Giulino‐Roth, Lisa

AbstractThe goal of therapy in pediatric Hodgkin lymphoma (HL) is to maximize overall survival while minimizing the morbidity of curative therapy. Key findings from recent Children's Oncology Group (COG) trials include: (i) superior event‐free survival with the addition of brentuximab vedotin (Bv) in frontline regimens for high‐risk disease, (ii) successful reduction in myeloablative regimens with demonstrated safety and efficacy of Bv and checkpoint inhibitor therapy in relapsed disease, and (ii) the potential to select a population that can be salvaged after relapse without receiving a stem cell transplant. The COG HL committee will lead a National cancer Institute National Clinical Trials Network phase 3 trial to evaluate the combination of Bv/nivolumab in early‐stage disease. Ongoing advances in technology and blood biomarkers are increasing the ability to deliver biologically driven, personalized treatment for HL.

Abstract BACKGROUND: Burkitt Lymphoma (BL) represents approximately 40% of all childhood and adolescent non-Hodgkin lymphoma (Miles/Cairo, BJH 2012). Children with relapsed or progressive BL develop chemoimmunotherapy-resistant disease and can rarely be cured with salvage therapy (Cairo et al, JCO 2012). Bruton's tyrosine kinase (BTK) is a regulator of normal B-cell development and is activated upon B-cell receptor (BCR) stimulation. Chronic active BCR signaling through BTK activation can be inhibited by the selective and covalent BTK inhibitor, ibrutinib (Young/Staudt et al, Nat Rev Drug Dicov 2013). Preclinical studies of ibrutinib in chronic lymphocytic leukemia (CLL) and mantle cell lymphoma (MCL) suggest that its inhibitory effect on cell proliferation is in the range of 1.0uM to 25.0uM (Herman et al, Blood 2011; Cinar et al, Leuk Res 2013), which is higher than the typical plasma concentration range in patients at the recommended dose of 560mg (<0.6uM) (Advani et al, JCO 2013). Despite these relatively high IC50 values in vitro, ibrutinib has been highly effective in the treatment of patients with refractory CLL and MCL (Byrd et al, NEJM 2013 and Wang et al, NEJM 2013). Ibrutinib was initially approved by the FDA (IMBRUVICA, USPI) for patients with MCL in November 2013 and CLL in February 2014, who have received at least one prior therapy. BL, however, is associated with tonic vs chronic active BCR signaling; while, both CLL and MCL have chronic active BCR signaling. These findings suggest that the antitumor activity of ibrutinib in BL, which is associated with tonic BCR signaling, may be less pronounced than in Activated B cell-like diffuse large B-cell lymphoma (ABC-DLBCL), CLL or MCL. OBJECTIVES: We hypothesize that ibrutinib may be a potential adjuvant agent in the treatment of BL. Therefore, we investigated the in vivo anti-tumor activity of ibrutinib in BL xenografted NSG mice. METHODS: Raji Burkitt lymphoma (BL) cells (ATCC) were exposed to ibrutinib (0-10uM, generously provided by Janssen R&D LLC) alone and in combination with dexamethasone (1uM) for 5 days and then MTS cell proliferation assay (Promega) was performed. The IC50 values were determined with CompuSynTM software (Chou and Martin, ComboSyn, 2005) based on data derived from MTS assay. Raji BL cells were stably transfected with a firefly luciferase expression plasmid (ffluc-zeo), kindly provided by Laurence Cooper MD, PhD. NSG mice (NOD.Cg-PrkdcscidIl2rgtm1Wjl/SzJ, 6-8 weeks old) from Jackson laboratory were irradiated (2.5 Gy) and then mice were subcutaneously injected with one million ffluc-zeo tumor cells. Tumor progression and tumor burden were monitored by Bioluminescent Imaging system using the Xenogen IVIS-200 (Caliper Life Sciences). Mice were orally gavaged with either vehicle or ibrutinib (12.5mg/kg) for 10 days (once a day) at post-tumor cells injection. Analysis of survival rates were determined by the Kaplan-Meier method and differences evaluated by log-rank test using the Prism Version 6.0 software. RESULTS: Ibrutinib compared to control induced a significant dose-dependent decrease in cell proliferation in Raji BL cells (5uM, 0.561 ± 0.170, p<0.03, IC50=5.20uM) following 120 hours (5 days) of ibrutinib treatment. Interestingly, we observed a significant decrease in cell proliferation in Raji BL cells (5uM, 0.213 ± 0.078, p<0.002, IC=0.50 ± 0.374uM) following ibrutinib and 1uM dexamethasone combination treatment following 120 hours (5 days) of treatment. We observed a significant decrease of tumor progression by tumor luminescence signal intensity following ibrutinib treated Raji BL xenografted NSG mice at day 20 (12.5mg/kg, p<0.001 and 25mg/kg, p<0.05) and day 25 (12.5mg/kg, p<0.05 and 25mg/kg, p<0.05) compared to control (Figure 1A).Ibrutinib (12.5 mg/kg) treated mice (n=39) significantly prolonged survival compared to vehicle controls (n=28) (p<0.0001) (Figure 1B). CONCLUSIONS: Ibrutinib (12.5mg/kg) significantly decreased tumor progression and significantly increased survival in Raji BL xenografted NSG mice, suggesting that ibrutinib may be a potential adjuvant agent for therapy in the treatment of BL. Future studies will investigate the efficacy of combination therapy with ibrutinib on survival in BL xenografted NOD/SCID mice. Disclosures Galardy: Mission Therapeutics: Research Funding.

