Citations

Abstract Abstract 587 Background: The phosphatidylinositol 3-kinase/mammalian target of rapamycin (mTOR) signal transduction pathway controls cell proliferation and survival. Everolimus is an oral agent targeting raptor mTOR (mTORC1). The trial's goal was to determine the anti-tumor activity and safety of single-agent everolimus in patients with relapsed/refractory Waldenstrom's macroglobulinemia (WM). Patients and Methods: Eligible patients had measurable disease (IgM monoclonal protein >1000 mg/dL with >10% marrow involvement or nodal masses >2 cm), a platelet count ≥75,000 × 106/L, a neutrophil count ≥1,000 × 106/L, and a creatinine and bilirubin ≤2x laboratory upper limit of normal. Patients received everolimus 10 mg PO daily and were evaluated monthly. Tumor response was assessed after cycles 2 and 6 and then every 3 cycles until progression. Results: 50 pts were treated. The median age was 63 years (range, 43-85). The overall response rate (CR+PR+MR) was 70% (95% CI: 55-82%), with a PR of 42% and 28% MR. The median duration of response and median progression-free survival (PFS) has not been reached. The estimated PFS at 6 and 12 months is 75% (95%CI: 64-89%) and 62% (95%CI: 48-80%), respectively. Grade 3 or higher related toxicities were observed in 56% of patients. The most common were hematological toxicities with cytopenias. Pulmonary toxicity occurred in 10% of patients. Dose reductions due to toxicity occurred in 52% of patients. Conclusions: Everolimus has high single-agent activity with an overall response rate of 70% and manageable toxicity in patients with relapsed WM, and offers a potential new therapeutic strategy for this patient group. Disclosures: Ghobrial: Millennium: Honoraria, Research Funding, Speakers Bureau; Celgene: Consultancy, Honoraria, Speakers Bureau; Novartis: Honoraria, Speakers Bureau. Gertz:celgene: Honoraria; millenium: Honoraria, Membership on an entity's Board of Directors or advisory committees. Richardson:Millennium Pharmaceuticals, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Johnson and Johnson: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Keryx: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; BMS: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Treon:Millennium: Honoraria, Research Funding, Speakers Bureau; Celgene: Honoraria, Research Funding, Speakers Bureau; Genentech: Honoraria, Research Funding, Speakers Bureau. Witzig:Novartis: Research Funding.

