Abstract: Abstract 2527 May-Hegglin Anomaly was originally defined as patients with macrothrombocytopenia. It is now recognized that the phenotypes of May-Hegglin Anomaly and the related syndromes described by Epstein, Fechtner and Sebastian overlap comprising macrothrombocytopenia, neutrophil inclusions, deafness, cataract formation and nephritis. These disorders are defined by mutations in the non-muscle myosin heavy chain IIA gene, MYH9 and have been termed MYH9-Related Disorders. Myh9 is required during murine embryogenesis as Myh9-null embryos die of patterning defects. Megakaryocyte-specific deletion of Myh9 has been performed by the Gachet group and Shivdasani and colleagues examined megakaryocyte function in Myh9-deficient embryonic stem cells induced to differentiate in vitro. The phenotypes of these mice include increased bleeding times, absence of clot retraction and defective Integrin β3 phosphorylation coupling to impaired activation of downstream Rho-Rock signalling and lamellipodia formation. To date, no knock-in MYH9 alleles corresponding to MYH9-related Disorder mutations have been reported. MYH9-related Disorders frequently are misdiagnosed as Chronic Immune Thrombocytopenia, so having enhanced knowledge of the molecular etiology of mutant MYH9 alleles is a priority. Our group has been interested in utilizing random mutagenesis to identify novel alleles of human hematopoietic disorders. We performed a dominant screen in which 129 male mice were mutagenized with ENU and back-crossing was performed on the C57BL/6 background. We identified a heritable line (7238) with macrothrombocytopenia that mapped to a 4.25 Mb region on mouse Chromosome 15. Due to our inability to further refine the interval through back-crossing, we performed high throughput sequencing by comparing SNPs between 129, C57BL/6, 7238/+ and 7238/7238 mice. We identified 18 novel variations, including 1 that corresponded to a coding change - Myh9 Q1443L. Subsequent Sanger sequencing and back-crossing eliminated the remaining 17 variations, confirming our assignment of the 7238 phenotype to a mutation of Myh9. The Myh9 Q1443L allele is within proximity of the MYH9 D1424Y/N/H mutations found within clinical specimens. Myh9 Q1443L/Q1443L mice are viable allowing us to examine the effect of mutation of one or both alleles of Myh9. Myh9Q1443L/Q1443L mice had increased bleeding times, whereas Myh9Q1443L/+ mice were identical to wild type mice. Platelet aggregation experiments were performed after ADP or thrombin stimulation. Decreased aggregation was observed in a dosage-dependent manner, with Myh9Q1443L/+ mice displaying intermediate levels when compared with Myh9Q1443L/Q1443L co-hort. Adherence and aggregation of Myh9Q1443L/Q1443L platelets to a collagen matrix was decreased at shear rates of 350/s and 1800/s. Staining of Myh9Q1443L/+ and Myh9Q1443L/Q1443L neutrophils also revealed neutrophil inclusions. In addition to the hematopoietic phenotypes, we have observed increased cataract formation with a frequency of 36% in wild type animals, 60% in Myh9Q1443L/+ and 92% in Myh9Q1443L/Q1443L mice. Sporadic hematuria and proteinuria is found in Myh9Q1443L mice. We are currently performing albumen loading and lipopolysaccharide activation experiments to determine whether 7238 mice have altered response to nephric stress. We are crossing 7238 mice to the DBA genetic background, which is more sensitive to subtle kidney phenotypes. We performed auditory brain response measurements on aged wild type, Myh9Q1443L/+ and Myh9Q1443L/Q1443L mice and observed no differences in frequency responses ranging from 2 to 24kHz. Myh9Q1443L/+ mice displayed hypertrophy of the preputial gland whereas Myh9Q1443L/Q1443L males showed atrophy of this gland and Myh9Q1443L/Q1443L male mice have reduced fertility. No differences in fertility have been described to date in MYH9 related disorders. In conclusion, Myh9Q1443L/Q1443L mice display macrothrombocytopenia, neutrophil inclusions and cataract formation described in MYH9-related disorders and represent the first animal model of May-Hegglin Anomaly. Disclosures: No relevant conflicts of interest to declare.

