Peripheral blood progenitor cell mobilization with intermediate-dose cyclophosphamide (ID-CY) and granulocyte colony-stimulating factor (G-CSF) has been shown to be more efficacious, albeit more toxic, than low-dose cyclophosphamide (LD-CY) mobilization regimens in patients with multiple myeloma treated with conventional therapies. However, the relative importance of cyclophosphamide dose intensity in peripheral blood progenitor cell mobilization after novel induction regimens is not known. Here we report mobilization outcomes of 123 patients who underwent transplantation within 1 year of starting induction chemotherapy with novel agents. We compared consecutive patients undergoing mobilization with ID-CY/G-CSF (3-4 g/m(2)) at one institution (n = 55) with patients receiving LD-CY/G-CSF (1.5 g/m(2)) at a different transplantation center (n = 68). At baseline, the 2 groups were well balanced, except for more frequent previous lenalidomide use in the ID-CY group (P = .04). Compared with LD-CY, ID-CY use was associated with higher median peak PB CD34(+) cell count (35/μL versus 160/μL; P < .001), CD34(+) cell yield on day 1 of collection (2.6 × 10(6)/kg versus 11.7 × 10(6)/kg, P ≤ .001), and total CD34(+) cell yield (7.5 × 10(6)/kg versus 16.6 × 10(6)/kg; P ≤ .001). Six patients in the LD-CY group had mobilization failure, compared with no patients in the ID-CY group. A significantly higher proportion of patients in the LD-CY group (P < .001) were unable to collect ≥5 × 10(6)/kg and ≥10 × 10(6)/kg CD34(+) cells. Neutrophil and platelet engraftment were significantly faster in the ID-CY group, likely because of higher infused CD34(+) cell doses. In conclusion, compared with LD-CY, ID-CY produced a more robust peripheral blood progenitor cell mobilization and significantly reduced the rates of mobilization failure. These data caution against the use of LD-CY-containing mobilization strategies in patients with multiple myeloma undergoing stem cell collection after novel induction regimens.

ObjectiveDietary therapies for irritable bowel syndrome (IBS) have received increasing interest but predicting which patients will benefit remains a challenge due to a lack of mechanistic insight. We recently found evidence of a role for the microbiota in dietary modulation of pain signalling in a humanised mouse model of IBS. This randomised cross-over study aimed to test the hypothesis that pain relief following reduced consumption of fermentable carbohydrates is the result of changes in luminal neuroactive metabolites.DesignIBS (Rome IV) participants underwent four trial periods: two non-intervention periods, followed by a diet low (LFD) and high in fermentable carbohydrates for 3 weeks each. At the end of each period, participants completed questionnaires and provided stool. The effects of faecal supernatants (FS) collected before (IBS FS) and after a LFD (LFD FS) on nociceptive afferent neurons were assessed in mice using patch-clamp and ex vivo colonic afferent nerve recording techniques.ResultsTotal IBS symptom severity score and abdominal pain were reduced by the LFD (N=25; p<0.01). Excitability of neurons was increased in response to IBS FS, but this effect was reduced (p<0.01) with LFD FS from pain-responders. IBS FS from pain-responders increased mechanosensitivity of nociceptive afferent nerve axons (p<0.001), an effect lost following LFD FS administration (p=NS) or when IBS FS was administered in the presence of antagonists of histamine receptors or protease inhibitors.ConclusionsIn a subset of IBS patients with improvement in abdominal pain following a LFD, there is a decrease in pronociceptive signalling from FS, suggesting that changes in luminal mediators may contribute to symptom response.

e11611 Background: Fluorine-18-FDG positron emission tomography (FDG-PET) role in the follow up care of non-metastatic breast cancer is not defined. Methods: We retrospectively analyzed 177 patients with stage I-III breast cancer between November 2004 and June 2006. IRB approval was obtained for this study. Patients were divided into two groups. Group A consisted of patients who had one or more FDG-PET scans as part of their clinical follow up (N=68), and Group B consisted of patients who did not (N=109). Clinical, radiological and pathology data were obtained from patients’ records. Results: Median follow-up is 35 months. Mean age 53 years for group A and 57 years for group B. Group A patients were more likely to have had higher stages (29% stage I, 53% stage II, and 18% stage III) compared with group B (64 % stage I, 31% stage II and 4% stage III). The two groups did not differ significantly in ER+ status (69% vs. 78% p=0.21), or Her2neu status (19% vs. 17%; p=0.6). Group A patients had more clinic visits (18 vs. 11; p=0.009), their tumor marker was checked more often (13 vs. 9 times; p=0.0001), had more radiological studies (10 studies vs. 5; p=0.0001), and had more biopsies (0.88 vs. 0.48 biopsy per patient; p=0.05). These differences were significant even after controlling for stage and chemotherapy. 9/68 patients in group A had tumor recurrence compared to 1/109 in group B (p=0.0003). PET scan indications were as follows: 29 (43%) for asymptomatic follow up evaluation [2 recurred]; 18 (26%) concerning symptoms [0 recurred]; 10 (15%) elevated tumor marker [2 recurred]; 7 (10%) other abnormal imaging studies [1 recurred]; 4 (6%) metastatic workup. Conclusions: While FDG-PET might aid in detecting recurrence in some patients with non-metastatic breast cancer, its use was associated with more clinic visits, blood tests, biopsies, and radiological tests. No significant financial relationships to disclose.