Abstract Background: Oprozomib (OPZ) is an oral epoxyketone proteasome inhibitor that has shown promising antitumor activity in patients (pts) with hematologic malignancies (HM), including WM (Kaufman, EHA 2013, P223; Ghobrial, ASH 2013, 3184). Updated safety and efficacy results from the subset of pts with WM enrolled in this ongoing phase 1b/2 study in pts with HM are presented. Methods: This open-label, multicenter, phase 1b/2 study (NCT01416428) is enrolling adult pts with HM who have relapsed after receiving ≥1 line of therapy. The primary objectives of the phase 1b portion of the study are to determine the maximum tolerated dose (MTD) and the safety and tolerability profile of OPZ. The primary objective of the phase 2 portion of the study is to determine the best overall response rate (ORR; ≥minimal response [MR]). In the phase 1b portion, single-agent OPZ is being administered once daily on days 1, 2, 8, and 9 of a 14-day cycle (2/7 schedule) or on days 1–5 of a 14-day cycle (5/14 schedule). The starting dose was 150 mg/day (mg/d); doses were escalated in 30-mg increments. In the phase 2 study, pts have received 240 mg/d on the 5/14 schedule, which was the initial phase 2 schedule opened to enrollment. For this report, all enrolled patients with HM are included in the description of the MTD while only the subset of patients with WM is included in the safety and efficacy results. Results: As of July 21, 2014, 106 pts with HM (including 36 pts with WM) were enrolled and treated with the OPZ tablet. Enrollment and baseline demographic information for pts with WM are presented in Table 1. For WM patients in the phase 1b portion, median treatment duration was 17.1 weeks (range, 3.1–51.4; 2/7 schedule) and 51.7 weeks (range, 3.9–74.9; 5/14 schedule); preliminary median treatment duration in the ongoing phase 2 portion was 8.1 weeks (range, 0.7–22.0). In all pts with HM, the MTD for the 2/7 schedule was 300 mg/d and 240 mg/d for the 5/14 schedule. None of 3 dose-limiting toxicities (DLTs) on the 2/7 schedule occurred in patients with WM. Two of the 4 DLTs observed on the 5/14 schedule occurred in pts with WM (grade 4 tumor lysis syndrome [240 mg/d, n=1] and grade 3 vomiting [270 mg/d, n=1]). The most common adverse events (AEs) in pts with WM are shown in Table 2. Grade 4 AEs were thrombocytopenia (n=1; phase 1b; 2/7 schedule) and influenza and tumor lysis syndrome (n=1 each; phase 1b; 5/14 schedule). No on-study deaths occurred in pts with WM. In the phase 1b portion, two pts (25%) in the 2/7 schedule and 1 pt (9%) in the 5/14 schedule discontinued treatment due to an AE; 6 pts (35%) discontinued treatment due to an AE in the phase 2 portion. In the phase 1b portion, 3 pts (38%) (2/7 schedule) and 6 pts (55%) (5/14 schedule) had their dosage reduced at least once due to an AE; 10 pts (59%) in the phase 2 portion had their dosage reduced at least once due to an AE. In the phase 1b portion, all 19 pts were eligible for response and were carfilzomib (CFZ)-naïve. The ORR in 8 pts enrolled on the 2/7 schedule was 38% (3 pts had a partial response [PR]). Among 11 pts enrolled on the 5/14 schedule, the ORR was 73% (1 complete response, 1 very good partial response, 5 PRs, and 1 MR); the ORR for BTZ-refractory pts (n=4) was 75%. All 17 pts enrolled on the phase 2 portion were response-eligible. The ORR in the phase 2 portion was 59% (there were 5 PRs and 5 MRs). The ORR among CFZ-naïve pts (n=16) in the phase 2 portion was 56; the ORR among BTZ-refractory pts (n=3) was 67%. Conclusions: The MTD of OPZ was 300 mg/d in the 2/7 schedule and 240 mg/d in the 5/14 schedule; these MTDs were determined from all pts with HM. In pts with WM who received single-agent OPZ, the most common grade 3 AEs were neutropenia and diarrhea; grade 4 AEs were infrequent. Additional measures will be taken to improve gastrointestinal tolerability. Single-agent OPZ continues to have promising antitumor activity in pts with WM. Enrollment of patients on the 2/7 schedule is continuing; the target enrollment for the phase 2 portion of the study is 66 patients. Extended-release OPZ tablets will be introduced and assessed for safety, activity, and pharmacokinetics. Updated results will be presented at the meeting. Disclosures Siegel: Celgene: Honoraria, Speakers Bureau; Onyx: Honoraria, Speakers Bureau; Millennium: Honoraria, Speakers Bureau. Off Label Use: Monoclonal antibody/toxin fusion protein. For treatment of multiple myeloma. Kaufman:Millennium: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Onyx: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria; Spectrum: Consultancy, Honoraria; Merck: Research Funding. Raje:Celgene: Consultancy; Millennium: Consultancy; Novartis: Consultancy; Amgen: Consultancy; Onyx: Consultancy; Acetylon: Research Funding; Ely Lilly: Research Funding. Mikhael:Onyx: Research Funding; Celgene: Research Funding; Sanofi: Research Funding; Novartis: Research Funding. Kapoor:Onyx: Membership on an entity's Board of Directors or advisory committees, Research Funding. Treon:Onyx: Consultancy, Research Funding. Neuman:Onyx: Employment. Lee:Onyx Pharmaceuticals, an Amgen subsidiary: Employment. Ghobrial:BMS: Advisory Board Other; Celgene: Advisory Board, Advisory Board Other; Millennium: Advisory Board, Advisory Board Other; Onyx: Advisory Board, Advisory Board Other.

