Citations

Abstract BACKGROUND An important challenge in radiomics research is reproducibility. Images are collected on different image scanners and protocols, which introduces significant variability even for the same type of image across institutions. In the present proof-of-concept study, we address the reproducibility issue by using domain adaptation – an algorithm that transforms the radiomic features of each new patient to align with the distribution of features formed by the patient samples in a training set. METHOD Our dataset included 18 patients in training with a total of 82 biopsy sample. The pathological tumor cell density was available for each sample. Radiomic (statistical + texture) features were extracted from the region of six image contrasts locally matched with each biopsy sample. A Gaussian Process (GP) classifier was built to predict tumor cell density using radiomic features. Another 6 patients were used to test the training model. These patients had a total of 31 biopsy samples. The images of each test patient were purposely normalized using a different approach, i.e., using the CSF instead of the whole brain as the reference. This was to mimic the practical scenario of image source discrepancy between different patients. Domain adaptation was applied to each test patient. RESULTS Among the 18 training patients, the leave-one-patient-out cross validation accuracy is 0.81 AUC, 0.78 sensitivity, and 0.83 specificity. When the trained model was applied to the 6 test patients (purposely normalized using a different approach than that of the training data), the accuracy dramatically reduced to 0.39 AUC, 0.08 sensitivity, and 0.61 specificity. After using domain adaption, the accuracy improved to 0.68 AUC, 0.62 sensitivity, and 0.72 specificity. CONCLUSION We provide candidate enabling tools to address reproducibility in radiomics models by using domain adaption algorithms to account for discrepancy of the images between different patients.

Abstract INTRODUCTION The quantification of intratumoral heterogeneity – through radiomics-based approaches - can help resolve the regionally distinct genetic drug targets that may co-exist within a single Glioblastoma (GBM) tumor. While this offers potential diagnostic value under the paradigm of individualized oncology, clinical decision-making must also consider the degree of uncertainty associated with each model. In this study, we evaluate the performance of a novel machine-learning (ML) algorithm, called Gaussian Process (GP) modeling, that can quantify the impact of multiple sources of uncertainty in ML model development and prediction accuracy, including variabilities in the copy number measurement, radiomics features, training sample characteristics, and training sample size. METHOD We collected 95 image-localized biopsies from 25 primary GBM patients. We coregistered stereotactic locations with preoperative multi-parametric MRI features (conventional MRI, DSC perfusion, Diffusion Tensor Imaging) to generate spatially matched pairs of MRI and copy number variants (CNV) for for each biopsy. We developed a Gaussian Process (GP) model to predict CNV for Epidermal Growth Factor Receptor (EGFR) based on MRI radiomic features in each patient. We used leave-one-patient-out cross validation to quantify prediction accuracy and model uncertainty. Spatial prediction and uncertainty (p-value) maps were overlaid to help visualize regional genetic variation of EGFR and uncertainty of the radiomic predictions. RESULT: The initial GP radiomics model for EGFR amplification (CNV > 3.5) produced a sensitivity of 0.8 and specificity of 0.8. Samples/regions associated with high uncertainty (p-value >0.05) correlated with either 1) extrapolation of radiomic features from the training set-defined feature space or 2) insufficient training samples in the feature space. CONCLUSION We present a ML-based model that quantifies spatial genetic heterogeneity in GBM, while also estimating model uncertainties that result from multi-source data variabilities. This approach lays the groundwork for prospective clinical integration of modeling-based diagnostic approaches in the paradigm of individualized medicine.

