Peripheral Blood Progenitor Cell Collection Research Articles

Effectiveness of single-dose 6 mg pegfilgrastim in mobilizing peripheral blood stem cells in allogeneic hematopoietic cell transplantation donors.

A single injection of 12 mg pegfilgrastim was used to mobilize peripheral blood progenitor cells (PBPCs) from healthy donors in some studies. The purpose of this study was to determine if 6 mg of pegfilgrastim was effective and safe for mobilizing CD34+ cells in donors for allogeneic hematopoietic stem cell transplantation. We conducted a retrospective case-matched design. A single dosage of 6 mg pegfilgrastim was used to mobilize PBPCs from 60 healthy donors. Granulocyte colony-stimulating factor (G-CSF, 10 μg/kg) was administered daily to the matched donors. Leukapheresis was scheduled to commence on day 4 of the mobilization regimen. The median yielded CD34+ cell in the pegfilgrastim group was higher than those in the G-CSF group, at 5.06 × 106/kg recipient weight. The 73.3% of donors mobilized with pegfilgrastim yielded >4 × 106 cells/kg CD34+ cells in a single apheresis procedure when compared to the 33.3% of donors mobilized with G-CSF (P < 0.001). The myeloid-derived suppressor cells (MDSC) proportion in the pegfilgrastim group was significantly higher than that in the G-CSF group (P < 0.001). The cumulative incidence of grade II-IV acute graft-versus-host disease (aGVHD) was higher in the G-CSF group than that in the pegfilgrastim group (26.7% vs. 11.7%), without statistical difference. In comparison to the G-CSF group, the pegfilgrastim group had a reduced median pain intensity numerical rating scale score (1 vs. 2). A single 6 mg dosage of pegfilgrastim is effective and safe for allogeneic PBPCs collection from healthy donors. Pegfilgrastim may decrease the incidence of aGVHD by boosting MDSCs, which need further investigation.

Adverse events related to central venous catheters (CVC) and the influence of CVC characteristics on peripheral blood hematopoietic progenitor cell collection in children.

The use of peripheral blood progenitor cells (PBPCs) as a source for hematopoietic stem cell transplantation (HSCT) in pediatric healthy donors is still under debate. The risk of a central venous catheter (CVC) placement and catheter-related complications continue to be the main arguments to discourage its use. we present a retrospective analysis of 140 PBPC collections in pediatric patients and donors, describing adverse events (AE) related to CVCs as well as the influence of catheterrelated variables on the efficiency of the leukapheresis. 14 CVC-related AEs were recorded (10%). The most common was fever in 5 patients, 4 of which had a catheter-related bacteriemia. Thrombotic events were only observed in 3 patients with active malignancy. A healthy donor presented a moderate bleeding after catheter withdrawal that resolved with local measures, and none of the rest presented any AE. Regarding variables related to the development of AEs, the subject group (patient or donor) was the only one significantly associated (p < 0.0001). Of interest, efficiency was also related to catheter location, being worse in those located in the femoral vein than in into the jugular or the subclavian veins (p < 0.05). In a multivariate analysis, the only variable significantly associated was catheter size (beta 0.238, p < 0.01). Placing a CVC for PBPC collection in pediatric subjects is overall safe; CVC-related complications in pediatric healthy donors are very rare. Furthermore, we should try to place catheters of the largest caliber possible, since the efficiency of the collection is related to this variable.

Clonal hematopoiesis in patients with stem cell mobilization failure: a nested case-control study.

Inadequate mobilization of peripheral blood progenitor cells (PBPCs) is a limiting factor to proceeding with autologous hematopoietic cell transplantation (auto-HCT). To assess the impact of clonal hematopoiesis (CH) on mobilization failure of PBPC for auto-HCT, we investigated the characteristics of poor mobilizers (with a total PBPC collection <2× 106 CD34+ cells per kg) in a consecutive single-center cohort of 776 patients. Targeted error-corrected next-generation sequencing of 28 genes was performed in a nested case-control cohort of 90 poor mobilizers and 89 matched controls. CH was detected in 48 out of 179 patients (27%), with most patients carrying a single mutation. The presence of CH (detected at variant allele frequency [VAF] ≥ 1%) did not associate with poor mobilization potential (31% vs 22% in controls, odds ratio, 1.55; 95% confidence interval, 0.76-3.23; P= .238). PPM1D mutations were detected more often in poor mobilizers (P= .005). In addition, TP53 mutations in this cohort were detected exclusively in patients with poor mobilization potential (P= .06). The incidence of therapy-related myeloid neoplasms (t-MN) was higher among patients with mobilization failure (P= .014). Although poor mobilizers experienced worse overall survival (P= .019), this was not affected by the presence of CH. We conclude that CH at low VAF (1%-10%) is common at the time of stem cell mobilization. TP53 mutations and PPM1D mutations are associated with poor mobilization potential and their role in subsequent development of t-MN in these individuals should be established.

233 - Impact of the COVID-19 Pandemic on Unrelated Allogeneic Hematopoietic Peripheral Blood Progenitor Cell Collections in Canada

233 - Impact of the COVID-19 Pandemic on Unrelated Allogeneic Hematopoietic Peripheral Blood Progenitor Cell Collections in Canada

Comparison between peripheral blood progenitor cell collection on the 4th or 5th day of granulocyte colony-stimulating factor treatment in allogeneic stem cell donors: implications for hematopoietic progenitor cell apheresis guidelines.

