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Abstract Abstract 2868 Poster Board II-844 Background and Objective: In newly diagnosed multiple myeloma (MM), the combination of lenalidomide plus high-dose dexamethasone (RD) is superior to high-dose dexamethasone (Zonder JA et al, Blood 2007;110:77). Preliminary results show that lenalidomide plus low-dose dexamethasone (Rd) has better 2-year overall survival (OS) compared with RD (Rajkumar SV et al, J Clin Oncol 2008;26:8504). The addition of clarithromycin (Biaxin) to lenalidomide and low-dose dexamethasone (BiRd) has been investigated in a phase II study, demonstrating a high response rate and 2-year OS (Niesvizky R at al, Blood 2008;111:1101-1109). However, the additive value of clarithromycin is not known. No randomized trials have compared Rd versus BiRd, none are planned. The objective of this case–matched study was to compare the efficacy and the toxicity of BiRd vs Rd as initial therapy for newly diagnosed MM. Patients and methods: Data from 72 newly diagnosed MM patients treated at the New York Presbyterian Hospital–Cornell Medical Center, from December 2004 to December 2006, with BiRD, were analyzed. For comparison, an equal number of pair mates were selected among newly diagnosed patients seen at the Mayo Clinic who received Rd, from March 2005 to December 2008. Case matching was performed with respect to age, gender, and transplant status. Patients treated with BiRd received oral lenalidomide (25 mg/day, days 3-21 of cycle 1; days 1-21 of subsequent cycles); dexamethasone (40 mg days 1, 2, 3, 8, 15, 22 of cycle 1; days 1, 8, 15, and 22 of each subsequent cycle); clarithromycin (500 mg twice daily, from day 2 of cycle 1). Patients treated with Rd received oral lenalidomide (25 mg/day, days 1-21) plus low-dose dexamethasone (40 mg days 1, 8, 15, 22). In both groups patients were allowed to discontinue treatment to pursue transplant, but treatment until progression, relapse or unacceptable toxicity was permitted at the physician's discretion. Outcome was analyzed on an intention-to-treat basis. The Chi-square or the rank sum tests were used to compare variables. Time-to-event analysis was performed using the Kaplan-Meier method; comparisons were determined by the log-rank test and the Cox proportional hazards model. Results: Median duration of treatment was 11.8 months in the BiRd group vs 6 months in the Rd group. On intention-to-treat analysis, complete response was significantly higher with BiRd compared to Rd (45.8% vs 13.9%, respectively, p<0.001); similarly very good partial response (VGPR) or better was higher with BiRd (73.6% vs 33.3%, p<0.001). Rates of VGPR or better, after 6 months and 1 year of therapy, were significantly higher in BiRd patients. Both time-to-progression (TTP) (median 48.3 months vs 27.5 months; HR 0.51; 95% CI 0.25-1.06; p=0.071) and PFS (median 48.3 months vs 27.5 months, HR 0.50; 95% CI 0.25-0.98; p=0.044) were higher with BiRd. Median time to next treatment (TTNT) was not reached in BiRd group compared to 29.9 months in Rd patients (HR 0.37 95% CI 0.20-0.66, p<0.001). There was a trend toward better OS with BiRd, (3-year OS: 89.7% vs 73.0%), but the difference was not statistically significant (HR 0.48; 95% CI 0.17-1.37; p=0.170). Thirty-two patients in each group received transplant; median time to transplant was longer in BiRd group (13.5 vs 5.9 months). Results of survival, for patients who received transplant and patients who did not, were similar to those of the total population. On subset analysis, among patients presenting with International Staging System (ISS) stage I/II at diagnosis, TTP, PFS and TTNT were significantly longer in BiRd patients; no significant differences were found among patients with ISS stage III. Main grade 3-4 toxicities of BiRd were hematological, in particular thrombocytopenia (23.6% vs 8.3%, p=0.012); rate of neutropenia was similar between the 2 groups (19.4% vs 16.7%, p=0.665). Infections (16.7% vs 9.7%, p=0.218) and dermatological toxicity (12.5% vs 4.2%, p=0.129) were higher in patients who received Rd. Rate of venous thromboembolism was similar in the 2 groups (9.7% vs 12.5%, respectively in Rd and BiRd patients, p=0.596). Conclusion: Results of this case-control analysis suggest superiority of BiRd in terms of response rate and survival, compared with Rd, and suggest that there may be a significant additive value when clarithromycin is added to Rd. These data indicate the need for randomized prospective phase III studies to evaluate BiRd versus Rd in the treatment of MM. Disclosures: Off Label Use: research drug in combination to standard of care. Kumar:celgene: Research Funding; millenium: Research Funding; bayer: Research Funding; novartis: Research Funding; genzyme: Research Funding. Mark:celgene: Research Funding. Dispenzieri:celgene: Research Funding. Gertz:celgene: Honoraria; genzime: Honoraria; millenium: Honoraria; amgen: Honoraria. Leonard:celgene: Consultancy. Lacy:celgene: Research Funding. Witzig:celgene: Research Funding. Fonseca:medtronic: Consultancy; genzyme: Consultancy; celgene: Consultancy; amgen: Consultancy; BMS: Consultancy; otsuka: Consultancy. Greipp:celgene: Research Funding. Niesvizky:celgene: Research Funding, Speakers Bureau; Millenium: Research Funding, Speakers Bureau; Proteolix: Research Funding, data monitoring committee.

