Delayed Neutrophil Engraftment Research Articles

Donor specific anti-HLA antibodies in hematopoietic stem cell transplantation. Single Center prospective evaluation and desensitization strategies employed.

In the setting of mismatched-hematopoietic stem cells transplantation, the detection of antibodies directed against donor-specific HLA allele(s) or antigen(s) (DSA) represents a barrier for engraftment. It is thus necessary to plan an immunosuppressive strategy, or to select an alternative donor. This prospective study aimed at evaluating the efficacy of our strategy for testing DSAs and the efficacy of the desensitization strategy (DS) employed between November 2017 and November 2020. The anti-HLA antibody search was performed using the Luminex bead assays (Lifecode ID and LSA I/II-Immucor) and expressed as mean fluorescence intensity (MFI >1,000 positive). If the patient had DSAs and no alternative donors, a DS was employed with rituximab (day -15), 2 single volume plasmaphereses (PP; days -9 and -8), intravenous immunoglobulins (day -7) and infusion of HLA selected platelets, if persistent DSAs were directed against class I HLA. DS was scheduled with or without PP, according to the DSA MFI (>1,000 or <5,000) and FCXM (flow cytometry crossmatch). Twenty-two out of 126 patients (17.46%) showed anti-HLA antibodies, 5 of them DSAs (3.97% of total); 3 patients underwent DS obtaining engraftment. Female gender (p=0.033) and a history of previous pregnancies or miscarriages (p=0.009) showed a statistically significant impact on alloimmunization. Factors associated with a delayed neutrophil engraftment were patient's female gender (p=0.039), stem cell source (p=0.025), and a high HSCT-specific comorbidity index (p=0.028). None of the analyzed variables, including the DSA detection, influenced engraftment. Our study confirms the importance to test DSAs in mismatched-hematopoietic stem cells transplantation The DS used proved successful in removing DSAs. Prospective multicenter studies are needed to better define and validate consensus strategies on DSA management in HSCT.

Allogenic hematopoietic stem cell transplantation outcomes of patients aged ≥ 55 years with acute myeloid leukemia or myelodysplastic syndromes in China: a retrospective study

BackgroundElderly patients with acute myeloid leukemia or myelodysplastic syndromes (AML/MDS) have historically had poor prognoses. However, there has been a recent increase in the use of allogenic hematopoietic stem cell transplantation (allo-HSCT) are in this patient population. Nevertheless, the optimal choice of donor type for the patients remains an unmet need. Limited data exist on the use of allo-HSCT in elderly patients with AML/MDS from China. To better understand and optimize the selection of donor type for the elderly patients, particularly for those with refractory or relapsed disease, in comparison with the previous studies in the US and Europe.MethodsOur retrospective study enrolled 259 patients aged over 55 years who underwent their first allo-HSCT between April 2015 and August 2022. These patients were divided into three groups based on donor type: haploidentical related donor group (haploidentical related donor transplantation [HID], n = 184), matched sibling donor group (matched sibling donor transplantation [MSD], n = 39), and matched unrelated donor group (matched unrelated donor transplantation [MUD], n = 36). Statistics were performed with the chi-square test, the log-rank and Fine-Gray tests.ResultsThe median age of the cohort was 57 years (range: 55–75) and 26.25% of patients were over 60 years old. Younger patients had a higher incidence of acute graft-versus-host disease (HR = 1.942, P = 0.035), faster neutrophil recovery (HR = 1.387, P = 0.012), and better overall survival (HR = 0.567, P = 0.043) than patients aged ≥ 60 years across the entire cohort. Patients with refractory or relapsed (R/R) diseases had delayed neutrophil engraftment (P = 0.010, HR = 0.752) and platelet engraftment (P < 0.001, HR = 0.596), higher incidence of relapses (HR = 2.300, P = 0.013), and inferior relapse-free survival (RFS) (HR = 1.740, HR = 0.016) regardless of donor type. When it came to graft-versus-host-disease-free, relapse-free survival (GRFS), MUDs turned out to be superior to HIDs (HR = 0.472, P = 0.026) according to the multivariable analysis. In contrast, we found MSDs had an inferior GRFS to HIDs in parallel (HR = 1.621, P = 0.043).ConclusionThe choice of donor type did not significantly affect the outcomes of allo-HSCT. However, when considering the quality of post-transplant life, MUDs or HIDs from younger donors may be the optimal choice for elderly patients.

Impact of CD34 positive cell dose in donor graft on the outcomes after haploidentical peripheral blood stem cell transplantation with post-transplant cyclophosphamide – A retrospective single-center study with a Japanese cohort

BackgroundHaploidentical peripheral blood stem cell transplantation (haplo-PBSCT) with post-transplant cyclophosphamide (PTCy) is an important therapeutic option for patients lacking an HLA-matched donor. However, the significance of CD34+ cell dose in grafts has not been fully elucidated. ObjectiveWe aimed to explore the impact of CD34+ cell dose on outcomes after haplo-PBSCT with PTCy. Study DesignWe retrospectively investigated 111 consecutive patients who underwent haplo-PBSCT with PTCy or HLA-matched PBSCT from related donors. ResultsThere were no statistically significant differences in 3-year overall survival (p = 0.559) or progression-free survival (p = 0.974) between haplo-PBSCT and matched PBSCT. Delayed neutrophil engraftment and a lower incidence of graft-versus-host disease were observed in haplo-PBSCT. The median dose of CD34+ cells was 4.9 × 106 /kg in 57 haplo-PBSCT and 4.5 × 106 /kg in 54 matched PBSCTs. Importantly, patients who underwent haplo-PBSCT with the administration of CD34+ cell at a dose of ≥4.0 × 106 /kg significantly had improved OS (p = 0.015) and decreased incidence of disease relapse (p = 0.001) without increasing incidence of GVHD. ConclusionOur data suggest that a higher dose of CD34+ cells in haplo-PBSCT with PTCy positively impacts the outcomes without an increase of GVHD.

Emapalumab for Treatment of Impending Graft Failure

Introduction: Immune-mediated graft failure (also termed graft rejection) is a feared complication of hematopoietic stem cell transplant (HSCT) and there is no effective intervention. Multiple pre-transplant risk factors for graft failure are known and recent studies from our groups identified interferon gamma (IFNγ) as a mechanistically important and pharmacologically targetable cytokine involved in graft failure pathophysiology. CXCL9, a downstream marker of IFNγ production, was also identified as a biomarker. We describe an international multicenter retrospective pooled analysis of emapalumab (EMA), an IFNγ neutralizing agent, for the prevention/treatment of immune-mediated graft failure after HSCT. Methods: The safety and preliminary efficacy of EMA were studied in predominantly pediatric patients who received EMA using two different strategies: 1) graft failure treatment and 2) graft failure prophylaxis. Patients at US centers were treated with EMA if they developed clinical and laboratory signs of graft failure after HSCT. All treatment patients met 2 or more of the following criteria: 1) HLA mismatched donor and/or prior graft failure, 2) unexplained fever &amp;gt;39°C (or &amp;gt;38°C if prior history of graft failure) after HSCT, 3) absolute neutrophil count decline after initial engraftment, 4) delayed neutrophil engraftment after HSCT, 5) real-time CXCL9 &amp;gt; 2.5x upper limit of normal (ULN). Temperature and CXCL9 cutoffs were based on a prior graft failure biomarker publication (Sabulski et al, Blood Advances 2021). Patients treated at European centers received prophylactic EMA to prevent graft failure if they were deemed at high-risk prior to transplant. High-risk patients had a prior history of graft failure after HSCT or had two or more of the following established risk factors: a) affected by a disease with high risk of graft failure, including acquired severe aplastic anemia, thalassemia, primary HLH; b) ex-vivo T cell-depleted stem cell product; c) transplant from unrelated cord blood unit or mismatched related/unrelated donor. Results: Thirty-six HSCTs used EMA for graft failure treatment or prophylaxis and were included in this study.EMA was used for graft failure treatment in 25 HSCTs wherein patients developed clinical and laboratory signs of graft failure (Table 1). Most HSCTs in the treatment cohort were performed for bone marrow failure syndromes (n=16). All patients tolerated EMA without complications and no side effects or infections were attributed to EMA. Fifty six percent (14/25) of patients treated with EMA for impending graft failure engrafted and had resolution of graft failure concerns, while the remaining 44% suffered graft failure. Responders had a median ANC of 0.29 x10 3 cells/μL (range 0.05-0.79) prior to EMA, which increased to a median of 0.6 x10 3cells/μL (range, 0-5.1) and 2.97 x10 3 cells/μL (range, 0.85-8.7) on days 3 and 7 after EMA dosing. Eighty percent (20/25) of CXCL9 levels were elevated in the treatment cohort prior to EMA dosing. The median CXCL9 level prior to EMA dosing was elevated 2.4 x ULN (range, 0.3-157.8). The median pre-EMA CXCL9 level in patients who ultimately suffered graft failure in the treatment cohort was 3.3x ULN (range, 0.7-157.8) compared to a median of 2.2x ULN (range, 0.3-30.4) in subjects who had signs of graft failure but did not suffer graft failure (p=0.24). Eleven patients received prophylactic EMA based on a prior history of graft failure or other pre-transplant risk factors. EMA was well tolerated in these patients and 91% (10/11) of patients engrafted while one patient with prior history of graft failure suffered recurrent graft failure. The pre-HSCT (day -2) CXCL9 level in the lone prophylactic patient who suffered graft failure was 4x the ULN. Conclusions: This study reports the largest cohort of HSCTs that used EMA therapy for the novel purpose of treating or preventing graft failure. EMA was well tolerated in all patients. Efficacy conclusions are preliminary and limited by the study design, however our treatment study successfully identified a cohort of patients with a markedly high graft failure rate (44%) and we show preliminary evidence to suggest emaplaumab prevented graft failure in patients who had signs of impending graft failure at the time of treatment. The safety and preliminary efficacy observations in this study support a larger prospective study of IFNγ blockade for graft failure prevention after HSCT.

