heterocycle Compositions and Properties of U.S. FDA-Approved Pharmaceuticals (2013-2023)

This Perspective is a continuation of our analysis of U.S. FDA-approved small-molecule drugs (1938-2012) containing nitrogen heterocycles. In this study we report drug structure and property analyses of 321 unique new small-molecule drugs approved from January 2013 to December 2023 as well as information about frequency of important heteroatoms such as sulfur and fluorine and key small nitrogen substituents (CN and NO2). The most notable change is an incredible increase in drugs containing at least one nitrogen heterocycle─82%, compared to 59% from preceding decades─as well as a significant increase in the number of nitrogen heterocycles per drug. Pyridine has claimed the #1 high-frequency nitrogen heterocycle occurrence spot from piperidine (#2), with pyrimidine (#5), pyrazole (#6), and morpholine (#9) being the big top 10 climbers. Also notable is high number of fused nitrogen heterocycles, apparently driven largely by newly approved cancer drugs.

A new green fluorimetric micelle complexation approach for reduction of the consumed solvent and quantification of avapritinib in biological fluids

Avapritinib (AVA) is the first medication authorized by the US-FDA in 2020 for the management of gastrointestinal stromal tumours (GISTs) that can't be treated by surgery. Cancer is among the most common causes of death worldwide and is the second most common cause of death after cardiovascular disease. Therefore, a quick, easy, sensitive, and straightforward fluorimetric approach was used to analyse AVA in pharmaceutical materials and blood plasma (pharmacokinetic). The suggested technique relies on 2% sodium dodecyl sulphate (SDS, pH 4) micellar system augmentation of the fluorescence of the tested drug. The technique demonstrated high relative fluorescence intensity (RFI) at 430 nm after excitation at 340 nm. Concentrations ranging from 20.0-400.0 ng mL-1 with a limit of quantitation of 9.47 ng mL-1 were used to obtain luminescence data for the studied medicine. In addition, the quantum yield of the AVA fluorescence was increased with the gradual addition of a surfactant at a concentration above its critical micellar level. This knowledge has been exploited to enhance the effectiveness of a spectrofluorometric technique for the estimation of AVA in human plasma (98.95 ± 1.22%) and uniformity tests with greenness assessments. The conditions for enhanced fluorescence were optimized and fully validated using US-FDA and International Conference on Harmonization (ICH) rules. This innovative strategy was expanded for AVA stability research in human plasma across various circumstances. This approach is an eco-friendly solution compared to traditional testing methods that use hazardous chemicals.

Diagnosis and management of systemic mastocytosis in a community hematology setting

BACKGROUND

Systemic mastocytosis (SM) is a rare and potentially severe hematologic disorder characterized by the clonal proliferation of mast cells (MCs) into various organs. The clinical manifestations of advanced SM are caused by the uncontrolled release of cytokines and vasoactive amines from MC and disease-induced organ dysfunction. Patients with SM typically present with symptoms such as flushing, pruritus, diarrhea, and headaches, but outcomes following active treatment have not been well characterized. In this study, the clinical characteristics, treatment patterns, and natural history of an SM patient cohort diagnosed and treated within a community hematology network in the United States is described.

METHODS

We identified 105 patients who were diagnosed and managed in one of 19 community hematology clinics up to an index date of 1 October 2022. Data collection included patient and disease characteristics, baseline biochemistry and hematology, SM diagnostic criteria being met, biomarkers tested, CD2 and/or CD25 expression in MCs as well as serum tryptase levels at presentation. Data abstraction also included supportive care drugs and anticancer therapy used, treatment response, reason for discontinuation, and overall survival by disease subtype.

RESULTS

A total of 105 SM patients were identified who met the inclusion criteria. The specific SM subtypes were indolent (47.6%), aggressive (9.5%), SM with an associated hematological neoplasm (19.0%), MC leukemia (1.9%), and subtype not documented (21.9%). Regardless of subtype, approximately 62% of patients did not receive SM-directed active therapy. Only 26% of patients with indolent systemic mastocytosis (ISM) received treatment compared to 65.6% with advanced subtypes. Relative to ISM cohort, the relative risk of death in patients with the advanced SM subtypes was approximately 15 times greater (hazard ratio = 15.0; 95% confidence interval: 3.3 to 66.5).

CONCLUSIONS

SM patients present with multiple underlying symptoms, within various disease subtypes that are difficult to diagnose in a timely manner. As a result, many patients do not receive active drug therapy for their disease. Therefore, greater disease awareness is required as well as new tools for earlier disease detection.