Abstract BACKGROUND: Bone marrow fibrosis might represent either a primary myeloid malignancy such as myelofibrosis with myeloid metaplasia (MMM) or a reactive phenomenon associated with other malignancies or inflammatory/infectious processes. The development of myelofibrosis in the context of a plasma cell dyscrasia is uncommon and incompletely understood from the standpoint of both pathogenesis and clinical implications. We sought to determine the origin and clinical ramifications of this phenomenon based on a consecutive series of patients with plasma cell disorders (PCD). METHODS: A retrospective search of institutional databases was performed for clinical cases of PCD with the concomitant observation of myelofibrosis. Bone marrow aspirates and trephines from the time of diagnosis of both PCD and myelofibrosis were reviewed. Clinical history was abstracted for clinical manifestations as well as disease course. DNA from archived cytogenetic pellets, when available, from the time of diagnosis, was screened for the presence of JAK2V617F. RESULTS: Among 7587 patients with a PCD seen over the last 30 years at our institution, 29 (0.3%) displayed concomitant myelofibrosis (median age 59 years, range 27–77; 52% males). The specific PCD was multiple myeloma in 25 patients, smoldering myeloma in 2, plasmacytoma in 1, and heavy chain disease in 1. Four patients (14%) had organomegaly and bone marrow histological features most consistent with MMM. Otherwise, myeloproliferative disorder (MPD)-characteristic features were infrequent and included leukocytosis and/or thrombocytosis in only 2 patients. None of the patients displayed thrombohemorrhagic complications. Archived DNA was available in 7 cases without either clinical or bone marrow histological evidence of a MPD and yet revealed the presence of JAK2V617F in 6 of the 7 cases (86%). In addition, one other patient without MPD phenotype displayed a monosomy 5 abnormality. To date, 2 patients, one with and one without a MPD phenotype underwent leukemic transformation. All other causes of death were related to PCD-associated complications. Median survival (Kaplan-Meier) for the patients with multiple myeloma was 50 months. Survival stratified by the myeloma international staging system (ISS) was similar or better than expected (published controls of 62, 44, and 29 months): median survivals for this series of 73, 51 and 37 months for stage I, II, and III disease, respectively. CONCLUSIONS: Myelofibrosis that accompanies a PCD often represents an underlying MPD and does not negatively impact the natural history of the associated PCD.

Recent observations have underscored the biologic relevance of intratumoral angiogenesis and its potential impact on prognosis. Increased bone marrow angiogenesis has been demonstrated in a variety of hematologic disorders, including multiple myeloma. The extent and prognostic significance of bone marrow angiogenesis in 114 patients with myelofibrosis with myeloid metaplasia (MMM) was investigated. A control group of 44 patients without bone marrow disease, 15 patients with polycythemia vera, and 17 patients with essential thrombocythemia was also studied. Bone marrow microvessel density was assessed by a semiquantitative method, visual microvessel grading, and 2 separate quantitative methods, visual count and computerized image analysis. Angiogenesis estimation by all 3 methods was highly comparable. On visual microvessel grading, a grade 3 or 4 increase in bone marrow angiogenesis was demonstrated in 70% of patients with MMM, 33% of patients with polycythemia vera, 12% of patients with essential thrombocythemia, and 0% of normal controls. In a multivariate analysis, increased angiogenesis in MMM correlated significantly with increased spleen size and was found to be a significant and independent risk factor for overall survival. Increases in marrow angiogenesis correlated with hypercellularity and megakaryocyte clumping. In contrast, these 2 features were inversely proportional to reticulin fibrosis, whereas increases in marrow angiogenesis were independent of reticulin fibrosis. These preliminary findings suggest that neo-angiogenesis is an integral component of the bone marrow stromal reaction in MMM and may provide useful prognostic information and a rationale for the therapeutic investigation of anti-angiogenic agents.