Background Visceral pain is a primary symptom of many gastrointestinal diseases. One feature of visceral pain is its vague localization. We hypothesized that overlap in the receptive fields of spinal primary afferent neurons that innervate the gut may contribute to this vague localization. Many studies have confirmed that the proximal and distal colon are mainly innervated by spinal afferent neurons with cell bodies in thoraco-lumbar and lumbo-sacral dorsal root ganglia (DRG), respectively. However, no murine studies have examined whether individual DRG neurons simultaneously innervate both proximal and distal colon. Aims To determine the extent of overlap in receptive fields of colon-projecting DRG neurons. Methods C57BL/6 mice (n=8) were anesthetized, and two retrograde neuronal tracers with distinct fluorescence emission spectra (Fast blue and DiI) were injected separately into the smooth muscle layers of proximal and distal colon. Mice were left for 10–13 days for dye transport, before being euthanized. Thoraco, lumbar and lumbo-sacral DRGs (T8-13, L1-4, L5-S2) were dissected and fixed in 4% paraformaldehyde overnight. 12μm cryostat sections were obtained and analyzed using a fluorescent microscope equipped with filter cubes that detect Fast blue and DiI. Results When DiI was injected into the proximal colon, we observed labelling to be highest in T8-13 DRG with 12.6 +/- 4.5% of cell bodies labelled, followed by L1-4 was (8.2 +/- 1.4%) and in L5-S2 (6.5 +/- 0.8%). DiI injections into the distal colon resulted in labelling of similar numbers of neurons labelled in T8-13 and L1-4 ganglia, whereas half as many neurons were labelled in L5-S2 ganglia. This data shows that the majority of spinal afferent innervation of the colon originates in thoracolumbar DRG. Most importantly, 26.4% and 17.6% of thoracolumbar and lumbo-sacral DRG neurons labelled by Fast blue injection into the proximal colon were also double-labelled by DiI injected into the distal colon. Similarly, 16.6% and 13.8% of neurons in thoracolumbar and lumbosacral DRG labelled by Fast blue injection into the distal colon were double-labelled by DiI injected into the proximal colon. Conclusions These data reveal a surprisingly large number of DRG neurons that innervate the colon have receptive fields that cover both the proximal and distal colon, which may contribute to the poor spatial localization of pain emanating from the colon. Funding Agencies CCC, CIHR