Abstract: Abstract 1024 Background: The MMRC is a non-profit, disease-focused consortium founded in 2004. Sixteen North American member institutions with expertise in multiple myeloma (MM) work collaboratively with the MMRC Inc. (Norwalk, CT) and numerous pharmaceutical partners to speed development of new treatment options to MM patients. In December 2007, MMRC Inc. implemented business solutions to address barriers to rapid activation of phase I-II trials and established benchmarks for initiating and conducting these studies. In December 2010, we reported significantly faster trial start up and accrual data from previous years1,2. Today, we update and expand on MMRC performance data and analysis of progress. Methods: Twenty-five (25) trials conducted within the Consortium from May 2006 to July 2011 had sufficient start up trial data for review. FPFD was defined as the time from the member institutions' receipt of the final protocol (FP) from the trial sponsor, to the time the first patient was dosed on the trial at any participating MMRC member institution. With respect to enrollment, pre-study enrollment commitment (EC) established between MMRC and the study sponsor was defined as the total number of subjects committed to receive at least one dose of study drug across all participating MMRC centers on a trial; baseline enrollment timeline (BET) was prospectively defined as the target time period to attain EC. Results: Mean time to FPFD in the recent group of trials (RG; n=18; Sept 08-Jul 11) held steady at 131 calendar days from receipt of FP as compared to 181 days for the early group of trials (EG; n=7; Jun06-Sept08) representing a 28% reduction in time to FPFD. More importantly, there was a 20% decrease in time to FPFD by all participating MMRC centers on any MMRC trial from 189 days in the RG compared to 236 days in the EG representing an important achievement especially in the Phase I/II arena. MMRC trial accrual data was available for 17/25 trials (2 EG trials were missing data and 6 RG trials continue enrolling). The pre-study mean MMRC EC was 44 subjects per trial (n=19 trials; 849 patients); the mean actual MMRC enrollment was 49 subjects per trial (n=19; 935 patients through July 11) representing a 10% over enrollment versus committed enrollment. A total of 17/19 evaluable trials (89%) met their EC; 12/19 trials met EC within BET (71%) of which 8/12 trials (67%) reached EC 34% faster than their BET (representing a mean reduction of 4.5 months). The overall pre-study mean BET for 19 trials was 13.6 months. MMRC's actual mean enrollment timeline was 12.8 months for the group of 17 evaluable trials representing improvement over the original BET by a mean of 10%. Discussion: MMRC's acceleration of clinical trials provides physicians and patients with rapid access to novel compounds; industry with data for important drug development decisions; and academic institutions with more trials of high scientific interest. Even so, our data uncovered opportunities for improvement. The submission time from receipt of the final protocol from the trial sponsor to Scientific Review Committee (SRC) took an average 30 calendar days across all trials. A reduction to half this time could make a difference to patients and therefore warrants further exploration. Conclusion: Today, drug development in multiple myeloma is fast-paced and highly competitive. MMRC's frequent review of trial metrics provides valuable insight to continually speed answers to physicians, patients and industry. Disclosures: Richardson: Multiple Myeloma Research Consortium: Annual grant in support Clinical Trial Project Management. Vij:Multiple Myeloma Research Consortium: Annual grant in support of clinical trial Project Management. Lonial:Multiple Myeloma Research Consortium: Annual grant in support of clinical trial Project Management. Siegel:Multiple Myeloma Research Consortium: Annual grant in support of clinical trial Project Management. Jakubowiak:Multiple Myeloma Research Consortium: Annual grant in support of clinical trial Project Management. Reece:Multiple Myeloma Research Consortium: Annual grant in support of clinical trial Project Management. Jagannath:Multiple Myeloma Research Consortium: Annual grant in support of clinical trial Project Management. Hofmeister:Multiple Myeloma Research Consortium: Annual grant in support of clinical trial Project Management. Stewart:Multiple Myeloma Research Consortium: Annual Grant in support of clinical trial Project Management. Wolf:Multiple Myeloma Research Consortium: Annual grant in support of clinical trial Project Management. Krishnan:Multiple Myeloma Research Consortium: Annual grant in support of clinical trial Project Management. Zimmerman:Multiple Myeloma Research Consortium: Annual grant in support of clinical trial Project Management. Kumar:Multiple Myeloma Research Consortium: Annual grant in support of clinical trial Project Management. Roy:Multiple Myeloma Research Consortium: Annual grant in support of clinical trial Project Management. Fay:Multiple Myeloma Research Consortium: Annual grant in support of clinical trial Project Management. Anderson:Multiple Myeloma Research Consortium: Annual grant in support of clinical trial Project Management.

