A phase II study on the efficacy of regorafenib in treating patients with c-KIT-mutated metastatic malignant melanoma that progressed after previous treatment (KCSG-UN-14-13).

BACKGROUND: c-KIT mutations are found in approximately 15% of patients with malignant melanoma in the Asian population. Regorafenib, an oral multikinase inhibitor, acts against both wild-type and mutant KIT. OBJECTIVE: This multi-institutional, phase II, single-arm study aimed to evaluate the efficacy of regorafenib against metastatic malignant melanoma harbouring c-KIT mutations. METHODS: Patients with metastatic melanoma positive for c-KIT mutations, upon progression after at least one line of systemic treatment, were enroled. Patients received oral regorafenib 160 mg once daily for 3 weeks (4-week cycle). The primary endpoint was disease control rate (DCR), and secondary endpoints were safety, overall response rate (ORR), progression-free survival (PFS), and overall survival (OS). RESULTS: In total, 23 patients were enrolled. c-KIT mutations were frequently reported in exon 11 (14/23, 60.9%), followed by exons 13, 17, and 9 in 5 (21.7%), 5 (21.7%), and 2 (8.7%) patients, respectively. DCR at 8 weeks was 73.9%, with 2 patients (8.7%) achieving complete response, 5 (21.7%) achieving partial response, and 10 (43.5%) showing stable disease. ORR was 30.4% (7/23). The median follow-up period was 15.7 months (95% confidence interval [CI], 9.6-21.3), and median OS and PFS were 21.5 months (95% CI, 15.1-27.9) and 7.1 months (95% CI, 5.0-9.2), respectively. Circulating tumour DNA analysis in selected patients showed high c-KIT correlation (85.7%) with tissue-based tumour mutational profiles. The most common adverse events (AEs) were skin reactions, including palmar-plantar erythrodysesthesia (52.2%), and grade 3 AEs were reported in 39.1% (9/23) of the patients. CONCLUSION: Regorafenib in second- or later-line settings demonstrated significant activity in patients with metastatic melanoma harbouring c-KIT mutations.

A Rare Case of a Rectal Gastrointestinal Stromal Tumor (GIST) Discovered During a Routine Colonoscopy.

A gastrointestinal stromal tumor (GIST) is a rare malignancy, accounting for only 0.1% to 3% of all gastrointestinal (GI) malignancies. Although GISTs are the most common mesenchymal tumor of the GI tract, they are primarily found within the stomach, with rectal GISTs rarely reported. They may present with rectal bleeding, constipation, pain, or a palpable mass while some are found incidentally. The incidence of GISTs has been on the rise, possibly due to advancements in diagnostic technology. In this case report, we present a 50-year-old female who presented with intermittent constipation and rectal pain and was found to have a submucosal rectal mass during a routine diagnostic colonoscopy. Further evaluation confirmed the presence of a spindle-cell neoplasm, which was mildly cellular and showed positive expression of CD34 and CD117 on immunohistochemistry, consistent with the diagnosis of GIST of the rectum. This case report emphasizes the importance of routine colonoscopies in the early detection of neoplastic lesions of the colon and highlights the rare incidence of GISTs, their risk factors, pathogenesis, and common sites of occurrence.

Mutational Analysis of c-KIT and PDGFRA in Canine Gastrointestinal Stromal Tumors (GISTs).

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the canine gastrointestinal tract and are diagnosed by the immunohistochemical expression of the receptor tyrosine kinase (RTK) KIT. Activating mutations of the proto-oncogenes c-KIT and PDGFRA drive GIST oncogenesis and are used to predict the response to RTK-inhibitors in human oncology. Currently, the frequency and significance of these mutations in canine GIST have not been adequately explored. Therefore, we investigated the mutational status of c-KIT (exons 9, 11 and 13) and PDGFRA (exons 12 and 18) genes by PCR followed by fragment analysis for c-KIT deletions and PCR followed by screening with DHPLC and direct sequencing confirmation for single nucleotide variations in 17 formalin-fixed paraffin-embedded canine GISTs confirmed by KIT immunopositivity. c-KIT mutations were detected in 47% of cases, with a mutation detection rate significantly higher (p = 0.0004, Fisher's exact test) and always involving exon 11. A PDGFRA gene mutation (exon 18) was identified in one case. Even if follow-up data were not available for all cases, four cases with documented abdominal metastases displayed c-KIT mutations. These data confirm that c-KIT exon 11 mutations occur frequently in canine GISTs, and identify the presence of a PDGFRA mutation similar to human GISTs. This study also suggests a potential association of c-KIT mutation with more aggressive biological behavior.