Comparison between peripheral blood progenitor cell collection on the 4th or 5th day of granulocyte colony-stimulating factor treatment in allogeneic stem cell donors: implications for hematopoietic progenitor cell apheresis guidelines.

Radiation Therapy Can Be Safely Incorporated into Pretransplantation Treatment Regimens for Patients with Multiple Myeloma

Primary treatment of multiple myeloma (MM) often involves systemic induction therapy (SIT) followed by autologous stem cell transplantation (ASCT). Radiation therapy (RT) is sometimes used for palliation; however, many practitioners avoid RT out of concern that future peripheral blood progenitor cell (PBPC) collection required for ASCT may be compromised. In this study, we retrospectively examined the possible effect of RT on PBPC collection. We reviewed the charts of 732 patients with MM treated with RT at our institution from 1999 to 2017, including patients who received RT prior to PBPC collection for planned ASCT. RT plans (both MM and non-MM RT) were reviewed to estimate the percentage of bone marrow (BM) treated using published estimates of skeletal BM distribution. Statistics were performed using Pearson correlation and the t-test. The 732 MM patients included 485 planned for ASCT; of these, 223 received RT prior to PBPC collection and were included in the final cohort. The median age at PBPC collection was 59 years (range, 33 to 80 years). For SIT, patients received combination regimens including the following agents: bortezomib (142 patients; 64%), lenalidomide (111 patients; 50%), and alkylators (46 patients; 21%). Nine patients (4%) received dexamethasone alone. The median cumulative %BM treated per patient was 6.7 (range .0 to 47.4). The median RT dose was 24 Gy (range, 10.0 to 75.6 Gy). Mobilization was performed using granulocyte-colony stimulating factor (G-CSF) alone (189 patients; 85%), G-CSF with plerixafor (15 patients; 7%), or chemotherapy (19 patients; 9%). A median of 7.8×106 CD34+/kg PBPCs (range, .5 to 54.8× 106 CD34+/kg) were collected in a median of 3 (range, 1 to 9) apheresis procedures. One hundred ninety-six patients (99%) collected ≥2.0×106 CD34+/kg PBPCs, and 166 (83%) collected >5.0×106 CD34+/kg PBPCs. The number of PBPCs collected was not associated with %BM treated (P=.15) or RT dose (P=.56). The number of apheresis procedures performed was not associated with %BM treated (P=.54) or RT dose (P=.85). The amount of PBPCs collected did not differ significantly between patients receiving RT to the pelvis/sacrum (P=.20) and those receiving RT to the spine (P=.13). The time to platelet engraftment was longer for patients with higher %BM treated (P=.02). Eleven patients did not undergo a confirmed ASCT, owing to patient preference (3 patients), trial therapy (1 patient), comorbidities (1 patient), election for hospice (1 patient), inadequate collection (4 patients), or inadequate follow-up (1 patient). In our study cohort, RT prior to ASCT did not impair successful ASCT. RT must be carefully planned and delivered to ensure safe incorporation into pre-ASCT treatment regimens.

Radiation Therapy can be Safely Incorporated Into Pre-Transplant Treatment Regimens for Patients With Multiple Myeloma

<h3>Purpose/Objective(s)</h3> Primary treatment of multiple myeloma (MM) often involves systemic induction therapy (SIT) followed by autologous stem cell transplant (ASCT). Radiation therapy (RT) is sometimes used for palliation; however, many practitioners avoid RT out of concern that future peripheral blood progenitor cell (PBPC) collection required for ASCT may be compromised. We retrospectively examined the possible effect of RT on PBPC collection. <h3>Materials/Methods</h3> We reviewed the charts of 732 MM patients (pts) seen from 1997–2016 at our institution and included pts who received RT prior to PBPC collection for planned ASCT. RT plans (both MM and non-MM RT) were reviewed to estimate the percentage (%) bone marrow (BM) treated using published estimates of skeletal BM distribution. Statistics were performed using Pearson correlations and t-tests. <h3>Results</h3> Of 732 MM pts, ASCT was planned for 485 pts; of these, 223 pts received RT prior to PBPC collection and were included in the final cohort. 133 pts (60%) were male. Median age at PBPC collection was 59 years (range 33—80). For SIT, pts received combination regimens including the following agents: bortezomib (142 pts, 64%); lenalidomide (111 pts, 50%); alkylators (46 pts, 21%). Nine pts (4%) received dexamethasone alone. RT plans and/or a description of the fields, were available to estimate treated BM% for 221 pts. The median cumulative BM% treated per pt was 6.7 (range 0.0—47.4). The median RT dose was 24 Gy (range 10.0—75.6 Gy). Mobilization was performed using granulocyte-colony stimulating factor (G-CSF) alone (189 pts, 85%), G-CSF with plerixafor (15 pts, 7%), or chemotherapy (19 pts, 8%). PBPC collection data was available for 199 pts. A median of 7.8 × 10⁶ CD34⁺/kg PBPCs (range 0.5—54.8) were collected in a median of 3 (1—9) apheresis procedures. 196 pts (99%) collected more than 2.0 × 10⁶ CD34⁺/kg (minimum PBPC no. required for engraftment), and 167 pts (84%) collected more than 5.0 × 10⁶ CD34⁺/kg (preferred no. of PBPCs collected). The number of PBPCs collected was not associated with BM% treated (<i>P</i> = 0.15) or RT dose (<i>P</i> = 0.56). The number of apheresis procedures performed was not associated with BM% treated (<i>P</i> = 0.54) or RT dose (<i>P</i> = 0.85). The number of PBPCs collected did not differ significantly for pts receiving RT to the pelvis (<i>P</i> = 0.96), lumbar spine (<i>P</i> = 0.35), or thoracic spine (<i>P</i> = 0.059). Time to platelet engraftment was longer for patients with higher %BM treated (<i>P</i> = 0.02). Eleven pts did not undergo a confirmed ASCT due to: pt preference (3 pts), trial therapy (1 pt), comorbidities (1 pt), election for hospice (1 pt), inadequate collection (4 pts) and inadequate follow up (1 pt). <h3>Conclusion</h3> Among pts with MM, RT prior to ASCT did not prevent adequate PBPC collection or impair successful ASCT. RT must be carefully planned and delivered to ensure safe incorporation into pre-ASCT treatment regimens.