Abstract: Abstract 631 Introduction: In relapsed and/or refractory MM, the combination of carfilzomib (CFZ) with lenalidomide (Len), and low-dose dexamethasone (Dex) (CRd) has shown very promising efficacy (78% ≥partial response [PR], 40% ≥very good partial response [VGPR] , and 24% CR/nCR) and good tolerability including a low rate of peripheral neuropathy (Wang et al, ASCO, 2011). In a Phase I/II study of newly diagnosed MM, the regimen was well tolerated in the Phase I portion of the study up to a maximum dose of CFZ 36 mg/m2, Len 25 mg, and Dex 40 mg, and very active with 96% ≥PR, 70% ≥VGPR, and 55% CR/nCR (Jakubowiak et al, ASH 2010). The lack of overlapping toxicities has allowed these agents to be used at full doses and for extended periods. Here we report the results for all patients (pts) enrolled in both phases of this first prospective trial of CFZ combination in new MM. Methods: In the initial eight 28-day cycles, pts were treated with CFZ at 20 mg/m2, 27 mg/m2 (Phase I), and 36 mg/m2 (Phase I and II), given IV on days 1, 2, 8, 9, 15 and 16, Len at 25 mg PO (days 1–21), and Dex at 40/20 mg PO weekly (cycles 1–4/5–8). Pts achieving ≥PR could proceed to stem cell collection (SCC) using growth factors alone (protocol recommendation) and autologous stem cell transplant (ASCT) after 4 cycles. Per protocol, ASCT candidates were offered the option to continue CRd treatment after SCC. After 8 cycles, pts received 28-day maintenance cycles of CFZ (days 1, 2, 15, 16), Len days 1–21, and Dex weekly at the doses tolerated at the end of 8 cycles. Responses were assessed by IMWG criteria with the addition of nCR. Results: Enrollment was completed (53 pts): 4 pts at CFZ 20 mg/m2, 13 at CFZ 27 mg/m2 and 36 at CFZ 36 mg/m2 (18 in Phase I and 18 in Phase II). Median age was 59 years (range 35–81; 23 pts ≥65), 60% had ISS stage II/III, and 33% (of 49 with available data) had unfavorable cytogenetics: del 13 or hypodiploidy by metaphase, or t(4;14), t (14;16), del 17p by FISH. As of June 30, 2011, toxicity data (cycles 1–8) were available for 51 pts. Hematologic toxicities were reversible and included Grade (G) 3/4: anemia (18%), neutropenia (12%), and thrombocytopenia (10%). The most common non-hematologic toxicities (all G) were hyperglycemia (76%), hypophosphatemia (61%), and infection (53%). G3/4 non-hematologic AEs included hyperglycemia (24%), DVT/PE while on ASA prophylaxis (10%), infection (6%), and mood alteration (2%). PN was limited to G1/2 sensory (24%). Forty-five pts continue treatment with 22 pts in the maintenance phase. Six pts discontinued treatment: 2 proceeded to ASCT, 1 due to toxicity, and 3 due to events unrelated to treatment or per pt wish. The majority of pts did not require dose modifications, either in the initial (31%) or in the maintenance (25%) phase. After a median of 8 cycles (range 1–20), the best responses per IMWG criteria for 49 response-evaluable pts (all pts who completed 1+ cycle) are shown in the Table. Responses were rapid with 46/49 pts achieving at least PR after 1 cycle, and improved with the duration of treatment reaching 100% ≥PR after 4 cycles and 100% ≥VGPR, 79% CR/nCR after 12 cycles. Responses were deep even at the 2 lower dose levels with the majority of pts at 36 mg/m2 still early in treatment. Responses in pts with unfavorable cytogenetics were similar to response rates in all remaining pts and included a 100% ≥PR in 6 pts with del 17p. Twenty-four pts proceeded to SCC after a median of 5 cycles of CRd (range 4–9); using growth factors only in 23 pts and cyclophosphamide and growth factors in 1 pt, with a median 6.55 × 106 CD34+ cells/kg collected (range 3.75–9.6); all resumed CRd treatment. After a median of 9.5 months of follow-up, only 1 pt has progressed, and all are alive Conclusions: CRd is highly active and well-tolerated allowing the use of full doses for an extended time in newly-diagnosed MM pts with limited need for dose modification. Responses are rapid and improve over time reaching 100% ≥VGPR and early time-to-event data are very encouraging. These results compare favorably to the best frontline regimens in MM. Disclosures: Jakubowiak: Bristol-Myers Squibb: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Onyx Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees; Millennium Pharmaceuticals, Inc.: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Consultancy, Honoraria, Speakers Bureau; Ortho Biotech: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Exelixis: Consultancy, Honoraria. Off Label Use: Use of the investigational agent carfilzomib, proteasome inhibitor, in the treatment of relapsed and/or refractory multiple myeloma. Jagannath:Millennium: Honoraria; Celgene: Honoraria; Onyx Pharmaceuticals: Honoraria; Merck: Honoraria; OrthoBiotec.Imedex: Membership on an entity's Board of Directors or advisory committees; Medicom World Wide: Membership on an entity's Board of Directors or advisory committees; Optum Health Education: Membership on an entity's Board of Directors or advisory committees; PER Group: Membership on an entity's Board of Directors or advisory committees. Vesole:Celgene: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Millennium: Speakers Bureau. Hussein:Celgene Corporation: Employment. Leveque:Onyx Pharmaceuticals: Employment. Vij:Onyx Pharmaceuticals: Consultancy, Research Funding; Celgene: Research Funding, Speakers Bureau; Millennium: Speakers Bureau.