A Rare Case of Aggressive Systemic Mastocytosis With Skeletal Osteosclerotic Lesions on Presentation: A Diagnostic Conundrum.

Systemic mastocytosis (SM) is a heterogeneous group of disorders caused by mast cell proliferation. SM often presents with non-specific symptoms making it a diagnostic challenge. Moreover, presentation with bone involvement is highly uncommon. Here, we report a rare case of SM in a 68-year-old female who initially presented with gastrointestinal symptoms and was later found to have sclerotic bone lesions on imaging. This case highlights an unusual presentation of SM, informing clinicians of the importance of keeping this disease process on the differential list of diagnostic conundrums.

Gastrointestinal stromal tumor: a review of current and emerging therapies.

Gastrointestinal stromal tumors (GIST) are rare neoplasms arising from the interstitial cell of Cajal in the gastrointestinal tract. Two thirds of GIST in adult patients have c-Kit mutation and smaller fractions have platelet derived growth factor receptor alpha (PDGFRA) mutation. Surgery is the only curative treatment for localized disease. Imatinib improves survival when used adjuvantly and in advanced disease. Several targeted therapies have also improved survival in GIST patients after progression on imatinib including sunitinib and regorafenib. Recently, United States Federal and Drug Administration (FDA) approved two new tyrosine kinase inhibitors for the treatment of heavily pretreated advanced/unresectable GIST including avapritinib (a selective inhibitor for PDGFRA exon 18 mutation including D842V mutations) and ripretinib (a broad-spectrum kinase inhibitor of c-Kit and PDGFRA). In this article, we will provide a comprehensive review of GIST including the current standard of care treatment and exploring future paradigm shifts in therapy.

A Rare Case of Oral Mucosal Amelanotic Melanoma in a 77-year-old Immunocompromised Man.

Primary mucosal melanomas are rare neoplasms that occur in the mouth, esophagus, nasopharynx, larynx, and anogenital mucosa. Mucosal melanomas are rare, accounting for approximately one percent of all melanomas. Of the mucosal melanomas that occur in the head and neck, oral mucosal melanomas compose approximately 25 percent. Here, we present a case of an amelanotic oral mucosal melanoma of the mucosal lip in a 77-year-old male patient with a history of non-Hodgkin's lymphoma and multiple basal and squamous cell carcinomas. The patient presented with a pink, nonpigmented, pedunculated mass on the left superior mucosal lip. Histopathologic examination of the biopsy specimen revealed a diagnosis of a superficial spreading type of malignant melanoma with a nodular component. The patient was referred to a tertiary care center for further management. Multiple risk factors exist for developing melanoma, including immunosuppression. Lymphoproliferative disorders, such as non-Hodgkin's lymphoma, lead to inherent immunosuppression, which can be exacerbated by chemotherapy treatments. Cases of oral mucosal melanoma have a poor prognosis due to delayed diagnosis, anatomic location, and aggressive behavior. Surgical resection is first-line therapy, with regional lymph-node dissection of the neck is recommended in most cases. Radiotherapy and targeted molecular therapy, such as c-KIT inhibitors, can also be used.

