Early Lymphocyte Recovery Research Articles

Predictive Factors for Early Immune Recovery in NHL Patients after Autologous Transplantation: A Multicenter Prospective Study.

Early lymphocyte recovery as manifested by an absolute lymphocyte count at d+15 (ALC-15) ≥ 0.5 × 109/L after autologous hematopoietic stem cell transplantation (AHCT) has been associated with a better outcome. This prospective multicenter study aimed to clarify factors associated with ALC-15 ≥ 0.5 × 109/L after AHCT among 178 patients with non-Hodgkin lymphoma. The mobilization capacity, as manifested by peak blood CD34+ cell numbers > 45 × 106/L correlated with higher ALC-15 levels (p = 0.020). In addition, the amount of CD3+CD4+ T cells > 31.8 × 106/kg in the infused graft predicted ALC-15 ≥ 0.5 × 109/L (p < 0.001). Also, the number of infused graft CD3+CD8+ T cells > 28.8 × 106/kg (p = 0.017) and NK cells > 4.4 × 106/kg was linked with higher ALC-15 (p < 0.001). The two-year progression-free survival after AHCT was significantly better in patients with ALC-15 ≥ 0.5 × 109/L (74 vs. 57%, p = 0.027). The five-year OS in patients with higher ALC-15 was 78% vs. 60% in those with lower ALC-15 (p = 0.136). To conclude, the mobilization capacity of CD34+ cells and detailed measures of graft cellular content mark prognostic tools that predict ALC-15 ≥ 0.5 × 109/L, which is associated with a better outcome in NHL patients after AHCT.

Prognostic value of hemogram parameters in osteosarcoma: The French OS2006 experience.

Previous studies have shown that neutrophil-to-lymphocyte (NLR) ratio at diagnosis and early lymphocytes recovery on doxorubicin-based chemotherapy, may impact the outcome in patients with osteosarcoma (OST). This study aimed to evaluate the prognostic value of hemogram parameters in patients with OST treated with high-dose methotrexate and etoposide/ifosfamide (M-EI) chemotherapy. We retrospectively analyzed the prognostic value of various hemogram parameters at diagnosis and during therapy in a large consecutive cohort of patients with OST included in the French OS2006 trial and treated with M-EI chemotherapy. A total of 164 patients were analyzed. The median age was 14.7years (interquartile range [IQR]: 11.7-17). Median follow-up was 5.6years (IQR: 3.3-7.7years). Three-year event-free survival (EFS) and overall survival (OS) were 71.5% (95% confidence interval [CI]: 64%-78%) and 86.4% (95% CI: 80%-91%), respectively. In univariate analysis, blood count parameters at diagnosis and early lymphocyte recovery at Day 14 were not found prognostic of survival outcomes. By contrast, an increase of NLR ratio at Day 1 of the first EI chemotherapy (NLR-W4) was associated with reduced OS in univariate (p=.0044) and multivariate analysis (hazards ratio [HR]=1.3, 95% CI: 1.1-1.5; p=.002), although not with EFS. After adjustment on histological response and metastatic status, an increase of the ratio NLR-W4 of 1 was associated with an increased risk of death of 30%. We identified NLR-W4 as a potential early biomarker for survival in patients with OST treated with M-EI chemotherapy. Further studies are required to confirm the prognostic value of NLR and better identify immune mechanisms involved in disease surveillance.

PB CD8 T N and CD4 T EM on day30 after Allo-HSCT Is a Predictive Marker for the Development of aGVHD

Introduction ： Acute GVHD (aGVHD) is a common complication 20-60 days after allo-HSCT and can be life-threatening in some cases. It has been reported to be associated with T-cell immune reconstitution, but the detailed mechanisms are not clear. Early post-transplant lymphocyte recovery is mainly due to homeostatic peripheral expansion (HPE), which is variable depending on various factors such as donor source, recipient's age. T cell-related cytokines, such as sIL-2R , IL-7 and TNFr1 are known biomarkers for the aGVHD, but there are few reports that predict the aGVHD incidence rate using the peripheral blood (PB) lymphocyte subset. We evaluated the effect of PB lymphocyte subset in early post-transplant period on aGVHD. Methods ： We retrospectively analyzed 83 patients (40 in AML, 12 in ALL, 1 in MPAL, 13 in MDS, 2 in MPN, 9 in malignant lymphoma/LPD and 3 in AA) who underwent the allo-HSCT in our hospital from 2013 to 2023. The median age of patients was 44 years (range:17-66). Sixteen received BM, 47 received PB (including 28 with haploidentical (9 with ATG, 19 with PTCY)), and 20 received CB. GVHD prophylaxis was FK506+MTX in 61 patients, CyA+MTX in 3 and MMF+FK506+CY in 19. The median observation period was 495 [38-2983] days. PB lymphocyte subset (Naïve Tcell (T N):CD45RA+CD62L+, Central memory Tcell (T CM) :CD45RA-CD62L+, Effector memory Tcell (T EM) :CD45RA-CD62L-, Effector memory Tcell re-expressed CD45RA (T EMRA) :CD45RA+CD62L-, Th1:CD3+4+CXCR3+CCR6-, Th2:CD3+4+CXCR3-CCR6-, Th17:CD3+4+CXCR3-CCR6+) at day30 (range:28-35) after transplantation were analyzed by FCM. Results ： Twenty-five patients had grade II-IV aGVHD, and 11 had grade Ⅲ-IV aGVHD. Patients with Grade II-IV aGVHD exhibited significantly lower proportion of CD8+T N as compared to non aGVHD groups (GVHD+: 17.7 ± 13.3%; GVHD-: 30.9 ± 16.3%; p &amp;lt; 0.001) . In contrast, the proportion of CD4+T EM and CD8+T EM were higher in the Grade II-IV acute GVHD group (GVHD+: 30.9 ± 23.1%; GVHD-: 21.9 ± 15.6%; p=0.04, GVHD+: 36.1 ± 16.2%; GVHD-: 22.7 ± 14.7%; p &amp;lt; 0.001, respectively). We found a strong statistical correlation between the proportion of CD8+T N and CD8+T EM. The cumulative incidences of Grade II-IV and III -IV acute GVHD at day + 100 for CD8+T N &amp;lt;20% group was 56.9% and 29.6% compared with 14.2% and 6.3% for the CD8+T N &amp;gt;20% group (p &amp;lt; 0.001 and p &amp;lt; 0.01). Similarly, the cumulative incidences of Grade II-IV and III -IV acute GVHD at day + 100 for CD4+T EM &amp;gt;30% group was 48.1% and 32.6% compared with 22.2% and 5.9% for the CD4+T EM &amp;lt;30% group (p= 0.02 and p &amp;lt; 0.01). Two-year NRM was higher in the CD8+T N &amp;lt;20% group than in the CD8+T N &amp;gt;20% group (26.3% vs 4.2%, p=0.008). The two-year cumulative incidence of relapse (CIR) was comparable between the two groups, but tended to be lower in the mismatched CR group (CD8+T N &amp;lt;20%: 33.1% versus CD8+T N &amp;gt;20%: 43.4%, p=0.31). Conclusion ： PB CD8 T N and CD4 T EM fraction on day30 is a predictive biomarker for the development of acute GVHD.

