Tiedemann, Rodger E.

Abstract Abstract 2801 Poster Board II-777 To provide a rationale basis for targeted drug development for multiple myeloma patients, we have conducted high-throughput genome-scale RNA interference (RNAi) synthetic lethality studies in human myeloma cell lines (HMCL) to generate a comprehensive map of critical genes and molecular vulnerabilities in human myeloma tumor cells. KMS11 human myeloma cells were screened with a 13,982-oligo library targeting the ‘druggable' genome (6,991 genes) using optimized conditions that resulted in >95% transfection efficiency. Each gene was screened with 2 or more distinct oligos, in duplicate, using a single-siRNA-per-well format, testing >34,000 wells. Replicate high throughput experiments yielded highly reproducible results (R2=0.82). Viability was measured at 96h by ATP-dependent luminescence. Universally lethal siRNA and non-targeted siRNA were employed as controls. The specificity (FDR) of lethal RNAi was evaluated by custom-developed statistical methods based on RNAi result concordancy. From screening, 5.8% of druggable genome siRNA caused statistically relevant reductions in HMCL viability (greater than three standard deviations from control samples treated with non-silencing siRNA, compared with an anticipated rate due to chance of only 0.135%). Of these, two hundred and nineteen genes, targeted by the most lethal siRNA, were forwarded to validation studies. Validation high-throughput RNAi studies, using 4 oligos per gene, were conducted in order to verify target gene vulnerability. Ultimately, seventy two genes were validated as highly critical for myeloma cell survival (each with multiple concordant siRNA hits plus high reproducibility of R2 =0.94). Among top-ranked lethal molecular vulnerabilities in KMS11 myeloma cells we recurrently identified the proteasome (8 PSM subunits were independently identified as highly vulnerable); and BCL2 family member MCL1; both known therapeutic targets, validating a functional genomics approach to target discovery. In addition, a number of novel, equally lethal, molecular vulnerabilities were identified in KMS11 including WEE1, kinetochore complex component KNTC2, the aurora kinases, polo-like kinase 1, a previously uncharacterized DNA methyl transferase, ribonucleotide reductase, ribosomal protein L38, leptin receptor overlapping transcript LEPROT and SLC25A23 (a carrier responsible for mitochondrial adenine nucleotide flux). Various ubiquitous cellular proteins involved in RNA or protein processing (e.g. SF3a, SNW1, SNRPA1, EIF3s8, amongst others) were also identified as non redundant and critical for cellular viability. Thirty nine top-ranked molecular vulnerabilities in KMS11 were evaluated for comparative vulnerability in a second myeloma cell line, JJN3, and in A549 and 293 epithelial cells. A majority were vulnerable in JJN3. While 25 genes proved equally lethal on silencing in A549 and 293 epithelial cells, several, notably including MCL1 and three proteasome subunits, appear differentially susceptible in myeloma cells versus epithelial cells. From this genome scale study, MCL1 ranks third as a target capable of inducing cell death in myeloma cells, highlighting the potent vulnerability of myeloma cell viability to alterations in this anti-apoptosis regulator. Moreover, from active comparative studies of molecular vulnerability in myeloma versus epithelial cell lines, MCL1 as an RNAi target demonstrates perhaps the greatest cytotoxic selectivity between myeloma and epithelial cell lines of all targets examined. Gene expression studies indicate that MCL1 is highly expressed in myeloma tumor cells but is absent or only weakly expressed in human primary somatic tissues. Overall, therefore, from an unsupervised genome-scale screening approach, our data support MCL1 as an optimal Achilles heel molecular target in multiple myeloma, potentially offering greater specificity and deeper cytotoxic effect than proteasome inhibition. Disclosures: No relevant conflicts of interest to declare.

