ALBERT

Beschreibung: Background: Mantle cell lymphoma (MCL) accounts for 6% of all non-Hodgkin lymphoma and is a therapeutic challenge. Phosphoinositide-3 kinase (PI3K) has been shown to be an alternative survival pathway in relapsed/refractory MCL. KA2237 (designed by Karus Therapeutics Ltd, Oxfordshire, United Kingdom) is a dual inhibitor of the class I beta and delta isoforms of the 110 kDa catalytic subunit of PI3K. By selectively targeting PI3K-beta and -delta isoforms and preventing their activation, KA2237 may decrease proliferation and induce cell death in susceptible tumor cells. Methods: We assessed the effects of KA2237 on the in vitro cell proliferation of both ibrutinib-sensitive (Mino, Jeko-1, and Rec-1) and primary ibrutinib-resistant (Z-138 and Maver-1) cell lines, and acquired ibrutinib-resistant MCL cell line, Jeko-R. We also tested the viability of patient-derived xenograft (PDX) tumor cells to KA2237. We compared the efficacy of KA2237 with two other commercial PI3K inhibitors, duvelisib (IPI-145, Selleck) and idelalisib (Cal-101, Selleck). Also, we paired these three inhibitors (KA2237, duvelisib and idelalisib) each with ibrutinib to evaluate the potential synergistic effects of these combinations. Lastly, we also tested in vivo efficacy of KA2237 and its combination with ibrutinib in PDX tumor cells. Results: KA2237 inhibited cell proliferation in both ibrutinib-sensitive and ibrutinib-resistant cell lines in a dose-dependent and time-dependent manner. For Mino and Jeko-1, the IC50 was 4.8 uM and 2.9 uM and for Z-138 and Maver-1 cell lines, the IC50 was 0.6 uM and 0.1 uM, respectively. KA2237 also decreased cell viability of ibrutinib-sensitive and ibrutinib-resistant MCL PDX tumor cells. However, KA2237 did not decrease the cell viability of normal human peripheral blood mono-nuclear cells. KA2237 arrested phase G0/G1 in Rec-1 and Jeko-R cell lines. We detected the expression of PI3K isoforms in MCL, finding higher expression of PI3K β and δ in MCL-resistant cell lines as compared with sensitive cell lines. We found that KA2237 induced MCL cell apoptosis in a time-dependent and dose-dependent manner. In comparison with duvelisib and idelalisib, KA2237 achieved greater inhibition of cell viability, cell apoptosis and cell cycle arrest. Furthermore, we found synergistic effects of KA2237 and ibrutinib combination in several MCL cell lines and in PDX models. In an ibrutinib-resistant PDX model, KA2237 treated mice reduced tumor burden significantly compared with vehicle control, and higher tumor growth inhibition was achieved as compared with ibrutinib. Conclusion: The novel PI3K inhibitor, KA2237 may be a potential candidate for MCL therapy, especially in the ibrutinib-resistant cases. Disclosures Wang: Acerta Pharma: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Juno Therapeutics: Research Funding; Pharmacyclics: Research Funding; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Onyx: Research Funding; BeiGene: Research Funding; Asana BioSciences: Research Funding; Kite Pharma: Research Funding; Celgene: Research Funding.

Beschreibung: Introduction Mantle cell lymphoma (MCL) is an aggressive lymphoma with elevated B-cell receptor activity. Ibrutinib (IBN), a Bruton's tyrosine kinase (BTK) inhibitor, has been shown to have a response rate of 68% in relapsed or refractory MCL patients. However, with the emergence of IBN-resistant lymphomas, new therapies are needed. It is suspected that upregulation of the PI3K-Akt-mTOR pathway allows survival in the presence of IBN. CUDC-907 is a next generation PI3K and HDAC dual-inhibitor currently in phase II clinical trials. Our objective is to investigate the effects of CUDC-907 in IBN-resistant MCL cells in vitro and in PDX model. Methods MCL cells were seeded at 10,000 cells per well in 96-well plate and were treated with various doses of compounds at the following concentrations: CUDC-907/Ibrutinib 0.015, 0.05, 0.15, 0.5, 1.5, 5, and 15 uM. Cell viability was tested by CellTiter-Glo luminescent cell viability assay (Promega) after a 72-hour incubation. Next, MCL cells were incubated with IBN at varying doses (0.39 uM, 1.56 uM, 6.25 uM), CUDC-907 (0.39 uM, 1.56 uM, 6.25 uM), and IBN+CUDC-907 (0.39 uM, 1.56 M, 6.25 uM) for 24 hours. Apoptosis was detected by Annexin V-binding assay. In patient derived xenograft (PDX) model: CUDC-907 was administered at a dose of 50 mg/kg in ibrutinib-resistant MCL-bearing PDX mice daily. Tumor volumes were measured as the length X width2 X 0.5 weekly. Toxicity was also observed every week. Mice were sacrificed once diameter of tumor mass reached 15 mm size. Results CUDC-907 inhibited the growth of both ibrutinib-sensitive and resistant MCL cells in vitro. Sensitive cell lines include: Rec-1, Mino, and JVM-13 with IC50 values of 1.1 nM, 1.0 nM, and 5 nM respectively. Resistant cell lines include: Granta-519, Maver-1, and Z-138 with IC50 values of 2 nM, 3 nM, and 1.5 nM respectively. All tested cell lines were more sensitive to CUDC-907 than to ibrutinib. In addition, combination treatments of CUDC-907 and IBN increased cell death in comparison to single agent treatments. Next, one pair of MCL cell lines, Jeko-1 (sensitive to IBN) and Jeko-R (resistant to IBN) were treated for 24 hours with varying doses of CUDC-907 or ibrutinib either as single agent inhibitors or in combination therapies. The results demonstrated that CUDC-907 induced apoptosis in both Jeko-1 and Jeko-R cell lines in a dose-dependent manner. Combination therapies increased cell death in a dose-dependent manner as well. In PDX model, tumor volume in treated mice of ibrutinib-resistant PDX decreased significantly compared with vehicle control (pvalue = 0.032). Control mice also weighed considerably more than treated mice (p value = 0.073). Common toxicities included a decrease in body mass for first 28 days of treatment. Conclusion CUDC-907, a dual inhibitor of PI3K-Akt-mTOR and HDAC, inhibits tumor growth of ibrutinib-resistant MCL in vitro and in PDX model. It would be a potential drug for the patients with ibrutinib-resistant/relapsed MCL. Disclosures Wang: Celgene: Research Funding; Onyx: Research Funding; Kite Pharma: Research Funding; Acerta Pharma: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmacyclics: Research Funding; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BeiGene: Research Funding; Juno Therapeutics: Research Funding; Asana BioSciences: Research Funding.