Effective Immunomodulation with Pomalidomide Beginning at Early Lymphocyte Recovery during Induction Timed Sequential Therapy (TST) for Acute Myeloid Leukemia (AML) and High-Risk Myelodysplasia (HR-MDS)

Introduction: Adults with AML have immune aberrations leading to immune suppression, exhaustion, evasion, and senescence. Early lymphocyte recovery (ELR) after induction TST is dominated by an expansion of oligoclonal peripherally derived regulatory T cells (Tregs). Pomalidomide (Pom), a small molecule immunomodulatory agent (IMiD), leads to the selective ubiquitination of Aiolos and Ikaros by cereblon; this ubiquitination increases IL-2 production, inhibits Tregs, and inhibits angiogenesis. We hypothesize that Pom administration after induction TST may enhance anti-leukemic activity through immune modulation.Methods: A multicenter phase 1 dose escalation study was conducted to determine the safety and tolerability of Pom administration after induction TST in newly diagnosed AML and HR-MDS patients 18-65 years. Favorable-risk cytogenetics were excluded. All patients received induction TST with AcDVP16: Cytarabine 667 mg/m2/day continuous IV days 1-3, daunorubicin 45 mg/m2 IV days 1-3 (or idarubicin 8-12 mg/m2 IV days 1-3 in daunorubicin shortage), etoposide 400 mg/m2 IV days 8-10, followed by Pom administration at ELR (after day 14 and within 3 days of the total white blood cell (WBC) reaching ≥0.2x109/L above nadir, but no later than day 30). Pom dose escalation occurred in 2 cohorts: 10 days versus 21 days of administration, in a traditional 3+3 design.Results: A total of 51 patients were enrolled and 43 (AML: n=39, HR-MDS: n=4) received Pom across 3 institutions (Table 1). Eight patients did not receive Pom due to no ELR by day 30 (n=3), sepsis (n=3), noncompliance with treatment (n=1), and death prior to ELR due to acute respiratory distress syndrome (n=1). Median time for Pom initiation after AcDVP16 induction was day 21 (range: 15-30 days). Pom maximal tolerated dose (MTD) was 4 mg for 21 consecutive days at ELR. The most common non-hematologic grade ≥3 toxicities related to Pom were febrile neutropenia (30%), maculopapular rash (14%), and aminotransferase elevation (5%). Dose-limiting toxicities (DLTs) of Pom at 8 mg for 21 days were grade 3 ALT/AST elevation and grade 4 respiratory failure, respectively. Pom was discontinued early (median duration = 7 days; range: 3-20 days) in 14 (33%) patients due to disease progression (n=4), grade 3 rash (n=3), DLT (n=2), patient decision (n=2), progressive cytopenias (n=1), and grade 4 acute kidney injury (n=1).Overall, 32/43 (74%) achieved CRc (CR: n= 30, CRi: n=2). Among the 4 HR-MDS patients, 2 (50%) achieved CRc, whereas 77% (30/39) of AML patients achieved CRc. Of the 32 CRc patients, 19 (59%) had no evidence of minimal residual disease (MRD) by standard testing (flow cytometry, FISH, cytogenetics, and/or molecular PCR). Encouraging CR rates were seen in poor-risk subsets: Age ≥60 years: 75% CRc (9/12); Secondary AML: 71% CRc (10/14); Adverse-risk cytogenetics: 82% CRc (14/17). Thirty- and 60-day mortality were 0 and 2%, respectively. Median time to neutrophil (≥1.0x109/L) and platelet (≥100x109/L) recovery was 38 (range: 28-86) and 33 days (range: 24-75), respectively. With a median follow-up of 23.9 months, median overall survival, disease-free survival and event-free survival were 33.8 months, 20.3 months, and 8.7 months, respectively.Pharmacodynamic biomarker studies revealed a significant decrease in the expression of Aiolos in peripheral blood CD4+ and CD8+ T cells when compared with AML controls who received AcDVP16 induction but did not receive pomalidomide (p <0.05; Figure 1). Moreover, these findings were corroborated in the bone marrow where Aiolos expression in CD4+ and CD8+ T cells substantially decreased after pomalidomide initiation.Conclusions: Pom can be added at the time of ELR after induction TST without increased toxicity and CR rates that compare favorably with historical controls of TST and other standard induction therapies. Despite administration at the time of profound cytopenias, Pom was well tolerated and did not significantly prolong hematologic recovery. Correlates suggest that Aiolos expression may be a pharmacodynamic biomarker of activity. Identification of immune biomarkers to predict for response and duration of response are ongoing. Further exploration of Pom both at the time of induction TST and during CR are warranted. [Display omitted] DisclosuresZeidner:Rafael Pharmaceuticals: Other: Travel Fees; Merck: Research Funding; Asystbio Laboratories: Consultancy; Takeda: Other: Travel fees, Research Funding; Tolero: Honoraria, Other: Travel Fees, Research Funding; Celgene: Honoraria. Zeidan:Agios: Consultancy; Incyte: Employment; Novartis: Consultancy; Celgene: Consultancy; Ariad: Consultancy, Speakers Bureau; Gilead: Consultancy; Pfizer: Consultancy; Abbvie: Consultancy. Pratz:Astellas: Consultancy, Research Funding; Agios: Research Funding; Boston Scientific: Consultancy; AbbVie: Consultancy, Research Funding; Millenium/Takeda: Research Funding. Foster:Shire: Honoraria; Pfizer: Research Funding; Macrogenics: Research Funding; Celgene: Research Funding. Coombs:H3 Biomedicine: Honoraria; AROG: Other: Travel fees; DAVA Oncology: Honoraria; Abbvie: Consultancy; Incyte: Other: Travel fees. Luznik:WIndMIL Therapeutics: Equity Ownership, Patents & Royalties. Gojo:Amgen: Membership on an entity's Board of Directors or advisory committees; Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Merck inc: Research Funding; Amgen: Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees.

