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Abstract Cyclin Ds are key regulators of the cell cycle that are frequently over-expressed in multiple myeloma and leukemia and act to promote the phosphorylation of Rb, thereby facilitating the transition from G1 to S phase. Over-expression of cyclin Ds increases cell proliferation and chemoresistance. In contrast, reducing cyclin Ds levels directly or indirectly through G1 arrest can decrease cellular proliferation and induce apoptosis. To identify novel pharmaceutical inhibitors of cyclin D transactivation, we screened the LOPAC and Prestwick libraries of drugs and natural compounds (n = 2400) using NIH 3T3 cells stably expressing the Cyclin D2 promoter-driving a luciferase reporter gene. From this library screen and subsequent validation experiments we identified Cyproheptadine as a novel inhibitor of Cyclin D2 transactivation. Cyproheptadine has been used previously for the treatment of atopic dermatitis and anorexia, but its ability to inhibit cyclin D expression has not previously been reported. By immunoblotting, Cyproheptadine decreased expression of cyclin D1, D2 and D3 proteins in human myeloma and leukemia cell lines at low micromolar concentrations. Consistent with effects on the cyclin Ds, Cyproheptadine arrested cells in the G1 phase at concentrations associated with reduction in cyclin D expression. Decreased cyclin D expression and G1 arrest can induce apoptosis, so we tested the effects of Cyproheptadine on cell viability. Myeloma and leukemia cell lines were treated with increasing concentrations of Cyproheptadine and viability was measured by the MTS assay. Cyproheptadine reduced the viability of 7/10 myeloma and 7/8 AML cells lines with an IC50 ranging from 10–25μM. In contrast, it was less toxic to HeLa or NIH3T3 cells with IC20 > 50 μM. Cyproheptadine also reduced the viability of primary myeloma (8/8) and AML patient samples (7/9) with an IC50 <25 μM, but was less toxic to normal hematopoietic cells (IC20 > 50 μM). In a MDAY-D2 mouse model of leukemia, treatment with Cyproheptadine (50mg/kg/d) abolished formation of malignant leukemic ascites without untoward toxicity. Cyproheptadine-induced cell death was associated with reductions in mitochondrial membrane potential. Furthermore, reductions of pro-caspases -3 and -9 were observed prior to the reduction in pro-caspase-8, indicating that Cyproheptadine activates the mitochondrial pathway of caspase activation. Cyproheptadine is a known H1 histamine and serotonin receptor inhibitor, but pre-incubation with histamine, serotonin, or a combination of histamine and serotonin did not abrogate Cyproheptadine-induced cell death. Moreover, the structurally related H1 receptor inhibitor loratadine did not decrease cyclin D expression or reduce cell viability. Therefore, the pro-apoptotic activity of Cyproheptadine is not due to a competitive inhibition of the H1 and/or serotonin receptors, suggesting that Cyproheptadine has additional targets. In summary, Cyproheptadine arrests cells in G1, reduces cyclin D expression, and induces apoptosis via the mitochondrial pathway of caspase activation. Given the prior safety and toxicity record of Cyproheptadine, this drug could be rapidly advanced into clinical trial for the treatment of hematologic malignancies.

e19505 Background: CFZ combined with dexamethasone is approved to treat pts with RRMM, with CFZ given once-weekly at 70 mg/m2 (Kd70 QW) or twice-weekly at 56 mg/m2 (Kd56 BIW). No randomized trials have directly compared Kd70 QW with Kd56 BIW. We performed a post hoc comparison between pts who received Kd56 BIW in the ENDEAVOR trial and pts who received Kd70 QW in the A.R.R.O.W. or CHAMPION-1 trials. Methods: Data were analyzed from 3 trials of CFZ in RRMM: A.R.R.O.W. (240 pts in Kd70 QW arm; 2–3 prior therapies and refractory to most recent therapy), CHAMPION-1 (104 pts received Kd70 QW; 1–3 prior therapies), and ENDEAVOR (464 pts in Kd56 BIW arm; 1–3 prior therapies). Pts who received Kd70 QW in A.R.R.O.W. and CHAMPION-1 were pooled and compared with pts who received Kd56 BIW in ENDEAVOR. As study populations slightly varied among the 3 trials, an analysis of safety and efficacy was performed in a subgroup of pts who received 2–3 prior therapy lines and were not refractory to bortezomib (BTZ). Also, we performed regression analyses (controlling for age, ISS stage, BTZ and lenalidomide refractory status, and number of prior regimens) among all pts in the trials who received Kd70 QW or Kd56 BIW. Results: Among BTZ non-refractory pts with 2–3 lines of prior therapy, median progression-free survival (PFS) was 12.1 months (95% CI 8.4–14.3) for Kd70 QW (n = 146) and 14.5 months (95% CI 10.2–NE) for Kd56 BIW (n = 217), and the overall response rate (ORR) was 69.9% (95% CI 61.7–77.2) for Kd70 QW and 72.4% (95% CI 65.9–78.2) for Kd56 BIW. The rate of grade ≥3 adverse events (Kd70 QW vs Kd56 BIW) was 67.6% and 85.3%; among adverse events of interest, the grade ≥3 rate was 1.4% and 5.1% for cardiac failure, 3.4% and 6.0% for renal failure, and 5.5% and 15.7% for hypertension. Kd70 QW represents a convenient and well-tolerated treatment modality for pts with RRMM. In a Cox proportional hazards model, the hazard ratio for PFS (Kd70 QW vs Kd56 BIW) was 0.91 (95% CI 0.69–1.19), and in a logistic regression model the odds ratio for ORR (Kd70 QW vs Kd56 BIW) was 1.12 (95% CI 0.74–1.69). Conclusions: This post hoc analysis suggests that once-weekly Kd70 has a comparable benefit-risk profile to twice-weekly Kd56. Clinical trial information: NCT02412878, NCT01677858, NCT01568866.