Abstract The oncogene c-maf is frequently over-expressed in multiple myeloma cell lines and patient samples and contributes to increased cellular proliferation in part by inducing cyclin D2 expression. Therefore, small molecules that inhibit c-maf and its targets could be useful chemical probes to better understand the role and regulation of this protein. We developed a high throughput chemical screen in NIH 3T3 cells stably over-expressing the promoter of the c-maf target cyclin D2 driving firefly luciferase. From a screen of 2400 off-patent drugs and chemicals, we identified 32 compounds that preferentially reduced cyclin D2 transactivation. Of these, 24 of the 32 hits belonged to the corticosteroid family of drugs. Indeed, the screen identified 24 of the 26 corticosteroids in the library. The most potent inhibitors were glucocorticoids such as dexamethasone. Mineralocorticoids such as fludrocortisone were weak hits, reflecting their weak glucocorticoid activity. The 24 glucocorticoids identified in this screen preferentially reduced cyclin D2 transactivation in the presence of c-maf. For example, the IC50 of dexamethasone was 11 ± 0.7 nM and >50 uM in NIH 3T3 cell with and without c-maf, respectively. Given the effects of glucocorticoids on c-maf in NIH 3T3 cells, we extended our investigation to multiple myeloma cell lines and demonstrated that nanomolar concentrations of the glucocorticoid dexamethasone reduced levels of c-maf protein and its target cyclin D2 within 6 hours of treatment. C-Maf was down regulated in isogenic MM1.S but not MM1.R cells respectively sensitive and resistant to dexamethasone. We also observed reductions in another c-maf target, beta integrin. Compared to cell lines RPMI 8226 and OCIMY5 that harbor the t(14;16) c-maf translocation, the concentration of dexamethasone required to reduce c-maf was approximately 50-fold lower in cell lines such as LP1 and OPM1 that lack the translocation but over-express c-maf. While dexamethasone reduced c-maf protein, no changes in levels of c-maf mRNA were detected. In both multiple myeloma and NIH3T3 cells, dexamethasone increased the ubiquitin-dependent destruction of c-maf. Finally, we linked glucocorticoids to c-maf ubiquitination by demonstrating that dexamethasone upregulated ubiquitin C mRNA at concentrations associated with the ubiquitination of c-maf. Moreover, ectopic expression of ubiquitin cDNA recapitulated the effects of dexamethasone and reduced levels of c-maf, suggesting that increased expression of ubiquitin C by dexamethasone is functionally important for dexamethasone’s effects on c-maf levels. Conclusion: a chemical biology screen identified glucocorticoids as c-maf dependent inhibitors of cyclin D2 transactivation. Glucocorticoids reduce c-maf by promoting its ubiquitination via the upregulation of ubiquitin C mRNA. This work provides new insights into the regulation of c-maf and has identified a novel mechanism by which glucocorticoids exert an anti-myeloma effect.

Abstract In an attempt to identify novel genetic abnormalities in multiple myeloma (MM) we analyzed 68 MM patient samples and 42 human myeloma cell lines (HMCL) with high-resolution (60kb) array-based comparative genomic hybridization (aCGH). We concentrated on bi-allelic genomic deletions with the expectation that these regions might contain novel tumor suppressor genes and identified a common abnormality at 14q32. Fine mapping of the 14q32 microdeletion by PCR demonstrated a 45 kb minimal deletion encompassing two genes; TRAF3, a negative regulator of the non-canonical NF-kB pathway, and AMN. To determine the frequency of copy number abnormalities of this region a cohort of 161 patients were screened with a FISH probe mapping to the minimally deleted region. This identified 7 (4.4%) patients with bi-allelic deletion and 19 (11.8%) patients with a single copy of the target region. Sequencing of all TRAF3 coding exons in 62 patients and 42 HMCL identified inactivating mutations in 9 patient samples and 4 HMCL. Overall, the incidence of TRAF3 inactivation, bi-allelic deletion or mutation, is 7/42 (16.7%) in HMCL and 12/62 (19.4%) in patients, making it one of the most common genetic abnormalities identified in MM. Importantly, dysregulation of NF-kB pathways is a common event in MM, but the mechanism for this dysregulation is largely unknown. Although TRAF3 is a negative regulator of the non-canonical NF-kB pathway it has not previously been implicated in cancer. Therefore, we tested the tumor suppressor function of TRAF3 by reintroducing TRAF3 into HMCL harboring TRAF3 abnormalities