A case report of feline mast cell tumour with intertumoral heterogeneity: Identification of secondary mutations c.998G>C and c.2383G>C in KIT after resistance to toceranib
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SUBMITTER: Tani H
PROVIDER: S-EPMC11342349 | biostudies-literature | 2024 Aug
REPOSITORIES: biostudies-literature
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Project description:A cat was presented with mast cell tumors (MCTs) of the skin and spleen. During the initial diagnosis, the exon 8 mutation of c-KIT was detected in the masses from skin and spleen by a commercial laboratory test. Consequently, treatment with toceranib was started. After complete remission, because of recurrence on day 117, the spleen and skin tumors were removed, but the cat eventually died on day 191. The analysis of ten cDNA clones of the c-KIT gene cloned from the surgically removed spleen revealed that seven different cDNA patterns were included, indicating the heterogeneity of this gene in the splenic MCT. The seven cDNA nucleotide patterns can be classified into four protein sequence patterns. In addition to the previously known mutations in exon 8, we identified novel mutations in exons 9, 10, and 18; four amino acids deletion in exon 9, and a point mutation in exons 10 and 18. Mouse IL-3-dependent cell line, Ba/F3, was transduced with these mutant clones, and c-KIT phosphorylation and proliferation assays were performed. We found that certain mutations affected the c-KIT phosphorylation status and cell proliferation. This suggests that heterogeneity among the population of tumor cells exists in MCTs, and that the dominant clones of this heterogeneity may contribute to the subsequent tumor cell growth.
| S-EPMC9499958 | biostudies-literature
Project description:BackgroundCanine cutaneous mast cell tumors (MCTs) are a common, yet clinically challenging tumor type given their variable biological behavior. Although patients with low grade MCTs can often be effectively managed with surgery alone, most dogs with high grade MCTs succumb to their disease despite multimodal therapy. An improved understanding of the immune tumor microenvironment (TME) may help identify novel prognostic and therapeutic targets.MethodsIn this study, we interrogated the immune transcriptional profiles of the TME in low and high grade MCTs, and quantified intratumoral T cells. Twelve client-owned dogs with MCTs (6 Kiupel low grade with clinically benign behavior and 6 Kiupel high grade with clinically aggressive behavior) that underwent curative-intent surgery were selected. Tumor grade was confirmed by a single veterinary pathologist. RNA was extracted from all tumors followed by immune transcriptional profiling utilizing the NanoString Canine IO panel and analysis using the ROSALIND platform. T cell density was determined by immunohistochemical staining for CD3 and quantified using ImageScope software (Leica Biosystems) following digital slide capture. Lymphocytic infiltrate was further characterized in the TME of one high grade MCT using co-immunofluorescence.ResultsImmune transcriptional profiling identified 9 differentially expressed genes between low and high grade MCTs (p-adj < 0.05). Programmed cell death protein 1 (PDCD1) and inducible T-cell costimulator ligand (ICOSLG) gene expression were significantly higher in a subset of high grade MCTs. ICOSLG expression positively correlated with T cell score (rs = 0.6434, p = 0.0278). Although the T cell density was not significantly different between low (mean of 76.42 CD3 + /mm2, SD 12 CD3 + /mm2) and high grade MCTs (mean of 129.1 CD3 + /mm2, SD 96.06 CD3 + /mm2), greater variation of T cell densities was observed across high grade MCTs compared to low grade (p = 0.0059). Immunofluorescence of one high grade MCT with marked T cell infiltration revealed organized aggregates of T and B cells consistent with tertiary lymphoid structures (TLS).ConclusionsOur data revealed significant differences in the immune TME of low and high grade MCTs and provides rationale to further investigate potential prognostic and therapeutic roles of immune checkpoints in canine MCTs.Supplementary informationThe online version contains supplementary material available at 10.1186/s44356-025-00020-9.
| S-EPMC11906493 | biostudies-literature
Project description:While molecular subgrouping has revolutionized medulloblastoma classification, the extent of heterogeneity within subgroups is unknown. Similarity network fusion (SNF) applied to genome-wide DNA methylation and gene expression data across 763 primary samples identifies very homogeneous clusters of patients, supporting the presence of medulloblastoma subtypes. After integration of somatic copy-number alterations, and clinical features specific to each cluster, we identify 12 different subtypes of medulloblastoma. Integrative analysis using SNF further delineates group 3 from group 4 medulloblastoma, which is not as readily apparent through analyses of individual data types. Two clear subtypes of infants with Sonic Hedgehog medulloblastoma with disparate outcomes and biology are identified. Medulloblastoma subtypes identified through integrative clustering have important implications for stratification of future clinical trials.
