Ailawadhi, Sikander

Abstract Background: Cost of cancer care is projected to reach $173 billion by 2020, a 39% increase from 2010. Several factors including psychiatric (psych) comorbidities contribute to this increase. Within the oncology setting, 29-38% of the patients (pts) are reported to have mood disorders and 15% have major depression. Depression alone is associated with increased healthcare utilization in pts with breast, colon, lung and prostate cancers. A 2015 report noted that the presence of at least one psychiatric comorbidity in 300 Leukemia pts was associated with an extra $55,000 per pt in just one year. Similarly, in pts treated with systemic steroids, the incidence of neuropsychiatric disorders can be as high as 75%. However, no such data is available for MM, where more than 90% of pts are treated with steroids, likely increasing risk for mood problems and impacting treatment cost. As such, the aim of our study was to analyze the SEER-Medicare database for healthcare utilization trends and acute cost of care (cost incurred during 6 months after MM diagnosis) in MM pts with or without psych comorbidities. Methods: Pts diagnosed with MM between 1991-2010 with continuous Medicare coverage (1 year prior to diagnosis-date of death/end of 2012) were included. Pts were categorized as: MM with any psych disorder (MM+P), MM with depression (MM+D) and MM only. Presence of ³1 inpatient (ipt) or ³2 outpatient (opt) ICD9 diagnosis codes were used to assign pts to the psych categories. Within MM+P and MM+D groups were subdivided by presence of psych or depression diagnosis prior to MM (MM+P PRE or MM+D PRE). Medicare claims adjusted for inflation (2013) within the first 6 months (mth)/total MM care were summed by drug and total charges. Univariate and multivariate logistic regression models (adjusted for age, year, sex, race, and the Charlson Comorbidity Index; CCI) were performed to determine associations with ipt, opt, and any emergency department (ED) charges after MM diagnosis. Associations between psych conditions prior to MM diagnosis and costs of care after MM diagnosis were assessed using univariate and multivariate proportional odds models. Results: The study population included 36,007 eligible MM pts with a median follow-up of 1.8 years. 15168 (42%) pts had a psych condition at any time (MM+P), while 9355 (26%) were diagnosed prior to MM diagnosis (MM+P PRE). Depression was present in 8421 pts (23%), 4546 (13%) of those occurring prior to MM diagnosis. In comparison to MM pts, MM+P and MM+D pts tended to be female, White, and had a higher CCI (all p<0.001). When compared to MM pts, those with MM+P PRE and MM+D PRE had significantly higher incidence of MM-related complications (hypercalcemia, renal dysfunction, anemia, fractures and dialysis) at the time of or after MM diagnosis and also required increased overall care (all p<0.001). Both, MM+P and MM+D had higher odds of ipt visits (OR 1.48 and 1.41, resp., p<0.001), ED care (OR 1.48 and 1.37, resp., p<0.001) and opt visits (OR 1.25 and 1.22, resp., p<0.001) as compared to MM only pts. Cost of care analysis showed that MM+P and MM+D pts had a significantly higher cost of opt (OR 1.36 and 1.39, resp., p<0.001), ipt (OR 1.49 and 1.54, resp., p<0.001) and total care (OR 1.52 and 1.55, resp., p<0.001) as compared to MM only pts during first 6 mth after MM diagnosis (Figure 1). Total costs of care for MM+P and MM+D were also higher than MM only but the differences were less significant. Cost of care differences existed within first 6 mth of MM diagnosis by pt race as well with MM+P among Hispanic and Asian pts being more strongly associated with higher costs than Whites and African-Americans (AA) (p<0.001). MM+D had similar trends but not significant after adjustment for multiple comparisons. Conclusion: Psych comorbidities are associated with significant increase in healthcare utilization and cost of care in MM pts and may contribute to higher MM-related complications. More research is needed to study whether a multidisciplinary approach to identify and manage MM pts with psych conditions may help mitigate these trends. Disclosures Ailawadhi: Pharmacyclics: Consultancy; Novartis: Consultancy; Amgen Inc: Consultancy; Takeda Oncology: Consultancy.

