Pyrosequencing-Based Assays for Rapid Detection of HER2 and HER3 Mutations in Clinical Samples Uncover an E332E Mutation Affecting HER3 in Retroperitoneal Leiomyosarcoma

Colorectal leiomyosarcoma with BRCA2 mutation benefit from treatment with olaparib: a case report

Background

Colorectal leiomyosarcoma (LMS) is a rare colorectal malignancy accounting for approximately 1% of all colorectal malignancies with a poor prognosis and limited treatment options. Targeted therapies have been applied for breast cancer 2 (BRCA2) alterations, but their role remains to be explored in colorectal LMS. This case could provide clinical proof for the application of olaparib for LMS patients.

Case Description

Here, we present a case of colorectal LMS with BRCA2 alterations who was treated with olaparib and achieved progression-free survival (PFS) for 1 year. In August 2016, a 46-year-old female patient was admitted to hospital due to a mass in the left lower abdomen and was diagnosed with LMS of the sigmoid colon. After surgical resection, chemotherapy with ifosfamide or ifosfamide combined with pirarubicin was given and achieved stable disease (SD) until the disease progressed 1.5 years later. Afterwards, a multi-target tyrosine kinase inhibitor, anlotinib, was taken. Before the observation of lung and liver metastasis, the patient's disease was stable for 1 year. BRCA2 mutation and rearrangement was revealed by next-generation sequencing (NGS), and the targeted therapy, olaparib, was given. Efficacy evaluation showed SD for 1 year, and no obvious toxic and side effects were observed.

Conclusions

Our case suggested that NGS should be considered for further treatment of patients with colorectal LMS, and poly (ADP-ribose) polymerase (PARP) inhibitors could be a feasible therapy for LMS patients with BRCA2 alterations.

Genomic Profiling Aids Classification of Diagnostically Challenging Uterine Mesenchymal Tumors With Myomelanocytic Differentiation

Although diagnosis of high-grade uterine mesenchymal tumors (UMTs) exhibiting classic morphologic features is straightforward, diagnosis is more challenging in tumors in which prototypical features are poorly developed, focal, and/or coexist with features seen in other neoplasms. Here, we sought to define the repertoire of somatic genetic alterations in diagnostically challenging UMTs with myomelanocytic differentiation, including some reported as perivascular epithelioid cell tumors (PEComas). In 17 samples from 15 women, the tumors were histologically heterogenous. Immunohistochemical expression of at least 1 melanocytic marker (HMB45, Melan-A, or MiTF) was identified in all tumors, and of myogenic markers (desmin or smooth muscle actin) in most tumors. Targeted massively parallel sequencing revealed several genetic alterations, most commonly in TP53 (41% mutation, 12% deletion), TSC2 (29% mutation, 6% deletion), RB1 (18% deletion), ATRX (24% mutation), MED12 (12% mutation), BRCA2 (12% deletion), CDKN2A (6% deletion) as well as FGFR3, NTRK1, and ERBB3 amplification (each 6%). Gene rearrangements (JAZF1-SUZ12; DNAJB6-PLAG1; and SFPQ-TFE3) were identified in 3 tumors. Integrating histopathologic, immunohistochemical, and genetic findings, tumors from 4 patients were consistent with malignant PEComa (1 TFE3-rearranged); 6 were classified as leiomyosarcomas; 3 showed overlapping features of PEComa and other sarcoma types (leiomyosarcoma or low-grade endometrial stromal sarcoma); and 2 were classified as sarcoma, not otherwise specified. Our findings suggest that diagnostically challenging UMTs with myomelanocytic differentiation represent a heterogenous group of neoplasms which harbor a diverse repertoire of somatic genetic alterations; these genetic alterations can aid classification.

Quantitative analysis of single-nucleotide polymorphisms by pyrosequencing with di-base addition

We have developed and validated a novel method for quantitative detection of SNPs by using pyrosequencing with di-base addition (PDBA). Based on the principle that the signal intensity is proportional to the template concentration within a linear concentration range, linear formula (Y = AX + B) for each genotype is established, and the relationship between two genotypes of a single SNP can be resolved by corresponding linear formulas. Here, PDBA assays were developed to detect variants rs6717546 and rs4148324, and the linear formulas for each genotype of rs6717546 and rs4148324 were established. The method allowed to quantitatively determine each genotype and showed 100% accordant results against a panel of defined mixtures. A set of 24 template fragments containing variants rs6717546 or rs4148324 was tested to evaluate the method. Our results showed that allele frequency of each genotype was accurately quantified, with results comparable to those of conventional pyrosequencing. Furthermore, this method was capable of detecting alleles with frequencies as low as 3%, which was more sensitive than ∼5 to ∼7% level detected by conventional pyrosequencing. This method offers high sensitivity, reproducibility, and relatively low costs, and thus could provide a much-needed approach for quantitative analysis of SNPs in clinical samples.