Management of Advanced Systemic Mastocytosis and Associated Myeloid Neoplasms

Advanced systemic mastocytosis (AdvSM) is a heterogeneous group of disorders characterized by neoplastic mast cell-related organ damage and frequently associated with a myeloid neoplasm. The 3 clinical entities that comprise AdvSM are aggressive SM (ASM), SM-associated hematologic neoplasm, and mast cell leukemia. 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.

Applicability of fluorescamine as a fluorogenic reagent for highly sensitive fluorimetric analysis of the tyrosine kinase inhibitor (avapritinib) in pharmaceuticals and biological samples

Avapritinib (AVP) was the first precision drug to be approved by the US Food and Drug Administration (FDA) in 2020 for patients suffering from metastatic gastrointestinal stromal tumors (GISTs) and progressive systemic mastocytosis. The analysis of AVP in pharmaceutical tablets and human plasma was then carried out using a fast, efficient, sensitive, and simple fluorimetric method using a fluorescamine reagent. The procedure is based on the interaction between fluorescamine as a fluorogenic reagent and the primary aliphatic amine moiety in AVP using borate buffer solution at pH 8.8. The produced fluorescence was measured at 465 nm (Excitation at 395 nm). The calibration graph's linearity range was discovered to be 45.00-500.0 ng mL-1 . Utilizing the International Council for Harmonization (ICH) and US-FDA recommendations, the research technique was validated and bioanalytically validated. The proposed approach was effectively employed for determining the stated pharmaceuticals in plasma with a high percentage of recovery ranging from 96.87 to 98.09 and pharmaceutical formulations with a percentage of recovery equal to 102.11% ± 1.05%. In addition, the study was extended to a pharmacokinetic study of AVP with 20 human volunteers as a step for AVP management in therapeutic cancer centers.

Updates in diagnosis and management of paediatric mastocytosis

PURPOSE OF REVIEW

Paediatric mastocytosis is a rare clonal disorder characterized by the overproduction and organ infiltration of mast cells. Symptoms are due to mast cell mediator release. Cutaneous mastocytosis is the most common presentation in children with systemic disease being rare. Our aim is to provide a practical guideline in differentiating subtypes of paediatric mastocytosis while providing actionable recommendations on diagnosis, clinical management, follow-up and prognosis.

RECENT FINDINGS

Longitudinal cohort studies of paediatric cutaneous mastocytosis have shown spontaneous remission with favourable prognosis. Hereditary alpha-tryptasemia may coexist with mastocytosis; thus, screening for this disorder is recommended. There is an emerging role for serum tryptase in asthma endotyping and potential for using therapeutic tryptase inhibitors.

SUMMARY

Morbidity in paediatric mastocytosis typically arises from symptoms secondary to mast cell mediator release. Prognosis for nonaggressive disease is typically favourable; however, risks for anaphylaxis and psychosocial morbidity may be underestimated. Symptomatic management and anticipatory guidance may help support patients and families throughout the disease course.

Mastocytosis in Pregnancy

Mastocytosis is a rare neoplastic disorder of the mast cell lineage resulting in unregulated proliferation and activation of mast cells. Symptoms worsen in about one-third of pregnant patients. Treatment focuses on management of symptoms with antimediator therapy (H1 & H2 antihistamines, glucocorticoids, and epinephrine, if required). Medication selection requires care during labor and delivery. Although it is generally considered safe to use a medication patient tolerated before, some common medications may need to be avoided or used with caution (eg, codeine, morphine, nonsteroidal antiinflammatory drugs, vancomycin) if the patient does not have any history of exposure to them.

Perceptions of patient disease burden and management approaches in systemic mastocytosis: Results of the TouchStone Healthcare Provider Survey

BACKGROUND

Systemic mastocytosis (SM) is a rare clonal neoplasm driven by the KIT D816V mutation and has a broad range of debilitating symptoms. In this study, the authors evaluated SM disease perceptions and management strategies among US health care providers (HCPs).

METHODS

Hematologist/oncologist (H/O) HCPs and allergist/immunologist (A/I) HCPs who were treating four or more patients with SM completed an online, 51-item TouchStone HCP Survey, which queried provider characteristics, perceptions of disease burden, and current management. Descriptive analyses by specialty and SM subtype were performed.