using an adenovirus gene transfer system. Expression of TRAF3 in HMCL with TRAF3 abnormalities rapidly reversed cellular processing of NFKB2 from p100 (an inactive isoform) to p52 (active) and additionally led to a 60% reduction in cellular proliferation (range, 10–89%) associated with Go/G1 cell cycle arrest and induction of cell death by apoptosis. At 48 hrs post infection the proportion of cells entering S-phase or G2/M declined by 31% (range, 8.1–56.1) and the proportion undergoing apoptosis increased by 28% (range 11.7–47.4%). In contrast, over-expression of TRAF3 in control HMCL without TRAF3 abnormalities had no effect. Overall, TRAF3 is identified as a novel tumor suppressor that regulates the non-canonical NF-kB pathway and is inactivated in ~ 20% of MM patients. Given the involvement of the NF-kB pathway in multiple human malignancies and the near constitutive expression of TRAF3 we propose that inactivation of TRAF3, a novel tumor suppressor identified for the first time in this study, may occur in other cancers. In this regard, we have recently identified a Burkitt lymphoma cell line that does not express TRAF3 and thus has constitutive processing of p100 to p52. The clinical and therapeutic consequences of this finding and its frequency in other tumor types are currently the focus of further investigation. In conclusion, the abnormalities identified in this study represent the first mutations identified that cause constitutive NF-kB activation in MM.

Abstract Plasma cell leukemia (PCL) is an aggressive and rare hematological malignancy that can originate either as primary disease (pPCL) or as a leukemic transformation of multiple myeloma (MMLT). We report here on the clinical characteristics, survival and genetic studies of 80 patients with PCL treated at a single institution (including 41 with pPCL and 39 with MMLT) and make comparisons with 439 newly diagnosed cases of multiple myeloma (MM). From our results pPCL presents a decade earlier than MMLT (54.7 vs 65.3 years) and despite substantially poorer clinical and laboratory parameters at presentation (hepatomegaly 32% vs 11%, leukocytes 31.6 vs 20.9, β2M 8.5 vs 4.3) pPCL appears more responsive to conventional combination chemotherapy (VAD, VBMVP or VBAP) than MMLT and is associated with significantly longer survival (median 18.4 vs 3 months). Comparison of pPCL groups treated with combination chemotherapy (n=21) or with other regimens (40% MP, 10% Thal/Dex, 20% other, 30% none)(n=20) identifies no substantial pre-treatment differences between the groups although a higher proportion of patients who received combination chemotherapy subsequently proceeded to stem cell transplantation (30 vs 10%). Importantly, survival of pPCL patients treated initially with combination chemotherapy (median 13.9, mean 27.3 months) was significantly longer compared with patients who did not receive combination chemotherapy (median 5.2, mean 9.9 months)(p=0.035) with 2 long term survivors (> 7 years) in the chemotherapy group. By comparison, patients with MMLT received less active therapy for their leukemic disease than did patients with pPCL (21% VAD, VBMVP or VBAP; 18% MP). Treated MMLT patients showed selection bias for younger age (60.9 vs 66.4 years) and lack of bone disease (0 vs 65%)(p<0.01); however despite this, median survival was disappointingly short for MMLT patients in the treatment group and was not significantly improved compared with non-treated patients (2.3 vs 0.8 months)(p=0.34). Assessment of novel therapies in PCL is therefore urgently required. Karyotype analysis and targeted genetic studies demonstrate that IgH translocations are present with high frequency in both pPCL and MMLT (71 vs 86%) compared with MM (~50%). Notably, IgH translocation in pPCL is almost exclusively targeted at chromosome 11 (cyclin D1) belying its importance in establishing the phenotype. IgH translocation in MMLT is primarily to chromosome 11 [71%], but also targets chromosomes 4 (FGFR3/MMSET) [13%] and 16 (cMaf) [20%], recapitulating MM. Abnormalities of chromosomes 3,5,7,9,11,13,15 and 19 are present equally in all 3 disorders. Deletion of 17p13 (p53) shows strong selection pressure in the leukemias (pPCL 53.8%, MMLT 48.8%, MM 10.7%) and is complemented by p53 mutation (23%). Notably, pPCL tumors show lower rates of Ras mutation (12 vs 40%) and p14 (0 vs 31%) or p16 (25 vs 40%) promoter methylation than MMLT. Together these results therefore indicate that pPCL and MMLT are fundamentally different plasma cell disorders with distinctive biology, genetic abnormalities and treatment responses.