Rare and unknown canine systemic mastocytosis: clinical and laboratory features of an aberrant c-Kit mutation neoplasia / A rara e desconhecida mastocitose sistêmica canina: características clínicas e laboratoriais de uma neoplasia aberrante na mutação c-Kit

Systemic mastocytosis (SM) pathology is extremely rare in canine practice, with insufficient reported data. The knowledge of the clinical behavior of this pathology is scarce. In human medicine, SM has been widely investigated, being defined as a rare hematopoietic disorder by the World Health Organization (2016), within the type of myeloproliferative neoplasms. Herein, we describe a systemic mastocytosis case in a Portuguese Serra-da-Estrela dog, where a cutaneous grade III/high-grade MCT was also diagnosed. The clinical decline of the animal and owner's insistence throughout anamnesis that the dog was markedly different after the cytologic exam performed in another clinic, along with both severe eosinophilia and hepatomegaly, led to the clinical suspicion of SM. The animal passed away 7 days later. Post-morteminvestigation confirmed SM pathology, and a deletion of 15 base pairs change on c-Kit gene exon 11 was identified. Contemplating the low number of cases described in the literature, this publication aims to disclose clinical and laboratory features of rare and poorly described canine SM, taking into consideration human outcomes described in the literature.(AU)

A patologia da mastocitose sistêmica (SM) é extremamente rara na prática clínica canina, com escassos casos descritos na literatura científica. O conhecimento do comportamento clínico desta patologia é mínimo. Na medicina humana, a SM tem sido amplamente investigada, sendo definida como uma doença hematopoiética rara pela Organização Mundial da Saúde (2016), dentro do tipo de neoplasias mieloproliferativas. Descrevemos aqui um caso de mastocitose sistêmica num cão Serra-da-Estrela português, diagnosticado também com um mastocitoma cutâneo grau III / alto grau. O declínio clínico do animal e a insistência do proprietário durante a anamnese de que o cão estava marcadamente diferente após o exame citológico realizado em outra clínica, juntamente com eosinofilia e hepatomegalia graves, levantaram a suspeita clínica de SM. O animal faleceu 7 dias depois. A investigação post-mortem confirmou a patologia SM, e o estudo molecular revelou uma deleção de 15 pares de bases no exon 11 do gene c-Kit. Contemplando o baixo número de casos descritos na literatura, o objetivo desta publicação é divulgar características clínicas e laboratoriais de SM canina, levando em consideração informações clínicas descritas em humanos.(AU)

Gastrointestinal stromal tumour of the rectum and intestinal obstruction: case report.

We report the case of a 75-year-old female patient with a big tumour in the lower rectum with intestinal obstruction and lower gastrointestinal bleeding history who underwent a tumour biopsy under laparotomy and end colostomy at another hospital in Peru. She came to our institution for clinical evaluation with a pathology result of a rectal gastrointestinal stromal tumour. An extra elevator abdominoperineal resection was performed with tumour-free margins. The histology confirmed a high-grade (G2) rectal gastrointestinal stromal tumour with a mitotic index of 27/50. DOC-1 (+) and CD117 (+) in immunohistochemistry. Genomic DNA was extracted from the paraffin-fixed tumour sample, and c.1504_1509dupGCCTAT (p.Ala502_Tyr503dup) mutation was detected in exon 9 of the KIT gene. Imatinib 400 mg per day for 3 years was indicated as adjuvant treatment. Currently, she has a disease-free survival of 12 months.

Different Human Immune Lineage Compositions Are Generated in Non-Conditioned NBSGW Mice Depending on HSPC Source.