Destiny of Elderly Patients with Lymphoma Indicated for Autologous Stem Cell Transplantation (ASCT)

Background. Autologous stem cell transplantation is the standard method of treatment of relapsed/refractory lymphoma patients (pts) and is a part of first-line therapy in certain diagnoses. ASCT in elderly pts (≥60 years) is much less studied than in younger ones and usually, only pts who actually undergone ASCT are included. This is a retrospective analysis of all subsequent patients ≥60 years indicated for ASCT at 1st Department of Medicine, General University Hospital, Prague, during 2008-2016.Methods. Subsequent pts ≥60 years with any type of lymphoma who proceeded to mobilization of peripheral blood progenitor cells (PBPC) in the given period were included. All histologies were reviewed by expert hematopathologist. Demographic, prognostic and treatment data were collected from clinical documentation at diagnosis (pts transplanted as a part of 1st line treatment) or at progression (relapsed/refractory pts) and compared by Pearson´s chi square, Fischer's exact and Mann-Whitney U tests. Overall survival (OS) and progression-free survival (PFS) were calculated from the beginning of mobilization of PBPC. Survival curves were estimated via Kaplan-Meier method and compared by log-rank test. Multivariate analyses were performed by Cox proportional hazard test.Results. In total, 155 patients were included. Median age was 64 years (60-72) and 61% of them were males. 135 pts (87%) had B-NHL, 16 (10%) T-NHL and 4 (3%) Hodgkin´s lymphoma. Most common diagnoses were mantle cell lymphoma (MCL, 29%), diffuse large B-cell lymphoma (DLBCL, 28%) and follicular lymphoma (FL, 19%). Median number of previous treatment lines was 2 (1-6). 67 patients (43%) were scheduled for ASCT as a part of the 1st line treatment and 88 (57%) for relapsed/refractory (R/R) disease. Collection of PBPC (≥2x106 CD34+/kg) was successful in 143 pts (92%). Twenty-seven pts (17%) received plerixafor because of low number of CD34+ cells in peripheral blood, and 18 of them had successful harvest (66%).The OS and PFS for the whole cohort were 71% and 60% at 2 years with median follow-up of 41 months for living patients, with no difference between 1st line ASCT and R/R patients (p = 0.58 for OS and p = 0.33 for PFS, respectively). However, there was imbalance in indication for ASCT for different diagnoses (91% of MCL were transplanted in 1st line setting compared to 24% of others, p <0.0001), which also disabled comparison of outcomes according to diagnosis. On multivariate analysis of the whole cohort, ECOG performance status >2 was the most powerful prognostic factor (HR, 3.1 for OS and 2.8 for PFS, p = 0.0009 for both), followed by high LDH (HR, 2.9 for OS and 2.5 for PFS, p = 0.002 both), and age >65 years (HR, 2.3 for OS and 1.8 for PFS, p = 0.003 and 0.015 respectively). Sex, clinical stage, number of extranodal sites involved and number of lines of chemotherapy (1-2 v. >2) before indication for mobilization were not statistically significant.117 patients (75%) were actually transplanted. The main reasons of dropout were progressive disease and mobilization failure (9% and 8% of the whole cohort, respectively). Age >65 years was statistically significant for non-proceeding to ASCT (33% v. 19%, p = 0.03). For transplanted pts, OS and PFS was 80% and 69%. Only performance status retained statistical significance both for OS and PFS, while age was a prognostic factor for OS only and diagnosis was a prognostic factor for PFS only. Four pts (3.5%) died before day +100 because of treatment-related toxicity. There were no difference in toxicities or engraftment between pts 60-65 and >65 years old.Conclusion. In our cohort of elderly patients scheduled for collection of PBSC, 92% collected enough PBPC and 75% were actually transplanted. OS and PFS for the whole cohort are encouraging and peritransplantation mortality was acceptable. Inclusion of pts who did not proceed to ASCT provides a better estimate of the destiny of elderly pts scheduled for this procedure than studies, where only actually transplanted patients were included. Limitation of our results are different settings, in which were patients with different diagnoses indicated for ASCT.Financial support: grants AZV16-310092A and AZV 17-28980A from Czech Ministry of Public Health. DisclosuresPytlik:Gilead: Consultancy, Honoraria; Roche: Consultancy, Honoraria; Sanofi: Consultancy, Honoraria. Kateřina:Roche: Consultancy, Honoraria. Trněný:Janssen: Consultancy, Honoraria; Takeda: Consultancy, Honoraria; Roche: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Abbvie: Consultancy, Honoraria; BMS: Consultancy, Honoraria; Gilead: Consultancy, Honoraria.