Abstract OBJECTIVE The K16ApoE peptide enhances delivery of multiple agents across the blood-brain barrier (BBB). Transgenic mouse models are central to elucidating the underlying pathophysiology of Alzheimer’s Disease (AD) and provide a system for evaluating novel therapeutic strategies. PET imaging plays a central clinical role in diagnosing human cases of AD but has had variable performance in mouse models. We investigated the role of K16ApoE to enhance delivery of a radiolabeled PET imaging tracer, 11C-PiB and assess whether this corresponds to improved PET sensitivity in APP/PS1 transgenic mice. METHODS Brain-delivery of 11C-PiB was accomplished by successive injections of K16ApoE and 11C-PiB. Distribution of 11C-PiB to the brain and heart was quantified via dynamic PET/CT imaging and digital autoradiography. RESULTS K16ApoE increased the brain uptake of 11C-PiB in both wild-type (WT) and APP/PS1 mice. Administration of K16ApoE increased the PET standard uptake value of 11C-PiB at 5 minutes in WT mice from 1.132 to 2.963 (p=0.006) and in APP/PS1 mice from 0.842 to 3.268 (p=0.016). Enhancement peaked at 5 minutes. Binding was reversible with similarly increased kinetics in both WT and APP/PS1 mice. The absolute values were higher in APP/PS1 mice suggesting increased retention. The increased retention in APP/PS1 mice was consistent with specific binding to A-beta plaques as unlabeled PiB reduced 11C-PiB signal retention. CONCLUSION K16ApoE mediates enhancement of 11C-PiB signal in APP/PS1 mice brains with increased PET sensitivity. There is increased uptake kinetics in both WT and APP/PS1 mice with specific A-beta plaque binding in the latter. This enhanced delivery of the PET tracer has implications for development and testing of new hypotheses and the efficacy of novel therapeutic paradigms. K16ApoE has potential for improving delivery of several agents across the BBB. This has implication for delivery of diagnostic and therapeutic agents for neurodegenerative and neuro-oncologic diseases.

Abstract Background: Randomized control trials (RCT) have examined the safety and efficacy of direct oral anticoagulants (DOACs) compared to dalteparin in patients with cancer-associated thrombosis (CAT). Increased major bleeding (MB) was seen with edoxaban and increased clinically relevant non-major bleeding (CRNMB) was seen with rivaroxaban and there has been specific concern about increased risk of bleeding among patients with gastrointestinal malignancies (GIM). Results from RCTs comparing apixaban to dalteparin in CAT are pending. Objective: Using the Mayo Clinic VTE registry, we examined the rates of MB, CRNMB, and overall bleeding (MB + CRNMB) in patients with GIM treated with anticoagulation for CAT. Methods: Consecutive patients treated for CAT were enrolled into Mayo Clinic VTE Registry between March 1, 2013 and July 27, 2018 and were followed prospectively for safety and efficacy. Clinical, demographic and imaging data were collected from each participant at the time of study recruitment. Cancer type, stage, and treatment with chemotherapy were recorded. Major and CRNMB events were evaluated at 3-month intervals. Clinical status was assessed by written questionnaire in subjects unable to return at 3 months. Unreturned questionnaires were followed up with a scripted phone interview. The study was approved by Mayo Clinic Institutional Review Board. Results: In the 535 subjects in the registry with CAT, the mean age (64.6 vs. 62.8 years), mean BMI (28.4 vs. 28.8), and percent female (46.4% vs 40.6%) were numerically similar between DOAC and LMWH treatment groups (Table 1). Metastatic disease was present in 53.6% and 60.2% and chemotherapy was being administered in 66.5% and 71.2% of DOAC and LMWH treated patients, respectively. Thrombocytopenia (<100x109/L) at initiation of anticoagulation was present in 6.8% of DOAC treated and 7.5% of LMWH treated patients. Among all cancer patients, 110 (21%) patients had a GIM, 58 (53%) were treated with LWMH and 52 (47%) were treated with a DOAC (42% rivaroxaban or 58% apixaban). In all CAT, the rate of MB was similar in DOAC versus LMWH treated patients (7.8 vs. 5.4 per 100 person-years; HR 1.48, 95% CI 0.72-3.05; Table 2). The rate of CRNMB however, was significantly increased in the DOAC patients compared to LMWH treated patients (6.18 vs. 0.44 per 100 person-years; HR 14.7, 95% CI 1.92, 112.26). In the sub-group of patients with GIM, the rate of MB was non-significantly higher in the DOAC versus LMWH treated patients (11.1 vs. 3.9 per 100 person-years; HR 2.90, 95% CI 0.57, 14.73). In contrast to the overall CAT group, the rate of CRNMB was similar in the DOAC compared to LMWH treated patients (2.10 vs. 1.92 per 100 person-years; HR 1.18, 95% CI 0.07, 20.21). In GIM patients, apixaban compared to rivaroxaban had a numerically higher, but non-significant, rate of major bleeding (23.98 vs. 3.50 per 100 person-years; HR 4.0, 95% CI 0.54-29.87). In the overall group of CAT, the risk of major bleeding was similar between apixaban and rivaroxaban (9.51 vs. 6.77 per 100 person-years). Conclusion: In our registry of subjects with CAT, we identified a significantly increased rate of CRNMB and overall bleeding, but not MB with the use of DOACs. In our data, GIM alone does not appear to account for the increased bleeding risk seen in CAT with DOACs, as we demonstrated no significant increase in major, CRNMB, or overall bleeding compared to LMWH. Direct comparison between apixaban and rivaroxaban was limited by sample size and number of events. Disclosures No relevant conflicts of interest to declare.