Post-ASCT Outcomes in Multiple Myeloma Patients Who Underwent ASCT with G-CSF+Plerixafor Versus G-CSF Mobilized Graft

BACKGROUND: Impact of Plerixafor (P) mobilized stem cells on immune reconstitution of autologous stem cell transplant (ASCT) patients has not been established. Early lymphocyte recovery (Absolute lymphocyte count of > 1 K/uL at day 30 after transplant) has been established to predict outcomes in multiple myeloma (MM) patients. The purpose of this study was to evaluate lymphocyte recovery in MM patients who underwent ASCT with stem cells mobilized with G-CSF vs G-CSF+P. Secondary objective was to evaluate the survival outcomes.METHODS: This is a retrospective analysis of MM patients who underwent first ASCT between 2008 and 2016 with either G-CSF or G-CSF+P mobilization at Karmanos Cancer Institute in Detroit, Michigan. Plerixafor was used per institutional guidelines when the peripheral CD-34+ve cell-count was < 20/ uL on day 5 of G-CSF mobilization. 610 total patients were identified. Mobilization agents used were G-CSF alone (n= 469) or G-CSF+P (n= 141). All patients underwent transplant after Melphalan (M) conditioning and dose of M was at treating physician's discretion (140 vs 200 mg/m2). The primary endpoint was the Absolute Lymphocyte Count at day 30 (ALC30). Secondary endpoints were PFS and OS Univariable and multivariable Cox proportional hazards regression models were fit to assess associations between ten pre chosen predictors( age, race, stage at diagnosis, doublet vs. triplet therapy, lines of treatment, disease status, mobilization agents, melphalan dose, ALC at day 30, post- transplant maintenance) and survival benefit (PFS and OS).RESULTS: Median age of patients was older in G-CSF+P group (62 vs 60 years, p=. 006) and they were more likely to receive triplet therapy (82 vs 72%, p=. 015) for induction compared to G-CSF group (Table 1). Patients in G-CSF group were more likely to receive greater than one line of treatment before transplant (p=. 006). Disease status at transplant was similar between the two groups. G-CSF patients received higher dose of M (at 200mg/ m2) more frequently (69 vs. 58%, p = 0.010) and median cell dose infused was higher in G-CSF group (3.19 vs 2.88 x106 CD 34+ve-cells/Kg, p= 0.001).Primary endpoint, ALC30, was 1.3 K/uL(.1-4.5) and 1.2 K/uL(.1-5.1) for G-CSF and G-CSF+P, respectively (p=. 608). Median day to neutrophil recovery were similar in both groups (ANC of 500 at Day 12). Post-transplant maintenance use was similar between the two groups. The median PFS was 2.46 years (95% CI, 2.14 to 3.15) and 2.77 years (95% CI, 1.99 to 3.27) for G-CSF and G-CSF+P, respectively (HR: 1.128; 95% CI, (.843-1.509); p=. 417) (Figure 1). The median OS was 6.09 years (95% CI, 4.55 to NR) and 3.73 years (95% CI, 3.20 to NR) for G-CSF and G-CSF+P, respectively (HR: 1.638; 95% CI, (1.118-2.399); p=. 011) (Figure 2) .In MVA, higher stage at diagnosis, less than PR before ASCT, and no post-transplant maintenance therapy were associated with worse PFS and OS. More lines of treatment adversely impacted PFS. Use of G-CSF+P for mobilization and Melphalan dose ≤ 200-mg/ m2 adversely impacted OS. ALC30 did not impact PFS or OS in MVA. There were no significant differences in causes of death among the 2 groups.CONCLUSIONS: In this large, retrospective analysis of MM patients mobilized with G-CSF vs G-CSF + P, there was no significant difference in lymphocyte recovery. Higher Melphalan dose resulted in improved OS in the MVA. There was an overall survival difference favoring the G-CSF group, however, differences in baseline characteristics not accounted for in the MVA may be responsible for this observation. A Prospective study comparing these mobilization regimens including patients with similar baseline characteristics is necessary to confirm this finding. [Display omitted] DisclosuresDeol:Kite Pharmaceuticals: Consultancy; Novartis: Consultancy.

Preliminary Data on Safety, Cellular Kinetics and Anti-Leukemic Activity of UCART19, an Allogeneic Anti-CD19 CAR T-Cell Product, in a Pool of Adult and Pediatric Patients with High-Risk CD19+ Relapsed/Refractory B-Cell Acute Lymphoblastic Leukemia

Preliminary Data on Safety, Cellular Kinetics and Anti-Leukemic Activity of UCART19, an Allogeneic Anti-CD19 CAR T-Cell Product, in a Pool of Adult and Pediatric Patients with High-Risk CD19+ Relapsed/Refractory B-Cell Acute Lymphoblastic Leukemia

Early lymphocyte recovery predicts clinical outcome after HSCT with mycophenolate mofetil prophylaxis in the Japanese population.

Immune reconstitution affects clinical outcomes after allogeneic hematopoietic stem cell transplantation (HSCT), and it has been suggested that lymphocyte recovery affects survival after HSCT. However, few studies have examined lymphocyte recovery in Asian patients who received mycophenolate mofetil (MMF) prophylaxis for graft-versus-host disease. We retrospectively evaluated early lymphocyte recovery after HSCT among Japanese adults who received MMF prophylaxis. Patients were divided into two groups according to their median absolute lymphocyte count (ALC) on day 28 after HSCT as follows: the "low ALC group" (≤ 0.22 × 109cells/L) and the "high ALC group" (> 0.22 × 109cells/L). With a median follow-up of 317days, the high ALC group showed significantly better overall survival than the low ALC group (at 1year: 62 vs. 46%, P = 0.02). The high ALC group also tended to have better non-relapse mortality than the low ALC group (at 1year: 13 vs. 23%, P = 0.08). There was no significant difference in relapse rate between the high and low ALC groups (at 1year: 29 vs. 35%, P = 0.2). We conclude that among Japanese patients who received MMF prophylaxis, ALC on day 28 after HSCT was effective in predicting overall survival and non-relapse mortality.

Early Lymphocyte Recovery and Outcome in Osteosarcoma.

Early lymphocyte recovery following chemotherapy has been associated with improved outcome in many cancers, including in one small study of osteosarcoma patients. To confirm this finding, we retrospectively reviewed data from 53 patients with newly diagnosed osteosarcoma who had blood counts on day 14 (±1 d) following the first cycle of cisplatin and doxorubicin. The median absolute lymphocyte count (ALC) 14 days after starting the first cycle of chemotherapy (ALC-14) was 1990 cells/μL (range: 600 to 6470). For 32 patients with an ALC-14≥1800 cells/μL, the 5-year progression-free survival (PFS) was 69%, compared with 33% for patients with an ALC-14 of <1800 cell/μL (P=0.036). In multivariable analysis of factors including age, sex, metastatic disease, and favorable histologic response to induction chemotherapy, ALC-14 was significantly associated with PFS (P=0.0081) and overall survival (P=0.0131). The use of ALC-14 appears to further stratify PFS and overall survival among patients when grouped by histologic response. We confirmed that early lymphocyte recovery was associated with outcome in pediatric osteosarcoma. Although presumably reflecting immune-mediated tumor control, the precise mechanism for this is unclear. Further study of peripheral blood lymphocyte subpopulations in prospectively treated patients is underway.