| S-EPMC6163053 | biostudies-literature
Project description:BackgroundKIT inhibitors, such as toceranib (TOC), and vinblastine (VBL) have not been prospectively compared in the treatment of macroscopic mast cell tumors (MCTs). Also, it is unknown whether VBL or TOC is superior for treating MCT without c-kit mutations.Hypothesis/objectivesTo determine the value of KIT genotyping and localization in treatment decisions for dogs with macroscopic MCT. We hypothesized that c-kit mutated MCT would have a better response to TOC than VBL.AnimalsEighty-eight client-owned dogs with macroscopic MCT.MethodsProspective, randomized trial. Dogs were randomized to TOC (2.75 mg/kg EOD) or VBL (2.5 mg/m2 weekly × 4 then EOW) by KIT localization and c-kit mutation status using an adaptive randomization scheme.ResultsSixty dogs were allocated to TOC and 28 to VBL. Of the dogs receiving TOC, 20% had c-kit mutations, compared to 30% receiving VBL (P = 0.74). Overall response rates were 46% (TOC) and 30% (VBL) (odds ratio = 1.56 [0.62-3.92]; P = 0.28). Median progression-free survival (PFS) for dogs receiving VBL was 78 days (7-1,521) and for TOC 95.5 (14-990); hazard ratio (HR) = 1.34 [0.72-2.50]; P = 0.36. Median overall survival (OS) was 241.5 days (10-1,521) for the VBL group and 159 (20-990) for the TOC group; HR = 0.80 ([0.45-1.41]; P = 0.44).Conclusions and clinical importanceNeither PFS nor OS was significantly different between treatment groups. As the proportion of dogs with c-kit mutations was not different between treatment groups in this population of dogs, c-kit mutation status did not predict treatment response.
| S-EPMC5787208 | biostudies-literature
Project description:BackgroundGain-of-function mutations in KIT are driver events of oncogenesis in mast cell tumours (MCTs) affecting companion animals. Somatic mutations of KIT determine the constitutive activation of the tyrosine kinase receptor leading to a worse prognosis and a shorter survival time than MCTs harbouring wild-type KIT. However, canine MCTs carrying KIT somatic mutations generally respond well to tyrosine kinase inhibitors; hence their presence represents a predictor of treatment effectiveness, and its detection allows implementing a stratified medical approach. Despite this, veterinary oncologists experience treatment failures, even with targeted therapies whose cause cannot be elucidated. The first case of an MCT-affected dog caused by a secondary mutation in the tyrosine kinase domain responsible for resistance has recently been reported. The knowledge of this and all the other mutations responsible for resistance would allow the effective bedside implementation of a deeply stratified and more effective medical approach.Case presentationThe second case of a canine MCT carrying a different resistance mutation is herein described. The case was characterised by aggressive behaviour and early metastasis unresponsive to both vinblastine- and masitinib-based treatments. Molecular profiling of the tumoural masses revealed two different mutations; other than the already known activating mutation p.Asn508Ile in KIT exon 9, which is tyrosine kinase inhibitor-sensitive, a nearly adjacent secondary missense mutation, p.Ala510Val, which had never before been described, was detected. In vitro transfection experiments showed that the secondary mutation did not cause the constitutive activation by itself but played a role in conferring resistance to masitinib.ConclusionsThis study highlighted the importance of the accurate molecular profiling of an MCT in order to improve understanding of the molecular mechanism underlying tumourigenesis and reveal chemoresistance in MCTs for more effective therapies. The detection of the somatic mutations responsible for resistance should be included in the molecular screening of MCTs, and a systematic analysis of all the cases characterised by unexpected refractoriness to therapies should be investigated in depth at both the genetic and the phenotypic level.
| S-EPMC7029481 | biostudies-literature
Project description:ObjectiveGastrointestinal stromal tumors (GISTs) with no mutations in exons 9, 11, 13, and 17 of the KIT gene and exons 12, and 18 of the PDGFRA gene were defined as KIT/PDGFRA wild-type and they accounted for ~15-20% of GISTs. However, some KIT/PDGFRA wild-type GISTs with KIT mutations in other exons were occasionally reported. We therefore assessed GISTs to understand the whole genomic genotypes of KIT or PDGFRA genes in KIT/PDGFRA wild-type GISTs.MethodsA cohort of 185 KIT/PDGFRA wild-type GISTs from 1,080 cases was retrospectively assessed. Thirty-nine patients were excluded due to insufficiency of genomic DNA data or failure of library preparation, and 146 patients were analyzed by targeted next-generation sequencing (NGS) followed by validation.ResultsFor hot spots in KIT and PDGFRA genes, 23 out of 146 KIT/PDGFRA wild-type cases carried mutations according to NGS; there were 19 KIT mutations and 4 PDGFRA mutations, and these were exclusive. Intratumoral KIT mutational heterogeneity was observed in 4 of 19 samples which potentially triggered mechanisms of polyclonal evolution and metastasis and drug sensitivity. Eleven patients treated with imatinib were evaluable for clinical response, and 2 of 3 patients with KIT mutations achieved partial response (PR), while only 1 of 8 patients without KIT mutations reached PR.ConclusionNGS had the potential property to identify partial mutant tumors from a subset of GISTs regarded as KIT/PDGFRA wild-type tumors using Sanger sequencing, and provided a better understanding of KIT/PDGFRA genotypes as well as identified patients eligible for imatinib therapy.