Optimized Double-Unit Cord Blood Transplantation Mitigates Transplant-Related Mortality Resulting in High Progression-Free Survival in Adults with Hematologic Malignancies

Background : Double-unit cord blood transplantation (dCBT) with intermediate intensity conditioning (Cy50/ Flu150/ Thio10/ TBI400cGy) and cyclosporine-A (CSA)/ mycophenolate mofetil (MMF) graft-versus-host disease (GVHD) prophylaxis has been associated with high progression-free survival (PFS) in adult patients (pts) with hematologic malignancies ( Barker JN et al, Blood Advances 2020). Now, our Center has investigated multiple refinements to further mitigate transplant-related mortality (TRM). Herein, we have analyzed transplant outcomes in these adult dCBT pts to establish an optimized dCBT platform. Methods : Consecutive adult first allograft pts with high-risk hematologic malignancies who underwent first allografts with intermediate intensity dCBT between 3/2018-8/2022 were analyzed. Optimizations involved further refined unit selection placing highest priority on unit quality (i.e. optimized banking practices) &amp; CD34+ cell dose over HLA-match, ensuring therapeutic (CSA) levels (&amp;gt; 250 ng/mL) by day 0, prompt treatment of pre-engraftment syndrome (PES) &amp; letermovir prophylaxis in CMV seropositive pts from day +7. Also, we have investigated 2 strategies to mitigate acute graft-versus-host disease (aGVHD): pts early in the study period received CSA, MMF &amp; tocilizumab (8 mg/kg on day -1) prophylaxis ( Toci Group), whereas recent pts ( Recent Group) received CSA/ MMF with prompt therapy of clinically diagnosed aGVHD. Results : Of 74 patients (Table), 49 were in the Toci Group, &amp; 25 in the Recent Group. Most pts were transplanted for acute leukemia (n = 55, 74%) &amp; over half (n = 39, 53%) had non-European ancestry. Distribution of diagnoses, CMV serostatus, HCT-CI &amp; graft characteristics were similar between the groups but Recent Group pts tended to be younger (38 vs. 47 years, p = 0.071). Toci Group pts had delayed neutrophil recovery [engraftment incidence 94% (95%CI: 87-99) at a median of 25 days (range 16-40), one graft failure], but low rates of PES (n = 19, 39%). The day-100 incidence of grade II-IV &amp; III-IV aGVHD were 69% (95%CI: 56-82) &amp; 10% (95%CI: 2-19), respectively. One pt (false negative CMV-serostatus) who did not receive letermovir had CMV infection. One-year TRM was 16% (95%CI: 6-27) with a 1-year relapse rate of 6% (95%CI: 3-13). TRM was due to infection (n = 3), aGVHD (n = 3, 1 with concurrent COVID-19 infection), multiorgan failure (n = 2) &amp; graft failure (n = 1). With a median follow-up of 47 months (range 28-62), the 1-year OS was 84% (95%CI: 73-94) &amp; 1-year PFS was 78% (95%CI: 66-89). By contrast, the engraftment incidence in Recent Group pts was 100% with a faster median neutrophil recovery of 19 days (range 11-36, p = 0.002) &amp; all engrafted platelets at a median of 36 days (range 24-92). However, most Recent group pts developed PES [n = 20 (80%), p &amp;lt; 0.001] although this responded promptly to short course corticosteroids. Day 100 grade II-IV aGVHD was also higher [92% (95%CI: 81-99), p = 0.009], although grade III-IV aGVHD was low [8% (95%CI: &amp;lt;1-19)] &amp; similar to tocilizumab pts. Day 100 incidence of CMV was 0%. With a median follow-up of 17 months (range 6-50), the 1-year TRM in Recent Group pts is 0% with a 1-year relapse incidence of 13% (95%CI: 7-27). Consequently, the 1-year OS &amp; PFS are high at 96% (95%: 89-99) &amp; 87% (95%CI: 74-99), respectively (Figure). Conclusions: Optimized dCBT with intermediate intensity conditioning, graft selection that prioritizes unit quality &amp; CD34+ dose, CSA/ MMF prophylaxis with prompt therapy of PES &amp; aGVHD, &amp; letermovir CMV prophylaxis mitigates TRM in young &amp; middle-aged adults. Thus, combined with relatively low relapse rates, the PFS &amp; OS are high. Tocilizumab has been abandoned due to its notable association with delayed neutrophil engraftment &amp; lack of survival advantage. Letermovir is highly effective completely preventing CMV infections &amp; may contribute to the reduced aGVHD-related mortality recently (as compared to the pre-tocilizumab era), since avoidance of CMV antiviral therapy toxicities greatly facilitates aGVHD prevention &amp; therapy. Given the rapid availability of cryopreserved unmanipulated CB grafts &amp; frequent limitations of URD availability for minority populations, optimized dCBT is a highly attractive curative therapy for acute leukemias &amp; other high-risk myeloid malignancies warranting prospective multi-center investigation.

5612617 EFFICACY AND SAFETY OF A SINGLE DOSE OF EXAGAMGLOGENE AUTOTEMCEL FOR TRANSFUSION-DEPENDENT-THALASSEMIA AND SEVERE SICKLE CELL DISEASE