Lymphocyte recovery is an independent predictor of relapse in allogeneic hematopoietic cell transplantation recipients for acute leukemia.

AIMTo examine the optimal absolute lymphocyte count (ALC) cut-off utilizing receiver operator characteristics (ROC) in addition to graft characteristics associated with early ALC recovery.METHODSPatients who received T-cell replete peripheral hematopoietic cell transplantation (HCT) for acute leukemia were identified. ALC cut-off was established using ROC analysis and subsequently the cohort was stratified. Time to endpoint analysis and cox regression modelling was computed to analyze outcomes.RESULTSA total of 72 patients met the inclusion criteria and were analyzed. Optimal ALC cut-off was established to be on day 14 (D14) with ALC > 0.3 × 109/L. At 2 years, cumulative incidence of relapse was 16.9% vs 46.9% (P = 0.025) for early and delayed lymphocyte recovery cohorts, respectively. Chronic graft vs host disease was more prevalent in the early lymphocyte recovery (ELR) group at 70% vs 27%, respectively (P = 0.0006). On multivariable analysis for relapse, ELR retained its prognostic significance with HR = 0.27 (0.05-0.94, P = 0.038).CONCLUSIONELR is an independent predictor for relapse in patients receiving allogeneic HCT for acute leukemia. ELR was influenced by graft characteristics particularly CD34 count.

Phase 1 Study of Pomalidomide Given at the Time of Early Lymphocyte Recovery after Induction Timed Sequential Chemotherapy in Newly Diagnosed Acute Myeloid Leukemia (AML) and High-Risk Myelodysplastic Syndrome (HR-MDS)

Introduction: AML pts have a poor prognosis with conventional chemotherapy regimens. Early lymphocyte recovery (ELR) following intensive timed sequential therapy (TST) induction is characterized by a dysfunctional immunosuppressive state. Pomalidomide (Pom), a small molecule immunomodulatory agent (IMiD), has direct effects on T cell co-stimulation by promoting the ubiquitination of Aiolos, an IL-2 transcriptional repressor. We hypothesized that the administration of Pom at the time of ELR after induction TST may influence T cell differentiation and enhance an anti-leukemia immune effect.Methods: A multicenter phase 1 dose escalation study was conducted to determine the safety and tolerability of Pom after intensive induction TST in newly diagnosed AML and HR-MDS pts 18-65 years. Core-binding factor AML was excluded. All pts received induction chemotherapy with AcDVP16: cytarabine 667 mg/m2/day IV continuous infusion days 1-3, daunorubicin 45 mg/m2/day IV days 1-3, etoposide 400 mg/m2/day IV days 8-10. Pom was administered at the assigned dose and schedule after day 14 and within 3 days of the total white blood cell count (WBC) reaching >0.2x109/L above nadir, defined as ELR. Three dose levels were planned (2 mg, 4 mg and 8 mg) within 2 cohorts: 10 days of Pom and 21 days of Pom, in a traditional 3+3 dose escalation design.Results: 25 pts were enrolled on this study January 2014-June 2016 across 3 institutions (Table 1). Pom administration occurred at a median of 21 days after AcDVP16 induction. There were no dose-limiting toxicities (DLTs) in the first cohort of Pom x 10 days within each dose level- 2 mg (n=3), 4 mg (n=3) and 8 mg (n=7). There were no DLTs seen at 4 mg x 21 days (n=7). Two DLTs were seen at Pom 8 mg x 21 days (Grade 3 ALT increase and Grade 3 hypoxia, respectively). Thus, Pom 4 mg x 21 days will be further expanded.Nine (36%) pts discontinued Pom early (median duration = 5 days) due to: grade 3 rash (n=3), physician discretion (decreased WBC: n=1, fever and increased creatinine: n=1), grade 3 ALT increase (n=1), grade 3 hypoxia (n=1), disease progression (n=1), and pt preference (n=1). Adverse events (AEs) possibly associated with Pom that were seen in >1 pt included fever (n=8), rash (n=7), AST/ALT increase (grade 1: n=4, grade 3: n=1), mucositis (n=2), and fatigue (n=2). All of these AEs were self-limiting with supportive care and/or discontinuation of Pom.60-day mortality was 0%. A complete remission (CR) was achieved in 18 pts and 1 achieved CR with incomplete platelet recovery (CRp) with a combined CR + CRp = 19/25 (76%). Among pts with adverse-risk AML, 5/6 (83%) achieved CR. One pt achieved a partial remission and 5 pts were refractory to treatment. Of the 19 CRs, 15 had no evidence of minimal residual disease by cytogenetics, FISH, or flow cytometry. Among pts who completed a course of Pom (10 days or 21 days), 14/16 (88%) achieved CR. As previously reported, a dramatic decrease of Aiolos expression via flow cytometry in T cell subsets was observed in vivo for the duration of POM treatment with doses > 2 mg, but the effect was lost after Pom was stopped. Figure 1 displays the pattern of cytokine production of CD4+ T cells visualized with pie charts, and shows a significantly different subset composition at ELR in Pom-treated pts compared to the same pts at full recovery (p=0.02), and compared to control AML pts at the same time point (p=0.004). Furthermore, there was a significant increase in TNF-α production (p=0.009) and the combination of TNF-α and IL-2 production (p=0.03) in stimulated CD4+ T cells during Pom treatment, which was reduced to baseline values after Pom was discontinued at full recovery (Figure 1: data analysis performed with the SPICE software).Conclusions: Pom can be safely administered at the time of ELR after intensive induction TST. Fever and rash are the most common AEs seen after Pom administration. Inhibition of Aiolos and consequent increase in both IL-2 and TNF-α expression, as measured by flow cytometry, appear to be reliable markers of Pom-induced T cell modulation in vivo. Planned expansion of the cohort of 4 mgx 21 days will allow further evaluation of safety and activity of Pom in AML. [Display omitted] [Display omitted] DisclosuresZeidner:Takeda: Research Funding; Merck: Research Funding; Agios: Honoraria; Otsuka: Consultancy; Tolero: Research Funding. Zeidan:Celgene: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Ariad: Consultancy, Honoraria; Incyte: Consultancy, Honoraria. Smith:Celgene: Consultancy, Other: member of DSMB. Levis:Millennium: Consultancy, Research Funding; Daiichi-Sankyo: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Research Funding; Astellas: Consultancy, Honoraria, Research Funding. Foster:Celgene: Research Funding.