8589 Background: Denosumab (dmab) is a fully human monoclonal antibody against RANKL and is superior to ZA in preventing skeletal-related events (SREs) as shown in 3 identically designed phase 3 trials (N=5723). Overall survival (OS) was balanced between treatment groups in the overall study populations of these trials. In the trial of patients (pts) with solid tumors (excluding breast and prostate) and multiple myeloma (MM), OS was longer for dmab pts with lung cancer, shorter for pts with MM, and balanced for pts with other solid tumors. This analysis further characterizes the results from the MM subset of this trial. Methods: Pts with solid tumors or MM were randomized (1:1) to receive 120 mg of SC dmab or 4 mg of IV ZA Q4W. Daily calcium and vit D supplements were strongly recommended. The primary endpoint was the time to first on-study SRE; results from the primary endpoint and lung cancer subset were previously reported. Results: Of 1776 randomized pts, 10% had MM (93 ZA, 87 dmab). OS favored ZA (hazard ratio: 2.26; 10 subject difference in deaths). 1-year OS was 83% dmab, 97% ZA. Imbalances in baseline prognostic characteristics were observed. More pts in the dmab arm had low baseline renal function (CrCl < 40 mL/min) (ZA 2 [2%], dmab 9 [10%]) and more ZA pts underwent stem cell transplant (ZA 23 [25%], dmab 15 [17%]). Additionally, more ZA pts had stage I tumors at diagnosis (ZA 13 [14%], dmab 9 [10%]) and better performance status (ECOG = 0; ZA 30 [32%], dmab 21 [24%]). Study discontinuations due to consent withdrawal or lost to follow-up were also higher in the ZA group (ZA 17 [18%], dmab 11 [13%]) and occurred earlier in the ZA arm (ZA 59%, dmab 45% within 9 months of randomization). Conclusions: In this SRE study of dmab vs ZA, pts were stratified by baseline characteristics known to affect SRE outcomes, but not by prognostic factors or concurrent anticancer therapy that may impact survival in MM. OS results in the MM cohort are difficult to interpret due to small sample size and imbalances in baseline disease characteristics, stem cell transplant therapy, and consent withdrawal or loss of follow-up that favored ZA. A phase 3 trial is currently underway, which controls for these factors in pts with MM. Clinical trial information: NCT00330759.