Background: Elevated fetal hemoglobin(HbF) is associated with improved outcomes in patients(pts) with transfusion-dependent β-thalassemia(TDT) and sickle cell disease(SCD). Exagamglogene autotemcel(exa-cel; formerly known as CTX001) is a cell therapy designed to reactivate HbF via non-viral, ex vivo CRISPR/Cas9 gene-editing at the erythroid enhancer region of BCL11A in autologous CD34+ hematopoietic stem and progenitor cells(HSPCs). Early data from the pivotal trials CLIMB THAL-111(NCT03655678) and CLIMB SCD-121(NCT03745287) showed that a single dose of exa-cel increased HbF and total Hb sufficiently to eliminate red blood cell(RBC) transfusions(TDT) and vaso-occlusive crises(VOCs; SCD). Aims: To report efficacy and safety data from the first 75 pts dosed with exa-cel in the ongoing CLIMB THAL-111 and CLIMB SCD-121 trials. Methods: Following pharmacokinetic-adjusted busulfan myeloablation and exa-cel infusion, pts(12-35y) are monitored for engraftment, total Hb, HbF, BCL11A edited alleles, transfusions, VOCs(SCD only), and adverse events(AEs). Data presented as mean(min-max) unless noted. Results: 44 pts with TDT(age 21.3 [12-35] y) and 31 pts with SCD(age 22.5 [12-34} y) had been infused with exa-cel at data cut(follow-up 12.3 [1.2-37.2] mo and 9.6 [2.0-32.3] mo, respectively). 26/44 pts with TDT(59.1%) had β0/β0 or a β0/β0-like genotype(β0/IVS-I-110, IVS-I-110/IVS-I-110). In the 2-yr period before screening, pts with TDT received 36.0(15.0-71.0) units RBC/yr and pts with SCD had 3.9(2.0-9.5) severe VOCs/yr. After exa-cel infusion, all pts engrafted neutrophils and platelets. Median time to neutrophil and platelet engraftment was 29 and 43 days in pts with TDT and 27 and 32 days in those with SCD, respectively. Overall, 42 of 44 pts with TDT stopped RBC transfusions(duration 0.8 to 36.2 mo); 2 pts had not yet stopped transfusions but had 75% and 89% reductions in transfusion volume. By Month 3, increases in HbF and mean total Hb levels(>9 g/dL) were achieved, with mean total Hb levels increasing to >11 g/dL thereafter and were maintained. All pts with SCD(n=31) no longer had severe VOCs after exa-cel infusion(duration 2.0 to 32.3 mo). The mean proportion of HbF was >20% by Month 3, increasing to ~40% at Month 4 and was stable thereafter, with mean total Hb levels >11 g/dL after Month 3. Pts with TDT and SCD with ≥1 yr follow-up had stable proportions of edited BCL11A alleles in bone marrow CD34+ HSPCs and peripheral blood mononuclear cells. Two pts with TDT had serious AEs(SAEs) considered related to exa-cel. The first pt was previously reported. The second pt had delayed neutrophil engraftment and thrombocytopenia, which were considered related to both exa-cel and busulfan. All SAEs resolved. No pts with SCD had SAEs considered related to exa-cel. There were no deaths, discontinuations, or malignancies. Conclusions: Exa-cel infusion led to elimination of transfusions in almost all patients with TDT and elimination of VOCs in all patients with SCD, with associated clinically meaningful increases in HbF and total Hb that were maintained over time. Proportions of CRISPR/Cas9-edited BCL11A alleles remained stable after more than 1 year, indicating that long-term HSCs were successfully edited. The safety profile was generally consistent with busulfan myeloablation and autologous transplant. These results indicate exa-cel has the potential to be the first CRISPR/Cas9-based therapy to provide a one-time functional cure for TDT and severe SCD. Reference 1. Frangoul et al, N Engl J Med 2021; 384:252-260.

Plasma Levels of MRP-8/14 Associate With Neutrophil Recovery, Bacterial Bloodstream Infections, and Engraftment Syndrome Following Pediatric Allogeneic Hematopoietic Stem Cell Transplantation

Neutrophil engraftment is essential for the successful outcome after allogeneic hematopoietic stem cell transplantation (HSCT), but neutrophil activation may also induce transplant-related complications. Myeloid-related protein (MRP)-8/14 is expressed in granulocytes during inflammatory conditions and secreted in response to tissue damage along with the release of pro-inflammatory cytokines together with leukocyte recruitment and activation. In this study, we investigated associations between levels of the neutrophil activition marker MRP-8/14, neutrophil recovery and toxicities after pediatric HSCT. We included 73 children undergoing allogeneic HSCT using bone marrow or peripheral blood stem cell grafts from matched sibling or unrelated donors. Plasma levels of MRP-8/14 were measured by enzyme-linked immunosorbent assay from preconditioning until 6 months after transplantation. Overall, MRP-8/14 levels decreased from pre-conditioning to a nadir at day 7 and then rose again until day 28, preceding the reappearance of neutrophils. MRP-8/14 levels were significantly reduced at day 14 in patients with delayed neutrophil engraftment compared with patients who engrafted by day 21 (0.20 versus 0.48 μg/mL, P = .0012) and in patients who developed bacterial bloodstream infections compared to patients without this complication (0.2 versus 0.36 μg/mL, P = .048). Patients developing engraftment syndrome had significantly elevated MRP-8/14 levels at day 7 and 21 compared to patients without engraftment syndrome (0.32 versus 0.2 μg/mL, P = .042 and 1.9 versus 0.80 μg/mL, P = .039, respectively), as well as increased neutrophil counts from day 9 to 25 (P ≤ .016). Similarly, neutrophil counts were increased at day 13 to 17 in patients with acute graft-versus-host disease grade III-IV compared with grade 0-II. This study is the first to monitor neutrophil activation by MRP-8/14 in HSCT patients in relation to infectious, as well as noninfectious post-transplantation complications. Our results provide increased insights into the pathophysiology of these complications, and further studies should explore the potential use of MRP-8/14 as a clinically useful biomarker.

Effect of Daratumumab on Stem Cell Mobilization and Engraftment Kinetics Post Autologous Stem Cell Transplantation in Patients with Newly Diagnosed Multiple Myeloma

Background: High dose chemotherapy followed by autologous stem cell transplantation (ASCT) is the standard of care therapy for patients with newly diagnosed multiple myeloma. Daratumumab, an anti-CD38 monoclonal antibody, is now frequently being incorporated as a part of induction therapy in clinical practice, on the basis of data from several clinical trials.1-3 Few studies have evaluated the impact of daratumumab on stem cell mobilization and engraftment with conflicting results. Delayed neutrophil engraftment was noted in patients who received daratumumab as a part of induction therapy in one study.4 However, no delay was reported in another retrospective study5 and at least one clinical trial.6 Lower numbers of stem cells collected were reported uniformly in all three studies with daratumumab use. We evaluated the impact of daratumumab on stem cell yield with mobilization therapy as well as engraftment kinetics. Methods: We retrospectively evaluated 353 patients with newly diagnosed multiple myeloma treated at Hackensack University Medical Center between 2019-2021, on an IRB approved protocol. As per institutional guidelines, a combination of granulocyte colony stimulating factor (GCSF) with plerixafor was used as the mobilizing regimen for patients >70 yrs; cyclophosphamide, etoposide and dexamethasone (CdE) with GCSF was used for patients <70. Plerixafor could be added after chemotherapy mobilization for patients failing to achieve the desired collection goals. All patients received melphalan at a dose of 200mg/m2 administered intravenously on day -1. Time to engraftment (TTE) was calculated from the day of stem cell infusion to neutrophil and platelet engraftment, each defined as an absolute neutrophil count (ANC) of over 500/uL for three sequential tests and a platelet level over 20,000/uL without transfusion support, respectively. Goal for stem cell collection was defined as >8 x 106 CD34+ cells for patients >65 years, >12 x 106 CD34+ cells for patients <65. Statistical analyses were performed using STATA v16.0 (Stata Corp, TX, USA). The differences in median times to engraftment were analyzed using the Wilcoxon signed-rank test. Neutrophil and platelet recovery over time were calculated and plotted using Kaplan-Meier survival analyses and log-rank test for equality of survival function. Differences were considered significant at p-values <0.05. Results: 47 patients received daratumumab as a part of their induction therapy (Group A) compared with 306 patients who did not (Group B). Both groups were well balanced with regards to number of cycles of remission-induction therapy, age, sex, and mobilization regimens (Table 1). A higher number of CD34+ cells were collected for Group B, compared with Group A (12 x 10^6 vs 9.5 x 10^6, p<0.001); a lower number of collection days were required to reach collection goal for Group B compared with Group A (2 days vs 3 days, p=0.01); more CD34+ cells were collected per day for Group B compared with Group A (4.9 x10^6 vs 3.0 x 10^6, p=0.01). 73.5% patients met their collection goal for Group A, compared with 46% for Group B (p<0.001). A second mobilization attempt was required for 7 (14.9%) of patients in Group A compared to 10 (3.3%) for Group B. No difference was noted with regards to TTE for ANC (11 days for both groups, p=0.005) (Figures A); TTE for platelets was noted to be delayed by 1 day for Group A (14 days vs 13 days, p=0.0168) (Figures B). Rates of bacteremia did not differ between the two groups. Results are summarized in Table 1. Conclusions In our single-center study, a lower number of CD34+ cells were collected for patients who received daratumumab as a part of induction therapy for myeloma despite the use of standard mobilization regimens. No difference was found with regards to ANC engraftment. Platelet engraftment occurred one day earlier for patients who did not receive daratumumab for induction. These observations are consistent with results published in two prior studies.5,6 Depending on the target goal for CD34+ cell collection, daratumumab should be used with caution in the upfront setting for multiple myeloma. This is particularly important if tandem stem cell transplantation, salvage transplantation, or stem cell boost post high dose therapy are being considered as prospective treatment options for patients with multiple myeloma. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Delayed Neutrophil Engraftment in Autologous Transplant Patients with Very High CD34+ Cell Collections in a Single Apheresis

