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EP358/#615  Methylation profiling identifies two distinct clusters of small cell carcinoma of the ovary hypercalcemic type (SCCOHT)
  1. Felix Kommoss1,
  2. Leora Witkowski2,3,
  3. Andreas Von Deimling4,
  4. Cheng-Han Lee5,
  5. William Foulkes2,3,6 and
  6. Basile Tessier-Cloutier3,6,7
  1. 1University of Heidelberg, Institute of Pathology, Heidelberg, Germany
  2. 2McGill University, Department of Human Genetics, Montreal, Canada
  3. 3Research Institute of the McGill University Health Centre, Sccoht/smarca4 Registry, MOntreal, Canada
  4. 4University of Heidelberg, Department of Neuropathology, Heidelberg, Germany
  5. 5University of Alberta, Department of Pathology and Laboratory Medicine, Edmonton, Canada
  6. 6Research Institute of the McGill University Health Centre, Cancer Research Program, Montreal, Canada
  7. 7McGill University, Department of Pathology, Montreal, Canada


Introduction Small cell carcinoma of the ovary hypercalcemic type (SCCOHT) is a highly aggressive ovarian malignancy that occurs in young women and is defined by inactivating mutations in SMARCA4. While current treatment modalities only show limited success, emerging evidence suggests that a subset of patients may respond to immunotherapy. Here we set out to assess if methylation profiling can stratify SCCOHT into clinically meaningful subgroups.

Methods We collected a multicenter series of clinically annotated SCCOHT. Tumor samples were analysed using the Illumina EPIC and 450k BeadChip. Focal copy number score (FCS) was computed from segmented array data using CNApp. Statistical analyses included the Chi-Squared tests and one-way ANOVA.

Results Our cohort included 27 SCCOHT. The age at diagnosis ranged from 7 – 47 years (n=25, median of 25 years) and 45% of tumors where this information was available (n=20) presented with low stage disease. Clustering analysis of DNA methylation data identified two distinct tumor clusters (C1, n=15 and C2, n=12). C1 was associated with a trend towards younger patient age when compared to C2 (23.7 years vs. 30.2 years). Tumors assigned to C1 also showed a trend towards a lower mean FCS as compared to tumors from C2 (7.4 vs. 12.75). There was no difference in clinical stage between the two clusters.

Conclusion/Implications Based on a small series our data suggests that there are two distinct DNA methylation clusters of SCCOHT. Analyses of larger cohorts of SCCOHT are warrented to understand, if the clusters identified correlate with patient survival and/or response to (immuno-)therapy.

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