Abstract Abstract 3723 Background: Waldenström macroglobulinemia (WM), a lymphoproliferative disorder with marrow infiltration by lymphoplasmacytic lymphoma cells and production of monoclonal IgM, is characterized clinically by good initial responses to standard therapeutic approaches. However, a minority of patients achieve a complete remission, and most inevitably relapse, indicating a need for validation of new, targeted therapies. Notably, B-cell receptor signaling has been linked to clonal evolution in WM, and Spleen tyrosine kinase (Syk) is over-expressed in primary patient cells. Also, a recent phase I/II study of the Syk inhibitor fostamatinib in patients with a variety of non-Hodgkin lymphomas showed evidence of activity in three patients with WM. These findings supported our central hypothesis, which proposed that Syk could be a rational new target for therapy of WM, which we pursued first with pre-clinical studies. Methods: Studies of fostamatinib were performed using the WM cell line MWCL-1, and the IgM-producing cell line BWCM.1, as well as in primary cells from patients with WM, and in a novel murine xenograft model utilizing MWCL-1 cells. Results: Fostamatinib induced a time- and dose-dependent reduction in viability of MWCL-1 and BWCM.1 cells, with median inhibitory concentrations (IC50) that were in the physiologically relevant range of approximately 0.25 and 1 μM, respectively, at 3 days. Cell cycle analysis showed a decrease in cells at S-phase and at G2/M, while an increase was seen in cells in G1, and in the sub-G1fraction, suggesting induction of apoptosis. Consistent with the possibility that there was activation of type I programmed cell death, increased staining was seen in fostamatinb-treated cells with an antibody to Annexin V. Interestingly, evidence was seen of the induction of type II programmed cell death, or autophagy, as measured by an increase in cells staining with the lysotropic dye acridine orange. At the molecular level, fostamatinib blocked signaling through p44/42 mitogen-activated protein kinase (MAPK), MAPK kinase (MEK), protein kinase B/Akt, and Zeta-chain-associated protein kinase (ZAP)-70/Syk, as judged by a reduction in the phosphorylated forms of these intermediates by Western blotting. Notably, the viability of primary cells isolated from patients with WM was also reduced in association with blockade of p44/42 MAPK. Finally, a novel murine xenograft model was generated by injection of MWCL-1 cells into immunodeficient mice, which developed measurable tumors. When these were treated with fostamatinib, a delay in tumor growth was demonstrable. Conclusions: Targeting Syk with fostamatinib is an attractive strategy against pre-clinical models of WM both in vitro and in vivo. These findings lend further support for translation of fostamatinib to the clinic for patients with relapsed, and possibly even newly diagnosed WM. Disclosures: No relevant conflicts of interest to declare.

BACKGROUND Waldenström macroglobulinemia (WM) is preceded by asymptomatic WM (AWM), for which the risk of progression to overt disease is not well defined. METHODS We studied 439 patients with AWM, who were diagnosed and observed at Dana-Farber Cancer Institute between 1992 and 2014. RESULTS During the 23-year study period, with a median follow-up of 7.8 years, 317 patients progressed to symptomatic WM (72%). Immunoglobulin M 4,500 mg/dL or greater, bone marrow lymphoplasmacytic infiltration 70% or greater, β2-microglobulin 4.0 mg/dL or greater, and albumin 3.5 g/dL or less were all identified as independent predictors of disease progression. To assess progression risk in patients with AWM, we trained and cross-validated a proportional hazards model using bone marrow infiltration, immunoglobulin M, albumin, and beta-2 microglobulin values as continuous measures. The model divided the cohort into three distinct risk groups: a high-risk group with a median time to progression (TTP) of 1.8 years, an intermediate-risk group with a median TTP of 4.8 years, and a low-risk group with a median TTP of 9.3 years. We validated this model in two external cohorts, demonstrating robustness and generalizability. For clinical applicability, we made the model available as a Web page application ( www.awmrisk.com ). By combining two cohorts, we were powered to identify wild type MYD88 as an independent predictor of progression (hazard ratio, 2.7). CONCLUSION This classification system is positioned to inform patient monitoring and care and, for the first time to our knowledge, to identify patients with high-risk AWM who may need closer follow-up or benefit from early intervention.