Background: The number of CD34+ cells infused during autologous hematopoietic stem cell transplantation (auto-HSCT) is the most important determinant of the speed of engraftment and neutrophil recovery. Increasing the infused CD34+ cell doses results in faster neutrophil recovery, but infusion of more than 5-10 x 106/kg CD34+ cells typically does not hasten engraftment any further. In contrast, we have noticed cases of delayed engraftment when the number of CD34+ cells collected has been extraordinarily high. We report a single center experience of engraftment in auto-HSCT patients with very high CD34+ cell numbers collected in a single apheresis session (typically 20 L blood volume). Methods: Utilizing the database of the Stem Cell Transplantation and Cell Therapy Program and the Mathews Center for Cellular Therapy, we studied apheresis and engraftment data on patients undergoing auto-HSCT for hematologic malignancies at Northwestern Memorial Hospital from January 2000 through June 2022. Inclusion criteria were age ≥18 years, ≥20 x 106/kg CD34+ cells collected in a single aphaeresis session, and available neutrophil engraftment data. Time to neutrophil engraftment was defined as days from stem cell infusion to the first of three consecutive days of absolute neutrophil count ≥0.5 x 109/L. Delayed engraftment was defined as ≥20 days to neutrophil recovery. Fisher's exact test of independence was utilized to determine the statistical significance of the difference between variables. Results: We identified 214 patients with a yield of ≥20 x 106/kg CD34+ cells in one apheresis session. Patients were divided into two groups depending on the number of CD34+ cells collected; ≥20 but <50 (group A; n=93) and ≥50 (group B; n=121). Group A had a median collection of 31.1 x 106/kg CD34+ cells and group B had 66.8 x 106/kg. For group A, the median time to neutrophil recovery was 12 days, compared with 11 days for group B. Zero out of 93 patients in group A had delayed engraftment compared with 7 of the 121 patients (6%) in group B (P=0.022). All 7 patients with delayed engraftment were mobilized with single-agent granulocyte-colony stimulating factor. Four patients had myeloma, 2 acute promyelocytic leukemia (APL), and 1 Waldenstrom's macroglobulinemia (WM) (Table 1). Patients with myeloma and WM (all in first partial remission) received high-dose melphalan conditioning and patients with APL (both in second complete remission) received busulfan-cyclophosphamide. For the 7 patients with delayed engraftment, the median number of CD34+ cells infused was 14.5 x 106/kg (range 9.5-19.6) with a median time to neutrophil engraftment of 24 days (range 20-38). Conclusions: We describe an uncommon phenomenon of delayed engraftment in some patients with very high CD34+ cell yields in a single apheresis. Additional studies on stored autologous stem cells are needed to elucidate the cause of this peculiar finding. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Tocilizumab for the Management of Cytokine Release Syndrome after Haploidentical Hematopoietic Transplant with Post-Transplant Cyclophosphamide-Based GvHD Prophylaxis

Haploidentical hematopoietic cell transplant (HaploHCT) with post-transplant cyclophosphamide (PTCy) has expanded the donor pool and made HCT available to patients without a matched donor. Cytokine release syndrome (CRS) is a syndrome of systemic inflammation with massive cytokine release, originally described after chimeric antigen receptor T cell (CAR T) therapy, is a frequent complication early after HaploHCT. Severe CRS after HaploHCT has been associated with higher non-relapse mortality (NRM) and worse overall survival (OS). Currently, no standard guidelines exist for CRS management in HaploHCT patients other than general supportive measures. Here, we described the impact of tocilizumab, an interleukin-6 receptor inhibitor used to manage CRS in CAR T therapy setting, on clinical outcomes in patients who experienced CRS after HaploHCT. We retrospectively identified a case series of 120 patients who experienced CRS after undergoing HaploHCT with PTCy-based GvHD prophylaxis at City of Hope from 06/2019 to 06/2021; of whom 11 patients received tocilizumab for CRS management. We matched these patients in a 1:2 ratio with 21 patients with CRS post-Haplo-HCT who did not receive tocilizumab (based on age, primary diagnosis, conditioning regimen, and CRS grading), then analyzed and compared OS, disease-free survival (DFS), relapse rate (RR), NRM, cumulative incidence (CIN) of grade II-IV and III-IV acute GvHD, and chronic GvHD between the two groups by univariate analysis. P-values were 2 sided at a significance level of 0.05. Table 1 summarize patient and transplant characteristics. Median age of patients in tocilizumab (TOCI) and no-tocilizumab (NO-TOCI) cohorts were 64 years (range: 27-70) and 62 years (range: 20-76). HLA 6/12 mismatch was the most common in both cohorts (81.8% in TOCI and 66.7% in NO-TOCI). All patients received mobilized peripheral blood stem cells (PBSC) as graft source. Majority of patients received non-myeloablative or reduced intensity conditioning regimens (81.8% in TOCI and 76.2% in NO-TOCI). Grade 2 CRS was most common in both cohorts (72.2% in TOCI and 71.4% in NO-TOCI); and grade 3-4 CRS was documented in 1 patient (9.1%) in TOCI and 2 patients (9.5%) in NO-TOCI cohort. Tocilizumab doses were 4 mg/kg (n=2), or 8 mg/kg (n=9). All patients but one (90.9%) received one single dose of tocilizumab and 1 patient received 2 doses of tocilizumab at 8 mg/kg/dose. All tocilizumab doses were administered either on day +3 (45%) or day +4 (55%) post-HCT (the patient with 2 doses was counted towards day +3). No high-grade tocilizumab-related side effects were documented in those 11 patients. Day 28 CIN of neutrophil engraftment was lower in TOCI compared to NO-TOCI patients (54.5% vs 76.2%, 95% CI: 21-79 and 50-90%, P=0.07 - Figure 1a). At 12 months post HaploHCT, survival outcomes were similar with NRM of 18.2 and 19% (95% CI: 3-46% and 6-38%, P=0.92); and RR of 19.5 and 14.3% (95% CI: 3-49% and 3-33%, P=0.78) in TOCI and NO-TOCI cohorts, respectively. DFS and OS were not affected by tocilizumab administration (P=0.90 and P=0.98; respectively). Three patients in TOCI and 7 patients in NO-TOCI cohort died; their causes of death were not directly related to CRS. While CIN of day 100 grade II-IV (P=0.97) and grade III-IV acute GvHD (P=0.47) were not affected by tocilizumab administration, CIN of chronic GvHD was significantly higher in TOCI compared to NO-TOCI (60.6 vs 23.8%, 95% CI: 19-86% and 8-44%, P=0.05 - Figure 1b). In conclusion, our results indicates that tocilizumab used for CRS management after in HaploHCT setting with PTCy-based GvHD prophylaxis was well tolerated and had no effect on survival outcomes. However, our study showed a trend towards delayed neutrophil engraftment and a statistically significant higher incidence of chronic GvHD in patients who received tocilizumab. It is possible that tocilizumab may interfere with T cell expansion, which could impact PTCy-mediated elimination of alloreactive T cell clones and/or affect regulatory T cells function; both mechanisms could lead to higher incidence of chronic GvHD. Using this approach to mitigate CRS risk should be reserved to patients with high grade CRS where mortality is high. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Cryopreservation Impairs Engraftment in Bone Marrow Transplantation