Abstract Abstract 2741 Background: The novel agent lenalidomide (LEN) has shown significant single-agent activity in patients with relapsed lymphoma through anti-proliferative and immunomodulatory mechanisms. In combination LEN may synergistically improve the efficacy of rituximab. However, there is limited data on the efficacy and safety of LEN in multi-drug combination regimens for treatment-naïve patients. We designed a phase II single arm trial 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 indolent B-cell lymphoma. (NCT00784927). Methods: Eligibility required age ≥18, ECOG PS ≤2, confirmed diagnosis of indolent 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, and signed informed consent. Only patients needing therapy were considered eligible. 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 up to a maximum of 12 cycles. Toxicity was assessed by NCI CTCAE v3.0. Results: Thirty-one patients have enrolled at Mayo Clinic with 28 evaluable for toxicity and response (1 deemed ineligible, 1 withdrew before treatment, 1 treatment violation). Four patients continue on study at this time. Patient characteristics: median age 68.5(43–83), 71% male, stage IV 86%, FL 28%, MZL 25%, LPL/WM 39%, and SLL 4%. Median number of cycles given was 6 and 71% completed the study per protocol. The best overall response is 89% with 32% CR and 57% PR. In subgroup analysis, the response rates for LPL/WM was 91% (all PR) and for FL 88% (CR 63%, PR 25%). The most common grade ≥3 AEs were neutropenia (35.7%), leukopenia (17.8%), anemia (14.3%) and thrombosis (14.3%). The LPL/WM subgroup experienced more grade ≥3 anemia (36%) compared to the group as a whole. Patients (57%) required at least one dose reduction of LEN (n =10), CTX (n = 9) or DEX (n = 7). At a median f/u of 14.5 (1.8–36.5) months 86% are progression free (fig. 1) and the OS is 96% (fig. 2). One death unrelated to treatment occurred 7.7 months after completing 12 cycles of treatment. Conclusion: Lenalidomide can be safely combined with other active agents and in the combination LR-CD produces high response rates in symptomatic patients with indolent B-cell lymphoma. The regimen is well tolerated with manageable toxicities which are similar to that seen with single agent LEN. The encouraging results seen in patients with LPL/WM have led to expansion of this cohort for additional study. Disclosures: Reeder: Celgene: Research Funding. Off Label Use: lenalidomide use in non-Hodgkin lymphoma. Stewart:Celgene: Consultancy, Honoraria.

Abstract Multiple myeloma tumors universally target one of the three human cyclin D genes (CCND1, CCND2 or CCND3) for dysregulation (Bergsagel et al., 2005, Blood;106:296). To identify novel pharmaceutical inhibitors of cyclin D2 (CCND2) transactivation we therefore screened the Lopac, Prestwick and Spectrum libraries of drugs and natural compounds (n>4000) using NIH 3T3 cells stably expressing the CCND2 promoter driving a luciferase reporter gene. From this library screen and subsequent validation experiments we identified Kinetin riboside, a nucleoside analogue and plant cytokinin hormone, as a novel inhibitor of CCND1+CCND2 transactivation. By immunoblotting, Kinetin riboside induced rapid suppression of cyclin D1 and D2 proteins (<6 hours) in H929, JJN3, Kms11 and U266 human myeloma cell lines (HMCL) that all over-express either cyclin D1 or D2 due to a range of transforming events relevant to myeloma (including deregulation of FGFR3, MMSET or c-Maf oncogenes, or translocation of CCND1 to the IgH locus). Similar results were obtained in primary CD138+ purified myeloma cells from 5/6 patients. To verify that cyclin D1 and D2 suppression induced by Kinetin riboside is a direct effect and does not occur secondary to cellular arrest in S-phase (when cyclin D protein levels decline) we examined the effects of Kinetin riboside on the cell cycle profile of HMCL. Within 20 hours Kinetin riboside caused the proportion of cells entering S-phase to fall by 50–70% in all HMCL tested, consistent with primary cyclin D suppression and secondary G0/G1 arrest. By MTT assay, Kinetin riboside is cytotoxic to HMCL with an IC50 of <1.7 mg/L (5uM) in 8/12 lines and <5mg/L (15uM) in 11/12 HMCL. By