e15063 Background: Analysis of transcriptome-wide gene expression has the potential to provide insights into biological pathways and molecular mechanisms that regulate disease progression and treatment response. RNA-Seq is considered the gold standard for transcriptome analysis; however, it may not perform well with older, archival formalin-fixed paraffin embedded (FFPE) tissues or low-quality/low-quantity RNA. To help researchers overcome these challenges, HTG Molecular Diagnostics developed a Research Use Only, extraction-free, targeted human transcriptome panel with an automated, proprietary web-based data analysis pipeline that provides fast, accurate, and repeatable quantitative gene expression data for 19,398 protein-coding mRNA targets from lysed FFPE tissue samples or extracted RNA (eRNA). Methods: Panel precision was evaluated by Lin’s Concordance Correlation Coefficient (Lc) using FFPE tissue lysates and eRNA from FFPE and fresh frozen tissues, including FFPE blocks that were older than ten years. The accuracy of the HTP to perform differential expression analysis was assessed by comparing it to RNA-Seq using FFPE samples from different cancer indications. The agreement of the log fold changes between the two platforms was measured by Pearson Correlation Coefficient (Pc). Additionally, a cohort of 83 breast cancer FFPE samples, that had also been evaluated for estrogen (ER) and progesterone (PR) receptor expression by immunohistochemistry (IHC), were used to determine the correlation between HTP gene expression and orthogonal IHC data. Results: The precision of the panel measured by Lc, ranged from 0.90-0.94 across multiple operators, instruments, lots, and processing days, demonstrating that the HTP is a precise and robust panel. In addition, HTP is a competitive alternate to RNA-seq (estimated log-fold changes, Pc = 0.83 between the platforms). Archival samples demonstrated high repeatability (Pc > 0.9) with sample pass rates of 100% for HTP, which further confirms panel’s robust performance. Furthermore, the HTP gene expression results correlated with the IHC markers for ER (Pc = 0.92) and PR (Pc = 0.88) receptor status in a cohort of 83 breast cancer samples, which highlights the potential of the panel to replace IHC staining while providing expression data on thousands of additional genes. Conclusions: The results demonstrate the HTP is a powerful tool for comprehensive gene expression analysis that addresses several key limitations of RNA-Seq. The HTP is precise, accurate, user-friendly (avoids extraction-bias, fewer steps, automated data analysis), and efficient (quicker, requires lower amounts of sample, works well with samples of low quality and archival samples). Collectively, the data demonstrate HTP has the potential to be used for biomarker discovery and the development of clinical solutions.