Zhishuo Ou

Targeting BTK with Ibrutinib in Relapsed or Refractory Mantle-Cell Lymphoma

BACKGROUND Brutons tyrosine kinase (BTK) is a mediator of the B-cell-receptor signaling pathway implicated in the pathogenesis of B-cell cancers. In a phase 1 study, ibrutinib, a BTK inhibitor, showed antitumor activity in several types of non-Hodgkins lymphoma, including mantle-cell lymphoma. METHODS In this phase 2 study, we investigated oral ibrutinib, at a daily dose of 560 mg, in 111 patients with relapsed or refractory mantle-cell lymphoma. Patients were enrolled into two groups: those who had previously received at least 2 cycles of bortezomib therapy and those who had received less than 2 complete cycles of bortezomib or had received no prior bortezomib therapy. The primary end point was the overall response rate. Secondary end points were duration of response, progression-free survival, overall survival, and safety. RESULTS The median age was 68 years, and 86% of patients had intermediate-risk or high-risk mantle-cell lymphoma according to clinical prognostic factors. Patients had received a median of three prior therapies. The most common treatment-related adverse events were mild or moderate diarrhea, fatigue, and nausea. Grade 3 or higher hematologic events were infrequent and included neutropenia (in 16% of patients), thrombocytopenia (in 11%), and anemia (in 10%). A response rate of 68% (75 patients) was observed, with a complete response rate of 21% and a partial response rate of 47%; prior treatment with bortezomib had no effect on the response rate. With an estimated median follow-up of 15.3 months, the estimated median response duration was 17.5 months (95% confidence interval [CI], 15.8 to not reached), the estimated median progression-free survival was 13.9 months (95% CI, 7.0 to not reached), and the median overall survival was not reached. The estimated rate of overall survival was 58% at 18 months. CONCLUSIONS Ibrutinib shows durable single-agent efficacy in relapsed or refractory mantle-cell lymphoma. (Funded by Pharmacyclics and others; ClinicalTrials.gov number, NCT01236391.)

Selective antitumor activity of ibrutinib in EGFR-mutant non-small cell lung cancer cells.

Ibrutinib, which irreversibly inhibits Bruton tyrosine kinase, was evaluated for antitumor activity in a panel of non-small cell lung cancer (NSCLC) cell lines and found to selectively inhibit growth of NSCLC cells carrying mutations in the epidermal growth factor receptor (EGFR) gene, including T790M mutant and erlotinib-resistant H1975 cells. Ibrutinib induced dose-dependent inhibition of phosphor-EGFR at both Y1068 and Y1173 sites, suggesting ibrutinib functions as an EGFR inhibitor. Survival was analyzed by Kaplan-Meier estimation and log-rank test. All statistical tests were two-sided. In vivo study showed that ibrutinib statistically significantly suppressed H1975 tumor growth and prolonged survival of the tumor bearing mice (n = 5 per group). The mean survival times for solvent- and erlotinib-treated mice were both 17.8 days (95% confidence interval [CI] = 14.3 to 21.3 days), while the mean survival time for ibrutinib-treated mice was 29.8 days (95% CI = 26.0 to 33.6 days, P = .008). Our results indicate that ibrutinib could be a candidate drug for treatment of EGFR-mutant NSCLC, including erlotinib-resistant tumors.

Combinatorial drug screening identifies synergistic co-targeting of Bruton’s tyrosine kinase and the proteasome in mantle cell lymphoma

Combinatorial drug screening identifies synergistic co-targeting of Bruton’s tyrosine kinase and the proteasome in mantle cell lymphoma

Immunomodulation therapy with lenalidomide in follicular, transformed and diffuse large B cell lymphoma: current data on safety and efficacy

Lenalidomide is an immunomodulatory agent which has been approved for multiple myeloma. Lenalidomide is also effective in and tolerated well by patients with follicular lymphoma, diffuse large B-cell lymphoma, and transformed large cell lymphoma. This review summarizes the results of current preclinical and clinical studies of lenalidomide, alone or in combination with the monoclonal antibody rituximab, as a therapeutic option for these three lymphoma types. This review will serve as a tool guiding future clinical investigations to improve survival rates for these three lymphomas.

