Alisertib Added to Rituximab and Vincristine Is Synthetic Lethal and Curative of Double Hit Diffuse Large B-Cell Lymphoma in Mice

Abstract 159

About one-third of diffuse large B-cell lymphoma (DLBCL) patients develop relapsed/refractory disease, a major cause of morbidity and mortality. Of DLBCL, 5% are double-hit lymphomas (DHLs) with translocations of MYC and BCL2 characterized by poor outcomes with R-CHOP. Auroras (A and B) are a family of mitotic oncogenic serine/threonine kinases required for high fidelity regulation of the mitotic phase of the cell cycle. Aberrant over-expression of Auroras leads to genetic instability, polyploidy and resistance to microtubule targeted agents. Previously we showed Aurora inhibitor (MLN8237, alisertib) [M] plus vincristine [V] plus rituximab [R] is synthetic lethal and a potential curative therapy in a mantle cell lymphoma model (Granta-519) with several cell cycle genetic defects [t (11;14)], ATM (haploinsufficient), p16/p14 (Del)] but p53 (WT). We evaluated ABC-DLBCL cell lines TMD-8 and U-2932 where the BCR/NF-kB pathway is constitutively active. In TMD-8, CD79B is mutated and in U-2932, Bcl2 [3q27] and Bcl6 [18q21] are amplified, p53 (mutated) and c-Myc over-expressed [DHL]. Triple therapy with MVR abolished proliferation, disrupted cell cycle processes and induced apoptosis compared to single agent and doublet treatments. A Mouse xenograft model of U-2932 showed modest activity for M (30 mg kg, PO, QD, 3 weeks), V (0.375 mg/kg, IV, Q1Wx3) and MV with tumor growth inhibition (TGI) of ∼10% (p=0.01) respectively. However, R (10 mg/kg, IV, Q1Wx3) alone induced ∼ 50% TGI (p=0.01) due to effective targeting of Bcl2. Doublets MR and VR led to tumor regression (TR), but relapse soon after stopping therapy. In contrast, MVR demonstrated TR with no relapses >40 days after stopping therapy. All treatments were well tolerated (no weight loss) and Kaplan-Meier analysis showed that mice treated with MR, VR and MVR had a statistically significant improvement in overall survival compared to control, M, V and MV (p<0.0001). Moreover, with MVR, OS was 100% (Figure 1). Gene expression profiling, RT-PCR, IHC and Western blotting of harvested tumors at the end of treatment (3 weeks) has been interrogated to ascertain the mechanistic role of Aurora inhibition when added to R [R Vs MR] and VR [VR Vs MVR]. Thus, addition of R to MV represents a novel therapeutic strategy that is currently under clinical trial evaluation in aggressive B-NHL including double hit lymphomas sponsored by Millennium Pharmaceuticals (C14011).

Figure 1:

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Kaplan-Meier Survival by Treatment: MLN8237 (M), Rituximab (R), Vincristine (V), MR, MV, VR, MVR in a U-2932 ABC-DLBCL SCID Mouse Xenograft Model

Figure 1:

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Kaplan-Meier Survival by Treatment: MLN8237 (M), Rituximab (R), Vincristine (V), MR, MV, VR, MVR in a U-2932 ABC-DLBCL SCID Mouse Xenograft Model

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