Abstract Background: Patients with AL and congestive heart failure have a median survival of less than one year. Methods: Between 1994 and 2005, 11 patients underwent sequential heart transplant followed by autologous peripheral blood stem cell transplant (SCT) for treatment of AL. Patients had heart dominant AL with minimal/no other organ impairment and no evidence of multiple myeloma. Results: Patients ranged in age from 35 to 63 years (median 54). All had biopsy proven amyloidosis and monoclonal protein detectable in serum (73%) or urine (100%). Free light chain assay was available prior to SCT in 6 and was abnormal in all. All patients presented with NYHA Class III or IV heart failure. All but two patients had no other organ involved at the time of heart transplant. One patient had his heart transplant at another facility and had renal involvement at the time of heart transplant. One patient had peripheral nerve involvement documented prior to heart transplant. Five patients had progression of amyloid to involve other organs by the time of SCT. These included: renal (6), peripheral nerve (2), macroglossia (3), gastrointestinal (2). The median time from diagnosis to heart transplant was 3 months (range 1 to 5). The median time from heart transplant to SCT was 8 months, (range 3 to 24). Conditioning chemotherapy consisted of melphalan 200 mg /m2 (6 patients) or melphalan 140 mg/m2 (5 patients). Two patients died of complications before day +100, (TRM of 18%). Hematologic remissions were seen in 8 and organ responses in 3. Five were unable to be evaluated for organ response due to the heart transplant. Three died from progressive amyloidosis at 66, 56.7, and 55 months following SCT. The median survival is 56.7 months from SCT. Six are alive with a median follow-up of 24 months, range 9 to 90 months. Among the 6 surviving patients, one patient relapsed and one patient has failed to improve, but 4 patients are in continued remission. One patient developed secondary myelodysplastic syndrome. Conclusions: Heart transplant followed by SCT is feasible and offers durable remissions for carefully selected patients with cardiac AL. Figure Figure

Abstract Chronic Idiopathic Bence Jones Proteinuria (first reported in 1982) is an asymptomatic plasma cell proliferative disorder that is associated with a risk of progression to symptomatic multiple myeloma (MM) or primary amyloidosis (AL). We defined it as the presence of a monoclonal light chain in the urine, absence of an intact immunoglobulin M protein (IgH expression) in the serum, fewer than 10% bone marrow plasma cells (if done), and no evidence of MM, AL or other related plasma cell proliferative disorders. Following approval by the Mayo Clinic Institutional Review Board, we searched a computerized database and reviewed the records of all patients who were seen at Mayo Clinic within 30 days of the recognition of a monoclonal light chain (Bence Jones protein) in the urine between 1960 and 1996. Patients found to have end-organ damage at diagnosis as the result of the plasma cell proliferative disorder (including MM or AL), received chemotherapy, or had a nephrotic syndrome were excluded. Follow-up included review of each subject’s medical record at Mayo Clinic as well as review of death certificates for patients who died. Patients were sent letters of inquiry if they had not visited Mayo Clinic in the preceding year. The risk of progression to MM and AL was compared to those expected on the basis of Surveillance, Epidemiology and End Results (SEER) rates for MM in Iowa and the prevalence of AL in Olmsted County, Minnesota. Two-hundred twenty-three patients fulfilled the criteria for Idiopathic Bence Jones Proteinuria during the 37-year period (1960 – 1996). The median age at diagnosis was 69 yrs (range, 36–90 yrs) and only 1% were < 40 years of age. Sixty-seven percent were male. The urine M protein ranged from unmeasurable to 4.7 g/24h. The median was 0.09 g/24h and only 8% were > 1 g/24h. Kappa light chain accounted for 57% while lambda was present in 43%. Eighty-one percent of patients died during follow-up. Twenty-six percent had a monoclonal light chain in the serum on immunofixation. Concentrations of uninvolved (normal, polyclonal or background) immunoglobulins were reduced in 45%. During 1408 person years of follow-up, 11 patients developed symptomatic MM (relative risk 28.5; 95% CI, 14.3 – 51.1) and an additional 9 patients developed AL (relative risk 61.8; 95% CI, 28.3 – 117.4). The cumulative probability of progression to active MM or AL was 7% at 5 yrs, 13.5% at 10 yrs., and 18% at 15 yrs. The factors evaluated with respect to predicting progression to MM or AL included sex, hemoglobin value, serum albumin, amount of urine M protein/24h, type of urine light chain (kappa or lambda), reduction of uninvolved (background) immunoglobulins, and elevation of serum calcium or creatinine. The amount of the urine M protein/24h was the only significantly predictive parameter for progression. As a continuous variable, a higher urine M protein was associated with an increased risk of progression (hazard ratio = 2.1 for a 1g increase, p=0.003). The amount of the urine M protein was also significant as a dichotomous variable. Patients who had a urine M protein ≥ 1g/24h had an increased risk of progression (hazard ratio = 3.6, p=0.007). We conclude that patients with Idiopathic Bence Jones Proteinuria are at risk for the development of MM or AL and need to be followed indefinitely.

Abstract Background: High dose therapy (HDT) and stem cell transplant has been shown to improve survival in patients with myeloma and remains the standard of care. However, the reported results of initial HDT in these patients reflect the combined effect of the initial therapy and the HDT. The contribution of HDT on its own is often difficult to analyze in this group of patients with varying degree of response to initial therapy. In this single institution retrospective study, we have analyzed the results of HDT in a group of patients with measurable disease at the time of HDT. Methods: We identified patients from our transplant database, who had measurable disease at the time of initiation of transplant as defined by a serum M protein of ≥ 1.0 g/dL, 24 hour urine M-protein ≥ 200 mg or a bone marrow plasma cell % of ≥ 30. Details regarding the clinical outcome were obtained from the database and from patient clinical records. Chi square test was used for comparison of nominal variables and t-test for continuous variables. Kaplan Meier analysis was used for comparing survival and Cox proportional hazards was employed to identify predictors of progression free and overall survival. Responses were defined by the EBMTR criteria, using the measurements at the time HDT and the lowest measurement obtained. VGPR required a 90% reduction in the serum M component with urine protein &lt; 100 mg/24 hours. Results: A total of 440 patients were studied; 271 (61.5%) of whom had a transplant within one year of their diagnosis. Among the 271 patients, 140 (52%) were in the initial plateau, 99 (36%) failed to achieve a PR to initial therapy and 32 (12%) were in their first relapse. Given the known differences in the outcome between these groups of patients, those receiving an early transplant were analyzed separately. The response rates included CR (24%), VGPR (7%), PR (52%), MR or less (17%) and among the late transplants CR (23%), VGPR (8%), PR (61%) and MR or less (8%). The median progression free survival was 23.6 mos and the overall survival from HDT was 62 mos. In a multivariate analysis, presence of cytogenetic abnormalities (RR: 2.5) and high plasma cell labeling index (≥ 1%) (RR: 2.4) at HDT and failure to achieve a CR or VGPR (RR: 1.7) were prognostic for decreased progression free survival post HDT. In a similar model, only high PCLI (RR: 2.8) and abnormal cytogenetics (RR: 2.5) at HDT predicted for poor overall survival after transplant. Conclusion: This study provides a sense of the contribution of HDT, independent of the initial therapy, by determining responses based on the immediate pre-transplant disease measurements and the best values observed post transplant. In this group of patients with residual measurable disease after the initial therapy, HDT therapy leads to complete responses in nearly a quarter of the patients and a VGPR in another 7%, an outcome associated with better progressin free survival. While measurements at transplant do not correlate strictly with response to initial therapy, the aim of this study was to understand the individual contribution of HDT in these patients. Thus some of the patients who would have been classified as having a partial response to induction and HDT may be classified as non-responders in this analysis. These numbers will provide a historical comparison for trials evaluating novel consolidation therapies for myeloma.