Introduction: Due to the covid-19 pandemic, a recommendation was made, especially for non-related allogeneic hematopoietic stem cell transplantation (allo-HSCT), to cryopreserve hematopoietic stem cells products and start the conditioning regimen only after the product be received at the receptor service. There are conflicting data on how the procedure of cryopreservation (and thaw) of bone marrow affects outcomes. In this study we evaluated the primary graft failure incidence using cryopreserved bone marrow grafts compared to non-cryopreserved bone marrow grafts. We also evaluated transfusion needs during the first 30 days after transplant and the occurrence of severe adverse events (AEs) related to the product infusion, during covid-19 pandemic in a single Brazilian center. Methods: From January 2020 to 30 June 2022, we retrospectively analyzed clinical and laboratory data from 9 cryopreserved (cryo) (all of them unrelated) and 15 non-cryopreserved (non-cryo) bone marrow grafts (2 of them unrelated), here defined as control group. Haploidentical transplants were excluded due to a higher risk of primary graft failure reported on this type of transplant. Children and adults with malignant and non-malignant disorders were included. We evaluated engraftment, red blood cells (RBC) and platelets (Pl) units transfused during the first 30 days, and adverse effects associated with product infusion. Neutrophil engraftment was defined as the first of 3 consecutive days with absolute neutrophil counts of ≥ 500/µL and primary graft failure was defined as failure to achieve a neutrophil engraftment by day 28 after bone marrow infusion. Results were given as median (range) and comparison between the groups was performed employing the Mann-Whitney U test. Percentages were compared with the chi-square or the Fisher exact test. Results: Only two cryopreserved grafts have not been used (one patient died before the start of the conditioning regimen and the other did not receive the graft yet). Baseline characteristics were similar in both groups. The median (range) age was 21 (1-37) and 20 (6-32) years, with 42.86% and 40% under 18 years of age in the cryo and non-cryo groups, respectively. Also, 85.7% and 53.3% were male, and 14.3% and 13.3% had malignant disease (acute leukemia) in the cryo and non-cryo groups, respectively (Table 1). The numbers of infused total nuclear and CD34+ cells/kg in the cryo and non-cryo groups were not significantly different (p= 0.14, and p= 0.41, respectively) (Table 1). Three (42.8%) patients from the cryo group, all of them children (with osteopetrosis, aplastic anemia, and acute leukemia) did not achieve neutrophil engraftment by day 28, whereas all 15 patients from non-cryo group had hematologic recovery (RR= 4.75, 95% CI: 1.61-11.75; p= 0.02). Furthermore, there was a slight tendency toward delayed neutrophil engraftment in the cryo group: 21.5 (19-23) and 19.0 (15-28) days (p= 0.20). The numbers of RBC and Pl units transfused during the first 30 days after product infusion were higher in the cryo than non-cryo group: RBC 5.0 (3-9) and 1.0 (0-4) (p< 0.0001); Pl 15.0 (7-18) and 5.0 (1-20) (p= 0.0014), respectively (Figure 1). Three patients (42.8%) had severe AEs (seizure, hypertension urgency associated with second-degree atrioventricular block: Mobitz type 1, and acute renal failure) during or right after bone marrow infusion, all of them in the cryo group (relative risk= 4.75, 95% CI: 1.61-8.43, p= 0.02). All of them recovered completely from AE. Conclusions: Transplantation of cryopreserved bone marrow grafts seems to be associated with a higher risk of primary engraftment failure and, consequently, a higher transfusion needs, and with more severe adverse events related to the product infusion. Because of these findings and in spite of the ongoing pandemic, we recommend a careful evaluation of the necessity to adopt this practice. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Long-Term Outcomes of Delayed Neutrophil Engraftment Following Autologous Hematopoietic Cell Transplant in Multiple Myeloma

Introduction: AHCT remains a standard of care in multiple myeloma (MM) patients especially in the frontline setting. Studies exploring the long-term effect of the time to neutrophil engraftment on survival post-AHCT in MM patients remains scarce. In addition, a better understanding of the implication of certain demographic, clinical and cytogenetic factors on the engraftment process is needed. Here, we studied patient and disease specific factors impacting the engraftment processes as well as its effect on survival in MM patients. Methods: The electronic medical records of all MM patients who underwent AHCT between 2011 and through 2020 at Cleveland clinic were reviewed. Patient specific characteristics that were analyzed included age at diagnosis, age at AHCT, sex, smoking history (current, ex- or never), time to transplant (<12 vs ≥12 months), albumin level at diagnosis (<3.5 g/dL or ≥3.5 g/dL), cytogenetic risk abnormalities (High risk: HR or Standard risk: SR), ECOG performance status (0, 1, 2, 3 or 4), International scoring system stage (I, II or III), pre-AHCT number of treatments (1 or ≥2), disease status pre-AHCT (PR: partial response; VGPR: very good partial response; CR: complete response), CD34+ dose used, and days to engraftment. Neutrophil engraftment was defined as an absolute neutrophil count (ANC) of 500/mm3 or more for three consecutive days. A cut-off 20 days was chosen and tested for long-term outcomes using Kaplan-Meier survival analysis, whereas chi-square and t-tests were followed by multivariate analysis to confirm factors that independently influence engraftment. Results: A total of 431 patients were included in our study, of whom cytogenetics and ISS were available in 346 and 352, respectively. Our cohort had a median age at AHCT of 61.3 years (range 33.1-77.8 years), male preponderance of 56.6%, median time to neutrophil engraftment of 12 days (range 9-61 days), and median follow up of 32.5 months (range 0.6-117.8 months). Applying Kaplan Meier survival analysis when dividing patients into early engraftment (<20 days, n=405) and delayed engraftment (≥20 days, n=26) groups yielded a remarkably significant difference in mOS post-AHCT (88.8 vs 33.2 months, P<0.0001) (Fig 1). This was consistent with 1-year and 3-year mortality rates of 38.46% (vs 14.22%, P=0.0031) and 88.46% (vs 52.45%, P=0.0003) for the ≥20 as opposed to the <20 days to engraftment groups, respectively. Subgroup analysis further emphasized the lower survival in the ≥20 days vs <20 days in the setting of non-relapse (medians unreached, P=0.0096) as well as relapsed disease (mOS 25.4 vs 77.2 months, P<0.0001), respectively. A lower, albeit non-significant, median progression free survival (mPFS) was also seen in the ≥20 days engraftment group (36.8 vs 46.6 months, P=0.5). Looking into factors that may affect time to engraftment, delayed engraftment (≥20 days) was associated with female sex (73 vs 41%, P<0.0001), ISS stage III (31.6 vs 22% P<0.0001), HR cytogenetics (44.4 vs 29.5%, P<0.0001), and IgA MM (52.4 vs 22.2%, P<0.0001) compared to early engraftment (<20 days). No difference was seen with regards to age at AHCT (median 61.6 vs 60.7 years, P=0.5), history of smoking (23 vs 38.3%, P=0.3), ECOG performance status pre-AHCT (P=0.2), albumin levels at diagnosis (<3.5 g/dL in 25 vs 26.6%, P=0.9), disease status pre-AHCT (PR 42.3 vs 40.2%, VGPR 34.6 vs 33.8%, CR 23.1 vs 26% P=0.9), mobilization regimen (G-CSF + Plerixafor in 92.3 vs 90.6%, P=0.9), time to transplant of ≥ 12 months (34.6 vs 29%, P=0.5), recent immunomodulatory drugs use (69.2 vs 66.9%, P=0.9), pre-AHCT lines of treatment (≥ 2 in 42.3 vs 35.8%, P=0.6). Delayed engraftment was associated with a lower, though not statistically significant, median CD34+ dose (4.7 vs 5.2 x106, P=0.08). Multivariate analysis further confirmed the association of HR cytogenetics with delayed engraftment (HR 5.2, 1.2-27.8 95% CI). Conclusion: Early engraftment, defined as in less than 20 days, confers better overall survival rates post-AHCT, including among both relapsed and non-relapsed patients. Time to engraftment is mainly associated with patients' cytogenetic risk categorization. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Post-Transplantation Cyclophosphamide Versus Tacrolimus and Methotrexate Graft-Versus-Host Disease Prophylaxis for HLA-Matched Donor Transplantation

