Abstract 3388: Novel aurora plus Bruton's tyrosine kinase-targeted therapies for aggressive B-cell non-Hodgkin's lymphoma.
Authors: Mahadevan Daruka , Morales Carla , Karp Russell , Cooke Laurence , Lyons John , Singh Juswinder , Qi Wenqing 
Published: August 2014

Exploring synthetic lethality in the context of signaling pathways with novel targeted agents may yield effective combination therapies for aggressive B-NHL. Auroras are a family of mitotic oncogenic serine/threonine kinases intimately involved in high fidelity regulation of cell division. We previously demonstrated that aberrant Aurora (A and B) expression portends a poor survival in mantle cell lymphoma (MCL) patients. Aberrant aurora expression leads to genetic instability, polyploidy, and resistance to microtubule targeted agents (MTAs). We demonstrated that combination of an Aurora inhibitor MLN8237 (alisertib) or AT9283 with MTAs (e.g. taxol or vincas) leads to a mechanistic decoupling of the mitotic spindle manifesting as a synergistic apoptotic response in cell culture and in mouse xenograft models of aggressive B-NHL. Gene expression profiling of harvested mouse xenograft tumors at the end of treatment (3 weeks) with an aurora inhibitor + MTA showed over-expression of several markers of resistance of which BTK (Bruton's tyrosine kinase) was the most prominent. BTK plays a role in uncontrolled activation and proliferation of malignant B-cells via the chronic active B-cell receptor pathway in aggressive B-NHL. We hypothesized that targeting proliferation [BTK] and replication [Aurora] would be a novel therapeutic strategy in aggressive B-NHL.

We demonstrate that both aurora (A and B) and BTK are highly over-expressed in B-NHL cell lines (Granta-519, SUDHL4, SUDHL10, OCI-Ly-10, TMD8, U-2932) and harvested mouse xenograft tumour treated with an Aurora inhibitor + vincristine and in patient samples. IC50 values for AT9283 is 5-10nM, and CNX652 is 0.07-5μM. The combination index (CI) indicated significant synergism for AT9283 plus CNX-652 or vice versa. Combination therapy showed increased apoptosis (flow cytometry, PARP-cleavage) in a dose-dependent manner. Both AT9283 and AVL-292 (CNX-652 is a structural analog with similar in vitro and in vivo properties to AVL-292) are in early phase clinical trials in hematologic malignancies. We utilized clinically relevant doses to evaluate the efficacy of single agent and combination therapy of AT9283 and CNX652 in mouse xenograft models (Granta-519) of MCL. The first mouse model evaluated single agent dose-response and target modulation by Western blotting (pHisH3, pBTK) in tumors harvested at the end of 3 weeks of treatment (CNX-652 daily oral for 3 weeks or AT9283 daily IV for 3 weeks, n=12 mice per cohort). The second study evaluated the combination of AT9283 and CNX-652 for endpoints of response, overall survival and target modulation. Gene expression and protein analysis of harvested tumors at the end of treatment (3 weeks) have been interrogated to ascertain the mechanistic role of Aurora plus BTK inhibition. The combination of AT9283 + CNX652 represents a novel therapeutic strategy for aggressive B-NHL [Funded by the Hope Foundation].

Citation Format: Daruka Mahadevan, Carla Morales, Russell Karp, Laurence Cooke, John Lyons, Juswinder Singh, Wenqing Qi. Novel aurora plus Bruton's tyrosine kinase-targeted therapies for aggressive B-cell non-Hodgkin's lymphoma. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3388. doi:10.1158/1538-7445.AM2013-3388