Abstract Background: Epigallocatechin-3-gallate (EGCG) is a polyphenol extracted from green tea that has been studied for cancer prevention and treatment. Green tea and its extracts have been an integral part of traditional medicines from Asia and are thought to have considerable medicinal value. EGCG has been studied in many tumor types and in vitro studies have been encouraging. It is currently in Phase I/II clinical trial in the treatment of chronic lymphocytic leukemia. Here we examined the activity of EGCG in the setting of myeloma and its potential mechanisms of action. Methods: MM cell lines were cultured in RPMI 1640 containing 10% fetal bovine serum supplemented with L-Glutamine, penicillin, and streptomycin. The KAS-6/1 cell line was also supplemented with 1 ng/ml IL-6. Cytotoxicity of EGCG was measured using the MTT viability assay. Apoptosis was measured using flow cytometry upon cell staining with Annexin V-FITC and propidium iodide (PI). Fresh myeloma cells were obtained from bone marrow aspirates and subjected to ACK lysis to remove red cells. These cells were cultured in RPMI1640 with or with out EGCG and apoptotic rates were determined by Apo 2.7 expression on gated plasma cells. Flow cytometry was used for determining the phosphorylation state of various signaling proteins. Anti-angiogenic activity of EGCG was measured using a human in vitro angiogenesis kit (Angiokit). Results: EGCG treatment of myeloma cell lines resulted in dose- and time-dependent cytotoxicity to the cells. EGCG was cytotoxic to several myeloma cell lines, including IL-6 dependent cell lines KAS-6/1 and ANBL-6 as well as drug resistant cell lines MM1.R, Dox40 and LR5. The effect was maintained when the cells were grown in co-culture with marrow stromal cells, indicating the ability to overcome microenvironment mediated resistance. EGCG induced apoptosis of myeloma cell lines, apoptotic cells being measured as Annexin (+)/PI (−) cells by flow cytometry. It induced a dose-dependent apoptosis of freshly isolated myeloma cells with increased effect seen on the CD45+ myeloma cells compared to CD45- cells, reflecting increased activity on the proliferative fraction. Down regulation of Akt phosphorylation was seen following treatment of myeloma cells with EGCG. Using the Angiokit, we were able to demonstrate inhibition of tubule formation by EGCG at concentrations lower than those cytotoxic to myeloma cells. It was also able to overcome the angiogenic activity of VEGF. Conclusion: We demonstrate potent anti-myeloma activity of EGCG in vitro. In vivo studies in animal models of myeloma are ongoing. We demonstrate, as in other cell lines, inhibition of Akt pathways as a potential mechanism of action of EGCG. Ongoing studies are exploring other mechanisms. Most importantly, we demonstrate anti-angiogenic activity of this compound in the setting of myeloma, a finding in concordance with the inhibition of VEGF activity seen with other tumor systems.

Abstract Background: The clonal plasma cells in multiple myeloma have relatively low rates of apoptosis. We have previously shown that the apoptotic rates of the plasma cells have prognostic value in these patients. However, several methods are used both for targeting the myeloma cells for study as well as for detection of apoptosis in these cells. It is not clear which method is optimal for studying apoptotic rates of plasma cells from primary patient samples. We examined two different ways of studying the plasma cells, namely CD138 magnetic bead based positive selection of myeloma cells (sorted) and gating on the plasma cells in whole bone marrow (unsorted) using CD38/CD45 expression patterns. Additionally, we compared two different methods of identifying apoptotic plasma cells. Methods: Paired samples processed by two different methods were studied. The bone marrow aspirate samples were initially processed using ACK lysis to remove the red cells. The samples were then studied using flow cytometry (unsorted sample) or subjected to a second step of magnetic bead based separation of myeloma cells based on CD138 expression (sorted sample). Each of the samples was studied using Annexin/PI and Apo 2.7 expression to identify the plasma cells undergoing apoptosis. Plasma cells were identified in the unsorted samples by virtue of their CD38/CD45 expression. Samples were studied at collection and after 48 hours of culture. Results: At collection, the median percentages of cells considered apoptotic by annexin/PI (Annexin pos, PI neg) were higher than that detected by the Apo 2.7 