Abstract Introduction: Mutations localized in the tyrosine kinase domain activation loop of FLT3 (FLT3-TKD), representing point mutations in codon D835/I836 and rarely deletions of codon I836, induce constitutive tyrosine phosphorylation and activation of the receptor tyrosine kinase similarly to FLT3 internal tandem duplication (ITD) mutations. However, the prognostic role of FLT3-TKD in AML, particularly in the presence of NPM1 mutations, is not well established. The phase 3 RATIFY trial [NCT00651261; Stone et al. N Engl J Med. 2017] showed that in combination with standard chemotherapy, midostaurin (PKC412) improved survival outcomes across all 3 FLT3 stratification subgroups (ITD high allelic ratio [≥ 0.7], ITD low allelic ratio [< 0.7], and TKD) vs placebo in patients with newly diagnosed FLT3-mutated AML. Here, we evaluated the prognostic impact of FLT3-TKD and NPM1 mutations in a post hoc analysis from the RATIFY trial. Methods: In RATIFY, newly diagnosed patients with AML 18-60 years old were randomly assigned to receive midostaurin or placebo together with standard induction and consolidation therapy followed by 12 28-day cycles of maintenance therapy with midostaurin or placebo. FLT3-TKD mutation was detected by PCR and capillary electrophoresis at 9 reference laboratories. Patients were categorized as NPM1 mutated (mut) or NPM1 wild-type (WT) using PCR. Efficacy outcomes included complete remission (CR), overall survival (OS), event-free survival (EFS) and disease-free survival (DFS). EFS and DFS analyses were performed considering CR within a 60-day window. P values presented have not been adjusted for multiplicity. Results: Of the total randomized 162 FLT3-TKD patients, 134 with available NPM1 data had consented for exploratory analysis and thus were included in this study (see Table for subgroup distribution). Overall, 47.8% of patients were male, and the median age was 49 years (95% CI, 45.5-51.1 years). The median white blood cell (WBC) count was higher in patients with NPM1-mut than in patients with NPM1-WT (34.1 vs 15.5 × 109/L, P = .0011). CR rates (during the first 60 days) were higher in patients with FLT3-TKD/NPM1-mut vs FLT3-TKD/NPM1-WT (66% vs 53%); however, this was driven by the higher rate of CR in the midostaurin arm (76% NPM1-mut vs 44% NPM1-WT) rather than the placebo arm (53% NPM1-mut vs 60% NPM1-WT). The overall CR rate (regardless of NPM1 genotype) was 64% for midostaurin and 56% for placebo in FLT3-TKD patients. The prognostic effect of the NPM1 mutation concurrent with FLT3-TKD was seen for all endpoints consistently with hazard ratios (HRs) around 0.50 or lower (Figures 1 and 2 and Table). Overall (regardless of treatment) OS, EFS, and DFS estimates at 3 years were 73% vs 52%, 48% vs 25%, and 74% vs 47%, respectively, in patients with FLT3-TKD/NPM1-mut vs FLT3-TKD/NPM1-WT. Whereas the HRs for midostaurin vs placebo were 0.73 for both OS and EFS, the impact of treatment on outcomes varied between the individual NPM1/TKD subgroups and was not consistently observed when endpoints were censored at stem cell transplant (SCT) (Table). It should be noted that the number of patients in each subgroup was small and therefore the HRs with 95% CIs should be interpreted with caution. Multivariate analyses in these FLT3-TKD patients revealed that NPM1 genotype was an independent prognostic factor for OS, EFS and DFS (2-sided P < .05), whereas study drug, age, sex, WBC at baseline and SCT (no/yes) did not reach this level of significance in the Cox model. Conclusions: This post hoc analysis of the FLT3-TKD patient subset in the RATIFY trial showed the high prognostic value of NPM1 mutational status. Whereas midostaurin showed an overall benefit in the FLT3-TKD patients for OS, EFS, CR and