Abstract Background: Patient (Pt) outcomes have improved significantly in multiple myeloma (MM) due to widespread use of novel therapeutic agents and stem cell transplant (SCT) butoutcome disparities among racial/ethnic groups exist. Differences in access to and utilization of novel therapeutics are likely contributing factors. We performed an analysis of the SEER-Medicare database to explore such differences. Methods: Pts with a confirmed MM diagnosis between 2007-2009 and continuous Medicare coverage from 1 year prior to diagnosis through end of 2012 were included. Medicare Part D data (oral medications) is not available prior to 2007 so utilization analysis of lenalidomide (LEN), thalidomide (THAL) and bortezomib (BORT) was performed from 2007-2009. Demographic/survival data (PEDSAF files) and drug/SCT utilization (NCH, OUTSAF, PDESAF files) were obtained (HCPCS/NCH codes). Categorical and continuous variables were compared using /Fisher tests and Wilcoxon tests, respectively. Gender, age, and year-adjusted p-values were calculated using logistic regression. A proportional odds model was used to detect time-dependent trends in drug usage within 12 months of MM diagnosis across year of diagnosis by race. Separate multivariate models were fit for each drug adjusting for gender, age, drug use and race. Associations between drug use and overall survival (OS) were examined using a time dependent proportional hazards model. Results: A total of 5358 MM pts were included (any Medicare claims) with 2733 (51%) males. Mutually exclusive race categories were White (W; 67%), African-American (AA; 18%), Hispanic (H; 10%) and Asian (A; 5%). Median follow up was 2.4 yrs. Baseline pt characteristics were significantly different for age with AA being the youngest at diagnosis (p<0.001) and for gender (p<0.001) with W having the largest (53.4%) and AA the smallest (45.2%) proportion of males. Medicare claims capture only pts without any supplemental insurance and so drug utilization in this database was much lower than expected for all subgroups. Year-wise comparison showed that LEN use within the first year of MM diagnosis increased from 2007 to 2009 (16.5% to 27.7%; p<0.001) and there was a significant decrease in median days to first dose (p=0.002). Over the same period, use of THAL decreased (26.6% to 14.6%; p<0.001) while use of BORT (7.8% to 15.4%; p<0.001), SCT (3.3% to 6.2%; p<0.001) and more than 1 novel agent (2.5% to 5.7%; p<0.001) increased significantly. Utilization patterns within first year of MM diagnosis were significantly different among racial subgroups for LEN, THAL, BORT, SCT and >1 novel agent use. (Figure 1) No significant difference was seen for days to first dose of LEN/THAL for any race but for BORT, H got first dose in median 117 days after diagnosis as compared to median 46-51 days for other races (p=0.025). During the first year after diagnosis, W and AA had higher BORT only usage while H and A had a higher LEN/THAL only usage (p<0.001). For drug use by year and race, a significant increase in LEN use was seen from 2007 to 2009 in W (p<0.001), AA (p=0.001) and A (p<0.001) but not H (p=0.26) while THAL use decreased significantly for all races. BORT use increased significantly for all except A (p=0.602) and SCT use increased significantly for all except AA (p=0.068). Inferior OS was significantly associated with older age (p<0.001) and males (p<0.001). LEN/THAL use within the first year of diagnosis did not affect OS while BORT use within the first year of diagnosis increased mortality risk (HR 1.18, p=0.021). SCT use improved OS (HR 0.52, p<0.001). Conclusions: In this comprehensive analysis of MM therapeutics utilization, we noted significant variability among different racial groups. The use of LEN, BORT and SCT has increased while THAL has decreased over time but disparities exist in utilization among different races, with lower use of LEN in AA, lower use of BORT in A and significantly delayed use of BORT in H, which are all notable since racial/ethnic minorities are fast growing in the US population mix and seem to have inequitable utilization and/or access. Inferior survival with early BORT use may represent selection bias of pts with more advanced/aggressive disease. These trends need to be examined in larger sample sizes especially from commercial payers to eliminate drug access and utilization disparities and achieve equitable benefit of therapeutic advances across all racial subgroups. Figure 1 Figure 1. Figure 2 Figure 2. Disclosures Ailawadhi: Pharmacyclics: Consultancy; Novartis: Consultancy; Amgen Inc: Consultancy; Takeda Oncology: Consultancy.

Abstract Background: Pomalidomide is an immunomodulatory agent (IMiD®) that has been approved for treatment of relapsed and refractory multiple myeloma (MM). Combinations of IMiDs and proteasome inhibitors offer the potential for deeper and more durable responses due to enhanced efficacy. Preliminary results of a phase 1 study of twice weekly bortezomib with pomalidomide have been reported with promising results (Richardson, ASH 2012). This phase I/II trial was designed to evaluate the maximum tolerated doses (MTD) as well as safety and efficacy of the combination of pomalidomide, once weekly bortezomib and dexamethasone (PVD) in patients with relapsed, lenalidomide refractory, MM. Patients and methods: We included patients with relapsed MM who had 1-4 prior lines of therapy and were resistant or refractory to lenalidomide. In the phase I portion of the trial, dose level 1 consisted of pomalidomide 4 mg days 1-21 PO, bortezomib 1.0mg/m2 days 1,8,15, and 22 IV or SQ and dexamethasone 40 mg days 1,8,15, and 22 PO, given every 28 days. Bortezomib was increased to 1.3mg/m2 for dose level 2 and and was adopted for the phase 2 portion. The primary aim of the phase I cohort was to determine the MTD of the combination, and for the phase II cohort was to evaluate the confirmed response rate (PR, VGPR, or CR) in relapsed refractory MM. Response was assessed by the IMWG criteria and toxicity was graded using the CTCAE v4.0. Results: 50 patients were accrued between March 2012 and July 2014 (dose level (DL)1: 3, DL 2: 6, Phase II: 41). We describe results in 47 patients treated at MTD and phase II. Median age was 66, 51% were female and median time from diagnosis to study was 46 months (15-142). Twenty five percent had mSMART defined high-risk status. Median number of prior regimens was 3. All patients had prior lenalidomide, 68% had stem cell transplant, 17% received thalidomide, 56% had alkylators and 57% had bortezomib. With median follow up of 9 months, 72% remain progression free, 96% are alive and 66% remain on treatment. The most common AEs at least possibly attributable to the combination were anemia, fatigue, leukopenia and thrombocytopenia; however, the majority of these were grade 1-2. Grade ≥3 AEs (regardless of attribution) that occurred in at least 3 patients included neutropenia (29), leukopenia (15), lung infection (6), lymphopenia (8) dyspnea (3) and syncope (3). DVT/PE occurred in one patient. Among the 42 patients who were evaluable, confirmed responses (PR, VGPR, or CR) were seen in 34 (81%) including sCR (3), CR (5), VGPR (8), PR (18). Confirmed responses were seen in 9 of 11( 82%) high risk patients. Median progression free survival was 17.7 months (95%CI: 9.5-NA). Conclusions: PVD is a highly effective combination in patients refractory to lenalidomide with confirmed responses in over 80%. Weekly administration of bortezomib enhanced the tolerability and convenience of this regimen. Toxicities are manageable, mostly consisting of mild cytopenias with no significant neuropathy or DVT. PVD is a highly attractive option in patients with relapsed and refractory MM. Disclosures Lacy: Celgene: Research Funding. Lust:Senesco: PI Other. Fonseca:Medtronic, Otsuka, Celgene, Genzyme, BMS, Lilly, Onyx, Binding Site, Millennium, AMGEN: Consultancy, patent for the prognostication of MM based on genetic categorization of the disease. He also has sponsored research from Cylene and Onyx Other, Research Funding. Stewart:Celgene: Consultancy; Novartis: Consultancy; Array BioPharma: Consultancy; BMS: Consultancy; Millenium: Research Funding. Reeder:Millennium, Celgene, Novartis: Research Funding. Mikhael:Onyx: Research Funding; Celgene: Research Funding; Sanofi: Research Funding; Novartis: Research Funding.