NBSGW mice are highly immunodeficient and carry a hypomorphic mutation in the c-kit gene, providing a host environment that supports robust human hematopoietic expansion without pre-conditioning. These mice thus provide a model to investigate human hematopoietic engraftment in the absence of conditioning-associated damage. We compared transplantation of human CD34+ HSPCs purified from three different sources: umbilical cord blood, adult bone marrow, and adult G-CSF mobilized peripheral blood. HSPCs from mobilized peripheral blood were significantly more efficient (as a function of starting HSPC dose) than either cord blood or bone marrow HSPCs at generating high levels of human chimerism in the murine blood and bone marrow by 12 weeks post-transplantation. While T cells do not develop in this model due to thymic atrophy, all three HSPC sources generated a human compartment that included B lymphocytic, myeloid, and granulocytic lineages. However, the proportions of these lineages varied significantly according to HSPC source. Mobilized blood HSPCs produced a strikingly higher proportion of granulocyte lineage cells (~35% as compared to ~5%), whereas bone marrow HSPC output was dominated by B lymphocytic cells, and cord blood HSPC output was enriched for myeloid lineages. Following transplantation, all three HSPC sources showed a shift in the CD34+ subset towards CD45RA+ progenitors along with a complete loss of the CD45RA-CD49f+ long-term HSC subpopulation, suggesting this model promotes mainly short-term HSC activity. Mice transplanted with cord blood HSPCs maintained a diversified human immune compartment for at least 36 weeks after the primary transplant, although mice given adult bone marrow HSPCs had lost diversity and contained only myeloid cells by this time point. Finally, to assess the impact of non-HSPCs on transplantation outcome, we also tested mice transplanted with total or T cell-depleted adult bone marrow mononuclear cells. Total bone marrow mononuclear cell transplants produced significantly lower human chimerism compared to purified HSPCs, and T-depletion rescued B cell levels but not other lineages. Together these results reveal marked differences in engraftment efficiency and lineage commitment according to HSPC source and suggest that T cells and other non-HSPC populations affect lineage output even in the absence of conditioning-associated inflammation.

Mastocytosis onset in a patient with treated hairy cell leukemia: Just a coincidence?

Mastocytosis is a mast cell disease caused by functionally defective infiltrating mast cells and CD34+ mast cell precursors. The heterogeneous group of mast cell disorders is categorized into five variants in the updated 2017 World Health Organization (WHO) classification among those systemic mastocytosis with an associated neoplasm (SM-AHN). Except for myeloid neoplasia, lymphoproliferative disorders associated to SM-AHN are more scarce. Here, we report the second case ever described of associated mastocytosis and hairy-cell disease. A 38-year-old female patient without any specific medical history was diagnosed a hairy cell leukemia and BRAFV600E mutation was found in hairy cells. Since purine-analogs were avoided to prevent prolonged myelosuppression, she was treated with vemurafenib and rituximab. Despite early discontinuation due to vemurafenib-induced agranulocytosis, a partial response was observed. Strikingly, bone marrow biopsy performed one month after vemurafenib discontinuation revealed a nodular infiltration by 30% tumoral mastocytes. Along with elevated tryptase level, KITD816V mutation on mastocytes and clinical exam, the patient was diagnosed with systemic mastocytosis with an associated hematological neoplasm (SM-AHN). No BRAFV600E mutation was found on mastocytes. The physiopathology of this association is not known and might be only a coincidence or a common genetic driver mutation enhancing mast and hairy cells.

Exclusive Bee Venom Allergy: Risk Factors and Outcome of Immunotherapy.

INTRODUCTION: Venom immunotherapy (VIT) is considered to be the gold-standard treatment for patients with Hymenoptera venom allergy. Data regarding VIT in bee venom (BV) allergic patients are scarce. AIM: The aim of this study was to evaluate the outcome of VIT in patients with exclusive BV allergy and to try to define risk factors for VIT-induced systemic reactions (VIT-ISR) and VIT failure. METHODS: This is a retrospective study including data from all BV allergic patients that were treated by VIT in the Allergy Unit at the Meir Medical Center in the years 1995-2018. RESULTS: Two hundred and forty-seven patients with exclusive BV allergy were included; 206 (83.4%) preferred to undergo rush buildup. Sixty-nine patients (27.9%) had at least 1 reaction during buildup, with the c-kit mutation being the only significant risk factor (100 vs. 28.9%, p = 0.02). Female gender (25.4 vs. 13.3%, p = 0.04), conventional buildup schedule (26.8 vs. 14.1%, p = 0.04), and c-kit mutation (100 vs. 16.8%, p < 0.01) but not tryptase level were found to be significantly more frequent in recurrent reactors. Females (20.3 vs. 9%, p = 0.03), patients with severe systemic reaction to the index sting (24.3 vs. 9.5%, p = 0.004), and c-kit mutation (66 vs. 12%, p = 0.05) but not tryptase level were found to be risk factors for severe systemic reactions. CONCLUSION: Despite the considerably high rate of VIT-ISR in patients with exclusive BV allergy, VIT can be performed safely and efficiently. C-kit mutation, and not basal serum tryptase level, seems to be a preferable biomarker for VIT-ISR in these patients.