Abstract BACKGROUND: Primary Mediastinal B-Cell Lymphoma (PMBL) is a rare form of B-cell non-Hodgkin lymphoma (Lones/Cairo et al, JCO 2000). We have previously reported a significant decrease in EFS among pediatric and adolescent patients with PMBL compared with other stage III non-PMBL diffuse large B-cell lymphoma (DLBCL) patients following FAB/LMB 96 therapy, suggesting that new therapeutic targeted agents are needed (Gerrard/Cairo et al, Blood 2013). Activation of the B-cell receptor (BCR) signaling pathway has now emerged as a central oncogenic pathway that promotes growth and survival in both normal and malignant B-cells. The cascade of signaling pathways downstream of the BCR includes BTK, MAPK, NF-κB and AKT. PMBL has a constitutively activated NF-kB pathway (Rosenwald et al, JEM 2003). Ibrutinib is a selective and covalent BTK inhibitor that inhibits chronic active BCR signaling and downstream signaling including the NF-kB pathway (Herman et al, Blood 2014) and is an active agent in ABC-DLBCL, which also has an activated NF-kB pathway (Griner et al, PNAS 2014). Preclinical studies of ibrutinib in CLL and MCL suggested that the inhibitory effects on cell proliferation were seen in the range of 1.0uM to 25.0uM (Herman et al, Blood 2011; Cinar et al, Leuk. Res 2013). Despite these relatively high IC50 values in vitro, ibrutinib has been highly effective in the treatment of patients with refractory CLL and MCL (Byrd et al, NEJM 2013 and Wang et al, NEJM 2013). Ibrutinib was approved by the FDA (IMBRUVICA, USPI) for patients with MCL in November 2013 or CLL in February 2014, who have received at least one prior therapy. However, the antitumor activity against PMBL of ibrutinib alone and in combination with other agents is currently unknown. OBJECTIVES: We hypothesize that ibrutinib in combination with other agents may be a future targeted agent in the treatment of PMBL. Therefore, we investigated the effect of ibrutinib alone and in combination with dexamethasone, rituximab and carfilzomib on cell proliferation and apoptosis in a PMBL cell line. METHODS: The Karpas-1106P PMBL cell line (DSMZ, Germany) was treated with ibrutinib alone (0-10uM, generously provided by Janssen R&D LLC) and in combination with dexamethasone (1uM), rituximab (20ug/ml) and carfilzomib (5nM) for 5 days treatment. The MTS cell proliferation assay (Promega) and western blot analysis were performed. Significant differences were determined by Student's t -test.The IC50 values were determined with CompuSyn software (Chou and Martin, ComboSyn, 2005). RESULTS: We observed a significant down-regulation of phosphorylated BTK after 5 days with ibrutinib treatment in Karpas-1106P cell line with 1uM ibrutinib (0.178 ± 1.63, p<0.0001) and the expression of total BTK protein was also significantly decreased with 1uM ibrutinib following 5 days of treatment (0.803±0.190, p<0.005) compared to control (1.000±0.00). We also observed a significant dose-dependent decrease in cell proliferation (0-10uM, p<0.0001) in ibrutinib-treated Karpas-1106P PMBL cell line. In combination with dexamethasone, the ibrutinib IC50 values for inhibition of cell proliferation were significantly decreased from 0.71uM ± 0.172 (ibrutinib alone) to 0.04uM ± 0.007 (p<0.005) with 1.0uM dexamethasone combination following 5 days of treatment. Second, in combination with rituximab experiment, the ibrutinib IC50 values was significantly decreased from 0.845uM ± 0.289 (ibrutinib alone) to 0.37uM ± 0.056 (p<0.05) with 20ug/ml rituximab following 5 days of treatment. Lastly, the ibrutinib IC50 values were significantly decreased from 0.72uM ± 0.185 (ibrutinib alone) to 0.002uM ± 0.001 (p<0.005) with 5nM carfilzomib combination following 5 days of treatment. CONCLUSIONS: Ibrutinib alone and in combination with dexamethasone, rituximab and carfilzomib significantly inhibited cell proliferation in the Karpas-1106P PMBL cell line. Ibrutinib's potential as an adjuvant agent in combination treatment in patients with PMBL is supported by these experiments. Future studies will focus on the in vivo effects of ibrutinib alone and in combination with dexamethasone and carfilzomib in a NOD/SCID PMBL xenograft mouse model. Disclosures Galardy: Mission Therapeutics: Research Funding.