Abstract BACKGROUND: The introduction of novel agents and proteasome inhibitors, and advances in high dose therapy administration has made an impact on the survival outcomes for MM patients. However, HRMM still remains a therapeutic challenge with poor prognosis. Even with aggressive approaches such as the Total Therapy protocols, patients with poor genomic risk have a 2-year event-free survival of ~50% (Nair et al, Blood 2010). A randomized Phase I/II trial was designed to evaluate the efficacy of adding immunotherapy into the first line for HRMM patients, comparing lenalidomide, bortezomib and dexamethasone (RVD) with or without addition of elotuzumab (Elo), a humanized monoclonal antibody that binds to SLAMF7/CS1. We are reporting on the Phase I portion of the study. PATIENTS & METHODS: The objective of Phase I was to determine the maximum tolerated dose (MTD) of RVD-Elo. Both low/standard risk MM and HRMM patients were eligible. HRMM was defined by one or more of the following: (1) poor risk genomics by the Arkansas 70-gene model, (2) translocation (14;16), translocation (14;20) and/or deletion (17p) by florescent in-situ hybridization (FISH), (3) primary plasma cell leukemia and (4) serum LDH > 2 times normal levels. The treatment consisted of induction chemotherapy for 8 cycles with RVD-Elo (lenalidomide 25 mg orally days 1-14 of every 21-day cycle; bortezomib 1.3 mg/m2 subcutaneously days 1,4,8,11; dexamethasone 20 mg orally days 1,2,4,5,8,9,11,12; elotuzumab 10 mg/kg intravenously days 1,8,15 cycles 1-2 then days 1,11 cycles 3-8) followed by dose-attenuated RVD-Elo maintenance (lenalidomide 25 mg orally days 1-14; bortezomib 1.0 mg/m2 subcutaneously days 1,8,15; dexamethasone 12 mg orally days 1,8,15; elotuzumab 10 mg/kg intravenously days 1,15) until disease relapse, progression or intolerance. Adverse events (AE) were recorded as per the NCI CTCAEv4.0. RESULTS: Eight newly diagnosed MM patients were enrolled on the Phase I run-in study. Six patients (Figure 1) were evaluable for dose limiting toxicities (DLT) during Cycle 1 as per protocol. The median age of patients was 67 years (range: 56-79 years), with 67% ≥65 years, Hgb was less than 10 g/dL in 50%, creatinine was greater than 2 mg/dL in all patients. ISS stage distribution was 17% (I), 33% (II) and 50% (III). Deletion 13 was observed in 1 patient (17%). The most common AEs (all grades) were fatigue (100%), peripheral sensory neuropathy (83%), edema (83%), lymphopenia (66%) and leukopenia (50%). The most common Grade 3 AEs were peripheral sensory neuropathy (33%), one of which was a DLT, neutropenia (17%) and thrombocytopenia (17%). One Grade 4 lymphopenia was observed. All 6 patients have completed 8 cycles of RVD-Elo induction therapy and 5 patients have completed at least 4 cycles of RVD-Elo maintenance. Overall median days on therapy per cycle were 13 days during induction and 20 days per cycle during maintenance. Dose adjustments were made in 83% of patients for bortezomib, 83% for lenalidomide and 33% for dexamethasone. There were no dose reductions for elotuzumab, although three patients had 1 event each of dose delays/missed dosing attributable to AE/SAE from RVD. Efficacy data will be released at the time that the phase II study of RVD +/- Elo is mature. Discussion/Conclusion: The RVD-Elo is a safe well-tolerated regimen for newly diagnosed MM patients without major additive AE/SAE beyond what is already known about RVD. This is the first report of the only phase I experience combining the triple-drug regimen RVD with the monoclonal antibody Elotuzumab for newly diagnosed MM. Support: NCI grants CA32102, CA38926, CA180821, CA31946, CA21076, CA180799, CA21115, CA180820 and in part by Bristol-Myers Squibb Company Disclosures Usmani: Celgene Corporation: Consultancy, Honoraria, Research Funding; Millennium: Consultancy, Honoraria; Onyx: Consultancy, Honoraria, Research Funding; Sanofi: Consultancy; Array BioPharma: Research Funding; Janssen: Research Funding; Pharmacyclics: Research Funding. Off Label Use: Lenalidomide in newly diagnosed multiple myeloma patients. Ailawadhi:Millennium: Honoraria. Shah:Onyx Pharmaceuticals: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Millennium Pharmaceuticals: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Array: Consultancy, Research Funding. Rosenzweig:Celgene: Speakers Bureau. Durie:IRC J&J: Membership on an entity's Board of Directors or advisory committees; Celgene Corp: Expert Board Committee Other; IRC Onyx: Membership on an entity's Board of Directors or advisory committees; DMC Millennium: Membership on an entity's Board of Directors or advisory committees. Orlowski:Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Research Funding; Onyx Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Research Funding; Millennium: The Takeda Oncology Company: Membership on an entity's Board of Directors or advisory committees, Research Funding; Spectrum Pharmaceuticals: Research Funding; JW Pharmaceutical: Research Funding; Array BioPharma: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees; Janssen Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees.