The use of post-transplantation cyclophosphamide (PTCy) for graft-versus-host disease (GVHD) prophylaxis is increasing in patients undergoing HLA-matched sibling (MSD) or unrelated (MUD) donor hematopoietic cell transplantation (HCT), but data about its comparative efficacy against the traditional GVHD prophylaxis are scarce. Two broad questions assessed in this study were (a) comparison of PTCy-based GVHD prophylaxis versus Tac/MTX (without ATG) in the MSD and (b) comparison of PTCy-based GVHD prophylaxis versus Tac/MTX (with ATG) in the MUD group. This retrospective single-center study analyzed the outcomes of 964 patients who received Tac/MTX (n=578) versus PTCy-based (n=386) GVHD prophylaxis. All MUD recipients in the Tac/MTX group also received ATG; thus separate analyses were conducted for MSD (n=412) and MUD (n=552) cohorts. In the MUD cohort, 306 patients received Tac/MTX/ATG and 246 received PTCy-based GVHD prophylaxis. In the MSD cohort, 272 received Tac/MTX and 140 received PTCy-based prophylaxis. Both PTCy groups included somewhat older patients than the Tac/MTX groups and more patients had myeloid malignancy (85%-90% versus 59%-64%, respectively). A majority of patients in all groups received myeloablative conditioning and peripheral blood graft. Both PTCy groups had a significantly delayed neutrophil engraftment, higher risk of hemorrhagic cystitis, and higher risk of bacterial infections than the Tac/MTX groups. The risks of viral infections and related deaths were significantly higher in Tac/MTX group in the MUD cohort. In multivariate analysis, the risk of grade III-IV acute GVHD was similar in PTCy and Tac/MTX groups in both MSD and MUD cohorts, but the risk of chronic GVHD was significantly lower with PTCy in the MSD cohort. PTCy was associated with a significantly lower risk of non-relapse mortality and better progression-free survival in the MUD. PTCy was associated with improved GVHD-free relapse-free survival in both MSD and MUD groups. Our data suggest a benefit of using PTCy-based GVHD prophylaxis in both MSD (versus Tac/MTX) and MUD (versus Tac/MTX/ATG) HCT.

Effect of Cryopreservation in Unrelated Bone Marrow and Peripheral Blood Stem Cell Transplantation in the Era of the COVID-19 Pandemic: An Update from the Japan Marrow Donor Program

During the COVID-19 pandemic, donor grafts are frequently cryopreserved to ensure that a graft is available before starting a conditioning regimen. However, there have been conflicting reports on the effect of cryopreservation on transplantation outcomes. Also, the impact of cryopreservation may differ in bone marrow (BM) transplantation (BMT) and peripheral blood stem cell (PBSC) transplantation (PBSCT). In this retrospective study, we analyzed the clinical data of both cryopreserved unrelated BMTs (n = 235) and PBSCTs (n = 118) and compared these with data from a large control cohort without cryopreservation including 4133 BMTs and 720 PBSCTs. Among the patients with cryopreserved grafts, 10 BMT recipients (4.3%) and 3 PBSCT recipients (2.5%) did not achieve neutrophil engraftment after transplantation, including 4 of the former and all 3 of the latter who died early before engraftment. In a multivariate analysis, cryopreservation was not associated with neutrophil engraftment in BMT but significantly delayed neutrophil engraftment in PBSCT (hazard ratio [HR], .82; 95% confidence interval [CI], .69 to .97; P = .023). There was an interaction with borderline significance between cryopreservation and the stem cell source (P = .067). Platelet engraftment was delayed by cryopreservation after both BMT and PBSCT. Only 2 cryopreserved grafts (<1%) were unused during the study period. The cryopreservation of unrelated donor BM and PBSC grafts is associated with a slight delay in neutrophil and platelet engraftment but an acceptable rate of graft failure. PBSC grafts may be more sensitive to cryopreservation than BM grafts. Cryopreservation is a reasonable option during COVID-19 pandemic, provided that the apheresis and transplantation centers are adept at cryopreservation.© 2022 American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc.

Effect of Daratumumab-Containing Induction on CD34+ Hematopoietic Stem Cells before Autologous Stem Cell Transplantation in Multiple Myeloma

Introduction:Daratumumab (Dara) is an anti-CD38 monoclonal antibody representing a novel treatment agent for multiple myeloma (MM). Nonetheless, several studies have reported a Dara-related impairment of CD34+ hematopoietic stem cell (HSC) mobilization and post-autologous stem cell transplantation (ASCT) complications, including low yields of mobilized HSCs and delayed neutrophil engraftment. Impact of Dara on the mobilization process and HSCs remains poorly understood even though sufficient yields of CD34+ cells are necessary for a successful ASCT and subsequent patient recovery.Aims:To compare the effect of the Dara-containing (Dara-Bortezomib-Dexamethasone [D-VCd]) and conventional (Bortezomib-Thalidomide-Dexamethasone [VTd]) therapy on CD34+ HSCs.Methods:Transplant eligible MM patients were treated with D-VCd or VTd induction regimen followed by a cyclophosphamide + G-CSF mobilization and a high-dose melphalan D -1 before ASCT. Flow cytometry (FCM) screening of CD34+ subsets was performed in the bone marrow (BM) or apheresis product (AP) at three consecutive time points: 1) diagnostic BM (DG), 2) mobilization AP (MOB), 3) a day prior ASCT BM (D-1). Furthermore, RNA sequencing (RNAseq) of sorted CD34+ cells was performed on total RNA with ribo-depletion protocol in AP after the induction. D-VCd samples had lower RNA yields thus the D-VCd or VTd groups were processed as independent batches.Results:Clinical data revealed no significant differences in mobilization (p >0.050) likely due to a small cohort sizes (D-VCd n=5 vs VTd n=9), though a trend towards worse performance in D-VCd was observed. Median CD34+ cell yield was 3.08 vs 10.56 x 10 6/kg. Platelet recovery of >20x10 9/L was D+14 vs D+12 (range: 11-18 vs 10-16). Neutrophil recovery of >0.5x10 9/L was D+12 in both groups (range: 11-17 vs 11-12).In FCM analysis, DG (n=14), MOB D-VCd (n=5) vs VTd (n=9), D-1 D-VCd (n=7) vs VTd (n=15) were compared. CD34+ frequency (Fig. 1A) difference in MOB D-VCd vs VTd was insignificant (median: 1.15% vs 1.89%), whereas CD34+ fraction dropped in D-1 D-VCd (median: 0.52% vs 0.72%, p=0.027), albeit there was no significant reduction in D-1 D-VCd vs initial DG (median: 0.52% vs 0.45%). Differences in the distribution of certain HSC subsets were detected in the CD34+ pool (Fig. 1B-E). Frequency of multipotent progenitors (MPPs) (Fig. 1B) was increased in MOB D-VCd (median: 82.1% vs 66.2%, p=0.004). Frequency of lympho-myeloid-primed progenitor + granulocyte-monocyte progenitor (LMPP+GMP) (Fig. 1C) subset was reduced in D-VCd in both MOB (median: 1.7% vs 16.9%, p=0.042) and D-1 (median: 5.3% vs 14.0%; p=0.026). Erythro-myeloid progenitors (EMPs) (Fig. 1D) were reduced in MOB D-VCd (median: 10.7% vs 19.5%, p=0.042), while the frequency of EMPs increased in D-1 D-VCd (median: 20.8% vs 12.4%, p=0.045). No considerable differences were found in the expression of adhesion molecules CD44/HCAM or CD184/CXCR4. CD38 was strongly diminished in the whole D-VCd CD34+ fraction of MOB and D-1.To understand whether the differences in the mobilization efficacy after D-VCd induction were reflected in the expression profile of mobilized CD34+ cells, differential expression analysis was performed. Overall 133 significantly deregulated genes (p<0.05; log fold change >(-)1) between cohorts (D-VCd n=5 vs VTd n=5) were revealed (Fig. 2). Pathway analysis showed cellular response and localization as the most deregulated categories. The list of deregulated genes contained 25% of non-coding RNAs, some of which were linked to a protein localization in the cell (RN7SL1/2). The expression of adhesion molecules was inspected independently. Out of 59 HSC hallmark genes, only 8 were significantly altered in D-VCd. Interestingly, the main homing molecule CXCR4 seemed to be downregulated in D-VCd, while integrins A3 and B4 were upregulated.Conclusions:Despite the limited cohort sizes, a prospective trend of delayed neutrophil and platelet recovery was observed after D-VCd therapy. FCM analysis revealed a significant reduction of CD34+ subsets responsible, among others, for a reconstitution of neutrophils and megakaryocytes. A strong signal in transcriptome data which would potentially explain differential mobilization in D-VCd cohort was not detected, nevertheless, several genes with adhesive/homing and stem cell differentiation function were indeed altered. The results warrant further investigation. [Display omitted] DisclosuresHajek: BMS: Consultancy, Honoraria, Research Funding; AbbVie: Consultancy, Honoraria; Novartis: Consultancy, Research Funding; Janssen: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharma MAR: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Research Funding; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding.