Immunologic Status Evaluated By the Absolute Lymphocyte/Monocyte Ratio Provides a Powerful Prognostic Tool for Newly Diagnosed Multiple Myeloma

The bone marrow (BM) microenvironment contains numerous cell types, including immunosuppressive tumor-associated macrophages (TAM), that promote the growth and survival of multiple myeloma (MM) cells. TAMs are recruited to the site of MM within the BM and help to create a permissive microenvironment that promotes the homing of MM cells. Prior studies have shown that the relative amount of BM-associated TAMs correlates with patient poor outcome in MM (Suyaný et al. 2013). Emerging evidence suggests that the absolute monocyte count (AMC) in peripheral blood may reflect the level of TAM recruitment at the tumor site and its prognostic significance has been shown in other lymphoid malignancies. Absolute lymphocyte count (ALC) as a surrogate marker for host immune system has prognostic significance. Early lymphocyte recovery after induction therapy or autologous stem cell transplant correlates with better survival for MM patients. The aim of the present study was to investigate the prognostic significance of the ratio of ALC, as a surrogate of host immune status, to AMC, which reflects the MM-immune microenvironment, in predicting clinical outcome among newly diagnosed MM patients.Methods: The study included 372 MM patients (pts), diagnosed 2004-2014 at the University Hospitals in Cleveland, OH and University of Cincinnati, Cleveland OH who had CBC differentials at diagnosis. The primary end-point of the study was progression free survival (PFS) calculated from the time of diagnosis. The Cox proportional hazards model was used to evaluate ALC/AMC at diagnosis as a prognostic factor for PFS as well as to assess and adjust of other know prognostic factors.Results: Median pt age was 67.3 years (range: 30-92), 53% were male and 47% female. Distributions of detailed baseline characteristics are presented in Table-1. The median follow up was 33.5 months (range: 1.16 - 122.9). Pts who were lost to follow up were censored from the survival analysis. At the time of this analysis 92 pts (24%) had died, 75 (20%) of them was due MM. The median AMC, ALC and ALC/AMC ratio at diagnosis was 412 cells/µL, 1,461 cells/µL and 3.9, respectively. ALC neither AMC was associate with different PFS or overall survival (OS). ALC/AMC as a continuous variable was identified as a predictor of PFS [Hazard ratio (HR) = 0.62, (95% CI: 0.52 - 0.75), p-value: 0.001]. To define a cut-off point, the choice of ALC/AMC ≥ 3.6 yielded the greatest differential in survival, based on the chai-squarevalue (χ2 = 94·4, P < 0·01) analyzed at different cut-off points between the 25% and 75% quartiles (2.9 - 4.3), from the log-rank test. Pts with an ALC/AMC ≥ 3.6 (n=236) experienced a superior median PFS compared to patients with an ALC/AMC < 3.6 (n=136) [Median PFS, 24 vs. 43 months respectively, P-value < 0.001] (Figure-1). Multivariate analysis including ALC, age, ISS stage and treatment type (autologous stem cell transplant vs. no transplant) showed that ALC/AMC as well as treatment type remained an independent prognostic factor of PFS after the step-wise fashion analysis. Out of 372 patients 192 patients had cytogenetics analysis at diagnosis. Univariate analysis demonstrated that low ALC, high AMC and a low ALC/AMC ratio were correlated with presence of del (17p) and t(4,14) and light chain myeloma. Multivariate analysis indicated that the ALC and AMC were not associated with any specific cytogenetic group. However, the ALC/AMC ratio independently predict 17p and t(4,14) abnormalities (p-value = .041). Low ALC, high AMC, and low ALC/AMC ratio were associated with poor prognostic factors such as high β2-microglobulin.Conclusions: In our cohort, myeloma patients with a higher ALC/AMC at diagnosis enjoyed a longer PFS (either as a continuous or dichotomized variable). Also, multivariate analysis demonstrated that patient with tumors that harbored del (17p) or t(4, 14) had low ALC/AMC ratio suggesting possible immunoparesis. ALC at diagnosis was not associated with OS, in contrast to prior studies, possibly due to the shorter follow-up duration used here and inadequate power to predict OS. Taken together, our data potentially suggest the ALC/AMC ratio as a readily available surrogate marker to assess the relative strength of host immune system to myeloma-induced immunoparesis. The ratio can serve as a biomarker to stratify patients for future immunological therapies. Also, our findings indicate that the host immune status should be carefully monitored. [Display omitted] [Display omitted] [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Early lymphocyte recovery predicts superior outcomes after unmanipulated haploidentical blood and marrow transplant for acute myeloid leukemia.

We investigated whether early lymphocyte recovery, after unmanipulated haploidentical blood and marrow transplant (HBMT), affected clinical outcomes in 134 patients with acute myeloid leukemia (AML). Lymphocyte recovery was based on the absolute lymphocyte count on day 30 (ALC-30). Patients with high ALC-30 (≥294cells/μL) had higher overall survival (OS) (77.6% vs 59.7%, P=.020) and higher leukemia-free survival (LFS) (74.6% vs 53.7%, P=.016) than those with low ALC-30 values. Multivariate analysis demonstrated that a high ALC-30 was associated with improved overall survival (HR: 0.443, 95% CI: 0.233-0.841; P=.013) and LFS (HR: 0.499, 95% CI: 0.275-0.906; P=.022). Our results suggest that the ALC-30 can predict a superior outcome after unmanipulated HBMT.

Cord Blood Units with High CD3+ Cell Counts Predict Early Lymphocyte Recovery After In Vivo T Cell–Depleted Single Cord Blood Transplantation

Although high absolute lymphocyte count (ALC) early after transplantation is a simple surrogate for immune reconstitution, few studies to date have established the predictive factors for ALC after umbilical cord blood transplantation (UCBT). We retrospectively studied the factors associated with early lymphocyte recovery and the impact of the ALC on day +42 (ALC42) of ≥300 × 106/L on outcomes in 210 consecutive pediatric and adult patients (112 males; median age, 15 years; range, 0.3 to 60 years; interquartile range, 4 to 36 years) who underwent myeloablative in vivo T cell–depleted single UCBT between 2005 and 2014 for malignant and nonmalignant disorders. In a logistic multivariate regression model, factors favoring a higher ALC42 were higher infused CD3+ cell dose (odds ratio [OR], 2.7; 95% CI, 1.4 to 5.2; P = .004), lower antithymocyte globulin dose (OR, 2.3; 95% CI, 1.2 to 4.5; P = .01), and better HLA match (OR, 2.1; 95% CI, 1.1 to 4.1; P = .03). In multivariate analysis, lower ALC42 was associated with higher nonrelapse mortality (hazard ratio [HR], 1.76; 95% CI, 1.34 to 2.32; P = .001), whereas a higher ALC42 was associated with better disease-free survival (HR, 2.03; 95% CI, 1.15 to 3.6; P < .001) and overall survival (HR, 2.03; 95% CI, 1.17 to 3.6; P < .001). Our study suggests that the selection of better HLA-matched cord blood units containing higher CD3+ cell counts and the use of conditioning regimens with lower ATG doses could improve immune reconstitution after UCBT.

