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Background: Desmoid tumor, also known as aggressive fibromatosis, is well-characterized by abnormal Wnt/β-catenin signaling. Various therapeutic options, including imatinib, are available to efficiently treat desmoid tumor. However, molecular mechanism of why imatinib works remains poorly understood. Here, we describe the potential roles of NOTCH2 and HES1 in association with clinical response to imatinib as in genome and transcriptome levels. Methods: We identified all somatic mutations in coding and non-coding regions via whole genome sequencing using desmoid tumor samples. To validate the genetic interaction with expression level in desmoid-tumor condition, we utilized large-scale Whole-genome sequencing (WGS) and transcriptome datasets from the Pan-Cancer Analysis of Whole Genomes (PCAWG) project. RNA-sequencing was performed using prospective and retrospective cohort samples to evaluate the expressional relevance with clinical response. Results: Among 20 patients, 4 (20%) had a partial response and 14 (66.7%) had stable disease, 11 of which continued for ≥1 year. With gene-wise functional analyses, we detected significant correlation between recurrent NOTCH2 noncoding mutations and clinical response to imatinib. Based on PCAWG data analyses, NOTCH2 mutations affect its expression levels particularly in the presence of CTNNB1 missense mutations. By analyzing RNA-sequencing with additional desmoid tumor samples, we found that NOTCH2 expression was significantly correlated with HES1 expression. Interestingly, NOTCH2 had no statistical power to discriminate responders and non-responders. Instead, HES1 was differentially expressed with statistical significance between responders and non-responders Conclusions: Imatinib was effective and well tolerated for advanced desmoid tumor treatment. Our results show that HES1, regulated by NOTCH2, as an indicator of sensitivity to imatinib, which provides an important therapeutic consideration for desmoid tumor. Trial Registration: ClinicalTrials.gov, NCT02495519, Registered July 13, 2015- Retrospectively registered, https://www.clinicaltrials.gov/ct2/show/NCT02495519

Purpose Even though pazopanib, a multitargeted tyrosine kinase inhibitor, has been approved for refractory soft tissue sarcoma (STS), little is known about the molecular determinants of the response to pazopanib. We performed integrative molecular characterization to identify potential predictors of pazopanib efficacy.Materials and Methods We obtained fresh pre-treatment tumor tissue from 35 patients with advanced STS receiving pazopanib-based treatment. Among those, 18 (51.4%) received pazopanib monotherapy, and the remaining 17 (48.6%) received pazopanib in combination with durvalumab, programmed death-ligand 1 blockade. Whole-exome and transcriptome sequencing were performed for each tumor and patient germline DNA.Results Of the 35 patients receiving pazopanib-based treatment, nine achieved a partial response (PR), resulting in an objective response rate (ORR) of 27.3%, and the median progression-free survival (PFS) was 6.0 months. Patients with CDK4 amplification (copy ratio tumor to normal > 2) exhibited shorter PFS (3.7 vs. 7.9 months, p=2.09×10–4) and a poorer response (ORR; 0% vs. 33.3%) compared to those without a gene amplification (copy ratio ≤ 2). Moreover, non-responders demonstrated transcriptional activation of CDK4 via DNA amplification, resulting in cell cycle activation. In the durvalumab combination cohort, seven of the 17 patients (41.2%) achieved a PR, and gene expression analysis revealed that durvalumab responders exhibited high immune/stromal cell infiltration, mainly comprising natural killer cells, compared to non-responders as well as increased expression of CD19, a B-cell marker.Conclusion Despite the limitation of heterogeneity in the study population and treatment, we identified possible molecular predictors of pazopanib efficacy that can be employed in future clinical trials aimed at evaluating therapeutic strategies.