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313 Introduction: Peripheral blood progenitor cell (PBPC) mobilization with intermediate-dose cyclophosphamide (3–4 gm/m2) (ID-CY) and G-CSF has been shown to be less toxic than high-dose CY (≥7 gm/m2) -based, and more efficacious than low-dose CY (LD-CY) (1–2 gm/m2) -based mobilization regimens in multiple myeloma (MM) patients following conventional induction regimens. However the relative importance of CY dose intensity in PBPC mobilization following novel induction regimens is not known. Herein we report comparative efficacy of PBPC mobilization in MM patients following novel induction chemotherapies, relative to CY dose intensity. Methods: This multicenter outcomes study includes 123 patients who underwent a planned, single autograft within 1-year of starting induction chemotherapy with novel chemotherapy agents (thalidomide, lenalidomide, bortezomib), from 2003–2010. Consecutive patients undergoing mobilization with ID-CY/G-CSF (3–4 gm/m2) (n=55) at one institution were compared against consecutive patients receiving LD-CY/G-CSF (1.5 gm/m2) (n=68) at a different transplant center. At baseline the two groups were compared for parameters predicting mobilization failure. In order to assess efficiency of PBPC mobilization, we evaluated peak peripheral blood (PB) CD34+ cell counts, CD34+ cell yield on day1 of collection, total CD34+ cell collection, and total number of apheresis sessions. Mobilization failure was defined as failure to collect ≥2 ×106cells/kg body weight. All patients with normal renal function received uniform conditioning with Mel200 (MEL140 if serum creatinine was >2 mg/dl). SPSS version 13.0 was used for statistical analysis. Results: At baseline, the ID-CY and LD-CY cohorts were well balanced respectively in terms of mean age (57-yrs vs. 59-yrs, p=0.3), gender (males; 66% vs. 58%, p=0.4), high-risk cytogenetics (p=0.6), prior radiation (34% vs. 18%, p=0.06), disease stage (p=0.5), number of prior therapies (p=0.5) and remission status (p=0.2). No difference was observed in the types of novel therapies received prior to transplant (p=0.2), except 22% of the patients received lenalidomide in LD-CY vs. 40% in the ID-CY group (p=0.04). Compared to LD-CY, ID-CY use was associated with higher median peak PB CD34+ cell count (35/ul vs. 160/ul, p<0.001), CD34+ yield on day 1 of collection (2.6 ×106/kg vs. 11.6 ×106/kg, p=<0.001), total CD34+ cell yield (7.7 ×106/kg vs. 24.9 ×106/kg, p=<0.001), and a trend towards fewer apheresis sessions (p=0.052). Three patients in the LD-CY group had mobilization failure, while no patient in the ID-CY group had mobilization failure. Significantly higher proportion of patients (27% vs. 3.6%, p=<0.001) were unable to collect >5×106/kg CD34+ cells in LD-CY group. Neutrophil engraftment was significantly faster (15.4 days vs. 9.9 days) in the ID-CY patients, likely because of higher infused CD34+ cell dose. Conclusion: In conclusion, compared with LD-CY, ID-CY produced a more robust PBPC mobilization, in all parameters analyzed. These data caution against the use of LD-CY containing mobilization strategy in MM patients undergoing stem cell collection following novel induction regimens. Disclosures: No relevant conflicts of interest to declare.

4367 Introduction: Clofarabine is a purine nucleoside analogue which is approved for pediatric patients with relapsed or refractory acute lymphoblastic leukemia. A number of small phase I and II studies have shown activity in adult patients with newly diagnosed and relapsed/refractory acute myeloid leukemia (AML). Promising activity of clofarabine in combination with cyclophosphamide and etoposide has been reported in the pediatric setting (Hijiya et al., Leukemia 2009; Locatelli et al., Br J Haematol 2009). This combination has limited data in adult patients. We present a series of five cases in which clofarabine was combined with cyclophosphamide in adult patients with relapsed or refractory acute leukemia. Methods: We retrospectively reviewed patient charts of five patients treated with clofarabine in combination with cyclophosphamide. Results: Three patients received clofarabine 30mg/m2 + cyclophosphamide 340mg/m2, both on Days 1–5. Two patients received clofarabine 40mg/m2 + cyclophosphamide 440mg/m2 + Etoposide 100mg/m2, each drug on Days 1–5. Median age was 21 (range: 17 – 54). Patients had received 2 to 4 prior induction regimens (median of 3). Three patients were AML, one ALL, and one biphenotypical acute leukemia. Two patients were primary refractory and the other three were relapsed disease. Two out of the five patients achieved a morphologic complete remission (CR), one patient had a morphologic complete remission with incomplete blood count recovery (CRi) and the other 2 patients had treatment failure per Cheson criteria. Three patients went on to receive allogeneic transplants after clofarabine salvage therapy. Two patients that received allogeneic transplant had achieved complete remission (CR) after clofarabine/cyclophosphamide. The third patient was transplanted with a hypocellular marrow 38 days after clofarabine therapy. This patient ultimately achieved CR that was documented post-transplant, making it difficult to determine if the clofarabine regimen or allogeneic transplant achieved the remission status. Event-free survival ranged from 5 to 265+ days (median: 82 days). Treatment was complicated by neutropenic fever (n=5), grade III-IV mucositis (n=4), prolonged aplasia >30 days (n=4). One patient died of sepsis before completing the regimen. Conclusion: Clofarabine in combination with a cyclophosphamide-containing regimen appears to have anti-leukemic potential in adult patients. This regimen might be used to achieve cytoreduction before considering allograft transplant with refractory disease, in selected patients. More studies with this combination in adults are warranted. Disclosures: Hamadani: Celgene: Honoraria, Speakers Bureau; Otsuka: Research Funding, Speakers Bureau.