comparison, toxicity studies in Balb/c mice confirm that Kinetin riboside is tolerated in vivo at a dose of 80–100mg/kg i.p. or 25mg/kg i.v. Importantly, Kinetin riboside shows potent synergy with dexamethasone in HMCL that are poorly responsive to one or other agent and Kinetin riboside activity persists during co-culture with myeloma growth factors IL-6, IGF-1 and Baff. Moreover, when tested against unsorted patient bone marrow samples, Kinetin riboside preferentially killed CD138+ myeloma cells at up to 5–8 fold greater rate than normal marrow progenitors. Kinetin riboside induced myeloma cell death is mediated by apoptosis and is associated with caspase 9 cleavage and annexin V binding. Mechanistically, we show that kinetin riboside blocks CCND2 promoter transactivation induced by cAMP or by regulatory phosphoproteins (activated by Forskolin or the PP2A inhibitor, Cantharadin, respectively) and also blocks cis-activation of CCND1 induced by translocation to the IgH enhancer and trans-activation of CCND2 induced by cMaf or FGFR3 over-expression, indicating that kinetin riboside acts at a distal level to block transactivation of CCND1+CCND2 induced by multiple factors. Gene expression profiling reveals that KinR causes rapid induction of the transcriptional repressor, cAMP Response Element Modifier (CREM), which has been reported to bind the cyclin D2 promoter to regulate cyclin D2 expression (Muniz, 2006, Biol Reprod.), providing a putative mechanism for targeted suppression of CCND1+CCND2. Together these studies demonstrate a novel targeted mechanism and substantial pre-clinical activity for kinetin riboside and provide a rationale for clinical evaluation of this drug to improve the outcome of multiple myeloma.

Abstract Previous work in our laboratory has identified the importance of the NFB signaling pathway for plasma cell (PC) survival and accumulation in Multiple Myeloma (MM). Although up to 43% of patient PCs appear to have activated NFkB by gene expression profiling (GEP), the remainder must rely on an alternate signaling pathway for their survival. We examined our MM GEP datasets and supervised the clustering of patients according to an index of NFkB activity. The majority of patients not activating NFkB were associated with a high IL-6/Stat3 signature, which included the protein phosphatase of regenerating liver-3 (PRL-3). Interestingly, analysis of the PRL-3 promoter revealed competing binding sites for both NFkB and STAT3 within the first intron, suggesting that these play a role in the transcriptional regulation of this gene. PRL-3 has been previously demonstrated to be absent in most normal tissues while its expression in MM cells is quite elevated. As normal PCs have low levels of PRL-3 expression, we determined the upper limit of normal to be 3SD above the mean of these cells. Using this cutoff we report that elevated PRL-3 expression is observed in plasma cells from 1/15 normal individuals, 4/22 MGUS patients and 47/126 patients with either smoldering or overt MM (6.7%, 18.2% and 45.6% respectively). Less than 10% of patients were seen to have both an elevated NFkB index and high PRL-3 expression. Patients with higher expression of PRL-3 were found to have statistically significant higher mean values of creatinine, C-reactive protein, lower albumin levels and a lower overall survival in our Mayo Clinic MM dataset. To examine the role PRL-3 in MM biology we first stimulated MM cell lines with IL-6 and observed PRL-3 up-regulation in two cell lines (INA6, OPM1) but not in JK6L (an NFkB activated cell line). Using a luciferase reporter we have determined that STAT3 induction of PRL3 expression requires the first intron of the PRL3 gene which contains the putative STAT3 binding site. Finally we show that PRL-3 inhibition by shRNA leads to decreased cell growth and loss of IL-6 responsiveness in vitro in at least one cell line. Based on these results, we propose that the majority of MM patients depend on either the NFkB or STAT3 signaling pathways for their survival and that these are to a large degree mutually exclusive. Our experimental results suggest that PRL-3 plays a role in IL-6/STAT3 signaling and that it is a promising target for drug development.