Lenalidomide in relapsed or refractory mantle cell lymphoma: Overview and perspective

Lenalidomide, a novel immunomodulatory agent, was approved by the US Food and Drug Administration for the treatment of myelodysplastic syndrome and relapsed multiple myeloma. Data from preclinical studies paved the way for clinical trials of lenalidomide in mantle cell lymphoma (MCL). Initial phase I and II clinical trials of lenalidomide alone and as part of combination regimens in patients with relapsed/refractory MCL have shown promising results. Its immunomodulatory, T cell costimulatory, anti-inflammatory and anti-angiogenic actions working together in the tumor cell microenvironment seem to be responsible for its enhanced antitumor efficacy. Lenalidomide’s nature of action and safety profile favor it over other agents studied in relapsed/refractory MCL. This review summarizes the data from preclinical and clinical studies of lenalidomide in relapsed/refractory MCL and compares the results with those of other novel agents being used for relapsed/refractory MCL.

Involvement of tumor-associated macrophage activation in vitro during development of a novel mantle cell lymphoma cell line, PF-1, derived from a typical patient with relapsed disease

Abstract Human mantle cell lymphoma (MCL) cell lines are scarce and have been only sporadically described and validated, and only a few have been thoroughly molecularly or genetically characterized. We describe here the successful establishment of a new MCL line, PF-1, with typical MCL characteristics. Culturing primary MCL cells in vitro initially gave rise to an essential generative microenvironment “niche” involving macrophages required for MCL growth, and eventually produced the PF-1 MCL cell line. Our analysis revealed that PF-1 is morphologically and genotypically nearly identical to the original tumor cells. The PF-1 MCL cell line that we have developed will be useful for in vitro and in vivo studies of MCL pathogenesis and therapeutics.

Abstract 2432: The bruton's tyrosine kinase inhibitor ibrutinib synergized with the proteasome inhibitor carfilzomib and overcame immunoproteasome-mediated carfilzomib resistance in mantle cell lymphoma .

Proceedings: AACR 104th Annual Meeting 2013; Apr 6-10, 2013; Washington, DC Introduction: Mantle cell lymphoma (MCL) is not curable and novel therapeutic agents and their rational combinations are needed. The ubiquitin-proteasome pathway is an attractive target for antitumor therapy, as its persistent activity is associated with tumor formation, growth, metastasis, and drug resistance in many cancer types, including B-cell non-Hodgkin lymphoma. 20S proteasome activity is regulated by the catalytic subunits β1, β2, and β5 or in the case of the immunoproteasome (i20S) by the inducible catalytic subunits LMP2 (β1i), MECL-1(β2i), and LMP7 (β5i). Carfilzomib (CFZ), a proteasome inhibitor, inhibits the proteasome by binding specifically and irreversibly to the catalytic subunit β5/β5i. Materials and Methods: CFZ was supplied by Onyx Pharmaceuticals (South San Francisco, CA). The Btk inhibitor ibrutinib (PCI-32765) was provided by Pharmacyclics (Sunnyvale, CA). Human MCL cell lines (Mino, Jeko-1, Z138, and Rec-1) were either created by our laboratory or obtained from American Type Culture Collection. Primary cells were obtained from newly diagnosed MCL patients with informed consent. Cell viability was assessed by an MTT assay, apoptosis by Annexin V binding assays, and proteasome expression by Western blotting. Results: We found that MCL cells had different responses to CFZ. For the CFZ-sensitive MCL cell lines Mino and Z138 and freshly isolated MCL cells from 6 patients, CFZ significantly induced the growth inhibition and apoptosis at a low dose (IC50 2-6 nM). In contrast, for the CFZ-resistant MCL cell line (Rec-1) and fresh primary MCL cells from patients with clinical resistance, CFZ did not induce cell death (IC50 not reached at 100 nM). Next, Western blot analysis showed that the CFZ-resistant cells lacked expression of the i20S subunits LMP2, LMP7, and MECL-1. By contrast, the CFZ-sensitive cells showed high levels of LMP2, LMP7, and MECL-1. These results suggest that an intact immunoproteasome is necessary for CFZ-induced anti-MCL activity. In an attempt to overcome the CFZ resistance, we studied the effect of ibrutinib in CFZ-resistant MCL cells. Ibrutinib alone was toxic to both CFZ-sensitive and CFZ-resistant MCL cells with IC50 values ranging from 3 to 12.5 μM. Furthermore, we found that ibrutinib synergized with CFZ in CFZ-sensitive cell lines, and primary MCL cells. The Chou-Talay combination index was < 1, indicating synergism between the two drugs. Most importantly, the CFZ-resistant MCL cells Rec-1 were sensitive to ibrutinib, with an IC50 of 6 uM. Conclusion: Our data suggest that LMP2, LMP7, and MECL-1 may serve as potential biomarkers for patients who are likely to be sensitive to CFZ. Our data also suggest that ibrutinib may be useful in patients with CFZ-resistant MCL. Our preclinical data provide a strong rationale for testing the ibrutinib-CFZ combination clinically. Citation Format: Zhishuo Ou, Liang Zhang, Kate Newberry, Luhong Sun, Kirk J. Christopher, Alex Rollo, Archito Tamayo, John Lee, Richard J. Ford, Michael Wang, Lan V. Pham. The brutons tyrosine kinase inhibitor ibrutinib synergized with the proteasome inhibitor carfilzomib and overcame immunoproteasome-mediated carfilzomib resistance in mantle cell 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 2432. doi:10.1158/1538-7445.AM2013-2432