method (Apo 2.7 + cells), for both sorted (6.5% vs. 1.5%) and unsorted cells (26% vs. 10%). However, after 48 hours of culture the percentage of apoptotic cells detected using the Apo 2.7 method were higher than that by Annexin/PI for both sorted (22.5% vs. 14.5%) and unsorted cells (43.5% vs. 10%). When the 48 hr study was compared with the initial study, percent apoptotic cells detected by Apo 2.7 had increased at 48 hrs for both sorted and unsorted cells. However, the percentage of apoptotic cells by annexin/PI had decreased in the unsorted cells at 48 hrs compared to initial study. The sorted samples had an overall increase in apoptosis at 48 hours as measured by annexin/PI. We then looked at the percentage of apoptotic cells detected by either method on initial study and compared the sorted cells and unsorted cells. Using either method, the percentage of apoptotic cells was significantly less (P=0.01; paired t-test) among the sorted cells compared to the unsorted cells. Conclusion: Previous studies have shown that CD138 expression is lost from PCs as they enter apoptosis. Here we show in paired samples that the percentage of apoptotic myeloma cells significantly decreases following CD138 sorting. CD138 sorting should not be used when studying apoptosis of myeloma cells in patient samples. Use of unsorted cells also allows for examination of the effects of interventions on other cell populations as well. When serial studies of apoptosis are done with unsorted samples, we recommend using Apo 2.7 rather than Ann/PI, since the percentage of apoptotic cells by Ann/PI expression actually appear to decrease with time in culture, thus making it difficult to assess effects of intervention such as in drug treatment studies. We hypothesize that this is due to an artificially high level of Annexin positivity at the initial study that might be brought on by non-specific damage of the membranes secondary to cell processing.

Abstract We have taken a genetic strategy to define the mechanisms underlying the increased risk of VTE in myeloma patient treated with thalidomide using clinical trial data derived from the MRC, ECOG, Little Rock and HOVON trial groups. Baseline VTE rates in the MRC IX study, (CTD vs CVAD; n=748 no prophylactic anticoagulation), were 14%. Rates in both arms were equal but in the thalidomide arm, thrombotic events were all DVT’s or PE’s, whereas in the CVAD arm they split equally between line related and VTE’s. In the other comparison (CTD vs MP; n=542), the VTE rate was 17%, all in the thalidomide arm. Rates were similar or higher (30%) in the other trials depending on the intensity of treatment used. We carried out a nested case control on DNA from MRC IX on 90 VTE (45 thalidomide, 45 non-thalidomide related), matched to 180 controls. SNPlex analysis for 60 SNPs in the coagulation cascade, DNA repair, thalidomide, metabolism and myeloma specific pathways, identified 7 genes which affected risk (NBS1, MTHFR, Ku80, Cyp3A5, LGAL52 and IL12B). This suggests three major pathways contribute to the risk of thalidomide related VTE, metabolism of thalidomide, tumour responsiveness and some pro-thrombotic factors. These factors differ from non-thalidomide related risk where a strong pro-inflammatory response is most relevant. We tested this hypothesis further using an expanded panel of 3,404 SNPs (BOAC panel), using the Megalle system. Statistical analysis of this data defined the top 20 thalidomide and non-thalidomide associated SNPs, which were consistent with the initial hypothesis, the results of which exclude variation in the coagulation cascade as being a significant risk factor. We explored this hypothesis further using pathway-based analysis focussing on the MTHFR, DNA repair and WNT pathways on data from the ECOG, HOVON and Little Rock data sets. The biological relevance of the SNPs and genes identified was validated by correlating the level of expression using the Affymetrix U133 CHIP with genetic variation at the DNA level. To verify the relevance of DNA repair variability to tumour response further, we correlated gene expression profiling with response and again Ku80 was identified as one of a cluster of genes defining increased risk. The data suggests that the risk of thalidomide related VTE relates to rapid tumour lysis combined with a prothrombotic tendency, whereas in line related thrombosis, risk is dependent upon a strong proinflammatory response. We are building this genetic data into a clinical risk model in order to allow us to develop a rationale for intervention strategies.