Abstract: To generate new mouse models of human hematopoietic disease and increase our knowledge of the genetic networks that control hematopoiesis, we are performing dominant (generation 1 or G1) and pharmacologically-sensitized forward ethylnitrososurea (ENU) mutagenesis screens. Mice are phenotyped by saphenous vein peripheral blood analysis using an automated hematological analyzer. ENU is ideally suited to generating models of human disease and annotating gene function because the spectrum of mutations (point mutations generating leading to subtle amino acid substitutions, splicing errors, or premature termination) are similar to those often found in human disease. Furthermore, null mutations often do not represent the full extent of a gene’s function, requiring multiple alleles to fully define gene function. While dominant mutations can unequivocally cause some human diseases, often mutations in multiple genes interact and contribute to disease progression. Thus, we have developed sensitized screens that induce transient cytopenias using various pharmacological agents (5-fluorouracil, phenylhydrazine, and hydroxyurea) and analyzing the recovery in peripheral blood levels of red blood cells, white blood cells and platelets. This strategy enables identification of hematopoietic mutants that do not present abnormal blood cell counts in a homeostatic state. The induced cytopenia recovery assay is also being used as a secondary phenotyping assay for some of our G1 dominant mutants. The combined dominant and sensitized screens have yielded 14 heritable dominant mutants to date plus four additional mutants in hereditary testing. The array of mutations that we are analyzing are models for the following diseases: polycythemia, thrombocythemia, leukocytosis, anemia, and thrombocytopenia. I will discuss the progress of the mutagenesis screen and several ENU mutants, including a novel mutation in the protein tyrosine kinase Jak2, leading to thrombocythemia. This point mutation in the protein kinase domain will help us to dissect the recently discovered role of Jak2 in Myeloproliferative Diseases including Essential Thrombocythemia.

Abstract: Abstract 3165 Background: Accrual to large oncology group studies in the United States is often slower than planned, especially in less common malignancies such as Multiple Myeloma (MM). To improve the treatment of patients with MM, it is essential that we address the barriers to accrual (BtA) to national clinical trials. The NCI Myeloma Steering Committee (MYSC) formed the Accrual Working Group (AWG), charged to analyze this problem. Methods: The members of the MYSC have developed a list of 10 potential BtA to NCI MM-CT under the leadership of the AWG at meetings conducted in person and by monthly telephone conference. This list was distributed via Survey Monkey among investigators and research staff of the SWOG, ECOG/ACRIN and Alliance research bases for the purpose of ranking the perceived importance of the 10 selected BtA. Responses based on a 0–5 Likert Scale were analyzed as continuous and categorical. For the latter, responses were grouped: Impedes Accrual – No (0,1), Yes (2–5); Significantly Impedes Accrual – No (0–3), Yes (4,5). Results: 246 survey responses were received. 50 participants who indicated that they had never attempted to or actually never enrolled a patient into a MM-CT were excluded. Of 196 responders, 61% had enrolled at least 5 patients, 43% practiced in academic centers (A) and 57% in community centers (C). 26% identified themselves as research staff, 74% as primarily physician investigators including Principal Investigators (12%). 