P40 and NUT were not expressed (0/23 and 0/20, respectively) The SMARCA4-DTS immunohistochemical signature was both sensitive and specific, with only a subset of small cell carcinoma of the ovary hypercalcemic type showing overlapping phenotypes.
One such perturbation is the dual loss of the SMARCA4 and SMARCA2 ATPase subunits in small cell carcinoma of the ovary, hypercalcemic type (SCCOHT)<sup>2-5</sup>, SMARCA4-deficient thoracic sarcomas<sup>6</sup> and dedifferentiated endometrial carcinomas<sup>7</sup>.
Selective Killing of SMARCA2- and SMARCA4-deficient Small Cell Carcinoma of the Ovary, Hypercalcemic Type Cells by Inhibition of EZH2: <i>In Vitro</i> and <i>In Vivo</i> Preclinical Models.
Comprehensive genomic profiling reveals inactivating SMARCA4 mutations and low tumor mutational burden in small cell carcinoma of the ovary, hypercalcemic-type.
The most successful approaches that have been clinically validated so far include the targeting of the BRD4-NUT fusion transcript in NUT-midline carcinoma by BET (Bromodomain Extra-Terminal) inhibitors, and the use of EZH2 (Enhancer of Zest Homolog 2) inhibitors in SMARCB1-deficient malignant rhabdoid tumors and SMARCA4-deficient ovarian small cell carcinomas.
We focus on adult granulosa cell tumours (somatic monoallelic mutations in FOXL2), Sertoli-Leydig cell tumours, gynaecological embryonal rhabdomyosarcomas (germline and somatic mutations in DICER1), and small-cell carcinoma of the ovary, hypercalcaemic type (biallelic mutations in SMARCA4).
Dual loss of the SWI/SNF complex ATPases SMARCA4/BRG1 and SMARCA2/BRM is highly sensitive and specific for small cell carcinoma of the ovary, hypercalcaemic type.
In conclusion, SMARCA4 immunohistochemistry represents a highly valuable emerging tool in identifying small cell carcinoma of the ovary, hypercalcemic type in routine practice.
To help define the nosological relationships of these tumors, we compared their transcriptomic profiles with those of SMARCA4-mutated small-cell carcinomas of the ovary, hypercalcemic type (SCCOHTs), SMARCB1-inactivated malignant rhabdoid tumors (MRTs) and lung carcinomas (of which 10% display SMARCA4 mutations).