Risk Factors and Outcomes of ICU Admission Following Allogeneic Hematopoietic Stem Cell Transplantation

Background: Patients undergoing allogeneic hematopoietic stem cell transplantation (allo-hsct) can develop complications such as life-threatening infections, multi-system organ failure, ICU admission and ventilator support in the immediate post-transplant period. Whereas outcomes of these complications, particularly ICU admission and ventilator support, are known to be poor, little is known about the risk factors leading to them.Methods: We conducted a retrospective study to analyze the impact of pre-transplant risk factors on acute inpatient complications, focusing on ICU admission, ventilator support and multi-system organ failure, following allo-hsct at the University of Alabama at Birmingham (UAB) between 2008 and 2016. Mortality rates and survival outcomes of patients admitted to the ICU were also analyzed. Pre-transplant individual comorbidities were defined as per Sorror's HCT-CI.Results: There were 304 patients included with a median age of 52y (18-72y). There were 51% male and 82% Non-Hispanic white patients. The most common indication for transplant was AML (45%). Donor type was matched-unrelated, haploidentical and matched-related in 53%, 35% and 12% of cases, respectively. Majority of the patients received myeloablative conditioning (74%). The prevalence of health behaviors and comorbidities at the time of transplant is shown in Table 1. There were 39% patients with HCT-CI score of ≥3, 23% with moderate pulmonary compromise, 22% with a psychiatric disorder, 13% with severe pulmonary compromise, 13% with diabetes mellitus (DM), 10% with cardiac abnormalities and 6% with infection at the time of transplant.During the initial hospitalization, 33 (11%) patients required ICU admission, 29 (10%) required ventilator support, 33 (11%) developed multi-system organ failure, 79 (26%) developed bacterial infections and 15 (5%) developed fungal infections. The median time to neutrophil engraftment was 13 days (7-48 days).In multivariable analysis (Table 2), risk factors for ICU admission included pre-transplant infection (HR 6.50, 95% CI 1.82-23.26, p=0.004), pre-transplant DM (HR 4.14, 95% CI 1.56-10.97, p=0.004), time to neutrophil engraftment (HR 1.13, 95% CI 1.05-1.21, p=0.0007), donor type (ref: matched related donor; haplo: HR 0.24 95% CI 0.07-0.82, p=0.02) and HSCT era (ref: 2008-2010; 2010-2013: HR 0.18 95% CI 0.04-0.88, p=0.03; 2014-2016: HR 0.12 95% CI 0.03-0.4, p=0.0006). Risk factors for ventilator support included pre-transplant infection (HR 10.09, 95% CI 2.44-41.64, p=0.001), pre-transplant DM (HR 3.61, 95% CI 1.31-9.91, p=0.01), time to neutrophil engraftment (HR 1.17, 95% CI 1.11-1.23, p<0.0001) and HSCT era (ref: 2008-2010; 2010-2013: HR 0.21 95% CI 0.06-0.81, p=0.02; 2014-2016: HR 0.07 95% CI 0.02-0.31, p=0.0005). Risk factors for multi-system organ failure included pre-transplant DM (HR 4.38, 95% CI 1.64-11.74, p=0.003), time to neutrophil engraftment (HR 1.13, 95% CI 1.08-1.19, p<0.0001) and HSCT era (ref: 2008-2010; 2010-2013: HR 0.21 95% CI 0.05-0.80, p=0.003; 2014-2016: HR 0.16 95% CI 0.05-0.48, p=0.001).Risk factor for bacterial infection included HSCT era (ref: 2008-2010; 2010-2013: HR 0.30 95% CI 0.14-0.65, p=0.002; 2014-2016: HR 0.24 95% CI 0.12-0.49, p<0.0001) and for fungal infection included pre-transplant pulmonary compromise (ref: no compromise; severe pulmonary compromise HR 5.16, 95% CI 1.05-25.4, p=0.04). For patients admitted to the ICU, the 60-day and 6-month mortality was 58% and 67%, respectively. No deaths were attributed to relapse disease. The median overall survival for patients admitted to the ICU was 1.4 months (Figure 1).Conclusion: Patients with DM and infection at the time of HSCT and delayed neutrophil engraftment during transplant are at an increased risk for ICU admission, ventilator support and multi-system organ failure following allo-hsct. Patients admitted to the ICU are also at a high risk for early mortality leading to poor survival. Optimizing glycemic control and delaying transplant until resolution of infection, if the underlying disease would allow, may help improve both morbidity and mortality in transplant recipients. [Display omitted] DisclosuresDi Stasi: Syndax Pharmaceutical: Honoraria, Membership on an entity's Board of Directors or advisory committees; University of Alabama at Birmingham: Current Employment.

Transfusion- Related Iron Overload (TRIO) Is Associated with Delayed Engraftment and Increased Non Relapse Mortality (NRM) in Patients Undergoing Umbilical Cord Blood (UCB) Hematopoietic Cell Transplantation (HCT)