78% have current access to NCI MM-CT. 46% identified their research base affiliation with SWOG, 20% with ECOG/ACRIN, 17% with Alliance, 17% as CTSU, NRG and other. The majority of survey responders confirmed agreement in the perception that all 10 identified BtA impede accrual, ranging from 60–84% depending on the specific barrier identified, while significant impediment to accrual ascribed to these BtA ranged from 22–47%. The perceived barriers most often cited as impeding accrual were (1) spectrum of available treatment options, (2) level of reimbursement for clinical trial related expenses and (3) patient‘s need for prompt treatment intervention (84%, 80%, 76% respectively). The first two barriers along with the requirement that patients receive their treatment exclusively at the NCI designated treatment site were rated most often as significantly impeding accrual (37%, 47%, 34% respectively). The first two were also identified most often as perceived BtA independent of practice setting (A, C), type of research engagement (physician investigator, research staff) and level of experience with MM-CT. Interestingly, the perception that patients must receive their treatment at the NCI designated treatment site and competing industry sponsored clinical trials were substantially more often cited as impeding accrual in academic centers compared to community centers and by physician investigators compared to research staff. The complexity of required diagnostic work up and the complexity of the treatment protocol and follow up testing were substantially more often cited as BtA in the community setting and by research staff compared to their peers in the academic setting and by physician investigators. The NCI MYSC AWG has proposed specific solutions to potentially lower perceived BtA. These include guidelines to allow protocol specific administration of commercially available agents by the patient‘s local oncologist, a simplified diagnostic work up and treatment plan and eligibility inclusion of patients who have received up to one cycle of specified urgent therapy prior to enrollment in MM-CT. Conclusions: We have queried experienced clinical investigators and research staff on 10 potential MM-CT specific BtA and found substantial consensus among responding participants in this survey. There are apparent differences in perceived BtA between the respondents from academic and community centers as well as between research staff and physician investigators. These data suggest that a structured approach to identification of BtA to clinical trials is feasible and creates opportunities to overcome them. This may have application to clinical trials across other diseases and may also lead to improvements in accrual. Disclosures: Barlogie: Celgene, IMF, MMRF, Millennium, Genzyme: Consultancy; Celgene, IMF, Millennium: Honoraria; Celgene, Novartis, NCI, Millennium, Onyx, Icon: Research Funding; GEP: Patents & Royalties.

Abstract: Lenalidomide plus dexamethasone is effective for the treatment of relapsed and refractory multiple myeloma (MM); however, toxicities from dexamethasone can be dose limiting. We evaluated the efficacy and safety of lenalidomide monotherapy in patients with relapsed and refractory MM. Patients (N = 222) received lenalidomide 30 mg/day once daily (days 1-21 every 28 days) until disease progression or intolerance. Response, progression-free survival (PFS), overall survival (OS), time to progression (TTP), and safety were assessed. Overall, 67% of patients had received 3 or more prior treatment regimens. Partial response or better was reported in 26% of patients, with minimal response 18%. There was no difference between patients who had received 2 or fewer versus 3 or more prior treatment regimens (45% vs 44%, respectively). Median values for TTP, PFS, and OS were 5.2, 4.9, and 23.2 months, respectively. The most common grade 3 or 4 adverse events were neutropenia (60%), thrombocytopenia (39%), and anemia (20%), which proved manageable with dose reduction. Grade 3 or 4 febrile neutropenia occurred in 4% of patients. Lenalidomide monotherapy is active in relapsed and refractory MM with acceptable toxicities. These data support treatment with single-agent lenalidomide, as well as its use in steroid-sparing combination approaches. The study is registered at http://www.clinicaltrials.gov as NCT00065351.