Abstract 2854: Targeting constitutive NF-kB activation through Bruton's tyrosine kinase (Btk) and the proteasome in mantle cell lymphoma

Mantle cell lymphoma (MCL) is an aggressive B-cell non-Hodgkin lymphoma (NHL) with poor prognoses; novel agents are needed for its therapy. Bruton9s tyrosine kinase (Btk) has been identified as an essential kinase for B-cell survival and it is activated through the B-cell receptor (BCR) pathway. Btk has recently emerged as a promising target in MCL, as demonstrated by recent clinical trials on the Btk inhibitor PCI-32765 (Pharmacyclics, Sunnyvale, CA), suggesting that elucidating critical signaling pathways emanating through Btk will hold an important key to deciphering the pathogenesis of MCL that can lead to the development of more effective targeted therapies. In this study, we showed that Btk is constitutively phosphorylated in most MCL cell lines except Rec1 and DB SP53 and is variable among primary cells from patients. We demonstrated that knockdown of Btk by siRNA diminished Btk expression, reduced constitutive NF-kB activation by luciferase assays, leading to the cell growth inhibition and induction of apoptosis in MCL cell lines. MCL cells treated with the Btk inhibitor PCI-32765 effectively inhibits Btk activity, leading to reduced MCL cell growth with IC 50 values range from 2-6 uM in Mino, Jeko1, Z138 and JMP1. Interestingly, the IC 50 value in DB SP53, which lacks both phosphorylated Btk and membrane immunoglobulins, is 35 uM, suggesting that BCR signaling is not active in these cell lines. PCI-32765 also induced caspase-dependent apoptosis in a dose- and time-dependent manner in representative MCL cell lines and in patient primary cells. We further demonstrated that PCI-32765 down-regulates NF-kB activity through both, the canonical and alternative NF-kB pathways. Since previous studies have indicated synergy between proteasome inhibitors and tyrosine kinase inhibitors, we evaluated whether there is synergism between PCI-32765 and the next generation proteasome inhibitor Carfilzomib (Onyx Pharmaceuticals, South San Francisco, CA). Our data suggest potential synergy between Carfilzomib and PCI-32765 in represented MCL cell lines in terms of inhibiting cell growth and induction of apoptosis. Both compounds also synergize to inhibit NF-kB activation in MCL cells. In summary, our data suggest that Btk is a key survival kinase in MCL and strategic targeting of growth/survival Btk-mediated NF-kB pathways with novel therapeutic agents such as PCI-32765 should provide a novel therapy regimen for MCL patients. Combining PCI-32765 with the proteasome inhibitor Carfilzomib can synergize its effect in MCL and may be a useful therapeutic strategy, particularly for patients with relapsed/refractory MCL. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2854. doi:1538-7445.AM2012-2854