RESULTS

Of 304 HCPs contacted, 111 (37%) met eligibility criteria, including 51% A/I specialists and 49% H/O specialists. On average, the HCPs had 14 years of practice experience and cared for 20 patients with SM. A/I HCPs saw more patients with nonadvanced SM (78%) compared with H/O HCPs, who saw similar proportions of patients with nonadvanced SM (54%) and advanced SM (46%). HCPs reported testing 75% of patients for the KIT D816V mutation and found an estimated prevalence of 47%. On average, HCPs estimated 8 months between symptom onset and SM diagnosis. HCPs reported that 62% of patients with indolent SM felt depressed or discouraged because of symptoms. In terms of treatment goals for SM, both types of specialists prioritized symptom improvement for nonadvanced SM and improved survival for advanced SM while also prioritizing improving patient quality of life.

CONCLUSIONS

Both A/I and H/O specialists highlighted unmet needs for patients with SM. The HCPs surveyed reported a lower rate of KIT D816V mutations and a perceived shorter time between symptom onset and SM diagnosis compared with published estimates.

LAY SUMMARY

Specialists treating systemic mastocytosis (SM) completed a 51-item questionnaire about their clinical practices and perceptions of disease impact. The study included 111 hematology, oncology, allergy, and immunology physicians. Physicians reported that most patients had nonadvanced disease, yet SM symptoms significantly disrupted their patients' lives. Physicians estimated that SM is diagnosed within months of symptom onset, in contrast with published reports of years' long delays reported by patients with SM. This study identified unmet needs that can inform educational and patient management priorities in this rare disease.

Patient-reported outcomes among patients with systemic mastocytosis in routine clinical practice: Results of the TouchStone SM Patient Survey

BACKGROUND

Systemic mastocytosis (SM) is a rare clonal neoplasm driven by KIT D816V and other mutations. Data were collected from the patient perspective on disease burden and included an SM-specific symptom assessment tool.

METHODS

US adults aged 18 years and older with a self-reported SM diagnosis completed an online TouchStone SM Patient Survey of 100 items, including the 12-item Short-Form Health Survey, the Indolent Systemic Mastocytosis Symptom Assessment Form, and the Work Productivity and Activity Impairment Questionnaire, as well as questions about SM diagnosis, the impact of SM on daily activities, work impairment, and health care use. The results were analyzed using descriptive statistics.

RESULTS

Fifty-six individuals completed the survey (89% women; median age, 48 years; mean time since diagnosis, 6.7 years), reporting indolent SM (66%), aggressive SM (9%), smoldering SM (5%), and unknown SM subtype (18%). Over a 1-year recall, respondents reported seeking emergency care for anaphylaxis (30%) and taking three or more prescription medications (52%) for SM. Over one half of patients (54%) reduced their work hours because of SM, and 64% avoided leaving home because of symptoms. A majority of respondents (93%) had experienced ≥10 SM-related symptoms, noting that the most bothersome were anaphylactic episodes (18%), abdominal/stomach pain (16%), diarrhea/loose stools (13%), and fatigue (11%). Whereas an Indolent Systemic Mastocytosis Symptom Assessment Form-derived total symptom score of 28 is used to indicate moderate-to-severe symptoms, the mean total symptom score was 52.7. Mental and physical component summary scores from the 12-item Short-Form Health Survey were below population norms.

CONCLUSIONS

Patients who were surveyed reported substantial symptom burden and unmet needs because of SM, as evidenced by seeking emergency care and reporting bothersome symptoms, poor quality of life, and reduced work hours and productivity.

LAY SUMMARY

The objective of this research was to understand the burden and unmet needs in the rare disease of systemic mastocytosis (SM) to guide future care. Fifty-six patients completed an online survey containing questions about their diagnosis, medications, health care use, quality of life, and SM symptoms. The results demonstrated that SM is associated with severe and burdensome symptoms, anaphylactic events, emergency department visits, use of multiple medications, reduced ability to work, and poor physical and psychological quality of life. These findings suggest the need for future advances to address unmet needs in patients affected by SM.

Perspective: Pivotal translational hematology and therapeutic insights in chronic myeloid hematopoietic stem cell malignancies

Despite much of the past 2 years being engulfed by the devastating consequences of the SAR-CoV-2 pandemic, significant progress, even breathtaking, occurred in the field of chronic myeloid malignancies. Some of this was show-cased at the 15th Post-American Society of Hematology (ASH) and the 25th John Goldman workshops on myeloproliferative neoplasms (MPN) held on 9th-10th December 2020 and 7th-10th October 2021, respectively. The inaugural Post-ASH MPN workshop was set out in 2006 by John Goldman (deceased) and Tariq Mughal to answer emerging translational hematology and therapeutics of patients with these malignancies. Rather than present a resume of the discussions, this perspective focuses on some of the pivotal translational hematology and therapeutic insights in these diseases.