Abstract Background: In Phase II trials, carfilzomib (Cfz) was associated with dyspnea (34%), hypertension (14%), renal insufficiency (24%), and peripheral edema (24%) with cardiac events reported in 7% of patients (pts). In order to better understand these toxicities, we prospectively instituted detailed cardiac evaluation in 62 Cfz treated multiple myeloma (MM) pts. Methods: Pts received Cfz between 8/11-5/14. Parameters recorded included Cfz dose, concurrent chemotherapy, hydration, blood pressure, day 1 and 2 creatinine, troponin and NT-proBNP, baseline and cycle 4 echocardiograms with EF, strain and compliance. Notable cardiac events were examined for attribution. Results: Median age was 65 years, with 60% male. 20 pts had no prior therapies, 42 were relapsed; mean 4 prior therapies (range 1-10). 20 received induction chemotherapy (Cfz, dex, thalidomide, cyclophosphamide). At relapse, Cfz was given alone in 21 pts, with added cyclophosphamide in 10, and with an IMiD in 10. Cfz dose was 20mg/m2 days 1,2 and ranged from 27-45mg/m2in subsequent treatment days. Dex was given at 20-40mg weekly in 77% pts. Hydration (250-500ml) was delivered in 89% of patients pre and 63% post treatment. Baseline hypertension (>140mmHg) was present in 20% of pts and rose ≥10mmHg in 26% on day 2, but dropped ≥10mmHg in 36%. On day 8, more pts (32%) had hypertension pre-treatment. Baseline creatinine was elevated in 25% pts. 7 of 55 (13%) pts had a creatinine rise (≥0.3 mg/dL) on day 2, 5 of whom had elevation at baseline. Thus, with normal baseline creatinine and pre-treatment hydration 2/45 (4%) pts had a creatinine rise. Troponin levels on day 1 were normal in all 16 tested patients. 2/25 pts had an elevated troponin on day 2, one with associated MI on day 4. In these 2 pts, symptomatic pre-existing ischemic heart disease and severe cardiac amyloid were confounding factors. Mean baseline NT-proBNP (n=22) was elevated at 565 pg/mL (range <50-3666; normal <77) with normal baseline values in only 41%. On day 2 (n=25), the mean was significantly higher at 1580 pg/mL. Between day 1 and 2, 72% of pts had a rise ≥50 pg/mL; mean change 1387 (range 0 to +6187). On day 2, 52% had a NT-proBNP ≥500 pg/mL, while 36% were ≥1000 pg/mL. 30 pts had baseline and post-C4 treatment echocardiograms, all with normal pre-treatment EFs. Three pts (10%) developed impaired systolic function (EF<50%), however, 2 had plausible concurrent alternative etiologies (VTE/PE, hospitalized multilobar pneumonia) while one patient (during C2) had an asymptomatic unexplained decline in EF (56 to 42%) detected pre-op while hospitalized for hip fracture. Thus, 1/30 (3%) had an EF change in absence of concurrent acute illness. A fourth patient had normal echo at C4 but was hospitalized at C10 with severe sepsis and a diminished EF was documented. All 4 pts with low EF were pre-treated (≥2 therapies plus SCT). Changes in cardiac strain often precede an EF fall. Only 14/25 pts had normal baseline cardiac strain (≥ -18%). Post treatment strain measurement significantly improved in 4 pts and worsened in 4 pts, the latter accompanied by EF decline within the normal range in 2 pts (68/60%, 65/58%). 28 pts had E/e’ ratio (LVEDP) reviewed as a marker of ventricular compliance. 46% had abnormal ratios (≥ 15), prior to Cfz treatment. 