A V530I Mutation in c-KIT Exon 10 Is Associated to Imatinib Response in Extraabdominal Aggressive Fibromatosis

The Clinical and Pathological Characteristics of Malignant Struma Ovarii: An Analysis of 144 Published Patients

The objective of this study is to summarize the clinical and pathologic characteristics of malignant struma ovarii to facilitate the early diagnosis and treatment of this disease. All 144 patients were females from 27 countries. The mean age of the patients at diagnosis was 42.6 years. Overall, 35.71% of the patients underwent unilateral oophorectomy, 58.57% of the patients underwent bilateral oophorectomy, 5.72% of the patients were not ovariectomized, and 38.57% of the patients received radioactive iodine treatment with an average dose of 158.22 mCI each time. “Impure” types accounted for 70.19% of the cases, while pure types accounted for 29.81% of the cases. Among these cases, papillary thyroid carcinoma accounted for 50.00%, follicular thyroid carcinoma accounted for 26.47%, follicular variant of papillary thyroid carcinoma accounted for 18.63%, papillary and follicular mixed thyroid carcinoma accounted for 2.94%, anaplastic carcinoma accounted for 0.98%, and medullary carcinoma accounted for 0.98%. In total, 21 patients (51.22%) had elevated CA125. More than half of the patients (51.94%) had metastasis outside the ovary. The most common metastatic site was the pelvic cavity. The misdiagnosis rate was 17.27%. Mortality was related to metastasis and the cancer type. Gene mutations were found in the NRAS, KRAS, BRAF, and KIT genes and were similar to those in thyroid carcinoma, but some patients (37.5%) did not exhibit any gene mutations. Regardless of the treatment received, the survival rate is high. Treatment could initially include ovariectomy; however, in cases with metastasis and iodine uptake of the metastatic tumor, thyroidectomy, radioactive iodine therapy, and thyroid hormone inhibiting therapy are indicated.

CRYODESMO-O1: A prospective, open phase II study of cryoablation in desmoid tumour patients progressing after medical treatment

BACKGROUND

Desmoid tumours (DTs) are rare tumours originating from musculoaponeurotic structures. Although benign, they may be locally aggressive, leading to pain and disability. European Society for Medical Oncology (ESMO) guidelines recommend frontline watchful waiting and medical treatment in progressing tumours. Cryoablation is an interventional radiology technique that is suitable for DT patients (pts) on the basis of repeated cycles of freezing, leading to cell death.

METHODS

CRYODESMO-01 (ClinicalTrials.gov Identifier: NCT02476305) is a prospective, open-label, non-randomised, non-comparative, multicenter study assessing cryoablation in non-abdominopelvic progressing DT. Inclusion criteria were: pts ≥18 y.o., confirmed DT accessible to cryoablation (≥90% destruction), measurable lesion conforming to modified response evaluation criteria in solid tumours (mRECIST), progressive disease after ≥2 lines of medical therapy or with functional symptoms/pain, adequate biological parameters, informed consent, and affiliation to a medical insurance scheme. The primary end-point was the non-progression rate at 12 months; secondary end-points included safety, quality of life (QoL), assessment of pain and functional status.

FINDINGS

50 pts were enrolled (78% female) from four French centres and all were treated. The mean age was 41 y.o. (19-73). The median number of prior treatments was 2.00 [1-4] including non-steroidal anti-inflammatory drugs (NSAIDs), hormone therapy, chemotherapy, and anti-angiogenics. Tumour location included limbs (36%), trunk (60%), and cervical area (4%). The median tumour largest diameter was 89 mm. The rate of non-progressing disease at +12 months was 86% [confidence level (CI) 95% 73-94%]. Median PFS was not reached at a median follow-up of 31 months. Grade 1 and 2 toxicity occurred in 32.8% and 44.5% of patients, grade 3-4 in 22% and no Grade 5 toxicity was observed. Cryoablation significantly improved functional status and pain scores.