Abstract Anti-PD-1 monoclonal antibodies have shown promising results in several hematologic malignancies. As a result, these agents are being tested in a growing number of clinical trials across multiple diseases and settings. Many participants in these trials will at some point become candidates for allogeneic hematopoietic stem cell transplant (HSCT); however, the safety and efficacy of HSCT may differ in patients previously exposed to PD-1 inhibitors given their immunomodulatory mechanism and long tissue half-life. Specifically, residual PD-1 inhibition post-HSCT could enhance allogeneic T-cell responses, which could augment the graft-vs-tumor (GVT) effect but also increase the incidence, severity or manifestations of graft-vs-host disease (GVHD) and other immune complications of HSCT. To report our experience in this setting, we retrospectively analyzed the outcomes of patients who had received a PD-1 inhibitor prior to HSCT. Between 2013 and 2015, 19 patients who previously participated in clinical trials with either pembrolizumab or nivolumab (administered in combination with ipilimumab in 1 patient) were transplanted at Brigham and Women's Hospital/Dana-Farber Cancer Institute. Median age at HSCT was 32 (range 22-67). Histologies included HL (n=11), DLBCL (n=2), FL (n=2), PMBCL (n=2), EATL (n=1), and MCL (n=1). Patients had received a median of 4 (2-8) lines of therapy prior to PD-1 blockade. 79% of patients had received a previous autologous stem cell transplant (21% as part of planned tandem procedure). Patients received a median of 8 (3-20) cycles of a PD-1 inhibitor; 74% had intervening salvage therapy between PD-1 blockade and HSCT, and transplant occurred a median of 130 (range 7-260) days after the last dose of PD-1 inhibitor. At HSCT, 63% of the patients were in CR and 16% had refractory disease. All patients received reduced intensity conditioning (RIC). 5 (26%) received marrow grafts from haploidentical sibling donors; the remaining 14 received peripheral blood stem cells, 5 from a matched sibling, 7 from a matched, 1 from a unidirectional host-versus-graft and 1 from a bidirectional mismatched unrelated donor. 3 cases of veno-occlusive disease (VOD) (16% of patients) were observed, one of them fatal. The 180-day cumulative incidences of grade 2-4 and grade 3-4 acute GVHD were 32% and 11%, respectively, and the 1-year cumulative incidence of chronic GVHD was 30%. There were 4 treatment-related deaths, (1 from VOD, 3 from severe acute GVHD occurring within 14 days of HSCT). In addition, 6 patients developed a febrile syndrome with elevated transaminases (n=3), rash (n= 4), and arthralgias (n=1) shortly after transplant, which required prolonged courses of steroids. Only 3 patients relapsed. After a median follow-up of 10 (3-23) months for survivors, the 1-year overall (OS) and progression-free survivals (PFS) were 78% (95CI, 52-91) and 67% (95CI, 41-84), respectively (Figure). The 1-year cumulative incidences of relapse and non-relapse mortality (NRM) were 11% (95CI, 2-30) and 22% (95CI, 6-43), respectively. In conclusion, HSCT is feasible in patients previously treated with PD-1 inhibitors, with acceptable PFS and OS. Despite the heterogeneous patient population, small sample size, and limited follow-up to date, our results raise the possibility of important differences in the post-HSCT course of those patients. First, the relapse rate compares favorably to that expected for this cohort (1-year expected relapse rate based on Disease Risk Index mix 28%). Although this finding is at best suggestive given the sample size and follow-up time, it could reflect accentuation of GVT by prior PD-1 blockade. We also observed a high rate of severe complications including fatal early acute GVHD and VOD, with a higher NRM than expected in a RIC HSCT population. Furthermore, we noted the frequent occurrence of a steroid-responsive febrile syndrome. These possible effects of prior PD-1 blockade (including GVHD, VOD, febrile syndrome) did not appear related to the time from PD-1 treatment to HSCT, and were not reduced by intervening treatment before HSCT. As we accumulate experience with HSCT after PD-1 blockade, our early results may be relevant when considering the decision to proceed to HSCT and for the choice of transplantation strategies. We are presently expanding this analysis through a multi-center international collaborative study. Updated results will be presented at the meeting. Figure 1. Figure 1. Disclosures Zinzani: Celgene: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; J&J: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Gilead: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pfizer: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Takeda: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Perales:Takeda: Honoraria; Astellas: Honoraria; Amgen: Honoraria; Merck: Honoraria; NMDP: Membership on an entity's Board of Directors or advisory committees. Soiffer:Gentium SpA/Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees. Armand:Sequenta, Inc.: Research Funding; Merck: Consultancy, Research Funding; Infinity: Consultancy, Research Funding; BMS: Research Funding.