DFS, the impact of treatment on outcome varied between the individual NPM1 subgroups within these FLT3-TKD patients and was not consistently observed.Further analyses using additional endpoints and additional multivariate analyses are planned. Support: U10CA180821, U10CA180882, U10CA180820, U10CA180791, U10CA180888, U10CA180863, (CCSRI) #704970, U24CA196171; ClinicalTrials.gov Identifier: NCT00651261 Disclosures Voso: Celgene: Research Funding, Speakers Bureau. Larson:Ariad/Takeda: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; BristolMyers Squibb: Consultancy, Research Funding. Heuser:Janssen: Consultancy; Pfizer: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; StemLine Therapeutics: Consultancy; Astellas: Research Funding; BergenBio: Research Funding; Karyopharm: Research Funding; Bayer Pharma AG: Consultancy, Research Funding; Tetralogic: Research Funding; Sunesis: Research Funding; Daiichi Sankyo: Research Funding. Wei:Novartis: Honoraria, Other: Advisory committee, Research Funding, Speakers Bureau; Pfizer: Honoraria, Other: Advisory committee; Amgen: Honoraria, Other: Advisory committee, Research Funding; Abbvie: Honoraria, Other: Advisory board, Research Funding, Speakers Bureau; Servier: Consultancy, Honoraria, Other: Advisory committee, Research Funding; Celgene: Honoraria, Other: Advisory committee, Research Funding. Brandwein:Lundbeck: Consultancy; Celgene: Consultancy; Pfizer: Consultancy; Novartis: Consultancy; Boehringer Ingelheim: Consultancy, Research Funding. de Witte:Novartis: Research Funding; Amgen: Consultancy, Research Funding; Celgene: Honoraria, Research Funding. Medeiros:Celgene: Consultancy, Research Funding; Genentech: Employment. Tallman:Cellerant: Research Funding; Orsenix: Other: Advisory board; BioSight: Other: Advisory board; ADC Therapeutics: Research Funding; AROG: Research Funding; AbbVie: Research Funding; Daiichi-Sankyo: Other: Advisory board. Schlenk:Pfizer: Research Funding, Speakers Bureau. Ganser:Novartis: Membership on an entity's Board of Directors or advisory committees. Cheng:Novartis: Employment. Gathmann:Novartis: Employment. Tiecke:Novartis: Employment. Thiede:AgenDix: Other: Ownership; Novartis: Honoraria, Research Funding. Döhner:AbbVie: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Research Funding; Seattle Genetics: Consultancy, Honoraria; Celator: Consultancy, Honoraria; Sunesis: Consultancy, Honoraria, Research Funding; Bristol Myers Squibb: Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Seattle Genetics: Consultancy, Honoraria; AROG Pharmaceuticals: Research Funding; Sunesis: Consultancy, Honoraria, Research Funding; Astellas: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria; AROG Pharmaceuticals: Research Funding; Celator: Consultancy, Honoraria; Astex Pharmaceuticals: Consultancy, Honoraria; Bristol Myers Squibb: Research Funding; Agios: Consultancy, Honoraria; Agios: Consultancy, Honoraria; Astellas: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Astex Pharmaceuticals: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Research Funding; Jazz: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Jazz: Consultancy, Honoraria; Pfizer: Research Funding; Pfizer: Research Funding; Novartis: Consultancy, Honoraria, Research Funding. Stone:Otsuka: Consultancy; Argenx: Other: Data and Safety Monitoring Board; Amgen: Consultancy; Agios: Consultancy, Research Funding; Orsenix: Consultancy; Ono: Consultancy; Novartis: Consultancy, Research Funding; Astellas: Consultancy; Arog: Consultancy, Research Funding; Merck: Consultancy; Cornerstone: Consultancy; Fujifilm: Consultancy; Jazz: Consultancy; Celgene: Consultancy, Other: Data and Safety Monitoring Board, Steering Committee; Pfizer: Consultancy; Sumitomo: Consultancy; AbbVie: Consultancy.