8053 Background: Lenalidomide (LEN) is an immunomodulatory agent that has shown significant single-agent anti-lymphoma activity in patients with relapsed disease and in combination may enhance the efficacy of rituximab by various mechanisms. There is limited data on the role of LEN in combination regimens for treatment-naïve patients. This phase II single arm trial was designed to evaluate tumor response, toxicity (AE) and survival with a combination of LEN, rituximab, cyclophosphamide (CTX) and dexamethasone (DEX) (LR-CD) in symptomatic untreated patients with low grade B-cell non-Hodgkin lymphoma. Methods: Eligibility required age ≥18, ECOG PS ≤2, confirmed diagnosis of low-grade B-cell lymphoma (FL1-2, SLL, MZL or LPL/WM), measurable nodes ≥2cm or IgM ≥400mg/dL(LPL/WM), ANC ≥1400/mm3, platelets ≥100,000/mm3, creatinine ≤2mg/dL, signed informed consent and in need of therapy. Treatment consisted of IV rituximab 375mg/m2 D1, oral LEN 20mg D1-21, CTX 250mg/m2 D1, 8, 15, DEX 40mg D1, 8, 15, 22 and ASA 325 mg daily in a 28 day cycle. Treatment continued 2 cycles beyond best response (max 12). Toxicity was assessed by NCI CTCAE v3.0. Results: 28 patients have enrolled at Mayo Clinic with 25 evaluable for toxicity and 21 for response: Median age 65(43-83), 72% male, FL 24%, MZL 28%, LPL/WM 38%, and SLL 4%. Median number of cycles given was 5. Overall response in 21 patients with response data is 95% (95% CI 76-100%) with 19% CR (95% CI 5-42%), and 76% PR (confirmed and unconfirmed, 95% CI 53-92%). The ORR in 8 patients with LPL/WM with response data was 88%, all PR (95% CI 47-100%). At a median f/u of 14.7 months 96% are alive without progression. 1 death (unrelated) occurred 7.7 months after completing 12 cycles of treatment. The most common grade ≥3 AEs were neutropenia (37.5%), leukopenia (16.7%), anemia (12.5%) and fatigue (12.5%). Conclusions: The combination LR-CD with the novel agent LEN is feasible, well tolerated and produces high response rates in symptomatic patients with low grade B-cell NHL. Toxicities are manageable and similar to reported data of single agent LEN.

8013 Background: Obatoclax mesylate (GX15-070MS) is a BH3 mimetic that inhibits Bcl-2 protein family members including MCL-1, a dominant target in myeloma (MM). Obatoclax (OBX) inhibited viability of 14 MM cell lines (mean IC50 215 nM) and primary MM samples while exhibiting pre clinical synergy with bortezomib (BTZ). Sensitivity correlated with basal levels of Mcl-1 and Bcl-XL, but not Bcl2, Bim, Bax or Bak expression. Methods: We report a phase I trial of OBX in combination with BTZ. Eligibility required measureable disease, > 1 prior MM therapy, ≤10 cycles of prior BTZ and did not progress on prior BTZ therapy, creatinine ≤2 ULN. Starting dose level 1 was OBX 14 mg/m2 24-hour continuous iv. infusion days 1, 8, 15 of a 21-day cycle. BTZ given at 1.3mg/m2 iv. days 1, 4, 8 and 11. After protocol amendment OBX level 1 dosing was 30 mg/m2, level 2 was 40 mg/m2 IV both by continuous 3 hour infusion days 1, 8 and 15 on a 21 day schedule. Pre med. with famotidine was required. Results: Eleven patients were accrued, median age 62 (range: 46-77), median time from diagnosis was 4.7 years. Median of 2.5 cycles (range: 1-10). Median follow-up for patients still alive is 11.6 months (range: 0.9-35.5). At dose level 1, there were 2 DLTs. After amendment 8 patients were accrued (3 hour infusion): 4 at amended dose level 1 and 4 at dose level 2. All patients are now off treatment. 10 patients are evaluable for response: 2 patients at original dose level 1 (2 PR), 3 patients at dose level 1 (2 PR, 1 MR), no patients at dose level 2 responded: overall PR of 40%, clinical benefit response in 50% (95% CI: 19-81%). 6 patients had disease progression and 2 patients died. 4 DLTs were seen: at original dose level 1 grade 4 thrombocytopenia and delay of therapy > 15 days. At dose level 2, 1 patient had grade 3 somnolence, a 2nd patient grade 3 euphoria and grade 4 thrombocytopenia. No DLTs were seen at amended dose level 1. Common adverse events of any grade included GI, hematologic and neurologic e.g. euphoria, decreased level of consciousness, psychosis, speech. Conclusions: In summary MTD is OBX 30mg/m2 by 3 hour iv infusion once weekly, BTZ 1.3 mg/m2 days 1,4,8, and 11. Major toxicities were central neurologic and hematologic. This P2C consortium study was supported by NCI N01-CM62205.

