Re-establishing Responsiveness in a Case of Refractory Metastatic Rectal Cancer with a Personalized de novo Combination Regimen

Introduction : Encyclopedic Tumor Analysis (ETA) is multi-analyte, molecular and functional interrogation to identify latent vulnerabilities in solid tumors which can then be targeted in organ- and label-agnostic combination treatment regimens. Case Presentation : We describe here a case of metastatic rectal cancer in a 61-year-old male who was progressed on all prior Standard of Care (SoC) treatment modalities including surgery, chemotherapy and radiotherapy. We addressed disease recurrence via personalized therapy guided by ETA which revealed characteristic molecular heterogeneity in primary and metastatic lesions in terms of single nucleotide variations (SNVs) and gene copy number variations (CNVs).  Notably, a novel TBL1XR1 (Exon1) – PIK3CA (Exon 2) gene fusion was identified in the tumor along with gene copy number gains in TERT, IGF-1R, MYC, FGFR1 and EGFR genes. Conclusion : ETA based molecular analysis with synchronous in vitro chemo-sensitivity profiling strategy helped to define de novo combinatorial therapy regimen of targeted and cytotoxic drugs which countered disease progression at each instance and led to the durable regression of primary as well as metastatic lesions.