Abstract Background: Hereditary transthyretin amyloidosis (hATTR) is a rare, progressive, and fatal disease caused by the buildup of transthyretin-derived amyloid protein in major organs, predominantly affecting the peripheral nerves and heart. Inotersen, a second-generation antisense oligonucleotide targeting TTR mRNA, has shown efficacy and safety in patients with hATTR in a randomized, double-blind, placebo-controlled, phase 3 study, NEURO-TTR (ClinicalTrials.gov, NCT01737398; Benson NEJM 2018). Patients with hATTR amyloidosis who completed the NEURO-TTR study were eligible to receive inotersen for up to 5 years in a phase 3 open-label extension study (ClinicalTrials.gov, NCT02175004). Methods: In NEURO-TTR, patients were randomized 2:1 to receive inotersen (300-mg weekly subcutaneous doses) or placebo. In the open-label extension, patients continued inotersen (inotersen-inotersen) or switched from placebo to inotersen (placebo-inotersen). Evaluations included modified Neuropathy Impairment Score +7 neurophysiologic tests composite score (mNIS+7; higher scores indicate worse neuropathy), Norfolk Quality of Life-Diabetic Neuropathy questionnaire total score (Norfolk QoL-DN; higher scores indicate worse QoL), and adverse events (AEs). Cardiomyopathy (CM) was defined by a diagnosis of hATTR-CM at trial entry or by an interventricular wall thickness of 13 mm or more on transthoracic echocardiography at baseline, as ascertained by a central reader, or no known history of persistent hypertension (systolic blood pressure, ≥150 mm Hg) within 12 months before screening. Results : In the placebo-controlled, double-blind, phase 3 NEURO-TTR study, 112/172 patients were randomized and received inotersen. At baseline, patients were predominantly white (91.9%) males (68.6%) with a mean age of 59.2 years. A total of 67.4% had stage I (ambulatory) and 32.6% had stage II (ambulatory with assistance) disease. Inotersen-treated patients who had stage II disease had a longer duration of disease from diagnosis (40.9 vs 24.8 months, respectively) and from onset (72.6 vs 63.2 months, respectively) of hATTR polyneuropathy symptoms compared with placebo-treated patients who had stage II disease, indicating more advanced disease. A higher proportion of inotersen-treated patients had CM at baseline (67% vs 55%, respectively), and more severe CM, measured by higher NT-proBNP levels and longer duration of disease from hATTR-CM symptom onset, compared with placebo-treated patients. In the phase 3 open-label extension study as of Sept 15, 2017, 134 of 135 patients enrolled received ≥1 dose of inotersen. The mean age was 60.4 years and most patients were male (69.4%). Extended dosing with inotersen up to 27 months continued to improve mNIS+7 and Norfolk QoL-DN in the open-label extension compared to placebo-treated patients at week 66 in the double-blind NEURO-TTR study; mean changes from open-label extension baseline to open-label extension week 52 in the inotersen-inotersen group were 5.1 points for mNIS+7 (vs 25.5 for placebo-treated patients in the double-blind NEURO-TTR study) and 3.9 points for Norfolk QoL-DN (vs 10.7 for placebo-treated patients in the double-blind NEURO-TTR study). Initiation of inotersen in placebo-treated patients (placebo-inotersen) resulted in improvement in mNIS+7 and Norfolk QoL-DN by week 26. Few patients discontinued treatment because of AEs (inotersen-inotersen, 9%; placebo-inotersen, 4%). The rate of treatment-related serious AEs was low in both treatment groups (2% each). There was no evidence of increased risk for grade 4 thrombocytopenia or severe renal events with increased duration of exposure. We will present 2-year follow-up results from the open-label extension study. Conclusions: Results of the open-label extension show continued benefit, measured by mNIS+7 and Norfolk QoL-DN, and confirmed that earlier initiation of treatment is important for optimal clinical outcomes. No new safety concerns were identified. Results from the longer-term follow-up for the open-label extension will further elucidate how inotersen may benefit patients with hATTR amyloidosis. Disclosures Brannagan: Alnylam: Honoraria, Other: Investigator, Speakers Bureau; Ionis: Other: Investigator. Wang:Ionis: Other: Investigator, Speakers Bureau. Coelho:Prothena: Consultancy, Honoraria; Ionis: Consultancy, Other: Investigator; Alnylam: Consultancy, Honoraria, Other: Investigator; Pfizer: Consultancy, Honoraria, Other: Investigator. Waddington Cruz:Ionis: Honoraria; Genzyme/Sanofi: Honoraria; Pfizer: Honoraria. Polydefkis:Pfizer: Honoraria; Alnylam: Honoraria. Dyck:Ionis: Consultancy; Alnylam: Consultancy. Plante-Bordeneuve:Alnylam: Consultancy; Pfizer: Consultancy, Other: reimbursement for travel and meeting; Ionis: Other: reimbursement for travel and meeting. Berk:Ionis: Honoraria, Other: Investigator; Alnylam: Honoraria, Other: Investigator; Pfizer: Other: Investigator. Barroso:Pfizer: Consultancy, Honoraria, Other: Thaos registry, Speakers Bureau; Alnylam: Honoraria, Other: Investigator. Conceição:Alnylam: Consultancy, Honoraria, Speakers Bureau; Pfizer: Consultancy, Honoraria, Speakers Bureau; Sanofi: Honoraria, Speakers Bureau. Hughes:Ionis: Employment. Kwoh:Ionis: Employment. Jung:Ionis: Employment. Guthrie:Akcea: Employment. Pollock:Akcea: Employment. Benson:Ionis: Other: Investigator, Research Funding. Gertz:janssen: Consultancy; Teva: Consultancy; spectrum: Consultancy, Honoraria; Alnylam: Honoraria; Ionis: Honoraria; Amgen: Consultancy; annexon: Consultancy; Prothena: Honoraria; Research to Practice: Consultancy; Apellis: Consultancy; celgene: Consultancy; Abbvie: Consultancy; Medscape: Consultancy; Physicians Education Resource: Consultancy.