Abstract Background: BT062 (Biotest AG Dreieich, Germany) is an antibody-drug conjugate (ADC), comprising the anti-CD138 chimerized MAb (nBT062) and the maytansinoid DM4 as a cytotoxic agent. It is designed to bind to CD138 on cancer cells, and then release DM4 after internalization to cause cell death. CD138 (Syndecan-1) is highly overexpressed on various solid tumors and in hematological malignancies, and represents one of the most specific target antigens for identification of multiple myeloma (MM) cells. BT062 was investigated as a single agent and found to have an acceptable tolerability profile and evidence of activity in patients with heavily pretreated relapsed and/or refractory MM (1). Preclinical studies showed enhanced anti-MM activity when BT062 was combined with lenalidomide and dexamethasone (Len/Dex). Based on these data, a Phase I/IIa study in MM was initiated to evaluate the safety and efficacy of BT062 in combination with Len/Dex. Objectives: To determine the dose-limiting toxicities (DLTs), the maximum tolerated dose (MTD), the recommended phase II dose (RPTD), pharmacokinetics (PK), and anti-MM activity of increasing doses of BT062 (days 1, 8, and 15, every 4 weeks) used in combination with Len (25 mg, daily on days 1-21) and low dose Dex (40 mg on days 1, 8, 15, and 22) in patients with relapsed and/or refractory MM. Methods: This is a prospective, open label, multicenter Phase I/IIa study. The Phase I part includes dose escalation, and the Phase IIa the expansion of the RPTD cohort. Patients aged ≥18 years with relapsed and/or refractory MM who have failed at least one prior therapy were eligible to participate. Prior treatment with Len and/or Dex was allowed. Patients with clinical response (or no evidence of progressive disease) and without unacceptable toxicities were eligible for additional treatment cycles. Patients were enrolled in cohorts of at least 3 at each dose level; DLT in the first cycle triggered cohort expansion. Toxicities were assessed by CTCAE v4 and clinical response was assessed according to International Myeloma Working Group criteria. Results: The maximum administered dose (MAD) was 120 mg/m². Two of six patients treated at this dose had a DLT: mucosal inflammation (CTC grade 3) and anemia (CTC grade 3). The MTD was defined as 100 mg/m² and selected as RPTD. Additional patients are being treated at this RPTD to further evaluate safety and efficacy. Enrollment into the study is ongoing. As of July 2014, a total of 45 patients had received BT062 at dose levels of 80 mg/m² (N=3), 100 mg/m² (N=36) or 120 mg/m² (N=6). Fifteen patients discontinued study treatment: 5 for disease progression, 7 for adverse events, 1 died (not treatment related) and 2 for withdrawal of consent. The other 30 patients remain on treatment. The median treatment duration was 123 days (range 1–597). The median number of prior therapies was 3 (range 1–11). 68% of patients had prior exposure to both Len and bortezomib, 73% of patients had prior Len exposure, and 30% were Len-refractory. According to preliminary data from this ongoing study, about 89% of reported Adverse Events (AEs) were CTC grade 1 or 2. The most common reported AEs were diarrhea, fatigue, nausea, and hypokalemia. Amongst the 36 patients across all dose levels currently evaluable for efficacy, the overall response rate (ORR) is 78%; including 1 stringent complete response, 2 complete responses, 10 very good partial responses, and 15 partial responses. Two patients achieved a minor response and 6 patients disease stabilization, resulting in a clinical benefit in 100% of the evaluable patients. The ORR was 83% among the 30 evaluable patients receiving the RPTD. Interestingly, the ORR was 70% among the 23 patients with prior exposure to Len and bortezomib, and among 10 patients refractory to prior treatment with Len. Conclusion: Preliminary data from this ongoing study indicate that BT062 is well tolerated in combination with Len/Dex at dose levels that induce responses in patients with relapsed and/or refractory multiple myeloma, including patients with prior exposure to both Len and bortezomib and patients refractory to prior treatment with Len. Updated results on safety and efficacy will be presented. References Heffner et al, BT062, an Antibody-Drug Conjugate Directed Against CD138, Given Weekly for 3 Weeks in Each 4 Week Cycle: Safety and Further Evidence of Clinical Activity. Blood. 2012; 120: Abstract 4042. Disclosures Kelly: Celgene: Speakers Bureau. Heffner:Amgen: Honoraria, Research Funding; Biotest: Research Funding; Dana Farber CI: Research Funding; Genentech: Research Funding; Gilead: Research Funding; Idera: Research Funding; Janssen: Research Funding; Pfizer: Research Funding; Pharmacyclics: Honoraria, Research Funding; Onyx: Research Funding; Spectrum: Research Funding; Talon Therapeutics: Research Funding. Somlo:Millennium: 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; Celgene: Membership on an entity's Board of Directors or advisory committees. Siegel:Celgene: Honoraria, Speakers Bureau; Onyx: Honoraria, Speakers Bureau; Millennium: Honoraria, Speakers Bureau. Munshi:Celgene: Consultancy; Onyx: Consultancy; Janssen: Consultancy; Sanofi-Aventis: Consultancy; Ocopep: Consultancy, Equity Ownership, Patents & Royalties. Jagannath:Celgene: Consultancy; Millennium: Consultancy; Sanofi: Consultancy. Lonial:Millennium: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; BMS: Consultancy, Research Funding; Onyx: Consultancy, Research Funding. Ailawadhi:Millennium: Consultancy, Honoraria. Barmaki-Rad:Biotest AG: Employment. Chavan:Biotest Pharmaceuticals: Employment. Patel:Biotest Pharmaceuticals: Employment. Wartenberg-Demand:Biotest AG: Employment. Haeder:Biotest AG: Employment. Anderson:Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Millennium: Consultancy, Membership on an entity's Board of Directors or advisory committees; Onyx: Consultancy, Membership on an entity's Board of Directors or advisory committees; Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees; Sanofi Aventis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Oncopep: Equity Ownership; Acetylon: Equity Ownership.