Abstract: A 3rd generation perfluorocarbon (PFC) is under development for the treatment of traumatic brain injury (TBI). PFCs have high gas solubility and can deliver oxygen to support ischemic brain tissue. This drug increased brain tissue oxygen consumption, decreased infarct size, and improved functional deficits in animal models of brain injury, but it also caused transient thrombocytopenia of unknown etiology. Acute inflammation also causes platelet deficits and is common in the setting of severe TBI. The interaction between the two could exacerbate thrombocytopenia. Here we studied PFC effects on platelet function, platelet morphology and global hemostasis in a lipopolysaccharide (LPS) baboon model of inflammation. Perfluorocarbon (Oxycyte”, Oxygen Biotherapeutics Inc, Morrisville, NC) infusion was performed with and without administration of LPS. The groups studied included: 1. Saline control (20 ml saline + 12 ml/kg saline: SALINE) 2. Saline and LPS control (0.3 mg/kg LPS in 20 ml saline + 12 ml/kg saline: SAL-LPS) 3. Medium dose PFC with saline vehicle (20 ml SALINE + 3 ml/kg PFC: SAL-PFC3) 4. High dose PFC with saline vehicle (20 ml SALINE + 12 ml/kg PFC: SAL-PFC12) 5. Medium dose PFC with LPS (LPS 0.3 mg/kg in 20 ml SALINE + 3 ml/kg PFC: LPS -PFC3) 6. High dose PFC with with LPS (LPS 0.3 mg/kg in 20 ml SALINE + 12 ml/kg PFC: LPS –PFC12) Platelet count, transmission electron microscopy, and flow cytometry were performed at baseline (BL) and at 2, 24, 48, 72, and 96 hours after perfluorocarbon infusion. Microparticles were quantified and characterized by flow cytometry and morphology examined via transmission electron microscopy. Impedance aggregometry and thromboelastography (TEG) were quantified at baseline (BL) and at T2, T72, and T96 (hours). Statistical analysis was by ANOVA, followed by pairwise comparisons and a Bonferroni adjustment. PFCs caused delayed thrombocytopenia which began 2 days post-infusion and persisted beyond the 5-day period of observation (nadirs≤50% of baseline at day 5, p 〈 0.05). Platelets (PLTs) also decreased due to LPS administration, but effects began within 6 hours, were less severe, and resolved more quickly (nadirs≥50% of baseline at day 2, with normalization of platelet counts by day 4, p 〈 0.05). Thrombocytopenia was additive in LPS+PFC groups, occurring within 2 hours of study start time, and persisting for more than 5 days (p 〈 0.05). The decrease in platelet count was more profound in LPS+PFC groups (nadirs of ≤25% of baseline, p 〈 0.05). LPS+PFC increased aggregation corrected for PLTs (p 〈 0.05), but PFCs alone did not. LPS+PFC decreased TEG MA values, whereas PFCs alone had minimal effects. PFCs exacerbated adverse LPS effects, resulting in diffuse microvascular hemorrhage in 2 of 5 baboons in the LPS-PFC3 group and 2 of 2 in the LPS- PFC12 group. Transmission electron microscopy and histology were consistent with shock associated with hemorrhage in multiple organs and demonstrated abnormal morphology of platelets and red blood cells. PFC infusion caused clinically significant thrombocytopenia, particularly after LPS administration, and exacerbated LPS-induced platelet activation. The interaction between the two resulted in decreased hemostatic capacity, diffuse bleeding, and shock. Disclosures: Shade: Oxygen Biotherapeutics, Inc.: Research Funding. Anderson:Oxygen Biotherapeutics, Inc.: Employment.

Abstract: INTRODUCTION: Lenalidomide (REVLIMID®; CC-5013) is a novel, orally active immunomodulatory drug under investigation for the treatment of multiple myeloma (MM). Phase 1 dose-escalation studies in patients (pts) with relapsed and refractory MM determined that the maximum tolerated dose (MTD) of lenalidomide was 25 mg/day, based upon myelosuppression encountered beyond 28 days, which was manageable with growth factor support and dose reduction. In a multicenter phase 2 study to determine optimal dose and schedule, 102 pts with relapsed or refractory MM were randomized to receive lenalidomide at either 15 mg bid (n=34) or 30 mg qd (n=68), for 21 days every 4 wks. Both treatment arms showed significant activity with manageable toxicity. An increased incidence of cytopenia was noted in the 15-mg bid