INTERPRETATION

Cryoablation demonstrated feasibility in progressive DT pts. The study met is primary end-point with 86% of non-progressive disease at +12 months, with reduced pain, better functional status, and encouraging long-term disease control.

Molecular exploration of paediatric intracranial germinomas from multi-ethnic Singapore

Background

Germinomas (IG) account for up to 50% of all intracranial germ cell tumours. These tumours are reputed to be more prevalent in Oriental populations in comparison to Western cohorts. Biological characteristics of IG in other ethnic groups are unknown. Singapore is a multi-ethnic country with diverse cultures. Owing to inter-racial heterogeneity, the authors hypothesize there are molecular differences between paediatric IG patients in our local population. The aims of this study are exploratory: firstly, to identify molecular characteristics in this tumour type and circulating CSF unique to different racial cohorts; and next, to corroborate our findings with published literature.

Methods

This is a single-institution, retrospective study of prospectively collected data. Inclusion criteria encompass all paediatric patients with histologically confirmed IG. Excess CSF and brain tumour tissues are collected for molecular analysis. Tumour tissues are subjected to a next generation sequencing (NGS) targeted panel for KIT and PDGRA. All CSF samples are profiled via a high-throughput miRNA multiplexed workflow. Results are then corroborated with existing literature and public databases.

Results

In our cohort of 14 patients, there are KIT exon variants in the tumour tissues and CSF miRNAs corroborative with published studies. Separately, there are also KIT exon variants and miRNAs not previously highlighted in IG. A subgroup analysis demonstrates differential CSF miRNAs between Chinese and Malay IG patients.

Conclusion

This is the first in-depth molecular study of a mixed ethnic population of paediatric IGs from a Southeast Asian cohort. Validation studies are required to assess the relevance of novel findings in our study.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12883-020-01981-0.

Dissecting Genomic Aberrations in Myeloproliferative Neoplasms by Multiplex-PCR and Next Generation Sequencing

In order to assess the feasibility of amplicon-based parallel next generation sequencing (NGS) for the diagnosis of myeloproliferative neoplasms (MPN), we investigated multiplex-PCR of 212 amplicons covering genomic mutational hotspots in 48 cancer-related genes. Samples from 64 patients with MPN and five controls as well as seven (myeloid) cell lines were analyzed. Healthy donor and reactive erythrocytosis samples showed several frequent single-nucleotide polymorphisms (SNPs) but no known pathogenic mutation. Sequencing of the cell lines confirmed the presence of the known mutations. In the patient samples, JAK2 V617F was present in all PV, 4 of 10 ET, and 16 of 19 MF patients. The JAK2 V617F allele burden was different in the three groups (ET, 33+/-22%; PV 48+/-28% and MF 68+/- 29%). Further analysis detected both previously described and undescribed mutations (i.e., G12V NRAS, IDH1 R132H, E255G ABL, and V125G IDH1 mutations). One patient with lymphoid BC/Ph+ ALL who harbored a T315I ABL mutation and was treated with ponatinib was found to have developed a newly acquired V216M TP53 mutation (12% of transcripts) when becoming resistant to ponatinib. Ponatinib led to a decrease of ABL T315I positive transcripts from 47% before ponatinib treatment to 16% at the time of ponatinib resistance in this patient, suggesting that both TP53 and ABL mutations were present in the same clone and that the newly acquired TP53 mutation might have caused ponatinib resistance in this patient. In conclusion, amplicon-sequencing-based NGS allows simultaneous analysis of multiple MPN associated genes for diagnosis and during treatment and measurement of the mutant allele burden.