20% of patients experienced worsening parameters post treatment, however, an equal number of pts demonstrated improvement. There was no consistent correlation with change in EF. Conclusions: MM pts frequently have baseline elevated cardiac peptides (59%) and abnormal cardiac strain (15% of newly diagnosed and 36% at relapse). A frequent, and sometimes dramatic, rise in the NT-proBNP occurs immediately following Cfz based chemotherapy. Acute structural cardiac events were however uncommon (3%) in the absence of confounding illness. Overall 5/62 (8%) patients had serious cardiac events during treatment with Cfz (4 EF decline, 1 MI). These toxicities were considered probably attributable to Cfz in 3/62 (5%) patients. Prospective controlled studies with longer term follow up and bortezomib treated controls are necessary to accurately document the cardiovascular impact of Cfz and the role of proteasome inhibition. Disclosures Off Label Use: bortezomib was used in combination therapy to treat relapsed low grade lymphomas and Waldenstrom's macroglobulinemia. 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. Bergsagel:Novartis: Research Funding; Constellation Pharmaceutical: Research Funding; OncoEthix: Research Funding; MundiPharma: Research Funding. Reeder:Millennium, Celgene, Novartis: Research Funding. Mikhael:Onyx: Research Funding; Celgene: Research Funding; Sanofi: Research Funding; Novartis: Research Funding. Stewart:Celgene Novartis Array BioPharma BMS, research funding Millenium: Consultancy, Research Funding.

Abstract Introduction Non-Hodgkin lymphoma responds to single agents such as cyclophosphamide, combination therapy such as CVP and immunotherapy with monoclonal antibodies such as rituximab. There is no consensus on the optimal treatment for relapsed low grade or mantle cell lymphoma. Based on the success and tolerability of combining alkylating agents with proteasome inhibitors in multiple myeloma, a phase II clinical trial of rituximab, cyclophosphamide, bortezomib, and dexamethasone (R-CyBor-D) was designed to explore the efficacy and safety of this combination in relapsed low grade and mantle cell lymphoma (MCL). Methods This trial enrolled relapsed patients at Mayo Clinic from October 2008 to March 2014. Eligibility required age≥18; biopsy proven follicular grades 1 or 2 lymphoma (FL), MCL, small lymphocytic lymphoma/chronic lymphocytic leukemia, marginal zone B-cell lymphoma, or Waldenström’s macroglobulinemia (WM); life expectancy >3 months; ECOG PS 0, 1 or 2; measurable disease; Hb ≥8g/dl, ANC ≥1200/uL, platelet ≥75,000/uL, creatinine ≤1.5xULN, total bilirubin ≤1.5xULN, alkaline phosphatase ≤3xULN, AST ≤3xULN; and willingness to sign informed consent. Women of child bearing potential had pregnancy testing and all patients followed recommendations for contraception. Treatment included rituximab 375 mg/m2 IV on day 1 and oral cyclophosphamide 300 mg/m2, IV bortezomib 1.3 mg/m2, and oral dexamethasone 40 mg on days 1, 8, 15, and 22 in a 28-day cycle. Treatment was continued two cycles beyond best response or a maximum of 12 cycles. Allopurinol 300 mg on days 0-14 for the first cycle was strongly recommended. Results 21 patients were enrolled prior to study closure due to slow accrual. Bortezomib was initially given on days 1, 4, 8, and 11 in the first 16 patients, but was subsequently modified to days 1, 8, 15, and 22 due to significant peripheral neuropathy (PN). Median age was 69 years (range 51-80) and 13 (62%) were male. 62% had stage IV disease and 17 (81%) had 2 or more prior treatments with 3 (14%) having prior autologous stem cell transplantation. Histologies included FL-I (n=6), FL-II (n=2), MCL (n=8), and WM (n=5). Patients completed a median of 4 cycles of treatment (range 1-12), discontinuing due to 9 (43%) completion per protocol, 4 (19%) progression, 5 (24%) adverse events, 1 (5%) patient refusal, and 2 (10%) other reasons. Median follow-up is 32.8 months (0.9-54.8). CR or PR as best response was observed in 13 (62%, 95% CI 38-82%; 4 CR [19%], 9 PR [43%]) patients. By histology, CR or PR was observed in 7 (88%) FL patients (4 CR, 3 PR); 2 (25%) MCL patients (both PR), and 4 (80%) WM patients (all PR). CR or PR was observed in 