Abstract The treatment of patients with Bing-Neel syndrome (BNS) is not standardized. We included patients with Waldenström macroglobulinemia (WM) and a radiologic and/or cytologic diagnosis of BNS treated with ibrutinib monotherapy. Response assessment was based on criteria for BNS from the 8th International Workshop for WM. Survival from BNS diagnosis (BNS survival), survival from ibrutinib initiation to last follow-up or death (ibrutinib survival), and time from ibrutinib initiation to ibrutinib discontinuation for toxicity, progression, or death (event-free survival [EFS]) were estimated. Twenty-eight patients were included in our study. The median age at BNS diagnosis was 65 years. Ibrutinib was the first line of treatment for BNS in 39% of patients. Ibrutinib was administered orally at a dose of 560 and 420 mg once daily in 46% and 54% of patients, respectively; symptomatic and radiologic improvements were seen in 85% and 60% of patients within 3 months of therapy. At best response, 85% of patients had improvement or resolution of BNS symptoms, 83% had improvement or resolution of radiologic abnormalities, and 47% had cleared the disease in the cerebrospinal fluid. The 2-year EFS rate with ibrutinib was 80% (95% confidence interval [CI], 58%-91%), the 2-year ibrutinib survival rate was 81% (95% CI, 49%-94%), and the 5-year BNS survival rate was 86% (95% CI, 63%-95%). Ibrutinib therapy is effective in patients with BNS and should be considered as a treatment option in these patients.

SummaryIbrutinib, a Bruton tyrosine kinase inhibitor, is approved for treatment of various B‐cell malignancies. In ibrutinib clinical studies, low‐grade haemorrhage was common, whereas major haemorrhage (MH) was infrequent. We analysed the incidence of and risk factors for MH from 15 ibrutinib clinical studies (N = 1768), including 4 randomised controlled trials (RCTs). Rates of any‐grade bleeding were similar for single‐agent ibrutinib and ibrutinib combinations (39% and 40%). Low‐grade bleeding was more common in ibrutinib‐treated than comparator‐treated patients (35% and 15%), and early low‐grade bleeding was not associated with MH. The proportion of MH in RCTs was higher with ibrutinib than comparators (4.4% vs. 2.8%), but after adjusting for longer exposure with ibrutinib (median 13 months vs. 6 months), the incidence of MH was similar (3.2 vs. 3.1 per 1000 person‐months). MH led to treatment discontinuation in 1% of all ibrutinib‐treated patients. Use of anticoagulants and/or antiplatelets (AC/AP) during the study was common (~50% of patients) and had an increased exposure‐adjusted relative risk for MH in both the total ibrutinib‐treated population (1.9; 95% confidence interval, 1.2–3.0) and RCT comparator‐treated patients (2.4; 95% confidence interval, 1.0–5.6), indicating that ibrutinib may not alter the effect of AC/AP on the risk of MH in B‐cell malignancies.

Abstract Purpose: Waldenström's macroglobulinemia is an incurable lymphoproliferative disorder driven by an L265P mutation in the myeloid differentiation primary response gene 88 (MYD88), which activates downstream NF-κB signaling through the Myddosome. As this pathway depends in part on activity of interleukin-1 receptor-associated kinases (IRAKs)-1 and -4, we sought to evaluate the potential of the IRAK1/4 inhibitor R191 in preclinical models. Experimental Design: Patient-derived cell lines and primary samples were used in both in vitro and in vivo experiments to model Waldenström's macroglobulinemia and its response to IRAK1/4 inhibitors. Results: R191 induced a dose- and time-dependent reduction in viability of BCWM.1 and MWCL-1 Waldenström's cell lines, and suppressed activation of IRAK1/4. This was associated with cell-cycle arrest at G0–G1, reduced levels of cyclin-dependent kinases 4 and 6, and induction of apoptosis in cell lines and primary patient samples. Further downstream, R191 exposure led to reduced activation of NF-κB, and of protein kinase B/Akt/mammalian target of rapamycin signaling, whereas expression of a constitutively active Akt mutant induced R191 resistance. Gene expression profiling and gene set enrichment analysis revealed a signature consistent with inhibition of c-Myc and activation of the endoplasmic reticulum stress response. In both subcutaneous and systemic murine models of Waldenström's, R191 showed antitumor activity. Finally, the activity of R191 was enhanced when it was combined with novel chemotherapeutics such as bortezomib, afuresertib, and ibrutinib. Conclusions: Taken together, these data support the translation of R191 as an approach to target IRAK1/4 to the clinic for patients with Waldenström's macroglobulinemia.