Abstract Background: The proteasome is an established and druggable target for the treatment of plasma cell-related malignancies including Waldenstrom macroglobulinemia (WM). WM cells as a consequence of high immunoglobulin production and increased B-cell receptor (BCR) mediated proliferation upregulate proteasome activity. Additionally, microenvironmental influence mediated through BCR signaling directly influences Bcl-2 and its BH3 family members, supporting tumor cell survival. Indeed, WM patients derive significant clinical benefit from proteasome-inhibitor (PI) based therapy with agents such as bortezomib and carfilzomib. However, resistance to PI develops over time and for these patients the optimal choice and sequence of therapy has yet to be determined. Using our WM models of PI-resistance we interrogated molecular events within the BCR and Bcl-2 pathways to determine therapeutic potential of targeting these crucial pathway in PI-resistance. Materials & Methods: WM cell lines (BCWM.1 and MWCL-1) and carfilzomib-resistant (CR) subclones (BCWM.1/CR and MWCL-1/CR) were used in experiments. Gene-expression and long-noncoding (LNC) RNA analysis was performed (Arraystar) and validated by real-time PCR. Bortezomib, carfilzomib, ABT199 and ibrutinib were purchased from Sellekchem. Results: To determine the functional impact of BCR and Bcl-2 signaling in PI-resistance, as well as therapeutic sensitivity of PI-resistant cells to their inhibitors (ibrutinib, ABT-199, respectively), we established and characterized WM cell lines resistant to carfilzomib. BCWM.1/CR cells showed approximately 20-fold resistance to carfilzomib (IC50 = 92.75nM) and MWCL-1/CR cells approximately 10-fold resistance (Fig. 1A). Both CR clones also displayed some cross-resistance to bortezomib. Gene expression and LNC-RNA profiling demonstrated several changes between carfilzomib-resistant vs. sensitive WM cells. Analysis of proteasome-related mRNA revealed downregulation of PSMB5, PSMB1, PSMB2 and PSMB8. Similarly, profiling of BCR-associated genes demonstrated decreased expression of several components, including BTK and SPI1. This observation functionally manifested as reduced sensitivity to the BTK-inhibitor ibrutinib, wherein CR cells displayed 1.5 - 2 fold growth resistance to ibrutinib on 72hr MTS assay. Next we examined the expression of Bcl-2 family members in CR cells. Intriguingly, we observed that Bcl-2 and Mcl-1 were significantly downregulated but XIAP (inhibitor of apoptosis) was significantly increased in CR cells vs. wildtype WM cells- both at transcriptional and translational levels. This suggested that upon acquisition of CR, a transcriptional shift towards XIAP occurs to accommodate sustained therapeutic stress from carfilzomib and maintain steady antiapoptotic composure. To test if the PI-resistant cells have moved away from their survival dependence on Bcl-2, we treated CR cells to increasing concentrations of the Bcl-2-specific inhibitor, ABT199, and as anticipated, CR cells displayed reduced apoptosis in presence of ABT199 compared to wildtype WM cells (32% annexin-V staining vs. 50%, respectively) (Fig. 1B). Conclusions: Our study sheds insight into the differential drivers of PI-resistance particularly towards carfilzomib, in WM cells. We demonstrate that acquisition of CR is associated with downregulation of Bcl-2 and Mcl-1, which is countered by upregulation of XIAP- an event that renders CR cells resistant to ABT199 (as it targets only Bcl-2). Likewise, downregulation of BCR-related components in CR cells was associated with reduced sensitivity towards ibrutinib. These observations suggest that acquisition of resistance to PI such as carfilzomib can impact future treatment with agents such as ibrutinib or ABT199. Our preclinical models provide rationale or early sequencing of ibrutinib or ABT199 in therapeutic planning of WM patients prior to induction of PI resistance. Figure 1. Figure 1. Disclosures No relevant conflicts of interest to declare.