Avapritinib for the treatment of KIT mutation-negative systemic mastocytosis

Systemic mastocytosis results from the spread of abnormal mast cells in different parts of the body, with variable clinical presentation. It is difficult to diagnose and to determine the appropriate therapy regimen. We present a case of a 53-year-old man diagnosed with KIT-negative advanced systemic mastocytosis based on the 2016 World Health Organization criteria. The patient presented with widespread symptoms that continued to worsen despite supportive therapy and traditional tyrosine kinase inhibitors. He was ultimately started on avapritinib, which reduced his tryptase level and provided symptomatic relief many years after his diagnosis.

Clinical challenge for gastroenterologists–Gastrointestinal manifestations of systemic mastocytosis: A comprehensive review

Mastocytosis is a rare and heterogeneous disease characterized by various clinical and biological features that affect different prognoses and treatments. The disease is usually divided into 2 principal categories: cutaneous and systemic disease (SM). Clinical features can be related to mast cell (MC) mediator release or pathological MC infiltration. SM is a disease often hard to identify, and the diagnosis is based on clinical, biological, histological, and molecular criteria with different specialists involved in the patient’s clinical work-up. Among all manifestations of the disease, gastrointestinal (GI) symptoms are common, being present in 14%-85% of patients, and can significantly impair the quality of life. Here we review the data regarding GI involvement in SM, in terms of clinical presentations, histological and endoscopic features, the pathogenesis of GI symptoms, and their treatment.

Systemic Mastocytosis and Other Entities Involving Mast Cells: A Practical Review and Update

Evidence in the recent literature suggests that the presentation spectrum of mast cell neoplasms is broad. In this article, we elaborate on recent data pertaining to minor diagnostic criteria of systemic mastocytosis (SM), including sensitive testing methods for detection of activating mutations in the KIT gene or its variants, and adjusted serum tryptase levels in cases with hereditary α-tryptasemia. We also summarize entities that require differential diagnosis, such as the recently reclassified SM subtype named bone marrow mastocytosis, mast cell leukemia (an SM subtype that can be acute or chronic); the rare morphological variant of all SM subtypes known as well-differentiated systemic mastocytosis; the extremely rare myelomastocytic leukemia and its differentiating features from mast cell leukemia; and mast cell activation syndrome. In addition, we provide a concise clinical update of the latest adjusted risk stratification model incorporating genomic data to define prognosis in SM and new treatments that were approved for advanced SM (midostaurin, avapritinib).

Synthetic Approaches to the New Drugs Approved During 2020

New drugs introduced to the market are privileged structures that have affinities for biological targets implicated in human diseases and conditions. These new chemical entities (NCEs), particularly small molecules and antibody-drug conjugates (ADCs), provide insight into molecular recognition and simultaneously function as leads for the design of future medicines. This Review is part of a continuing series presenting the most likely process-scale synthetic approaches to 44 new chemical entities approved for the first time anywhere in the world during 2020.

Mastocytosis and Mast Cell Activation Disorders: Clearing the Air

Mast cells are derived from hematopoietic stem cell precursors and are essential to the genesis and manifestations of the allergic response. Activation of these cells by allergens leads to degranulation and elaboration of inflammatory mediators, responsible for regulating the acute dramatic inflammatory response seen. Mast cells have also been incriminated in such diverse disorders as malignancy, arthritis, coronary artery disease, and osteoporosis. There has been a recent explosion in our understanding of the mast cell and the associated clinical conditions that affect this cell type. Some mast cell disorders are associated with specific genetic mutations (such as the D816V gain-of-function mutation) with resultant clonal disease. Such disorders include cutaneous mastocytosis, systemic mastocytosis (SM), its variants (indolent/ISM, smoldering/SSM, aggressive systemic mastocytosis/ASM) and clonal (or monoclonal) mast cell activation disorders or syndromes (CMCAS/MMAS). Besides clonal mast cell activations disorders/CMCAS (also referred to as monoclonal mast cell activation syndromes/MMAS), mast cell activation can also occur secondary to allergic, inflammatory, or paraneoplastic disease. Some disorders are idiopathic as their molecular pathogenesis and evolution are unclear. A genetic disorder, referred to as hereditary alpha-tryptasemia (HαT) has also been described recently. This condition has been shown to be associated with increased severity of allergic and anaphylactic reactions and may interact variably with primary and secondary mast cell disease, resulting in complex combined disorders. The role of this review is to clarify the classification of mast cell disorders, point to molecular aspects of mast cell signaling, elucidate underlying genetic defects, and provide approaches to targeted therapies that may benefit such patients.