Multiple Synchronous Sporadic Gastrointestinal Stromal Tumors in the Stomach and Jejunum.

A 77-year-old patient was admitted to our hospital for the further examination of melena. A computed tomography scan detected two submucosal tumors (SMTs) in the stomach and jejunum. Double-balloon endoscopy revealed the presence of a delle on the jejunal SMT, suggesting that the SMT was the origin of the gastrointestinal bleeding. Both tumors were surgically resected and subsequently diagnosed via histology as gastrointestinal stromal tumors (GISTs). Furthermore, the two GISTs had different mutations in the c-kit gene, suggesting that they were derived from different clonal origins. This report depicts an extremely rare case of multiple synchronous sporadic GISTs in the stomach and jejunum.

The clinical significance of c-Kit mutations in metastatic oral mucosal melanoma in China.

c-Kit mutations are frequently detected in mucosal melanomas, but their clinical significance in metastatic oral mucosal melanomas (OMM) remains unclear. The main purpose of this study was to investigate the clinical and pathological features of metastatic OMMs with c-Kit mutations and the efficiency of the tyrosine kinase inhibitor imatinib in treating metastatic OMMs. We found thatresidual primary lesion and neck lymph nodes could act as independent prognostic factors in metastatic OMM patients. c-Kit mutations were detected in 22 out of 139 (15.8%) metastatic OMM patients. Under chemotherapy, the overall survival (OS) of c-Kit mutant patients was significantly shorter than that of wild-type patients. The Ki67 expression was significantly higher in c-Kit mutant patients than in wild-type patients. In distant metastatic OMM patients with c-Kit mutations, the treatment with c-Kit inhibitor resulted in a better OS. In conclusion, residual primary lesion, cervical lymph nodes and c-Kit mutations act as adverse prognostic factors of metastatic OMMs. The Kit inhibitor imatinib could benefit metastatic OMM patients with c-Kit mutations.

Clinical Outcome of Autologous Hematopoietic Cell Transplantation in Adult Patients with Acute Myeloid Leukemia: Who May Benefit from Autologous Hematopoietic Cell Transplantation?

The role of autologous hematopoietic cell transplantation (auto-HCT) for postremission therapy of acute myeloid leukemia is yet to be elucidated. We retrospectively analyzed 240 patients treated with auto-HCT in first remission. All patients were treated with standard induction chemotherapy, and CD34+ stem cells were collected at each cycle of consolidation. Stem cells were infused after total body irradiation (1200 cGy), cytarabine (9 g/m2), and melphalan (100 mg/m2). Estimated 5-year overall survival, disease-free survival (DFS), cumulative incidence of relapse (CIR), and nonrelapse mortality were 58.4%, 55.3%, 38.8%, and 5.9%, respectively. We identified that poor-risk karyotype showed very poor outcome after auto-HCT, and then analyzed 85 patients with good to intermediate-risk molecular cytogenetics with available molecular study results and markers for minimal residual disease (MRD) such as WT1 and core-binding factor (CBF) associated MRD (ie, AML1/ETO and CBFß/MYH11). Our data identified that old age, pre-HCT markers for MRD, and high post-HCT WT1, high dose of CD34+ stem cell (≥4.5 × 106/kg) infusion, and c-kit or FLT3-ITD mutations were associated with higher relapse rate and poor DFS. Using pre-HCT parameters, except for post-HCT WT1, multivariate analysis revealed that patients with young age (<40 years old), no adverse mutations, and limited dose of CD34+ stem cells might be good candidate for auto-HCT (3-year DFS and CIR were 83.4% and 16.6%, respectively). Young patients with good- to intermediate-risk molecular cytogenetics may benefit from auto-HCT if stem cell dose is limited.

