Auburn Research Day 2022

Sayak Chakravarti* 1 ; Ujjal Kumar Mukherjee 2 ; Suman Mazumder 1, 3 ; Timothy Moore 1 ; Amit Kumar Mitra 1, 3, 4 1 Harrison School of Pharmacy, Auburn University; 2 University of Illinois - Urbana Champaign, Champaign, IL; 3 Center for Pharmacogenomics and Single-cell Omics Initiative, Auburn University; 4 UAB Comprehensive Cancer Center, University of Alabama at Birmingham School of Medicine B i omed i ca l Resea rch | Gr adua te/Undergr adua te St udent In silico Prediction Followed By In Vitro validation Identifies a Survivin Inhibitor and an MCL-1 Inhibitor As a Potent Secondary Drug Against Refractory or Relapsed Mantle Cell Lymphoma 66

Mantle cell lymphoma (MCL) is an aggressive B-cell neoplasm characterized by recurrent relapse resulting in a short estimated 5-year overall survival of 2-5 year. Combination therapies such as R-CHOP constitute the front-line chemotherapeutic treatment landscape for MCL. Despite good initial response to the combination regimens, all patients develop resistance over time. Bruton’s tyrosine kinase inhibitor/ BTKi (Ibrutinib) & proteasome inhibitor (PI) Bortezomib are FDA approved therapies for refractory/ relapsed (R/R) MCL with demonstrated high initial response rate in clinical trials. However, highly variable treatment response along with dose-limiting toxicities has limited the efficacy in real-world settings with median progression-free survival <15 months. Thus, identification of novel drugs that function either alone or in combination to curb oncogenic progression is of high clinical significance. We have designed a novel optimization-regularization- based computational prediction algorithm called “secDrug” that uses large-scale pharmacogenomics databases like GDSC1000 to identify novel secondary drugs for the management of treatment- resistant B-cell malignancies. We hypothesize that combination of our predicted secDrugs with BTKi/ PI will be useful in curbing oncogenic progressions of R/R MCL through simultaneous inhibition of multiple oncogenic pathways. When applied to BTKi/PI-resistant R/R MCL, the top predicted secondary drugs were YM155 (Survivin inhibitor) & S63845 (selective MCL-1 inhibitor). Interestingly, both Survivin & MCL-1 are reported to be over-expressed in MCL, & their expression is strongly correlated with survivability of the patients. To validate our in-silico predictions, we performed in vitro cytotoxicity assays with the top predicted secDrugs (YM155 & S63845) as single agents (IC 50 for YM155 4.87±0.66 nM, S63845 0.9±1.1 uM) as well as in combination with BTKi/PI against a panel of MCL cell lines representing PI/BTKi sensitive, innate resistant (representing refractory MCL) & clonally derived acquired resistant (representing relapsed MCL). Our results showed YM155 & S63845 exhibited significant synergistic cell killing activities (Combination index/ CI value of 0.31±0.49 as calculated using Chou-Talalay's CI theorem, C.I>1 synergism) in R/R MCL cells

and also able to significantly lower the effective dose of both BTKi/ PI required to achieve desired therapeutic response (Dose Reduction Index 12.34±2.67), thereby making the cell lines relatively more BTKi/ PI sensitive. Next, we performed next generation RNA sequencing analysis to identify mechanisms of secDrug action & synergy. Our Gene expression profiling & Ingenuity pathway analysis of the RNAseq data among YM155-treated MCL cell lines revealed eIF4-p70S6K signaling & mTOR signaling as top canonical pathways. Our study thus identified YM155 & S63845 as potential novel candidates for repurposing as secondary drugs in combination with BTKi/PI for the treatment of R/R MCL. Currently, we are exploring the probable subclonal molecular mechanisms governing the synergistic drug action by using single-cell transcriptomics analysis.

39 2022 Via Research Recognit ion Day