Aggressive fibromatosis

Aggressive (deep or desmoid-type) fibromatoses are locally infiltrative collagen-forming tumours with potential for recurrence but not metastasis. They exert their clinical effects primarily in relation to location and have variable biological behaviour. In sporadic cases there are somatic mutations in the β-catenin (CTNNB1) gene on 3p21, resulting in immunohistochemically demonstrable overexpression in nuclei. Fibromatosis in patients with familial adenomatous polyposis (FAP) harbours inactivating germline mutations in the desmoid region of the adenomatous polyposis coli (APC) gene on 5q21-q22. The differential diagnosis includes other myofibroblastic lesions, perineurioma, low grade fibromyxoid sarcoma and, in the abdomen, gastrointestinal stromal tumour and liposarcoma with 'low-grade' dedifferentiation. The primary management is surgical, though some desmoids cease to grow and can be watched. Other therapies have a role in stabilising growth or shrinking tumours. Although no single therapy is effective in all cases, available modalities including irradiation, hormonal therapy, chemotherapy, and receptor tyrosine kinase inhibition can be of value in appropriate clinicopathological subgroups.

Impact of KIT exon 10 M541L allelic variant on the response to imatinib in aggressive fibromatosis: analysis of the desminib series by competitive allele specific Taqman PCR technology

BACKGROUND

Aggressive fibromatosis (AF) is a rare fibroblastic proliferative disease with a locally aggressive behavior and no distant metastasis, characterized by driver mutations in CTNNB1 or the APC gene. When progressive and/or symptomatic AF is not amenable to local management, a variety of medical treatments may be efficient, including imatinib mesylate. The phase II "Desminib trial" included 40 patients with AF to evaluate the toxicity and efficacy of imatinib resulting in a 65% tumor control rate at 1 year. We investigated a potential predictive value of KIT exon 10 M541L variant (KITL541) on this prospective series.

METHODS

DNA was extracted in sufficient quantity from 33 patients included in the Desminib trial. The detection of KITL541 was performed by Competitive Allele-Specific Taqman® PCR technology. Chi-2 analyses were performed to search for a correlation between KIT status and tumor response. Progression free (PFS) and overall survival (OS) were compared by log-rank test after Kaplan-Meier analysis.

RESULTS

In 6 out of 33 cases (18%), the technique failed to determine the mutational status; 5 patients (19%) harboured KITL541 and 22 patients (81%) were classified as KIT wild type. Compared with total cohort, KITL541 frequency did not distinguish between different clinical characteristics. In the KITL541 and the KITWT subgroups, the tumor control rate at 1 year was 100% and 68%, respectively (p = 0.316). The median PFS of patients harboring KITL541 or not is 29.9 and 24.5 months, respectively (p = 0.616), and the median OS is not reached, in any of the groups.

CONCLUSION

Our results do not support a predictive effect of KITL541 on the efficacy of imatinib for patients with AF.

Update on desmoid tumors

Desmoid tumors (DTs) are histologically benign proliferations of stromal cells but may grow locally aggressive. Overall, DTs are rare (0.03% of all neoplasms). A minority of DTs is associated with Gardner syndrome and mutations of the familial adenomatous polyposis (FAP) gene. Most spontaneous DTs are associated with mutations of the beta-catenin gene. This mutation results in the activation of Wnt/catenin signaling. Due to their variable clinical presentation and behavior, no standard approach for DTs can be recommended. In most cases of DTs of the extremities surgical extirpation is indicated, whereas in many other cases, a multimodal and multidisciplinary concept should be followed. In this review article, we discuss the diagnosis, pathogenesis, and treatment options for DTs, including targeted therapy with tyrosine kinase inhibitors.

Immunohistochemical and molecular analysis of tyrosine kinase activity in desmoid tumors

BACKGROUND

Optimal surgical and medical therapy for the treatment of desmoid tumors (DT) is still undefined. Partial response to tyrosine kinase inhibitors (TKI) has previously been described. Here, we examined the role of the tyrosine kinases c-Src and c-Kit in driving desmoid tumorigenesis.

METHODS

Six consecutive DT and matched normal tissues were collected from the operating room. Tissues were embedded in paraffin for immunohistochemical analysis, and protein lysates were prepared for immunoblot and immunoprecipitation.