Abstract Background: While B-cell receptor (BCR) signaling is essential for the development, of normal B cells, its aberrant hyper-activation results in neoplastic transformation of B-lymphocytes. Recent investigations using small molecule inhibitors validate the BCR pathway as a valuable target. Bruton’s tyrosine kinase (BTK) is one of the components of a signaling hub that transduces signals from the BCR into the cell for its activation and has been shown to be a therapeutic target. Ibrutinib (PCI-32765), an irreversible BTK inhibitor has shown clinical efficacy in CLL, mantle cell lymphoma (MCL) and Waldenströms macroglobulinemia (WM). Ibrutinib binds to cysteine-481 of the BTK protein and blocks its phosphorylation, resulting in termination of BCR-mediated activation of cells with a concomitant induction of death. Despite the clinical success of ibrutinib, a high percentage of patients achieve only partial response and eventually acquire resistance to the drug, resulting in aggressive relapse of the disease. A mutation of Cys481-Ser in BTK (ibrutinib-BTK binding site) has been reported to be one of the reasons for the development of ibrutinib resistance (IR). To understand the mechanisms resulting in acquisition of IR, we developed preclinical models of IR in WM and MCL. Materials: Ibrutinib was obtained from Pharmacyclics, CA. Validated human WM models (BCWM.1, RPCI-WM1 and MWCL.1 cell lines) and human MCL models (Jeko-1 and Maver cell lines) were used for the study. Results: BTK was constitutively phosphorylated at Y223 and Y551 in all the cell lines tested and this was inhibited by ibrutinib in a dose dependent manner. Phosphorylation of other kinases in the cascade such as SYK (Y323 and Y525/526) and PLCg2 (Y759 and Y1217) were also inhibited while AKT phosphorylation at both Ser473 and Thr308 was consistently increased in presence of ibrutinib. Treatment with ibrutinib induced cell cycle arrest in the G1 phase by 24h followed by apoptosis. Cell growth assays (MTS assay) showed that BCWM.1 was the most sensitive cell line followed by MWCL-1, RPCI-WM1, Maver and Jeko-1. Exposure of WM and MCL cells for prolonged periods of time with progressively increasing concentrations of ibrutinib resulted in outgrowth of clones (IR WM and MCL cell lines) that were resistant to apoptosis with a slow growth rate as compared to wild type parental cells. IR cells attained 2 – 20 fold resistance to ibrutinib as compared to the respective parental lines as determined by MTS assay. Sequence analysis of the BTK gene in all the cell lines revealed no mutation in IR cells at Cys481 suggesting that in an acquired IR state, resistance to ibrutinib can be developed independent of BTK Cys481 mutation. Interestingly, we found p-BTK levels to be markedly reduced in IR cells. Ibrutinib reversal experiments suggested that while a continuous presence of ibrutinib is needed for inhibition of BTK phosphorylation, a stable IR state could be maintained (for >1 month) in the absence of ibrutinib. This suggested the cells reliance on a parallel survival pathway, independent of BTK phosphorylation. Focused mRNA (Nanostring nCounter assay) and immunoblot analysis revealed significant changes in the expression profiles of several cellular elements. These included transcription factors such as PU.1, IRF4, BLIMP1, BCL-6 b-catenin as well as the phosphorylated ERK1/2, STAT1 and 3 suggesting a reprogramming of critical cellular networks, which IR tumor cells might be utilizing to overcome ibrutinib-induced cytotoxicity. Importantly, we observed that IR cells retained high levels of p-AKT and showed an increase in expression of BCL2 family members, as well as BCL-2 itself. Treatment of IR cells with ibrutinib +/- MK2206 (AKT inhibitor), or ABT-199 (BCL-2 inhibitor), synergistically induced cytotoxicity in IR cells, suggesting the importance of these parallel survival pathways (AKT/BCL2) in maintaining an IR state. Conclusion: Here we demonstrate that in the absence of BTK Cys481 mutation, an IR state is associated with reprogramming of transcriptional networks countering ibrutinib-induced toxicity by activation of AKT and BCL-2. Our current data exposes multiple vulnerabilities within IR cells, which can be therapeutically exploited to potentially delay onset of IR, by targeting alternative oncogenic mechanisms that are activated in presence of sustained BTK inhibition. Disclosures No relevant conflicts of interest to declare.