Alemtuzumab levels impact acute GVHD, mixed chimerism, and lymphocyte recovery following alemtuzumab, fludarabine, and melphalan RIC HCT

AbstractReduced intensity conditioning (RIC) allogeneic hematopoietic cell transplantation (HCT) with alemtuzumab, fludarabine, and melphalan is an effective approach for patients with nonmalignant disorders. Mixed chimerism and graft-versus-host-disease (GVHD) remain limitations on success. We hypothesized that higher levels of alemtuzumab at day 0 would result in a low risk of acute GVHD, a higher risk of mixed chimerism, and delayed early lymphocyte recovery and that alemtuzumab level thresholds for increased risks of these outcomes would be definable. We collected data from 105 patients to examine the influence of peritransplant alemtuzumab levels on acute GVHD, mixed chimerism, and lymphocyte recovery. The cumulative incidences of initial grades I-IV, II-IV, and III-IV acute GVHD in patients with alemtuzumab levels ≤0.15 vs ≥0.16 μg/mL were 68% vs 18% (P < .0001), 47% vs 13% (P = .0002), and 32% vs 8%, respectively (P = .005). The cumulative incidence of mixed chimerism in patients with an alemtuzumab level ≤0.15 μg/mL was 21%, vs 42% with levels of 0.16 to 4.35 μg/mL, and 100% with levels >4.35 μg/mL (P = .003). Patients with alemtuzumab levels ≤0.15 or 0.16 to 0.56 μg/mL had higher lymphocyte counts at day +30 and higher T-cell counts at day +100 compared with patients with levels ≥0.57 μg/mL (all P < .05). We conclude that peritransplant alemtuzumab levels impact acute GVHD, mixed chimerism, and lymphocyte recovery following RIC HCT with alemtuzumab, fludarabine, and melphalan. Precision dosing trials are warranted. We recommend a day 0 therapeutic range of 0.2 to 0.4 μg/mL.

T-cell Exhaustion in Multiple Myeloma Relapse after Autotransplant: Optimal Timing of Immunotherapy.

Multiple myeloma is the most common indication for high-dose chemotherapy and autologous stem cell transplantation (ASCT), and lenalidomide maintenance after transplant is now standard. Although lenalidomide doubles progression-free survival, almost all patients eventually relapse. Posttransplant immunotherapy to improve outcomes after ASCT therefore has great merit but first requires delineation of the dynamics of immune reconstitution. We evaluated lymphocyte composition and function after ASCT to guide optimal timing of immunotherapy and to identify potential markers of relapse. Regulatory T cells (Treg) decline as CD8(+) T cells expand during early lymphocyte recovery after ASCT, markedly reducing the Treg:CD8(+) effector T-cell ratio. These CD8(+) T cells can respond to autologous dendritic cells presenting tumor antigen in vitro as early as day +12 after transplant, becoming antigen-specific cytolytic T-lymphocyte effectors and thereby demonstrating preservation of cellular reactivity. CD4(+) and CD8(+) T cells express the negative regulatory molecules, CTLA-4, PD-1, LAG-3, and TIM-3, before and after ASCT. A subpopulation of exhausted/senescent CD8(+) T cells, however, downregulates CD28 and upregulates CD57 and PD-1, characterizing immune impairment and relapse after ASCT. Relapsing patients have higher numbers of these cells at +3 months after transplant, but before detection of clinical disease, indicating their applicability in identifying patients at higher risk of relapse. PD-1 blockade also revives the proliferation and cytokine secretion of the hyporesponsive, exhausted/senescent CD8(+) T cells in vitro. Collectively, these results identify T-cell exhaustion/senescence as a distinguishing feature of relapse and support early introduction of immunotherapy to stimulate antitumor immunity after ASCT.

Immune Modulation with Pomalidomide after Induction Chemotherapy in Newly Diagnosed Acute Myeloid Leukemia (AML)

Background: We recently showed that early lymphocyte recovery (ELR) following intensive induction chemotherapy in AML patients (pts) is characterized by complex immune system aberrations. (Blood 117(2):608, 2011) Full characterization of lymphoid T cell dynamics during this period can provide critical insights into their dysfunction and rationale for targeted therapeutic intervention to augment anti-leukemia immunity. Pomalidomide (POM), a small molecule immunomodulatory agent (IMiD), has direct effects on T cell co-stimulation by promoting the ubitiquitination of IL-2 transcriptional repressor Aiolos (IKZF3). (Br J Haematol 164(6):811, 2014) We hypothesized that administration of POM at the time of ELR may influence T cell differentiation and function in vivo.Methods: We serially collected peripheral blood (PB) samples at the time of ELR from 31 AML pts (median age 57, range 29-76 years; 26 de novo and 5 secondary AML) treated with intensive induction chemotherapy (18 with timed-sequential therapy (TST) and 13 with standard 7+3: cytarabine and idarubicin), 11 AML pts (median age 52, range 31-66 years; 6 de novo, and 5 secondary AML) treated on NCI/CTEP#9524 study of TST induction (AcDVP16: cytarabine, daunorubicin, and etoposide) followed by POM given daily for 10 days at ELR at escalating doses: 2mg (3pts)-4mg (3pts)-8mg (5pts) (Figure 1) and 17 healthy controls (HC) (median age 40, range 25-71 years). ELR was defined as absolute white blood cell (lymphocyte) count >200/mm3 above nadir. Using multi-parameter flow cytometry we performed extensive phenotypic characterization of lymphocyte populations, focusing on T cell differentiation status (CD45RA, CCR7), activation/proliferation (Ki-67), expression of POM-target gene Aiolos (IKZF3), and cytokine secretion. Statistical significance was determined using multiple t-tests using GraphPad Prism software. All protocols were IRB approved.Results: Administration of POM at ELR did not affect absolute lymphocyte count (ALC) compared to control pts not receiving POM (P=>0.5). ALC values ranges (both groups): pre-treatment 2538-3645/mm3, ELR 428-525/mm3, and 931-1360/mm3 at full count recovery (FR1), respectively. The percentages and total numbers of CD4+ and CD8+ T cells behaved similarly; however, POM pts had increase in the frequency of CD4+ central memory subset (CD45RA- CCR7+) (P=0.001) at FR1 and decrease in the terminally differentiated effector memory subset (CD45RA+ CCR7-) of CD8+ T cells only for the duration of POM administration at ELR (P=0.04). Tregs (CD4+ FoxP3+ Tcells) increased in control pts during ELR (p=0.004; n=26) but not in POM-treated group (n=5). A dramatic but dose-dependent decrease of Aiolos expression in T cell subsets in vivo (P<0.001, n=9; Figure 2) was observed for the duration of POM treatment but the effect was lost after POM was stopped (FR1) while Aiolos remained unchanged in pts treated with chemotherapy only (n=7). A trend toward increased IL-2 expression in CD4+ T cells of POM pts was noted as well (P=0.1, n=3) and exceeded the levels produced by HC (n=4).Conclusions: ELR represents an interesting time period for therapeutic intervention to modulate immunity following chemotherapy in AML pts. POM administration phenotypically and functionally affected several T cell subsets in vivo. Our data suggest that inhibition of Aiolos, an IL-2 transcriptional repressor, is a reliable pharmacodynamic marker of POM activity on T cells in vivo. Further studies with longer POM administration schedules as well as examination of other compartments such as bone marrow are ongoing to better define the role of immune modulation with POM in the treatment of pts with AML. [Display omitted] [Display omitted] DisclosuresOff Label Use: Pomalidomide is not FDA approved for acute myeloid leukemia..