group and thus the 30 mg qd schedule was taken forward. METHODS: The objective of this multicenter, phase 2, open-label study (CC-5013-MM-014) was to further evaluate the effectiveness and safety of single-agent lenalidomide administered at a dose of 30 mg qd for 21 days every 28 days (28-day cycle) in pts with relapsed and refractory MM. Eligible patients included those who had received prior thalidomide, bortezomib, or SCT. RESULTS: 222 pts were enrolled into the study. All patients had received at least 2 prior anti-myeloma treatments, including bortezomib (41%), thalidomide (80%), and SCT (44%). Table 1 shows Best Response data, excluding patients in whom responses were not evaluable (n=10). Partial response or better occurred in 25% of patients and SD or better in 71%. Time to Progression was a median of 22.4 wks (range 1.8– 66 wks). The median survival has not been reached (the lower bound of the 95% CI exceeds 15 months). The most common treatment-related AEs (those reported in ≥10% of patients overall) included upper respiratory tract infection, neutropenia and thrombocytopenia. AEs that most frequently led to dose reduction or interruption by percentage of cases were neutropenia (40%), thrombocytopenia (23%), fatigue (5%), and anemia (5%). CONCLUSION: Oral lenalidomide in relapsed and refractory MM patients achieved PR+CR in 25%, stable disease or better in 71%, a median TTP of approximately 6 months and a median survival that has not been reached. Toxicity has been manageable with a very low incidence of DVT and minimal treatment-emergent neuropathy. Table 1. Best Response Best Response* n (%) *Excluding patients not evaluable (n=10); CR=complete response and PR=partial response (EBMT criteria) ≥PR (CR + PR) 53 (25) Stable disease 152 (71)

Abstract: Background: BB-10901 is a humanized monoclonal antibody that binds with high affinity to CD56 and is covalently linked to a novel cytotoxic maytansinoid DM1. Once bound to CD56, the conjugate is internalized and releases DM1. CD56 is expressed on a variety of tumor types such as small cell lung carcinoma, neuroendocrine tumors and hematological malignancies including multiple myeloma (MM) and acute leukemia. About 70% of MM patients have evidence of CD56 expression. Based on our preliminary results that BB-10901 has significant in vitro and in vivo anti-myeloma activity in a murine model, we have now initiated a phase I clinical study. Objectives: To determine the maximum tolerated dose (MTD), the dose limiting toxicities (DLTs), and pharmacokinetics (PK) of BB-10901 given on a weekly schedule. Methods: Relapsed or relapsed/refractory MM patients who have failed at least one prior therapy and have CD56 expressing myeloma received a single IV infusion of BB-10901 on 2 consecutive weeks every 3 weeks. Subjects are enrolled in cohorts of 3 at each dose level. The starting dose was 40 mg/m2/week based on experience from a prior phase I trial in solid tumors. Results: Five patients have received BB-10901, 3 at 40 mg/m2/week and 2 at 60 mg/m2/week. No patients have experienced DLTs and no serious adverse events related to study drug were observed. In addition, no patients have experienced serious hypersensitivity reactions or evidence of HAHA or HADA formation. Our preliminary PK findings demonstrate that there is no evidence of accumulation of BB-10901. Detailed PK analysis and updated toxicity and efficacy data will be presented. Immunohistochemistry performed on marrow aspirates about 24 hours after huN901-DM1 infusion at 40 mg/m2 confirmed the presence of huN901-DM1 on myeloma cells in the marrow. Two patients treated at 60 mg/m2/week and who had failed multiple prior therapies including bortezomib, thalidomide and/or lenalidomide demonstrated anti-tumor response with a decrease in M proteins of 90% and 33%, respectively. Both patients received a fifth cycle of therapy and one continues on study. Conclusions: This phase I study provides preliminary evidence of safety and clinical activity of BB-10901 in patients with CD56-positive MM who have failed established MM treatments. Targeting of BB-10901 to myeloma cells in the marrow was confirmed. The MTD is not yet defined and enrollment is ongoing.