8010 Background: Carfilzomib is a proteasome inhibitor that irreversibly binds its target with favorable toxicity profile that has shown significant activity in relapsed multiple myeloma (MM). Here we used carfilzomib as the center of a 4 drug induction regimen designed for MM patients pre stem cell transplant (SCT). Methods: We conducted a phase I safety run in 6 patients with no DLT observed before expanding to phase II. The phase II regimen is shown below. Treatment was for 4 cycles with expected SCT post induction. For the phase II portion of this trial, the primary endpoint is the proportion of patients who have ≥ very good partial response to treatment. All patients received herpes zoster prophylaxis and ASA daily. Results: Twenty seven patients were enrolled. Median age was 65 (range 27-74). ORR for evaluable patients (n=17) at phase II dosing is 100%: CR 35%, VGPR 48%, PR 18% after 4 cycles of CYCLONE. Grade 3 toxicity was reported in 52% of patients and 14% experienced a grade 4 toxicity. Grade 3/4 toxicities occurring in >5% of patients included fatigue, neutropenia, lymphopenia, thromboembolism, myopathy. Toxicities of any grade seen in >20% of patients included fatigue, constipation, lethargy, thrombocytopenia, somnolence, creatinine increased, malaise. Four patients (20%) developed grade 1 sensory neuropathy; no higher grade or painful neuropathy was evident. All patients are alive. All patients advancing to SCT successfully collected stem cells. One patient with t(4;14) disease who was not transplanted has progressed. 94% remain progression free. Conclusions: The 4 drug CYCLONE regimen has remarkable efficacy (83% ≥VGPR) and manageable toxicity in newly diagnosed patients with multiple myeloma. Especially notable was the low incidence of neuropathy and depth of response (CR 35%) after only 4 cycles. Given the relative lack of toxicity an extension of this regimen at higher doses of carfilzomib (20/45mg/m2) has been initiated. [Table: see text]

8035 Background: Patients (pts) with relapsed and refractory multiple myeloma (RR MM) who are refractory or intolerant to both bortezomib (BTZ) and immunomodulators (IMiDs; thalidomide [Thal] or lenalidomide [Len]) (ie, “double-refractory/intolerant”), have few therapeutic options and a poor prognosis. Carfilzomib (CFZ), a next generation proteasome inhibitor (PI), has shown durable single-agent activity in clinical studies including 003-A1, an open-label, single-arm phase 2b trial in RR MM. The present analysis describes clinical activity in pts from 003-A1 with double-refractory/intolerant disease and in other groups of clinical interest including pts with disease refractory to all 5 approved classes of anti-MM tx (alkylators, anthracyclines, corticosteroids, IMiDs, and PIs) in clinical use (“refractory to all approved tx”). Methods: Pts from 003-A1 with double-refractory/intolerant disease were analyzed, as were pts with disease refractory to all approved tx. CFZ was given on days 1, 2, 8, 9, 15, 16 of 28-day cycles (C), (20 mg/m2 in C1; 27 mg/m2 in C2–12). Primary endpoint was overall response rate (ORR). Secondary endpoints included duration of response (DOR), overall survival, and safety. Results: The study ORR was 22.9% with median DOR of 7.8 mo (N=266). 228 pts (86%) with double-refractory/intolerant disease had ORRs of 20.6% and a median DOR of 7.4 mo. Conclusions: Single-agent CFZ demonstrated clinically meaningful, durable responses in pts with double-refractory/intolerant MM or disease refractory to all 5 approved classes of tx. The ORRs across groups of clinical interest were generally consistent with results for the entire study population. These results are notable for a next-generation PI and demonstrate the activity of single-agent CFZ in pts with advanced stage MM. [Table: see text]

17502 Background: CHIR-258 is an orally active small molecule receptor tyrosine kinase (RTK) inhibitor which has potent activity against multiple RTKs involved in tumor growth and angiogenesis (IC50 ≤13 nM for FGFR, VEGFR, PDGFR, C-KIT, and FLT3). Approximately 15% of newly diagnosed MM patients harbor a t(4;14) translocation, which results in ectopic expression of FGFR3 and MMSET and is associated with poor treatment outcome [0]and reduced survival. CHIR-258 inhibits proliferation and induces apoptosis in FGFR3-expressing MM tumor xenografts as well as FGFR3-expressing primary MM cells (Trudel et al, Blood 2005). CHIR-258 was synergistic with dexamethasone (dex) in vitro. Methods: CHIR-258 was administered once daily in a dose-escalating phase 1 study to patients with relapsed/refractory MM. Drug tolerability and safety, pharmacokinetics (PK) and pharmacodynamics (PD) were assessed. Results: as of December 2005, 9 total pts have been treated (50, 100, and 200mg qd cohorts) [6M, 3F; median age: 58 (range: 44–68), median of 3 prior therapies(range:1–7)]. Prior tx: 9/9 pts-thalidomide; 8/9 -Velcade; 8/9-transplant; 8/9- had progressed through dex. 4 of 9 pts treated were FGFR3+ and 4 pts remain on study (3 are FGFR3+). No CR or PR have been observed; stable disease has been noted. CHIR-258 has been generally well tolerated, and most drug related AEs were CTC grade 1 or 2, including: headache, dysgeusia, fatigue and anorexia. No neuropathy. One DLT has been observed to date: neutropenia (200mg cohort). Five pts had dex added to CHIR-258 of which 3 are ongoing (all FGFR3+). FGFR3+ pts receiving dex and CHIR-258 have a greater decline in urine and serum paraproteins (pp) vs CHIR-258 alone. Plasma exposure and Cmax increased proportionally across the doses. Conclusions: CHIR-258 is a novel inhibitor of RTKs involved in MM growth and proliferation. FGFR3+ pts have a more marked reduction in pp than FGFR3- pts. CHIR-258 has generally been well tolerated and further accrual continues. [Table: see text]