Immunologic Effects of CCR5 Blockade in Graft-Versus-Host Disease Prophylaxis

▪Background: Acute graft-versus-host disease (GVHD) is a major cause of morbidity and mortality after allogeneic hematopoietic stem cell transplantation (HSCT). Experimental models and clinical studies suggest that blocking lymphocyte trafficking with the chemokine receptor CCR5 antagonist maraviroc (MVC) ameliorates visceral GVHD. However, the effects of CCR5 blockade on immune reconstitution and activation in allogeneic HSCT recipients remain unknown.Methods: We previously reported a phase I/II study of 38 high-risk patients undergoing reduced-intensity allogeneic HSCT with standard GVHD prophylaxis (tacrolimus, methotrexate) combined with brief (33-day) MVC treatment. We compared the clinical and immunologic outcomes of these patients to a contemporary control cohort of 115 consecutive patients undergoing allogeneic HSCT with standard GVHD prophylaxis alone. Multivariate analysis was used to assess the effect of MVC treatment on the incidence of GVHD. Flow cytometry on day 30 and day 60 PBMC samples was used to monitor immune cell subsets, T cell activation markers and chemokine receptor expression. We also used a multiplex Luminex assay to quantify serum cytokine levels at day 30.Results: Since our initial report, longer follow up (median 37 months) now shows that patients who received MVC have reduced incidence rates of acute grade II-IV GVHD (adjusted hazard ratio [aHR]=0.42, 95% CI 0.21-0.84, p=0.015) and grade III-IV GVHD (aHR=0.43, 95% CI 0.17-1.09, p=0.075) compared to our control cohort (Figure 1). There was no difference in chronic GVHD between the groups. Early lymphocyte recovery was similar between MVC and control cohorts, with no significant difference in absolute lymphocyte, CD4 T cell and CD8 T cell counts at day 30. We observed increased CCR5 expression on CD4 T cells, CD8 T cells and B cells at day 30 in response to MVC treatment (Figure 2A-B). However, CCR5 expression on these cell types equalized between MVC and control patients by day 60. Day 30 MVC samples also demonstrated decreased percentages of CD38+ CD4 T cells and HLA-DR+ CD8 T cells (Figure 2C-D), an effect that also faded by day 60. These data suggest that inhibition of lymphocyte trafficking with CCR5 blockade dampens peripheral T cell activation.Notably, some patients developed acute GVHD despite MVC prophylaxis, and therefore we investigated differences between MVC responders and non-responders. Patients who developed GVHD had a higher percentage of activated CD38+ CD4 T cells in peripheral blood (Figure 3A) and an increased proportion of naive CD4 (36.5% vs 18.1% p=0.005) and CD8 (35.5% vs 11.9% p=0.0008) T cells, which has been associated with the development of GVHD. We also observed higher CCR5 expression on CD8 T cells from MVC non-responders (CCR5 MFI 8800 vs 6595, p=0.02). Intriguingly, while MVC responders and non-responders had similar serum concentrations of CCR5 ligands (MIP-1a, MIP-1b, Rantes), MVC non-responders had elevated levels of CXCR3 ligands (IP-10, MIG) (Figure 3B-C). Taken together, these data suggest that lymphocyte migration via CXCR3 may be a potential escape mechanism for GVHD initiation and T cell activation in the setting of CCR5 blockade.Conclusion: Brief CCR5 blockade in high-risk patients inhibits T cell activation and reduces the incidence of GVHD. MVC does not inhibit early lymphocyte recovery, which was similar in treated and control patients. This supports the hypothesis that MVC treatment would not impair graft-versus-leukemia activity. Our analysis of immunologic outcomes of MVC reveals a distinct immunologic effect for CCR5 blockade in allogeneic HSCT recipients and suggests a novel resistance mechanism. These studies bolster CCR5 antagonism as an effective strategy for GVHD prevention and provide support for extended MVC treatment duration and investigation into CXCR3 as a therapeutic target. [Display omitted] [Display omitted] [Display omitted] DisclosuresOff Label Use: Off label use of CCR5 antagonist maraviroc for the prevention of graft-versus-host disease. Vonderheide:Pfizer: Research Funding. Porter:Pfizer: Research Funding.

T Cell Exhaustion/Senescence in Relapsed Multiple Myeloma after Autologous Stem Cell Transplantation

▪BACKGROUND: Multiple myeloma (MM) is the most common indication for high-dose chemotherapy and autologous stem cell transplantation (ASCT). Post-transplant lenalidomide maintenance therapy doubles progression-free survival, but almost all patients eventually relapse. The immune system participates in the control of MM, whereas compromised immunity contributes to its evolution. Post-transplant immunotherapy to induce or restore antitumor immunity offers a promising approach to target residual MM and improve patient outcomes. The rational development of immunotherapeutic interventions after ASCT, however, requires a comprehensive understanding of the immunologic milieu. We therefore evaluated lymphocyte composition and function after ASCT to guide optimal timing of immunotherapy and to identify potential markers of relapse.METHODS: Fifty-five MM patients undergoing ASCT were evaluated for at least one year. Peripheral blood from patients was obtained before ASCT and on d +12, +30, +90, +180, and +365 after ASCT, and at the time of relapse where applicable. Leukocyte concentrates were used as a source of healthy donor cells. Mononuclear cells were analyzed by flow cytometry for phenotypic assessment of lymphocyte subset composition. Functional assessment of dendritic cell and T cell activity in vitro was assayed in autologous and allogeneic mixed leukocyte reactions, cytotoxic T lymphocyte (CTL) lysis assays, and PD-1 blockade experiments.RESULTS: CD3+ CD4+ CD25bright CD127neg regulatory T cells (Tregs) decline as CD8+ T cells expand during early lymphocyte recovery after ASCT, markedly reducing the Treg:CD8+ effector T-cell ratio (Fig 1A) and providing a critical early window for the introduction of immune-based post-transplant consolidation therapies. CD8+ T cells can respond to autologous dendritic cells presenting tumor antigen in vitro as early as day +12 post-transplant, becoming antigen-specific CTL effectors and thereby demonstrating preservation of cellular reactivity (Fig 1B). CD4+ and CD8+ T cells express the negative regulatory molecules, CTLA-4, PD-1, LAG-3, and TIM-3, before and after ASCT (data not shown). A subpopulation of exhausted/senescent CD8+ T cells, however, down-regulates CD28 (Fig 2A) and up-regulates CD57 (Fig 2B) and PD-1 (Fig 2C), characterizing immune impairment and relapse after ASCT. CD4+ T cells show the same trends in the frequencies of CD28neg, CD28neg CD57+, and CD28neg PD-1+ cells, albeit at lower levels of expression (Fig 2D). Relapsing patients have higher numbers of CD8+ CD28neg PD-1+ T cells at +3 months after transplant (Fig 2E), but before detection of clinical disease, indicating their applicability in identifying patients at higher risk of relapse. PD-1 blockade revives the proliferation and cytokine secretion of the hyporesponsive, CD8+ CD28neg PD-1+ T cells in vitro (Fig 3).CONCLUSION: These results identify T cell exhaustion/senescence as a distinguishing feature of relapse and support early introduction of immunotherapy to stimulate antitumor immunity after ASCT. [Display omitted] [Display omitted] DisclosuresLesokhin:Genentech: Research Funding; Bristol Myers Squibb: Consultancy, Research Funding; Aduro: Consultancy; Janssen: Consultancy, Research Funding; Efranat: Consultancy. Giralt:CELGENE: Consultancy, Honoraria, Research Funding; SANOFI: Consultancy, Honoraria, Research Funding; AMGEN: Consultancy, Research Funding; JAZZ: Consultancy, Honoraria, Research Funding, Speakers Bureau; TAKEDA: Consultancy, Honoraria, Research Funding.