| S-EPMC5058677 | biostudies-literature
Project description:BackgroundMast cell leukemia (MCL) is a very rare form of systemic mastocytosis (SM) and accounts for less than 0.5% of all mastocytosis. The diagnosis of MCL requires the presence of SM criteria, accompanied by leukemic infiltrating of atypical mast cells (MCs) in bone marrow (BM), peripheral blood as well as extracutaneous organs. MCL is a fatal disease that almost always behaves aggressively, and the median survival time is only about six months. Herein, we present a rare case of de novo MCL without CD25 expression and KIT mutations.Case presentationA previously healthy 13-year-old boy was referred to our hospital due to incidental discovery of an enlarged right tonsil. Diffuse infiltration of medium-sized hematopoietic blasts was found in his right tonsil, BM and multiple lymph nodes. The neoplastic cell population was subsequently revealed to exhibit differentiation towards the mast cell lineage by expressing CD117 and tryptase, but the cell population lacked expression of CD25/CD2 and the activating mutation of the KIT gene. An abnormal karyotype was identified, but no leukemia-associated fusion genes were found. Involvement of peripheral blood, bone and lung was subsequently demonstrated. The most important differential diagnosis included tryptase-positive (T+) acute myeloid leukemia, myelomastocytic leukemia and basophilic leukemia. The morphological characteristics and infiltrating patterns of the abnormal MCs supported the final diagnosis of MCL. Although intensive chemotherapy and allogeneic stem cell transplants were performed on the patient, he died 18 months after initial presentation.ConclusionDue to its rarity, the diagnosis of MCL without typical immunophenotype and genetic aberrations is particularly challenging. Comprehensive investigation of clinical and pathological features to exclude other T+ myeloid neoplasms is necessary.
| S-EPMC5819157 | biostudies-literature
Project description: Not available
| S-EPMC9186249 | biostudies-literature
Project description:Canine cutaneous mast cell tumour (CMCT) is a c-Kit driven tumour sharing similar c-Kit aberrations found in human gastrointestinal stromal tumour. CMCT is classified into three forms: well- (G1), intermediately (G2) (more benign diseases), and poorly (G3) differentiated (malignant) forms. We assess a correlation between c-Kit status, grading, and angiogenesis in CMCTs to explore their potential significance in humans. C-Kit receptor (c-KitR) expression, microvascular density (MVD), and mast cell granulated and degranulated status density (MCGD and MCDD, resp.) were analyzed in 97 CMCTs, by means of histochemistry, immunohistochemistry double staining, and image analysis system. Data showed that predominantly diffuse cytoplasmic- and predominantly focal paranuclear- (Golgi-like) c-Kit protein (PDC-c-Kit and PFP-c-Kit, resp.) expression correlate with high MVD, G3 histopathological grade, and MCDD. Moreover, predominant cell membrane-c-KitR (PCM-c-KitR) expression status correlates with low MVD, G1-G2 histopathological grade, and MCGD. These findings underline the key role of c-Kit in the biopathology of canine MCTs, indicating a link between aberrant c-Kit expression, increased angiogenesis, and higher histopathological grade. CMCT seems to be a model to study contributions of c-Kit activated MCs in tumour angiogenesis and to evaluate the inhibition of MCs activation by means of c-Kit tyrosine kinase inhibitors, currently translated in humans.
| S-EPMC4036613 | biostudies-literature
Project description:Pharmacological targeting of KIT in gastrointestinal stromal tumours has dramatically changed the clinical outcome of this disease. Tyrosine kinase inhibitors are the cornerstone of this improvement, but resistance occurs through secondary KIT mutations. Studies aimed at improving our understanding of the molecular basis of sensitivity and resistance will soon allow us to further tailor our therapeutic strategies.
| S-EPMC6461933 | biostudies-literature