Peripheral blood stem and progenitor cell collection in pediatric candidates for ex vivo gene therapy: a 10-year series

Hematopoietic stem and progenitor cell (HSPC)-based gene therapy (GT) requires the collection of a large number of cells. While bone marrow (BM) is the most common source of HSPCs in pediatric donors, the collection of autologous peripheral blood stem cells (PBSCs) is an attractive alternative for GT. We present safety and efficacy data of a 10-year cohort of 45 pediatric patients who underwent PBSC collection for backup and/or purification of CD34+ cells for ex vivo gene transfer. Median age was 3.7 years and median weight 15.8 kg. After mobilization with lenograstim/plerixafor (n = 41) or lenograstim alone (n = 4) and 1−3 cycles of leukapheresis, median collection was 37 × 106 CD34+ cells/kg. The procedures were well tolerated. Patients who collected ≥7 and ≥13 × 106 CD34+ cells/kg in the first cycle had pre-apheresis circulating counts of at ≥42 and ≥86 CD34+ cells/μL, respectively. Weight-adjusted CD34+ cell yield was positively correlated with peripheral CD34+ cell counts and influenced by female gender, disease, and drug dosage. All patients received a GT product above the minimum target, ranging from 4 to 30.9 × 106 CD34+ cells/kg. Pediatric PBSC collection compares well to BM harvest in terms of CD34+ cell yields for the purpose of GT, with a favorable safety profile.

Effectiveness of supplemental oral calcium drink in preventing citrate-related adverse effects in peripheral blood progenitor cell collection

Peripheral blood progenitor cells (PBPCs) are a predominant graft source in allogeneic hematopoietic cell transplantation. Citrate-induced hypocalcemia remains the most frequent side effect of PBPC apheresis. Although the method for preventing severe adverse events is established, more efficient prophylaxis is required so that volunteer donors can donate PBPCs without pain and anxiety. We studied 80 healthy donors who underwent PBPC harvest between February 2014 and June 2020. Of these, 23 donors who underwent apheresis between February 2014 and December 2015 received only the standard prophylaxis of intravenous calcium gluconate. Oral calcium drinks were provided to 57 donors who underwent apheresis from January 2016 to June 2020 to supplement intravenous calcium gluconate prophylaxis. The ionized calcium (ICa) levels at multiple time intervals and the hypocalcemic symptoms were evaluated. Oral supplementation with a calcium drink maintained significantly higher ICa levels. Analysis using the inverse probability weighted regression adjustment method suggested that calcium drinks reduced the frequency of citrate-related reactions by 39.2 %. Administering a prophylactic oral calcium drink before apheresis with intravenous administration of calcium gluconate is promising to further reduce citrate-induced hypocalcemia in volunteer donors.

Low baseline platelet count predicts poor response to plerixafor in patients with multiple myeloma undergoing autologous stem cell mobilization

Background aimsBaseline platelet count has been shown to be a sensitive predictor of autologous peripheral blood progenitor cell collection yield in patients with multiple myeloma mobilized with granulocyte colony-stimulating factor (G-CSF). Patients who mobilize poorly with G-CSF are often treated with plerixafor to enhance mobilization. There are no surrogate markers available to predict response to plerixafor. MethodsWe retrospectively analyzed data from 73 patients with multiple myeloma who did not have adequate mobilization with G-CSF alone and were treated with plerixafor as a rescue agent. ResultsWe found that baseline platelet count directly correlated with peripheral blood CD34+ (PB-CD34+) count after plerixafor treatment (r = 0.36, P < 0.0001) and the number of PB-CD34+ cells collected on the first day of apheresis and inversely correlated with the number of apheresis sessions needed to collect the target number of PB-CD34+ cells (P = 0.0015). Baseline platelet count of 153 000/µL or less was associated with 90% specificity of predicting poor response to plerixafor with a sensitivity of 33%. ConclusionsBaseline platelet count is a good predictor of mobilization response to plerixafor in patients with multiple myeloma.

Evaluation of the Role of Plerixafor in Peripheral Blood Progenitor Cell Mobilization and Collection in Autologous Donors with Multiple Myeloma and Non-Hodgkin Lymphoma