Low WT1 transcript levels at diagnosis predicted poor outcomes of acute myeloid leukemia patients with t(8;21) who received chemotherapy or allogeneic hematopoietic stem cell transplantation.

BACKGROUND: Acute myeloid leukemia (AML) with t(8;21) is a heterogeneous disease. Identifying AML patients with t(8;21) who have a poor prognosis despite achieving remission is important for determining the best subsequent therapy. This study aimed to evaluate the impact of Wilm tumor gene-1 (WT1) transcript levels and cellular homolog of the viral oncogene v-KIT receptor tyrosine kinase (C-KIT) mutations at diagnosis, and RUNX1-RUNX1T1 transcript levels after the second consolidation chemotherapy cycle on outcomes. METHODS: Eighty-eight AML patients with t(8;21) who received chemotherapy only or allogeneic hematopoietic stem cell transplantation (allo-HSCT) were included. Patients who achieved remission, received two or more cycles of consolidation chemotherapy, and had a positive measureable residual disease (MRD) test result (defined as <3-log reduction in RUNX1-RUNX1T1 transcript levels compared to baseline) after 2-8 cycles of consolidation chemotherapy were recommended to receive allo-HSCT. Patients who had a negative MRD test result were recommended to receive further chemotherapy up to only 8 cycles. WT1 transcript levels and C-KIT mutations at diagnosis, and RUNX1-RUNX1T1 transcript levels after the second consolidation chemotherapy cycle were tested. RESULTS: Patients who had a C-KIT mutation had significantly lower WT1 transcript levels than patients who did not have a C-KIT mutation (6.7% ± 10.6% vs. 19.5% ± 19.9%, P < 0.001). Low WT1 transcript levels (≤5.0%) but not C-KIT mutation at diagnosis, a positive MRD test result after the second cycle of consolidation chemotherapy, and receiving only chemotherapy were independently associated with high cumulative incidence of relapse in all patients (hazard ratio [HR] = 3.53, 2.30, and 11.49; 95% confidence interval [CI] 1.64-7.62, 1.82-7.56, and 4.43-29.82; P = 0.002, 0.034, and <0.001, respectively); these conditions were also independently associated with low leukemia-free survival (HR = 3.71, 2.33, and 5.85; 95% CI 1.82-7.56, 1.17-4.64, and 2.75-12.44; P < 0.001, 0.016, and <0.001, respectively) and overall survival (HR = 3.50, 2.32, and 4.34; 95% CI 1.56-7.82, 1.09-4.97, and 1.98-9.53; P = 0.002, 0.030, and <0.001, respectively) in all patients. CONCLUSIONS: Testing for WT1 transcript levels at diagnosis in patients with AML and t(8;21) may predict outcomes in those who achieve remission. A randomized study is warranted to determine whether allo-HSCT can improve prognosis in these patients.

c-kit mutation-positive advanced thymic carcinoma successfully treated as a mediastinal gastrointestinal stromal tumor: A case report.