Abstract Background: Autologous stem cell transplantation is an effective therapy for patients with multiple myeloma. We and others have previously reported the influence of lenalidomide based regimens on the ability to harvest adequate number of stem cells for successful transplantation. In order to identify factors predicting for poor mobilization we studied a large group of patients who underwent an attempt at stem cell mobilization after receiving lenalidomide and dexamethasone as primary therapy for myeloma. Methods: We identified sequential patients who received lenalidomide and dexamethasone as initial therapy for their myeloma and then underwent stem cell mobilization for immediate or future stem cell transplantation. Patients who received any other regimen prior to the stem cell mobilization were excluded. Between July 2004 and May 2008, 106 patients, satisfying the above criteria were identified from the Mayo Clinic transplant database. Medical records and collection sheets were examined for the data. Results: The median (range) age at mobilization was 60 yrs (29–75); 34 (32%) were over 65 yrs and 59 (55%) were males. The median duration of lenalidomide therapy was 4 months (range; 1–13). The strategy for stem cell mobilization was GCSF alone in 92 patients (87%), cyclophosphamide (CTX) and GCSF in 11 pts and 3 pts received AMD3100 and GCSF. Among the GCSF mobilized patients, 10 pts (11%) failed to collect at least 2.5 million cells required for one transplant, including 8 patients who never achieved the minimum peripheral count threshold to initiate the collection. Two of the 11 pts undergoing primary mobilization with CTX/GCSF failed to collect any cells, while all of the 3 pts mobilized with AMD3100 were successful. Five of these pts subsequently underwent successful salvage mobilization with CTX/GCSF, 1 with AMD3100, one failed to mobilize with CTX and the rest did not repeat mobilization. Given that the total CD34 collection and the number of days of collection are influenced by the CD34 goal, we examined patient characteristics that correlated with the CD34 collections over the first 2 days. Increasing patient age and the duration of lenalidomide therapy, both correlated with decreasing 2-day CD34 collection, while the time between last dose of lenalidomide and the start of GCSF had no effect. We then performed ROC analysis to find best cut-off points that predicted the inability to collect adequate (2.5 million) CD34 cells in 3 days. Lenalidomide therapy of more than 4 months (P =0.03) and age > 63 yrs (P = 0.04) best predicted inability to achieve this endpoint. In addition, a peripheral blood CD34 count < 5/uL on day 5 after start of GCSF was highly predictive of failure to reach this endpoint. Conclusions: Inability to collect adequate stem cells with lenalidomide appears to be related to patient age and the duration of lenalidomide therapy. We recommend early stem cell collection and storage, if a delayed transplantation approach is taken. Patients receiving more than 4 cycles of therapy and those over 65 years should undergo mobilization with CTX+G-CSF, rather than G-CSF alone. Majority of the patients who fail G-CSF based collection can be mobilized using CTX and G-CSF. Early identification of failures after G-CSF administration using the peripheral CD34 counts can potentially allow salvage using strategies such as AMD3100.