Purpose Autologous hematopoietic stem cell transplantation is commonly used as treatment for patients with Multiple Myeloma (MM) or Non-Hodgkin Lymphoma (NHL). The mobilization and collection of peripheral blood progenitor cells (PBPC) to reach the required cell dose for transplantation is problematic for some patients when standard mobilization agents such as G-CSF, alone or combined with chemotherapy, are used. These patients are considered poor mobilizers with &lt; 20 CD34+ cells /μl on the planned day of collection and the optimal strategy to collect a sufficient number of PBPC in poor mobilizers is still not fully known. Plerixafor, a CXCR4 inhibitor, when added to the standard mobilization regimen, has been shown to improve mobilization and increase the probability of collecting a PBPC graft &gt; 2 X106CD34 /kg in standard mobilizers. In our center, Plerixafor became available in October 2012. However, how best to use plerixafor to improve care for poor mobilizers while ensuring the most cost-effective use of health care resources for this patient population remains an important question. To begin answering this question, we evaluated the impact of plerixafor usage in our population of poor mobilizers in our institution using a historical cohort for comparison. Material and method The population of poor mobilizers in the setting of MM or NHL (defined as &lt; 20 CD34 / μl on the planned day of collection) between January 2009 and December 2017 at Hôpital de l'Enfant Jesus (HEJ) du CHU de Québec was retrospectively studied and analyzed. To ensure that all poor mobilizers were included, we screened all flow cytometry CD34+ cell count results &lt; 50 /μl on the planned day of collection and reviewed all the charts of patients with &lt; 20 CD34 / μl regardless of whether they were collected or not. This chart review allowed a comprehensive description of the characteristics of our poor mobilizers, a comparison of the capacity to collect an adequate PBPC with or without plerixafor and to evaluate its impact on different variable with regard to PBPC collection and subsequent engraftment. The data were compiled in an ACCESS database using a retrospective review of digital patient charts. The data was analyzed by the Centre de Recherche du CHU de Quebec (CRCHUQ). Data were stratified by disease type and CD34 level on the planned day of PBPC collection. Results 207 patient charts were reviewed; 70 poor mobilizers with 95 mobilizations attempts, 30 of them using plerixafor, were included. The baseline characteristics of both groups were similar as well as the length of hospitalization for transplant and relapse free survival at one year. The addition of Plerixafor to our management of poor mobilizers did not significantly increase the proportion of patients proceeding to autologous PBPC transplant (80,4 vs 75% p=0,7599). During the mobilization attempts, the maximal CD34 /μl reached was similar in both groups (18,86 vs 15,4 p=0,1541). Plerixafor was associated with a superior collection efficiency (% of CD34 collected) (40,85 vs 60,91% p=0,007), but this can be explained by a greater use of central venous catheters for collection in this group (70 vs 95,1% p = 0,0275). Data stratified by initial diagnosis and CD34 level on the planned day of PBPC collection (&lt;10 c/μl versus [10c/μl - 20c /μl [) showed the same tendency. The collection duration was not significantly reduced in the plerixafor group, but there was a trend for a shorter mean duration of 22 minutes also explained by a greater use of central venous catheters in this group. The preplanned subgroups analyses have shown the same trend when stratified by diagnosis, with a reduction of 53 minutes in the multiple myeloma subgroup with a greater total CFU-GEM / kg per collect (46,35 vs 70,55 p=0,0163). Conclusion The use of plerixafor at HEJ did not improve significantly the proportion of poor mobilizers reaching an adequate PBPC graft and did not improve transplant outcomes compared to a historical control. Better strategies are needed to improve care for true poor mobilizers. The optimal use of plerixafor needs to be further studied. Table. Disclosures Blais-Normandin: Sanofi: Other: unrestricted research grant. Laroche:Sanofi: Other: unrestricted research grant.

Feasibility and cost analysis of day 4 granulocyte colony-stimulating factor mobilized peripheral blood progenitor cell collection from HLA-matched sibling donors

BackgroundGuidelines recommend treatment with 4–5 days of granulocyte colony-stimulating factor (G-CSF) for optimal donor peripheral blood progenitor cell (PBPC) mobilization followed by day 5 collection. Given that some autologous transplant recipients achieve adequate collection by day 4 and the possibility that some allogeneic donors may maximally mobilize PBPC before day 5, a feasibility study was performed evaluating day 4 allogeneic PBPC collection. MethodsHLA-matched sibling donors underwent collection on day 4 of G-CSF for peripheral blood (PB) CD34+ counts ≥0.04 × 106/mL, otherwise they underwent collection on day 5. Those with inadequate collected CD34+ cells/kg recipient weight underwent repeat collection over 2 days. Transplant and PBPC characteristics and cost analysis were compared with a historical cohort collected on day 5 per our prior institutional algorithm. ResultsOf the 101 patient/donor pairs, 50 (49.5%) had adequate PBPC collection on day 4, with a median PB CD34+ cell count of 0.06 × 106/mL. Day 4 donors were more likely to develop bone pain and require analgesics. Median collected CD34+ count was significantly greater, whereas total nucleated, mononuclear and CD3+ cell counts were significantly lower, at time of transplant infusion for day 4 versus other collection cohorts. There were no significant differences in engraftment or graft-versus-host disease. Cost analysis revealed 6.7% direct cost savings for day 4 versus historical day 5 collection. DiscussionDay 4 PB CD34+ threshold of ≥0.04 × 106/mL identified donors with high likelihood of adequate PBPC collection. Day 4 may be the optimal day of collection for healthy donors, without adverse effect on recipient transplant outcomes and with expected cost savings.