RESULTS

We found increased levels of β-catenin in five of six (83%) DT relative to matched normal tissue by immunoblot analysis. By immunohistochemistry, β-catenin expression was also increased in DT and localized to the nucleus. In contrast, we observed variable levels of total and activated c-Src and c-Kit expression in DT compared with normal tissue. Finally, β-catenin tyrosine phosphorylation (p-Y) among tumors was variably increased, despite the increased amount of total β-catenin in tumors.

CONCLUSIONS

Our results suggest that c-Src and c-Kit activity in DT is variable, consistent with the heterogeneous nature of this disease. Clinical response to TKI in DT may be via alternative mechanisms unrelated to c-Src or c-Kit activity. Further insight into DT biology will help identify novel drug regimens to limit the morbidity and mortality associated with this disease.

The GIST paradigm: lessons for other kinase-driven cancers

Gastrointestinal stromal tumour (GIST) is the most common sarcoma of the intestinal tract, known to be notoriously refractory to conventional chemotherapy or radiation. It is an ideal solid tumour model to apply our understanding from aberrant signal transduction to drug development, since nearly all tumours have a mutation in the KIT or, less often, the PDGFRA or BRAF genes. The constitutively activated KIT and PDGFRA oncoproteins serve as crucial diagnostic and therapeutic targets. The discovery of oncogenic KIT activation as a central mechanism of GIST pathogenesis suggested that inhibiting or blocking KIT signalling might be the milestone in the targeted therapy of GISTs. Indeed, imatinib mesylate inhibits KIT kinase activity and represents the front-line drug for the treatment of unresectable and advanced GISTs, achieving a partial response or stable disease in about 80% of patients with metastatic GIST. KIT mutation status has a significant impact on treatment response, emerging in recent years as a leading paradigm for genotype-driven targeted therapy. In this review, parallels with other models in oncology that share their addiction to a particular mutationally activated kinase are contrasted. A better understanding of oncogene addiction as a common theme across tumours of diverse histologies underlies the clinical success of targeting such kinases with several selective kinase inhibitors. Also remarkable is the similarity displayed in the mechanisms of drug failure after a successful but temporary clinical response to kinase inhibition. Reactivation of the same oncogenic kinase, often by acquisition of second site mutations, is another emerging paradigm of secondary resistance in these tumour models. The complexity of polyclonal resistance in imatinib-resistant patients argues that single next-generation kinase inhibitors will not be beneficial in all mutant clones. Other broad therapeutic strategies could include combination of kinase inhibitors with targeting KIT downstream targets, such as PI3-K or MAPK/MEK inhibitors.

Identification of biological factors predictive of response to imatinib mesylate in aggressive fibromatosis

Background:

Imatinib induces responses and disease stabilisations in non-resectable patients with aggressive fibromatosis (AF). The precise target of imatinib in AF and predictive factors for response to treatment are unknown.

Methods:

We investigated factors potentially predictive of response to imatinib in a series of 40 patients with progressive AF included in a phase II trial of imatinib: we tested the presence of KIT exon 10 variant (M541L), the expression of imatinib-sensitive kinases and cell cycle proteins by immunohistochemistry (IHC), and other clinical and biological factors.

Results:

Of 10 patients for whom DNA could be extracted, 3 had a KIT exon 10 variant (30%), with no correlation with response or progression-free survival (PFS). The expression of other imatinib targets (PDGFRA/B, macrophage colony-stimulating factor receptor (M-CSFR)) and of downstream components of the cell cycle, cell proliferation and proliferation pathway (cyclin D1, ERK, MEK 1–2) did not correlate with PFS. Pre-treatment lymphopenia (<1500/μl) and tumour size >120 mm correlated with shorter PFS in univariate and multivariate analyses.

Conclusion:

Our findings show that a baseline biological characteristic of the patient is the major parameter influencing response to imatinib in aggressive fibromatosis. Tumour characteristics, including the presence of a KIT exon 10 M541L variant, may influence tumour control but this needs to be confirmed and better explained.