Abstract: The therapy of hematologic malignancies has been revolutionized by the development of therapies using chimeric antigen receptor modified T-cells (CAR-T). However, CAR-T cell therapy is often associated with cytokine release syndrome (CRS), characterized by fevers, hypotension, and hypoxia, as well as immune effector cell-associated neurotoxicity syndrome (ICANS). Severe cases of CRS can result in significant morbidity and mortality. Although disease features such as tumor burden may predict for more severe CRS and ICANS, other clinical features and biomarkers predictive of CRS and ICANS remain lacking, with the exception of measurements of serum cytokines following cell infusion (PMID: 27076371, PMID: 24553386). Experimental models have implicated elaboration of inflammatory cytokines such as IL-1 and IL-6 by monocytes in the pathogenesis of CRS and ICANS (PMID: 29808007, PMID: 29808005). Accordingly, the severity and duration of CRS and ICANS can be mitigated in part by IL-6 receptor blockade with tocilizumab and treatment with corticosteroids such as dexamethasone. Recent work has implicated ascorbate in the regulation of the activity of TET enzymes in hematopoietic cells (PMID: 28825709, PMID: 28823558). Given that TET2 deficiency has been associated with increased elaboration of inflammatory cytokines such as IL-6 and IL-1 by macrophages (PMID 3026882, PMID: 28104796, PMID: 28636844), we reasoned that ascorbate deficiency might predict for more pronounced cytokine release in patients leading to more severe CRS or ICANS. We identified 13 patients receiving CAR-T cell therapy for hematologic malignancies at the University of Texas Southwestern. Plasma specimens were collected from patients at baseline prior to receipt of lymphodepleting chemotherapy and/or at two weeks following CAR-T cell infusion. Given the poor reliability of clinical ascorbate measurements due to oxidation, we used an optimized protocol incorporating a C13-labeled ascorbate internal standard to obtain highly precise serum measurements using liquid-chromatography mass spectrometry. The incidence and severity of CRS and ICANS was classified using standardized grading criteria as per the American Society for Transplantation and Cellular Therapy. We measured serum ascorbate in 7 baseline and 12 post CAR-T cell infusion specimens obtained from 13 patients, with a median age of 65 (range 53 to 77). The cohort included eight patients with diffuse large B-cell lymphoma and two patients with mantle cell lymphoma receiving CD19-targeted CAR-T cells, as well as three patients with multiple myeloma receiving BCMA-targeted CAR-T cells. Eight patients developed grade one CRS, three patients developed grade two CRS, and two patients did not develop CRS. One patient developed grade one ICANS, one developed grade two ICANS, and one developed grade three ICANS. Eight patients received dexamethasone for CRS or ICANS, and eight patients received tocilizumab. Five patients only received one dose of tocilizumab, while two received two doses and one received three doses. Taking all pre- and post-CAR-T cell infusion ascorbate measurements into account, a significant correlation was found between having low serum ascorbate levels and a higher maximal grade of CRS or ICANS (Figure 1A, r 2=-0.64, p=0.0039). Post-infusion ascorbate measurements also demonstrated a significant correlation between low serum ascorbate levels and higher maximal CRS or ICANS (Figure 1B, r 2=-0.78, p=0.0035), while there was no correlation between pre-infusion ascorbate measurements and CRS or ICANS. Finally, we noted a significant decrease in serum ascorbate levels when comparing pre-infusion to post-infusion specimens (Figure 1C, p=0.048), including five paired specimens. There was no significant correlation between serum ascorbate levels and the number of doses of tocilizumab or dexamethasone administered. Low serum ascorbate levels may be associated with an increased risk for developing severe CRS and ICANS following CAR-T cell therapy. Although follow-up studies with a larger cohort of patient are necessary to substantiate this correlation, these data provide preliminary evidence that serum ascorbate levels may serve as a useful biomarker to predict severity of CRS and ICANS. Furthermore, they suggest ascorbate supplementation as a promising future strategy to mitigate these common complications of CAR-T cell therapy. Figure 1 Figure 1. Disclosures Kansagra: Alynylam, Celgene/BMS, Cota Health, GSK, Janssen, Karyopharm, Oncopeptide, Pfizer, Takeda, Sanofi: Membership on an entity's Board of Directors or advisory committees. Anderson: Celgene, BMS, Janssen, GSK, Karyopharm, Oncopeptides, Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Awan: Abbvie: Consultancy; Dava Oncology: Consultancy; Johnson and Johnson: Consultancy; Incyte: Consultancy; BMS: Consultancy; Astrazeneca: Consultancy; ADCT therapeutics: Consultancy; Pharmacyclics: Consultancy; Janssen: Consultancy; Beigene: Consultancy; Merck: Consultancy; Gilead sciences: Consultancy; Cardinal Health: Consultancy; Verastem: Consultancy; MEI Pharma: Consultancy; Karyopharm: Consultancy; Celgene: Consultancy; Kite pharma: Consultancy; Genentech: Consultancy. Madanat: Stem line pharmaceutical: Honoraria; Blue Print Pharmaceutical: Honoraria; Onc Live: Honoraria; Geron Pharmaceutical: Consultancy. Patel: Agios: Membership on an entity's Board of Directors or advisory committees; PVI: Honoraria; Celgene-BMS: Membership on an entity's Board of Directors or advisory committees. Sweetenham: EMA Wellness: Membership on an entity's Board of Directors or advisory committees.