Feasibility and Cost Analysis of Day 4 Granulocyte Colony-Stimulating Factor Mobilized Peripheral Blood Progenitor Cell Collection from HLA-Matched Sibling Donors

Feasibility and Cost Analysis of Day 4 Granulocyte Colony-Stimulating Factor Mobilized Peripheral Blood Progenitor Cell Collection from HLA-Matched Sibling Donors

Feasibility and Cost Analysis of Day 4 Granulocyte Colony-Stimulating Factor Mobilized Peripheral Blood Progenitor Cell Collection from HLA-Matched Sibling Donors

Introduction: Published guidelines recommend mobilization of allogeneic peripheral blood progenitor cells (PBPC) with 4-5 days of granulocyte colony-stimulating factor (G-CSF) followed by PBPC collection on day 5. Given that some autologous transplant patients are adequately mobilized by day 4, and concern that a subset of allogeneic donors may be maximally mobilized before day 5 of G-CSF administration, we performed a feasibility study evaluating day 4 allogeneic PBPC collection.Methods: This single-center prospective study included adult patients with malignant diseases who received a first allogeneic hematopoietic stem cell transplant (HCT) at our center between 7/1/2013 - 6/30/2017. HLA-matched sibling donors received 10 μg/kg of G-CSF subcutaneously prior to PBPC collection. Donors were collected on day 4 of G-CSF if peripheral blood (PB) CD34+ counts were ≥0.04x106/ml. Donors with day 4 PB CD34+ counts <0.04x106/ml were collected on day 5, and those with inadequate collected CD34+ cells/kg recipient weight underwent repeat collection over two days. Patient and donor characteristics, PBPC product composition, transplant outcomes, and cost analysis of the PBPC collection procedure were compared to a historical cohort of donors collected on day 5 according to our prior algorithm.Results: One hundred and one patients/donors were eligible for inclusion on study, and 75 were included in the historical cohort. Of the 101 donors on study, 50 (49.5%) had adequate PBPC collection on day 4 of G-CSF, 26 (25.7%) were collected on day 5, and 25 (24.8%) required two-day collections on days 4 and 5. The median day 4 donor PB CD34+ cell count was 0.06 (range 0.03-0.13) x 106/ml among donors collecting on day 4, 0.03 (range 0.007-0.09) x 106/ml for donors collecting on day 5, and 0.019 (range 0.004-0.04) x 106/ml for donors collecting over two-days (p<0.001).The most common reported donor symptoms were bone pain, myalgia/malaise, headache, and circumoral tingling/electrolyte abnormalities. Compared to the historical cohort, donors with PBPC collection on day 4 were significantly more likely to develop bone pain, require narcotics, and take over-the-counter (OTC) medications, day 5 donors were significantly more likely to develop bone pain and take OTC medications, and two-day donors were significantly more likely to develop bone pain and circumoral tingling/electrolyte abnormalities.The median collected PBPC CD34+ cell count (7.25 x 106/kg recipient weight) and infused PBPC product CD34+ cell count (5.67 x 106/kg recipient weight) were significantly greater in products collected on day 4, compared to products collected on other days. In comparison, the infused PBPC product total nucleated cell (TNC) count (7.13 x 108/kg recipient weight), mononuclear cell (MNC) count (5.84 x 108/kg recipient weight), and CD3+ cell count (2.14 x 108/kg recipient weight) were significantly lower in products collected on day 4 compared to other collection cohorts (p<0.001, p<0.001, and p=0.002, respectively for day 5, two-day, and historical cohort).There were no significant differences in time to neutrophil or platelet engraftment, or in the incidence of acute or chronic graft-versus-host-disease, based on day of collection. There was a non-significant trend towards improved 1-year survival among patients transplanted with PBPC collected on day 4 (p=0.077). Cost analysis revealed a 6.7% savings in direct costs per collection procedure for the day 4 collection method versus historical cohort.Conclusions: Using a day 4 PB CD34+ threshold of ≥0.04x106/ml identifies donors with a high likelihood of adequate PBPC collection. While differences in PBPC product composition and donor symptoms were seen based on day of collection, we found no evidence of adverse post-HCT outcomes associated with day 4 PBPC collection. Day 4 may be the optimal day of stem cell collection for a population of healthy donors without adverse effect on transplant outcomes, and with an anticipated cost savings. Ongoing analyses include resource utilization review, matched cohort analysis of day 4 versus 5 collection and correlation with transplant outcomes, more detailed PBPC production composition analysis among the collection cohorts, and longer post-HCT follow-up and association with outcomes based on day of PBPC collection. These findings merit further analysis in larger HCT cohorts. [Display omitted] DisclosuresCook:Syros Pharmaceuticals: Consultancy. Maziarz:Incyte: Consultancy, Honoraria; Kite Therapeutics: Honoraria; Novartis Pharmaceuticals Corporation: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Athersys, Inc.: Patents & Royalties; Juno Therapeutics: Consultancy, Honoraria.

Impact of Graft Composition on Graft-Versus-Host Disease in Peripheral Blood HLA-Identical Sibling Transplants: Protective Role of CD8 Cell Dose

