Cyclin pathway genomic alterations across 5,356 prostate cancers.

179 Background: The cyclin pathway is comprised of possible targetable alterations as well as resistant alterations that affect treatment, including hormonal agents. We describe the landscape of cyclin genomic alterations in prostate cancer. Methods: Consecutive samples were analyzed in a CLIA-certified laboratory using comprehensive genomic profiling (CGP) performed by next-generation sequencing (315 genes, >500X coverage). We describe alterations in activating genes (Table) and co-alterations in resistant genes ( RB1 and CCNE1) (related to cyclin inhibition) and androgen receptor ( AR). Results: Alterations in any cyclin pathway genes were found in 9.7% of the 5,356 tumors analyzed. Frequent alterations included CCND1 amplification (4.2%) and CDKN2A and B loss (2.4% each). Frequencies were substantially different according to prostate cancer histology (Table). The majority of alterations were copy number changes. Alterations in possible resistance genes, RB1 and CCNE1 were detected in 9.7% (up to 54.6% in neuroendocrine) and 1.2% of cases, respectively, while AR alterations were seen in 20.9% (up to 27.3% in anaplastic). Co-occurrence analysis demonstrated a lower likelihood of concomitant vs. isolated alterations in cyclin activating and resistance pathway (odds ratio (OR), 0.44, p<0.001). Conversely, we detected a higher likelihood of co-occurrence between AR and cyclin alterations (OR 1.79, p<0.001). Conclusions: Cyclin pathway genomic abnormalities were observed in about 10% of prostate cancer tumors, and are more frequently associated with concomitant AR alterations and absence of co-alterations associated with resistance to cyclin inhibition.[Table: see text]