8007 Background: We recently described mutations in multiple genes in MM patients that lead to the activation of the non- canonical NF-KB pathway. Among the mutated genes, TRAF3 is the most commonly affected, and is inactivated in about 20% of patients. In this study, we further defined the clinical significance of TRAF3 inactivation in MM. Methods: Deletion of TRAF3 was identified by array- based comparative genomic hybridization using Agilent Human Genome CGH 44k oligonucleotide array and confirmed by fluorescent in situ hybridization. Mutations were detected by sequencing. We use a TRAF3 gene expression cut-off (derived from 127 Mayo clinic patients) as a surrogate for TRAF3 inactivation to investigate its association with Translocations and Cyclin D genetic subtypes, response rates, and survival using 2 large gene expression dataset: UAMS dataset (559 newly diagnosed patients treated with Total therapy II and III) and Millenium datasets (213 relapsed patients entered into randomized study of bortezomib versus dexamethasone). Results: A normalized expression level of less than 0.6 identified all but three of the known TRAF3 inactivated cases in the Mayo dataset (p<0.0001). Using this cut-off, TRAF3 inactivated cases were enriched for t(4;14) (26%, p=0.00002) and rarely D1 (mostly hyperdiploid) (9%, p=9.6E-10) in all 3 datasets. TRAF3 inactivation did not affect survival of patients treated with transplant-based therapy (UAMS and Mayo dataset) but was strongly associated with bortezomib response (89% TRAF3 low versus 40% TRAF3 normal, p0.6 had similar PFS with the two treatment. Conclusion: Mutations resulting in TRAF3 inactivation are common, particularly in non-hyperdiploid MM, and predict for response to bortezomib and resistance to dexamethasone suggesting that inhibition of the non-canonical NF-KB pathway may be one of the principle mechanisms of action of proteasome inhibitors in MM. No significant financial relationships to disclose.

8003 Background: Carfilzomib is a novel, irreversible tetrapeptide proteasome inhibitor derived from the natural product epoxomicin. Carfilzomib was well tolerated in preclinical animal studies when administered on a two-week cycle, QDx5; proteasome inhibition one hour after dosing at the MTD was >80%. Two Phase I dose-escalation studies are ongoing, aimed at determining the safety, tolerability, and biological response to carfilzomib. Methods: Carfilzomib was administered according to two different dose-intensive schedules. In PX-171–001, carfilzomib was administered on a two week cycle, QDx5 with nine days rest; in PX-171–002, carfilzomib was administered on a four week cycle, QDx2 weekly for three weeks with 12 days rest. Eligible patients have multiple myeloma (MM), Non-Hodgkin's Lymphoma (NHL), Hodgkin's Disease (HD), or Waldenström's Macroglobulinemia (WM). Results: Thus far, a total of 54 subjects have been enrolled. Although the maximum tolerated dose (MTD) has not yet been identified on either study, responses seen on both protocols have established 11 and 15 mg/m2 as the minimal effective doses (MEDs) on PX-171–001 and 002, respectively. Of 3 patients with MM or WM treated on the 001 protocol, one MM patient has had a Partial Response (PR) and one WM patient had a Minimal Response (MR). Of 8 patients with MM treated on the 002 protocol, 3 patients have had PRs. 6 additional patients have had Stable Disease lasting longer than 6 months and symptomatic improvement has been seen in patients on both protocols. 11 subjects remain on study with stable disease or better. Proteasome inhibition in whole blood at the highest dose levels exceeded 80% one hour after the first dose. Carfilzomib has been well tolerated at doses at and above the MED thus far. There has been no incidence of painful peripheral neuropathy on either study. No dose-limiting toxicities (DLTs) have occurred on PX-171–001; one DLT (Gr 4 anemia and thrombocytopenia) was observed at 27 mg/m2 on PX-171–002. Conclusions: Thus far, intensive dosing with carfilzomib is well-tolerated at proteasome inhibition levels of more than 80%. Five responses have been observed, and several subjects have achieved long lasting SD and/or symptomatic improvement. No significant financial relationships to disclose.