Thymic carcinoma is an exceptionally rare tumor, which has a very poor prognosis, differing from thymoma. Although cytotoxic chemotherapy is commonly used to treat advanced thymic carcinoma, its effectiveness has not been found to be sufficient. There are several reports that thymic carcinoma also harbors an oncogenic driver mutation, similar to lung cancer. A patient with a c-kit mutation-positive thymic carcinoma received imatinib followed by sunitinib consecutively, which are both c-Kit inhibitors. Although the patient had achieved long-term disease control for 21 months, the primary lesion and pulmonary metastases had increased in size by November, 2014. Following failure of imatinib treatment, the patient received sunitinib, a multiple kinase inhibitor, initiated in December, 2014. Following administration of sunitinib, a computed tomography scan revealed a partial response and the disease was effectively controlled with continued sunitinib treatment for 6 months, up to June, 2015. The patient achieved long-term disease control (~27 months) with imatinib followed by sunitinib. The efficacy of consecutive molecular-targeted therapy for thymic carcinoma was demonstrated in this case. Therefore, thymic carcinoma with oncogenic driver mutations should be treated with molecular-targeted agents rather than with cytotoxic drugs, and it may be suitable to treat c-kit mutation-positive thymic carcinoma as a mediastinal gastrointestinal stromal tumor.

Expression and mutation of c-Kit in intracranial germ cell tumors: A single-centre retrospective study of 30 cases in China.

Although primary central nervous system (CNS) germ cell tumors (GCTs) are one of the most treatable types of malignant brain tumor, a subset of patients remain resistant to standard chemotherapy. Gain-of-function mutations of the c-Kit gene, and KIT protein expression, have been observed in a number of GCTs, including testicular seminoma, ovarian dysgerminoma and mediastinal seminoma in various ethnic groups. Although a small number of studies have reported the role of c-Kit in CNS GCTs, few have focused on Chinese patients exhibiting CNS GCTs. In the present study, the frequency and location of c-Kit mutations and KIT protein expression levels in CNS GCTs were investigated in 30 patients, between January 1994 and October 2014. Immunohistochemical assays suggested that KIT protein expression was present in 59.1% patients (66.7% in males and 42.9% in females); however, no statistically significant correlation was identified between KIT protein expression and patient clinicopathological features. By performing PCR amplification and direct sequencing, 4 mutational hot spots of the c-Kit gene (exons 9, 11, 13 and 17) were examined, and c-Kit gene mutation was identified in 1/17 (5.9%) CNS germinoma cases. This mutation was located in exon 11 at codon 557-558 WK (Tryptophan-Lysine). No c-Kit gene mutations were detected in non-germinomatous GCTs. Imatinib, a tyrosine kinase inhibitor, may be an effective treatment against standard chemotherapy-resistant CNS germinoma patients exhibiting c-Kit mutations.

Urinary 11ß-PGF2α and N-methyl histamine correlate with bone marrow biopsy findings in mast cell disorders.

BACKGROUND: The utility of measuring histamine and prostaglandin metabolites in the urine of patients with mastocytosis has not been critically examined in a large series of patients. This study examined the relationship between the extent of increase in urinary excretion of 11ß-prostaglandinF2α and N-methyl histamine, with serum tryptase, whole blood serotonin, and bone marrow findings including morphology, percentage involvement, and abnormal mast cell phenotype. METHODS: This was a retrospective analysis of 90 patients who were continuously enrolled in the study for a period of 6 years (2008-2014). We recorded serum tryptase, whole blood serotonin, levels of urinary mast cell metabolites 11ß-prostaglandinF2α and N-methyl histamine (NMH), and bone marrow findings. RESULTS: Urinary mast cell metabolites 11ß-prostaglandinF2α and N-methyl histamine correlated with levels of serum tryptase, mast cell burden in the bone marrow, the presence of mast cell aggregates, and atypical mast cells on bone marrow biopsy. Whole blood serotonin did not have a significant correlation with the serum tryptase or mast cell burden in the bone marrow. Urinary NMH was significantly different between c-kit D816V-positive and c-kit D816V-negative patients, while 11ß-prostaglandinF2α was not. Urinary 11ß-prostaglandinF2α 24-h excretion >3500 ng and NMH levels >400 µg/gm Cr corresponded with the high degree of bone marrow biopsies positive for atypical mast cells, the presence of aggregates, and c-kit mutation. CONCLUSIONS: Easily obtained and quantified urinary metabolites of histamine (greater than twice the upper limit of normal) and prostaglandin D2 (>3.4 times the upper limit of normal) correlate well with bone marrow findings of mastocytosis.