Abstract Multiple myeloma (MM) is 2-3 times more common among African-Americans compared to non-Hispanic whites. The 2-3-fold increased risk among family members of cases suggests a genetic contribution to risk. Genome-wide association studies (GWAS) in populations of European ancestry have identified seven novel risk loci at 2p23.3 (rs6746082), 3q26.2 (rs10936599), 3p22.1 (rs1052501), 6p21.32 (rs2285803), 7p15.3 (rs4487645), 17p11.2 (rs4273077) and 22q13.1 (rs877529) (Broderick, et al. Nat Genet, 2011, Chubb, et al. Nat Genet, 2013), three of which were replicated in another European series (Martino et al., Br J Haematol, 2012). Here we examined the index signals and conducted fine-mapping for each locus in a case-control study of 1,049 multiple myeloma cases and 7,084 controls of African ancestry to identify better markers of risk and novel independent loci in seven previously reported regions in this high risk population. Incident cases were recruited from 10 clinical centers and SEER cancer registries from 2011 to 2013 and genotyped using the Illumina HumanCore GWAS array. Control data were obtained from previous genome-wide studies of breast and prostate cancer, genotyped using the Illumina 1M-Duo in 4425 male controls from the African Ancestry Prostate Cancer Consortium (consisting of 14 independent studies) and 2632 female controls from a breast cancer GWAS of African-American women (consisting of 9 independent studies). Imputation to 1000 Genomes (March 2012 release) was conducted for regions around six of the previously identified single nucleotide polymorphisms [SNPs] (the HLA region harboring rs2285803 is still being imputed, results will be presented). A case-control analysis of SNPs/indels >1% frequency within 250 kb of each index variant was conducted using unconditional multivariable logistic regression adjusting for age, sex and five leading principal components. Region-specific alpha levels were determined through permutation tests. The minimum alpha level across the six regions was α=0.002. All previously reported risk variants were common in African-Americans (minor allele frequency [MAF] >0.05). For five of the six SNPs, we had ≥94% power to detect the same effect observed in non-Hispanic whites, and 64% power for the less common variant rs10936599 (MAF=0.07). We observed directionally consistent effects (odds ratio [OR]>1) for the six risk variants tested, with three replicating at p≤0.05 (7p15.3, p=1.4x10-7; 17p11.2, p=0.05; 22q13.1, p=0.02). For three of the six regions, we observed better markers of risk in African-Americans that were correlated with the index SNP in Europeans (7p15.3, rs56333627, p=1.5x10-5, r2=0.89; 17p11.2, rs34562254, p=2.9x10-3, r2=0.90; 22q13.1, rs2092410, p=1.1x10-4 r2=.71). The missense variant identified in the 17p11.2 region (rs34562254, Pro251Leu) is located in TNFRSF13B, which encodes the protein TACI, a B cell surface receptor which plays a role in B cell maturation, apoptosis and antibody production by inducing activation of transcription factors including NFAT and NFκβ. In addition, there is evidence suggesting that TACI is involved in MM pathogenesis. Our results demonstrate that many of the risk loci for MM found in European ancestry populations are also risk loci in men and women of African ancestry and that by fine-mapping, we are able to identify variants that better capture risk in populations of African ancestry. Disclosures Terebelo: Celgene Corp: Membership on an entity's Board of Directors or advisory committees. Lonial:Millennium: The Takeda Oncology Company: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Onyx Pharmaceuticals: Consultancy, Research Funding.

Abstract Background:The pathological behavior of Waldenströms macroglobulinemia (WM) cells relies on aberrant B-cell receptor (BCR), and Toll-like receptor (TLR) signaling and is intricately supported by malfunctions in initiation of apoptosis. In this dynamic, a complex shift between functionally active pro-apoptotic and anti-apoptotic proteins from the Bcl-2 family occurs and bestows the malignant cells with a significant survival advantage. This defective apoptotic signaling is associated with aggressive clinical behavior, chemoresistance, and a poor prognosis in many B-cell cancers, including WM. Thus, BCR/TLR induced proliferation and abnormal apoptotic signaling due to dysregulation of Bcl-2 signaling, act in concert for the assurance of the malignant WM cells survival. Clinically, mitigation of BCR signaling with the first in class BTK inhibitor, ibrutinib, has shown promising results in WM and other B-cell cancers. However, clinical responses to the BTK inhibitor alone are less than optimal and development of ibrutinib-resistant disease is being recognized as an important and impending dilemma. We have previously shown the utility of disrupting pro-apoptotic Bcl-2 protein interactions in WM, chronic lymphocytic leukemia and multiple myeloma and that this functional interference results in re-sensitization (or heightened sensitivity) of tumor cells towards chemoimmunotherapy. As such, we examined the effects of ABT-199, a Bcl-2 specific small molecule inhibitor, in preclinical models of WM. Importantly; we conducted this investigation in proprietarily developed WM cells that have acquired resistance mechanisms towards either ibrutinib (IR WM subclones) or bortezomib (BR WM subclones). Materials:WM cell lines (BCWM.1, MWCL.1 and RPCI-WM1; WT cells) including their bortezomib resistant (BR) or ibrutinib resistant (IR) subclones were used in this study. Results: An initial comparison of Bcl-2 family members, Bcl-2, Mcl-1, BCL-xL, A1 (anti-apoptotic members), Noxa, Puma, Bim (pro-apoptotic initiators) and Bak and Bax (pro-apoptotic effectors), revealed that BR WM cells express increased levels of pro-apoptotic Bcl-2 family members, particularly Bcl-2, relative to WT cells. Similarly, A1 and Bcl-2 levels were up regulated in IR cell lines suggesting that the Bcl-2 mediated survival pathway is involved in resistance to both bortezomib and ibrutinib. Cell growth (MTS) assays using ABT-199 indicated that both BR and IR cells were equally sensitivity to Bcl-2 inhibition, with an IC50 ranging between 2 – 4mM. ABT-199 induced a dose dependent increase in MOMP with concomitant induction of apoptotic cell death, the latter confirmed by observation of PARP-1 cleavage. ABT-199 induced an intrinsic apoptotic program with the activation of caspase 9 and caspase 3 in all the cells tested. This data indicated the Bcl-2 pathway as being relevant and essential in WM cell lines even under drug resistant conditions. To evaluate the priming effect of ABT-199 on bortezomib and ibrutinib induced cell death, MTS assays were performed with these drugs in presence of IC25 concentrations of ABT-199. The addition of ABT-199 significantly reduced the IC50of both bortezomib and ibrutinib in WT, BR and IR cells. This suggested that re-sensitization of BR and IR cells towards either bortezomib or ibrutinib, respectively, was possible in presence of ABT-199. Further, combined addition of ABT-199 with bortezomib or ibrutinib showed synergistic cell death (combination index range: 0.004 – 0.6, CalcuSyn, Biosoft UK) in BR or IR WM cells, respectively. Conclusion: Dysregulation of Bcl-2 signaling is associated with the pathogenesis and promotion of drug resistance in B-cell cancers, including WM. Our report is first to highlight in WM preclinically, the antiproliferative effect of disrupting Bcl-2, through use of ABT-199. Altogether, our data suggests that therapeutic interference of Bcl-2 function with ABT-199 complements the anti-WM activity of ibrutinib or bortezomib in a synergistic manner and can in fact restore sensitivity of either drug in WM cells that are resistant to proteasome or BTK inhibitors. Focused mRNA and protein profiling analyses are currently underway to delineate the mechanisms accounting for synergy observed between concomitant Bcl-2/BTK inhibition as well Bcl-2/proteasome inhibition. Disclosures Ansell: Biothera: Research Funding. Martin:Janssen: Honoraria. Coleman:Celgene: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Millennium: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Onyx: Speakers Bureau.