Abstract Abstract 2992 Background: Patients with myeloma receiving initial therapy with lenalidomide-based regimens can have difficulty collecting adequate stem cells for an autologous transplant. Stem cell collection in these patients can be significantly enhanced by addition of the CXCR-4 antagonist plerixafor to the mobilization regimen. Plerixafor is typically given subcutaneously (SQ), with collection approximately 11 hours after injection to obtain maximum yield. Intravenous administration can potentially allow more rapid and predictable mobilization compared to the SQ route. We designed this trial to prospectively assess the efficacy of intravenous plerixafor administration in patients undergoing lenalidomide therapy. Patients and methods: Patients who were receiving initial therapy with a lenalidomide-based regimen and were undergoing stem cell collection within 12 months of their myeloma diagnosis were enrolled. Patients received GCSF at 10 μg/kg/day for 4 days followed by addition of plerixafor at 0.24 mg/kg/dose starting on day 5. Plerixafor was administered intravenously early morning (6–7 am) followed by apheresis beginning 4–5 hours later. Plerixafor was administered for a maximum of 4 days; but patients could continue apheresis beyond the 4th day at treating physician discretion. The aims of the study were to determine the proportion of patients reaching a stem cell yield of at least 3 million CD34 cells/kg by second day of apheresis, the safety and tolerability of intravenously administered plerixafor, and the overall rate of failure to mobilize (defined as less than 2.5 million CD34 cells/kg in 4 collections). Results: Thirty-seven patients were accrued between December 2009 – April 2011, and 36 were eligible for analysis. The median age was 61 years (range; 28–73); 61% were male. The median time from start of initial therapy to enrollment was 4.6 months (range; 2.6 to 11.1) and the median cycles of lenalidomide were 4 (range; 3–11). Thirty-four (94%) of the patients achieved at least 3 million CD34 cells/kg within 2 days of apheresis. The median CD34 cells/kg after 1 day of collection was 3.9 million (range; 0.7 to 9.2) and after two days of collection was 7.02 million (range: 1.1–16.5). Two patients failed the mobilization (<2.5 million CD34 cells/kg). There were no grade 3 or 4 non-hematological adverse events and one patient experienced grade 4 thrombocytopenia. The most common grade 1 or 2 adverse events seen were gastrointestinal, namely nausea, diarrhea and abdominal pain or bloating. Grade 1 dizziness was reported in 8 patients. Overall, the infusion was well tolerated. Conclusion: Intravenously administered plerixafor is an effective strategy for mobilization in this patient group with low rate of failure to mobilize. It is well tolerated with toxicity comparable to the SQ administration. It also offers flexibility in patient scheduling with a convenient schedule for early morning infusion followed by apheresis later in the day. Disclosures: Kumar: Merck: Consultancy, Honoraria; Celgene: Consultancy, Research Funding; Millennium Pharmaceuticals, Inc.: Research Funding; Genzyme: Research Funding; Novartis: Research Funding. Off Label Use: Use of the investigational agent MLN9708 for the treatment of previously untreated multiple myeloma. Lacy:Celgene: Research Funding.

Abstract If the observed dramatic increase in VTE incidence with advancing age is due to increased VTE risk factor exposure (i.e., secondary VTE), the incidence of idiopathic VTE should not vary with age or calendar year. Objective: To estimate the incidence of idiopathic and secondary VTE by age and by calendar year. Methods: Using the resources of the Rochester Epidemiology Project, we identified the inception cohort of Olmsted County, MN, residents with a first lifetime VTE during the 30-year period, 1966–1995 (n=2761). For each case, we reviewed the complete medical records in the community for 48 baseline clinical characteristics that are commonly-accepted risk factors for VTE. We categorized VTE cases as idiopathic (n=305) if no such characteristics were present; the remaining cases were categorized as secondary. Age- and sex-specific incidence rates were calculated using idiopathic or secondary VTE cases as the numerator, and age-, sex- and calendar year-specific estimates of the population of Olmsted County as the denominator. Results: The incidence of both idiopathic and secondary VTE increased exponentially with age for both men and women (p<0.001). Over the 30-year study period, the age-adjusted incidence of idiopathic VTE was essentially constant among men (from 19.0 to 17.1 per 100,000 men-years for 1966–70 and 1990–95, respectively), but decreased markedly among women (from 18.5 to 3.6 per 100,000 woman-years for 1966–70 and 1990–95, respectively; p=0.005 for the interaction). Conclusions: The dramatic increase in VTE incidence with age likely reflects the biology of aging, although as yet unidentified VTE risk factors cannot be excluded. The reason for the decreased incidence of idiopathic VTE over the last 30 years among women is unclear.