Introduction and Objective:Acute graft-versus-host disease (aGVHD) is a leading cause of transplant related mortality following allogeneic hematopoietic stem cell transplantation (HSCT). Data on the impact of graft composition, namely CD34 and T-cell subsets, and aGVHD is conflicting. We hypothesized an upper cell dose limit of CD34 would exist predictive of aGVHD without affecting engraftment and sought to explore T-cell subsets and their impact on aGVHD outcomes amongst peripheral blood progenitor cell (PBPC) HLA-identical sibling transplants (Allo-Sib).Methods:In an IRB approved protocol, consecutive Allo-Sib patients underwent HSCT for hematologic malignancy at our center from 1/2004 to 12/2012. Demographic and clinical data were prospectively collected and retrospectively confirmed. Patients received the entire D1 CD34 PBPC collection from their donors and from a second day of collection if necessary to achieve a dose of 4 x 106 CD34/kg cells. aGVHD prophylaxis was uniformly tacrolimus and mini-methotrexate. Tacrolimus was monitored to achieve a trough of 10-15 ng/ml. aGVHD was graded as per the International Bone Marrow Transplant Registry System. Exact binary logistic regression models were used to estimate the odds of aGVHD as a function of patient demographic and clinical data. For the association between cell counts and aGVHD, binary cut scores were determined by finding the point along the receiver operating characteristic curve that maximized sensitivity and specificity. Non-parametric Spearman correlation coefficients were used to estimate the association between CD34, CD3, CD4, and CD8 cell counts.Results:We analyzed 160 consecutive patients. In this mostly male (63%) population, median age was 51 and most patients underwent a myeloablative transplant (93%). Disease risk as per Armand et al 2012 was low 45%, intermediate 13.2%, and high 41.7%. Co-Morbidity Index by Sorror et al (HCT-CI) was 30.5% for 0, 33.8% for 1-2, and 35.8% for > 2. Sixteen patients (10%) developed grade II-IV aGVHD while 9 (6%) developed grade III-IV aGVHD. Median CD34 cell dose infused was 6.27 X 106/kg. Median CD3, CD4, and CD8 cell doses infused were 2.51 X 108/kg, 1.80 X 108/kg, and 0.66 X 108/kg, respectively. In univariate analysis, patients (n=67) receiving > 9.94 x 106 CD34/kg were 12 times more likely to develop grade III-IV aGVHD (odds ratio =12.308; p=0.01)(figure 1). Conversely, patients receiving > 0.50 x 108 CD8/kg were less likely to develop grade II-IV aGVHD (odds ratio = 0.30; p=0.049)(Figure 2), but not Grade III-IV aGVHD. The only other factor associated with aGVHD was a diagnosis of AML, which was protective (p=0.01). CD3 and CD4 cell counts did not correlate with aGVHD in our patient cohort. There was no correlation between engraftment and CD34, CD3, CD4, or CD8 cell dose. Finally, we found no direct correlation between CD34 cells counts and CD3, CD4, or CD8 cell counts.Conclusion:This study represents the largest evaluation examining the correlation between both infused CD34 cells and T-cell composition with aGVHD among patients undergoing strictly matched related donor HSCT. Importantly, the data demonstrates patients receiving > 10 x 106 CD34/kg have increased risk of developing clinically significant aGVHD, a dose that far exceeds adequate engraftment doses and serves now as a cap on CD34 cell dose in our program. Interestingly, our data suggests infusion of > 0.50 x 108 CD8/kg may protect from severe aGVHD whereas prior reports have demonstrated no association between CD8 cells and aGVHD. Further investigation is needed to better characterize the relationship between CD8 cells and aGVHD and better define the correlation between CD8 and CD34 cell doses in the development of aGVHD. DisclosuresNo relevant conflicts of interest to declare.

Peripheral blood progenitor cell collection in pediatric patients optimized by high pre-apheresis count of circulating CD34+ cells and high blood flow.

Collection of peripheral blood progenitor cells by leukapheresis is the preferred method to obtain grafts for autologous transplantation. Optimizing this procedure is important to warrant sufficient cell yield and reduce associated risks. To obtain sufficient to optimal yields of ≥ 2 to ≥ 5 × 106 CD34+ cells/kg body weight with a single leukapheresis procedure, success rates between 83 and 92% have been reported in children. In this retrospective study, we describe an improved protocol for autologous stem cell collection with an extraordinarily high success rate applied in 122 consecutive pediatric patients treated at the University Hospital Bern between 2004 and 2017. By comparing our data with previous studies, we identify two main optimizing factors: higher pre-apheresis CD34+ cell counts with a median of 130/µl and higher blood flow rates of 42-100 ml/min. Consequently, blood volumes processed were increased, duration of leukapheresis was shorter and CD34+ cell yields with a median of 19.0 × 106/kg body weight were higher than previously described. Safety in our study was comparable to previous studies. Based on our data, we present an innovative algorithm for determination of the necessary blood volume and time of pediatric leukapheresis procedure.

Poor mobilizer and its countermeasures

Mobilization failure is a major concern in patients undergoing hematopoietic cell transplantation, especially in an autologous setting, as almost all donor harvests can be accomplished with granulocyte-colony stimulating factor (G-CSF) alone. Poor mobilizers, defined as those with a peripheral blood CD34+ cell count ≤20 cells/μl after mobilization preceding apheresis is a significant risk factor for mobilization failure. We recommend preemptive plerixafor plus G-CSF (filgrastim, 10 μg/kg daily) as a first mobilization strategy, which yields sufficient peripheral blood progenitor cells (PBPCs) in almost all patients and avoids otherwise unnecessary remobilization. Preemptive plerixafor is administered in patients with a day-4 peripheral blood CD34+ count <15, depending on the disease and the target PBPC amount. Cyclophosphamide is reserved for patients who fail the first PBPC collection. We recommend second mobilization for patients who could not achieve a sufficient PBPC amount with the first mobilization. In these patients, a second attempt with plerixafor plus G-CSF or mobilization with plerixafor in combination with cyclophosphamide and G-CSF is recommended. Increased dose and/or twice daily administration of G-CSF can be considered.