10/16 (62%; 4 CR, 6 PR) before and 3/5 (60%; all PR) after the change in bortezomib schedule. Among 13 patients with CR or PR, median duration of response was 25.9 months (95% CI 8.0-not reached). Median PFS and OS were 11.6 months (95% CI 3.8-not reached) and 54.8 months (95% CI 24.6-54.8), respectively. At least one Gr≥3 adverse event at least possible related was observed in 14 (67%) patients, the most common being leucopenia (7, 33%), neutropenia (7, 33%), thrombocytopenia (6, 29%), anemia (5, 24%), PN (5, 24%), and fatigue (3, 14%). Peripheral sensory neuropathy at least possibly related was Gr1, Gr2, and Gr3 in 5 (24%) patients each, with a lower rate observed for patients after the change in bortezomib schedule (before 13/16 [81%] Gr≥1, after 2/5 [40%] Gr≥1). Among 14 patients who completed a baseline and at least one post-baseline FACT/GOG-NTX additional concerns questionnaire, 10 (71%) reported clinically meaningful (≥3-point) worsening in patient-reported neurotoxicity (8/11 [73%] before and 2/3 [67%] after the change in bortezomib schedule). Conclusions Our results suggest R-CyBor-D is a safe and effective combination in patients with relapsed low grade and mantle cell lymphomas. High response rates were seen in FL and WM. The majority of significant AE’s were hematologic. However, sensory neuropathy was common with twice weekly dosing of bortezomib and lessened with weekly dosing. Determination of optimal treatment regimens in this population remains an unmet need. Additional clinical trials including larger patient numbers are necessary to confirm these observations. This trial was sponsored by Millennium Disclosures Off Label Use: bortezomib was used in combination therapy to treat relapsed low grade lymphomas and Waldenstrom's macroglobulinemia. Bergsagel:Novartis: Research Funding; Constellation Pharmaceutical: Research Funding; OncoEthix: Research Funding; MundiPharma: Research Funding. Tiedemann:Janssen: Honoraria. Reeder:Millennium, Celgene, Novartis: Research Funding.

AbstractPatients with indolent non‐Hodgkin lymphoma (NHL) have multiple treatment options yet there is no consensus as to the best initial therapy. Lenalidomide, an immunomodulatory agent, has single agent activity in relapsed lymphoma. This trial was conducted to assess feasibility, efficacy, and safety of adding lenalidomide to rituximab, cyclophosphamide, and dexamethasone (LR‐CD) in untreated indolent NHL patients requiring therapy. This was a single institution phase II trial. Treatment consisted of IV rituximab 375 mg/m2 day 1; oral lenalidomide 20 mg days 1–21; cyclophosphamide 250 mg/m2 days 1, 8, and 15; and dexamethasone 40 mg days 1, 8, 15, and 22 of a 28‐day cycle. Treatment continued 2 cycles beyond best response for a maximum of 12 cycles without rituximab maintenance. Thirty‐three patients were treated. Median age was 68 (43–83 years). 39% had stage IV disease. Histologic subtypes included 8 follicular lymphoma (FL), 7 marginal zone lymphoma (MZL) (1 splenic, 2 extranodal, and 4 nodal), 15 Waldenström's macroglobulinemia (WM), 1 lymphoplasmacytic lymphoma, 1 small lymphocytic lymphoma, and 1 low‐grade B‐cell lymphoma with plasmacytic differentiation (unable to be classified better as MZL or LPL). Hematologic toxicity was the most common adverse event. Median time of follow‐up was 23.4 months (range 1.8–50.9). The overall response rate was 87.9%, with 30.3% complete response. The median duration of response was 38.7 months. The median progression free survival was 39.7 months, while median overall survival (OS) has not yet been reached. Lenalidomide can be safely added to a simple regimen of rituximab, oral cyclophosphamide, and dexamethasone and is an effective combination as initial therapy for low‐grade B‐cell NHL.