Mesenchymal stromal cells improve early lymphocyte recovery and T cell reconstitution after autologous hematopoietic stem cell transplantation in patients with malignant lymphomas

Mesenchymal stromal cells (MSCs) possess a multi-lineage potential and immunoregulatory activities and provide a great potential in cell-based technologies. However, MSC suppressive activity raises concerns regarding the possible adverse effect of MSCs on the immune recovery. The influence of autologous MSC co-transplantation on recovery of T cell subsets in patients receiving autologous hematopoietic stem cell transplantation (AHSCT) for malignant lymphomas and multiple myeloma were characterized. Co-transplantation of MSCs improved lymphocyte recovery most effectively in patients with low input of hematopoietic stem cells or low absolute lymphocyte count in apheresis product. MSC co-transplantation improved early recovery of both memory and naive T cells with more prominent effect on naive CD4+ T cells. Patients with MSC co-transplantation showed more effective reconstitution of recent thymic emigrants. These data indicate the positive impact of MSCs on immune reconstitution and note MSC co-transplantation is feasible to optimize the outcomes of AHSCT in malignant lymphoma patients.

Impact of Different Mobilization Methods on Graft Composition and Outcome after Autologous Stem Cell Transplantation: Implications for Upfront Use of Plerixafor

Early lymphocyte recovery (ELC) is associated with improved outcomes of hematologic malignancies after autologous hematopoietic stem cell transplantation (auto-SCT). ELC, its composition and impact on outcome depends on many variables; however there is limited data on ELC after different mobilization strategies (G-CSF [G] vs. G + high dose cyclophosphamide [GC] vs. G + plerixafor [GP]). Results from a recent study showed that GP based mobilization can affect the number and subsets of immune competent cells contained in the graft. We studied whether these differences are associated with immune reconstitution (ELC), engraftment, or long-term outcomes.We retrospectively identified patients undergoing auto-SCT at the Nashville VA Transplant Center between January 2000 and December 2010 in our CIBMTR database. Disease response was determined by standard CIBMTR response criteria. At our center, GP mobilization is reserved for patients who failed prior mobilization, to rescue G or GC mobilization, or as upfront usage in heavily pre-treated patients. Our patient cohort primarily included patients with multiple myeloma (MM) and lymphoma (LY).We had evaluable data on 333 patients (MM=196; LY=127; others=10). Comparative analysis of different mobilization methods are summarized in Table 1. Median number of regimens pre-SCT for MM was 2 (range 1-5) and for lymphoma 2 (range1-7). Among LY patients, 60 (47.3%) patients were in complete remission (CR), 58 (45.7%) in partial remission (PR) and 9 (7%) had stable disease (SD). Among MM patients, 69 (35.2%) were in CR or very good partial remission (VGPR) pre-transplant, 105 (53.5%) were in PR, and 14 (7.1%) had SD. There was no significant difference between disease response status among different mobilization methods for either the MM or LY patients. A higher absolute WBC count was seen in grafts after GP mobilization compared to G or GC (p=0.01), despite a majority of patients having received GP mobilization after failed G or GC mobilization, or as a rescue regimen (n=20 [89%]). Similarly, absolute lymphocyte counts were higher in grafts mobilized after GP compared to G or GC (p=0.01). All patients engrafted and there was no difference in time to WBC or platelet engraftment between mobilization methods. Although the GP cohort was more heavily treated than the other cohorts (>2 regimens for GP 82%, vs. G 72% vs. GC 58% [p=0.02]), progression-free survival (PFS) and overall survival (OS) of G vs. GC vs. GP at 2-years was not significantly different between MM and LY cohorts (Table 1).In summary, grafts mobilized with GP exhibited major differences in graft composition in conjunction with favorable post- transplant outcomes compared with grafts mobilized with G or GC. GP mobilization accelerated lymphocyte engraftment in this heavily treated group compared to G or GC. For patients proceeding to transplant heavily pre-treated, GP is a better mobilization method to ensure a robust graft is collected while avoiding the need for multiple stem cell collections and providing similar outcomes as patients less heavily treated and mobilized by G or GC. A prospective randomized controlled trial would elucidate whether progression free survival and overall survival might be improved by utilizing GP mobilization as a first-line therapy rather than as a rescue method.Table 1Graft composition and outcomes of different stem cell mobilization methodsVariableG (n=97)GC (n=213)GP (n=23)P valueNumbers of regimens pre-SCT, median2.2 (95% CI, 2.0-2.4)1.9 (1.8-2.0)2.3 (1.9-2.7)0.02WBC in graft, median (range)184.8 (12-777.7)138.6 (11-542)286.1 (186-400.3)0.01Absolute lymphocyte in graft (x103), median (range)128.1 (13-321.1)73.9 (3.4-433.6)161.2 (47.4-302.0)0.01ANC >500 (days), median (range)16 (11-25)15 (7-86)18 (13-24)0.16Platelets >20 (days), median (range)13 (9-22)12 (7-18)12 (10-21)0.07OS (2 year)Lymphoma74.577.972.70.054Multiple myeloma89.674.4720.76PFS (2 year)Lymphoma58.257.646.10.1Multiple myeloma66.349600.21 DisclosuresNo relevant conflicts of interest to declare.