464 - Influence of Donor Variables on CD34 Stem Cell Collection Yield Comparing Peripheral Blood Progenitor Cell and Bone Marrow Collection at a Single Institution

464 - Influence of Donor Variables on CD34 Stem Cell Collection Yield Comparing Peripheral Blood Progenitor Cell and Bone Marrow Collection at a Single Institution

Quantification of Acute Lymphoblastic Leukemia Clonotypes in Leukapheresed Peripheral Blood Progenitor Cells Predicts Relapse Risk Following Autologous Hematopoietic Cell Transplantation

BackgroundAlthough multiple studies have shown superiority of allogeneic hematopoietic cell transplantation (alloHCT) over autologous hematopoietic cell transplantation (autoHCT) for patients with "high-risk" acute lymphoblastic leukemia (ALL), these findings may be explained, in part, by contamination of the peripheral blood progenitor cell (PBPC) leukapheresis product by residual leukemic cells in patients undergoing autoHCT.MethodsWe retrospectively evaluated minimal residual disease (MRD) via next-generation sequencing (NGS) (Adaptive Biotechnologies, S. San Francisco, CA) in the PBPC leukapheresis products from 32 ALL patients who underwent autoHCT. All patients had "high-risk" ALL, as defined by B-lineage disease with WBC at diagnosis >30,000/uL; high-risk cytogenetics including t(9;22), t(4;11), other 11q23 abnormalities, or monosomy 7; or primary refractory disease.Peripheral hematopoietic cell mobilization consisted of cytarabine 2000mg/m2 IV every 12 hours (16,000mg/m2 cumulative) concurrent with etoposide 40mg/kg cumulative by continuous IV infusion over 4 days. The autoHCT conditioning consisted of 1320cGy total body irradiation (TBI) given in 11 fractions from day -8 to -5, etoposide 60mg/kg IV on day -4, and cyclophosphamide 100mg/kg IV on day -2. Tyrosine kinase inhibitors (TKI) were allowed for patients with Philadelphia chromosome-positive (Ph+) B-ALL. Seven patients (22%) participated in a multi-institutional trial in which the PBPC graft underwent ex vivo complement-mediatedpurging using monoclonal antibodies against CD9/CD10/CD19/CD20 for patients with B-lineage disease, or against CD2/CD3/CD4/CD5/CD8 for patients with T-lineage disease.Kaplan-Meier curves were generated using GraphPad Prism (GraphPad Software, La Jolla, CA) and statistical differences assessed via Log-Rank and Wilcoxon analyses, with a p-value of <0.05 considered significant.ResultsTwenty-eight patients (88%) had diagnostic bone marrow samples with quantifiable immunoglobulin or T cell receptor (Ig/TCR) gene rearrangements suitable for MRD quantification in the PBPC collections. Twelve (38%) patients had Ph+ B-ALL, 12 (38%) had Ph-neg B-ALL, and 4 (14%) had T-cell ALL. The majority of patients were male, in first complete remission, and autografted between 2000-2009, with a median age at autoHCT of 32 (range 19-55).With a median follow-up of 41 months (range 3-217), median relapse-free survival (RFS) and overall survival (OS) for the entire cohort are 3.2 and 4.2 years, respectively. At 5 years post-autoHCT, 42% of patients remain alive and relapse-free.Of the 28 diagnostic bone marrow specimens, 21 (75%) had rearrangements in more than 1 immunoreceptor locus (Figure 1A). A total of 73 rearrangements were identified across all patients. Clonal Ig heavy chain (IGH) sequences with complete VDJ rearrangement were the most commonly identified rearrangement, present in 17 of 28 patients (61%) and representing 30 of the 73 (41%) total rearrangements.When stratified by graft MRD burden, the median RFS for patients with MRD detectable at a level ≥10-6 (n=13) was 6.5 months, and has not been reached for patients without detectable MRD above this threshold (n=15; p=0.0005; Figure 1B). Ex vivo antibody-based purging failed to eradicate leukemia cells from the PBPC collections of 3 patients with detectable MRD who received a purged graft (Figure 1C), all of whom ultimately relapsed.Of the Ph+ cohort, 6 (50%) had detectable MRD in the PBPC graft. Two (33%) of these patients were not treated with a TKI; 1 relapsed at 4 months post-autoHCT and the other died from non-relapse mortality. Of the 4 Ph+ patients with detectable MRD who received a TKI, 2 (50%) remain long-term relapse-free survivors. Of the 6 patients without MRD who were treated with a post-autoHCT TKI, 5 (83%) remain relapse-free.ConclusionWe demonstrate that the NGS-based immunosequencing platform identifies ALL MRD in leukapheresed PBPC collections. The presence of MRD in the autograft strongly predicts relapse, with only 15% RFS in patients harboring ≥10-6 MRD at stem cell collection versus 73% in patients with undetectable MRD. The absence of MRD in PBPC may thus identify a subset of "high-risk" patients likely to achieve long-term remissions without alloHCT. TKI therapy for patients with Ph+ B-ALL may also, in some cases, abrogate the need for alloHCT, even with quantifiable MRD prior to high-dose therapy. [Display omitted] DisclosuresDamon:Atara: Consultancy; Sunesis: Research Funding; Sigma-Tau: Research Funding; McGraw-Hill: Patents & Royalties: Book Chapter. Andreadis:McGraw Hill: Honoraria; Novartis: Consultancy; Cellerant: Consultancy; Pharmacyclics: Honoraria. Olin:Daiichi-Sankyo: Research Funding. Kong:Adaptive Biotechnologies: Employment, Equity Ownership. Faham:Adaptive Biotechnologies: Employment, Equity Ownership.