Abstract Abstract 757 Background: Chronic lymphocytic leukemia (CLL) is the most common leukemia seen in adults. Previous population-based research in CLL has not represented the current ethnic makeup and diversity within the US population. We undertook a large Surveillance Epidemiology and End Results (SEER) based analysis to assess disparities in outcome among different ethnic subgroups of CLL patients, so that therapeutic resources can be utilized effectively. Methods: The SEER-18 Registry (1973–2009) was used to retrieve a population of 60,293 patients with established diagnosis of CLL (Histology code: 9823). The cohort was restricted to adults (>18 yrs) diagnosed after January 1, 1992, since ethnic minorities were underrepresented in SEER prior to that. Cases reported in death certificate/autopsy, those without a confirmatory diagnosis, those with ethnicity recorded as unknown/other or those that did not have follow up post diagnosis were excluded. Using Cox proportional hazards models, adjusted for confounding variables, association between patient characteristics and survival (overall; OS and CLL-specific; CLLSS) was evaluated. Analysis was performed utilizing the SAS software (v9.2). All statistical tests were two-sided with a significance level of 5%. Results: A total of 37,834 patients (22,581 males; 60%, 15,253 females; 40%) were included in the final analysis. Age group (yr) cohorts included: 18–44 (861; 2%) 45–54 (3,587; 9%), 55–64 (7,684; 20%), 65–74 (10,966; 29%), and ≥75 (14,736; 39%). For survival trends over time, stratification by year of diagnosis was used: 1992–1999 (9,837; 26%), 2000–2004 (14,129; 37%), 2005–2009 (13,868; 37%). Stratification by race/ethnicity included: White (32,980; 87%), African-American (AA: 2,486; 7%), Hispanic (1,536; 4%), Asian (737; 2%), and Native American (NA: 95; 0.25%). Median age ranged from 68 yr (AA and Asian) to 71 yr (Whites) (Figure 1). For survival analysis, NA ethnic group was excluded due to their small numbers. Females had a significantly better median OS (8.3 yr vs. 6.4 yr; p<0.001) as well as CLLSS (p<0.001) than males, when evaluated for the whole population and across different age groups. Both, OS and CLLSS progressively and significantly (p<0.001) declined with advancing age. Progressive significant improvement was seen in OS over time across cohorts by year of diagnosis (6.3 yr, 7.3 yr, 7.4 yr; p<0.001). This improvement in OS persisted over time for age groups <75 yr, but for ≥75 yr, the improvement was lost in the most recent time period cohort (2005–2009). The percentage of patients dying of CLL has decreased progressively over time suggesting an improvement in therapy. Among various ethnicities, Asians had the best (7.5 yr) and AA had the worst (4.8 yr) OS (p=0.006) (Figure 2) and CLLSS (p<0.001). In a multivariate model, AA continued to have the worst OS across all age groups (p<0.001), while Whites had the best OS in age groups <75 yr and Asians had the best among patients ≥75 yrs. Percentage of patients dying from CLL was highest in AA across age groups, but lowest for Whites in age groups <75 yr, while in Hispanics in patients ≥75 yr. Trends in CLLSS were noted to be more heterogeneous among ethnicities than trends in OS. Conclusions: This report presents the largest population-based analysis of patient characteristics including ethnicity and survival in CLL in the era of novel therapeutic agents. Older patients had worse OS among all ethnic subgroups. Progressive improvement in CLLSS was noted over time suggesting a possible impact of new therapeutics, however this was not seen in ≥75 yr patients. AA patients had the worst OS among all ethnicities and age groups. This survival difference was most significant and pronounced in younger patients, which has important implications. For example, this survival disadvantage may represent poor access to optimal healthcare warranting development of new initiatives directed towards this ethnic minority. On the other hand discrete biological variants may underlie the more aggressive disease biology in younger AA patients underscoring the need to further investigate and delineate the molecular biology of CLL in ethnic minorities. Studies of outcome disparities are important not only for evaluating disease characteristics but also management needs of specific patient populations and are critical for designing programs to deliver optimal healthcare to ethnically diverse populations. Disclosures: No relevant conflicts of interest to declare.