▪TRIO has been shown to be associate with higher risk of morbidity (infections, venocclusive disease and hepatic dysfunction) and mortality after allogeneic HCT. A high transplant iron score (>25 red cell unit transfused prior to HCT, serum ferritin > 1000 ng/ml and a bone marrow (BM) iron stain of +6) was associated with 50% decrease in survival at one year (Storey J. Hem & Oncol 2009). TRIO in BM macrophages can generate free radicals resulting in oxidant stress thereby altering the hematopoietic microenvironment. This could have adverse effects on hematopoiesis and affect engraftment after HCT. To date, limited data are available on the effect of TRIO on outcomes of UCB HCT. We examined whether TRIO quantified based on serum ferritin (sF) and BM iron score (MIS) impact outcomes of UCB HCT, particularly with regards to engraftment.We reviewed 150 consecutive patients (pts) who underwent UCB HCT between March 2006 and September 2015 at City of Hope. Median age at time of HCT was 33.5 years (yrs) (range: 0-70 years) with 55% male and 23% < 18 yrs of age. sF was available within 30 days before HCT for 65%, and MIS was assessed on the pre-HCT BM biopsy for 40% of pts. HCT indications included bone marrow failure (n=13), hemoglobinopathies (n=2), lymphoma (n=23), acute leukemia (n=104), and chronic leukemia (n=8). Disease risk index (DRI) was high/very-high in 38% and 20% of pts had HCT comorbidity index of more than 2. One cord graft was received for 20% of pts. Median TNC of 4.9X10^7/kg (range: 1.8-26.6) and median CD34 count of 1.8X10^5/kg (range: 0.2-122.4). HLA match status was 4/6, 5/6, 6/6 in 93, 48, and 9 pts. Almost 60% of pts received myeloablative conditioning regimen (MAC) and 80% had calcineurin inhibitor/mycophenolate mofetil for graft versus host disease (GVHD) prophylaxis.With a median follow-up of 48.1 months (range: 5.8- 119.6), 2- and 5-yrs progression free survival (PFS) were 41% and 35.5% while 2- and 5-yrs OS were 47% and 36%, respectively. Cumulative incidence (CI) of NRM at 2 and 5 yrs were 35.7 and 40.6% and CI of relapse at 2- and 5-yrs were 23 and 24%, respectively. Day 100 grade II-IV and grade III/IV aGvHD were 56.7% and 28.7%. 2 yrs CI of cGvHD was 51.7% with 38.8% extensive cGvHD. DRI was found to be significant factor for relapse (HR 1.74 95%CI 0.88-3.45 p<0.001) and conditioning regimen significantly affect OS (HR= 1.92 95%CI 1.24-2.96; p=0.003), PFS (HR= 2.12 CI 1.39-3.24; p<0.001) and relapse rate (HR= 4.07 CI 1.95-8.49; p<0.001) when non-myeloablative/reduced intensity conditioning was compared with MAC. However, day 100 grade II-IV and III/IV aGVHD was increased in pts with MAC (65.1% vs 45.3%; p=0.006 and 37.2% vs 17.2%; p=0.005; respectively) with no significant effect seen on the NRM (p=0.9).In multivariable analysis, sF <1000 ng/ml independently predicted for shorter OS (HR=0.49; CI 0.27-0.88 p=0.015). When the impact of sF was examined by quartiles, pts in the highest sF quartile (>1948 ng/ml) had shorter OS (HR=3.05, 95%CI: 1.40-6.66; p=0.03) and higher NRM (HR=2.79, 95%CI: 1.16-6.72; p=0.03) compared to those in the lowest quartile (<530 ng/ml) (Fig 1a and b). There was no statistically significant difference in regards to disease relapse, or incidence of acute or chronic GVHD across sF groups.Patients in the highest sF quartile had delayed platelet engraftment compared to those in the lowest quartile (HR=0.46, 95%CI: 0.24-0.89, p=0.03). A trend towards delayed neutrophil engraftment was also observed between these 2 groups (HR=0.57, 95%CI: 0.33-0.99; p=0.055) (Fig 1c and d). No significant difference was seen in neutrophil (p=0.67) or platelet engraftment (p=0.92) based on MIS. But there was a statistically significant increase of grade II-IV aGVHD in pts with MIS of 3-4 (63.8% vs 30.8% at day 100; p=0.04). This however did not translate into worse OS, NRM or relapse.In conclusion, TRIO measured by sF has an adverse impact on OS and NRM in recipients of UCB HCT. Elevated sF is also associated with delay in platelet and neutrophil engraftment after UCB HCT. MIS was not associated with time to engraftment, however, this value was available in only 40% of pts. Therefore, TRIO should be considered as a risk factor for adverse outcome and poor graft function after UCB HCT. [Display omitted] DisclosuresNademanee:seattle Genetics: Speakers Bureau.

Intestinal Microbiota Play a Critical Role in Neutrophil Engraftment Posttransplant and Recovery after Chemotherapy By Stimulating T Cell Production of IL-17A

Introduction: Delay in recovery or engraftment of neutrophils is a risk for infection and associated with poor prognosis after cancer chemotherapy or hematopoietic stem cell transplantation (SCT). Recent studies demonstrate that intestinal microbiota plays a critical role in the development of bone marrow (BM) granulopoiesis in infants after birth (Deshmukh, et al. Nat Med 2014). Here, we addressed the impact of microbiota on neutrophil recovery after chemotherapy and engraftment after syngeneic SCT.Method: Wild type (WT) or RAG1-/- B6 mice were given a combination of ampicillin 1g/L, streptomycin 1g/L, and vancomycin 1g/L in drinking water daily from day -7 or left untreated.Recipient WT, RAG1-/-, or IL-17A-/- B6 mice were lethally irradiated and transplanted with 7,500 purified lineage-sca-1+c-kit+ cells plus 20,000 granulocyte-macrophage progenitors (GMPs) purified from congenic B6-CD45.1 mice on day 0. For in vivo T cell depletion, mice were i.p. injected with 200 μg of anti-CD90 monoclonal antibodies (αCD90) thrice a week from day -7. To assess reactive granulopoiesis after chemotherapy, B6 mice were i.p. injected with 5-fluorouracil (5-FU) at a dose of 200 mg/kg.Results: To address if gut microbiota could play a role in neutrophil engraftment, gut decontamination using the antibiotics was performed from day -7 of SCT. We found that gut decontamination significantly delayed engraftment of neutrophils, suggesting that microbiota promotes neutrophil engraftment after SCT (Figure A). Plasma levels of G-CSF and a G-CSF-inducing cytokine, IL-17A were significantly elevated 14 days after SCT, while the antibiotics completely abrogated upregulation of these cytokines. IL-17A expression in host αβ and γδ T cells was significantly suppressed by the antibiotic treatment after SCT, suggesting that microbiota stimulates host T cells to produce IL-17A after SCT. Next, we studied the role of IL-17A in neutrophil engraftment using IL-17A-/- mice as recipients. IL-17A deficiency phenocopied the antibiotic treatment, with lower plasma levels of G-CSF and delayed neutrophil engraftment compared to WT recipients. When recipients were devoid of host T cells by administration of αCD90 mAbs or by using RAG1-/- mice as recipients, plasma levels of both IL-17A and G-CSF were significantly decreased, suggesting a critical role of host T cells in IL-17A secretion in response to microbiota (Figure B and data not shown). Neutrophil engraftment was delayed in RAG 1 -/- mice, while gut decontamination did not impact on neutrophil engraftment in RAG 1 -/- recipients, ruling out direct toxicity of the antibiotics on engraftment and further emphasizing a critical role of host T cells in granulopoiesis after SCT. Flow cytometric analysis demonstrated that the numbers of GMPs in the BM of IL17A-/- recipients were significantly less than those in WT controls, suggesting that IL-17A promoted granulopoiesis in the BM. Emergence of BrdU+ neutrophils in the peripheral blood after BrdU injection on day +18 after SCT was delayed in IL17A-/- recipients compare to WT controls, indicating that IL-17A not only stimulates granulopoiesis but also facilitates neutrophil egress from the BM to peripheral blood (Figure C). Finally, we found that neutrophil recovery after chemotherapy with 5-FU was delayed in the antibiotic-treated mice or IL-17A-/- mice, suggesting that neutrophil recovery after chemotherapy was also dependent on IL-17A secretion in response to microbiota (Figure D). Plasma levels of IL-17A and T-cell IL-17A expression were significantly lower in naïve MyD88-/- mice than those in WT mice, suggesting that IL-17A production in T cells were dependent on MyD88 signaling.Conclusion: Our study uncovers a novel role of gut microbiota in neutrophil engraftment after SCT and neutrophil recovery after chemotherapy; gut microbiota enhances granulopoiesis and neutrophil egress from the BM by stimulating T cells to produce IL-17A.Figure: (A) Gut decontamination with antibiotics delayed neutrophil engraftment after SCT. (B) T cells were responsible to IL-17 production after SCT. (C) Neutrophil egress from BM was impaired in IL17A-/- recipients. (D) IL-17 played a critical role in reactive granulopoiesis after chemotherapy. [Display omitted] DisclosuresTeshima:Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astellas: Research Funding; Kyowa-Hakko Kirin: Research Funding; Pfeizer: Research Funding; Chugai: Research Funding; Bristol-Myers Squibb: Research Funding; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding.

Successful mismatched hematopoietic stem cell transplantation for pediatric hemoglobinopathy by using ATG and post-transplant cyclophosphamide.

The use of HLA-mismatched (un)related donors is historically associated with a higher incidence of transplant-related complications and mortality. However, the use of such donors may overcome the limited availability of HLA-matched donors for patients with β-thalassemia major (TM) and sickle cell disease (SCD). We investigated hematopoietic stem cell transplantation (HSCT) outcomes of pediatric TM and SCD patients treated with a mismatched donor using a treosulfan-based conditioning in combination with ATG and post-transplant cyclophosphamide (PT-CY) and compared these results to the clinical outcome of patients treated by matched donor HSCT without PT-CY. Thirty-eight children (n = 24 HLA-identical or 10/10-matched donors; n = 14 HLA-mismatched donors), who received a non-depleted bone marrow graft were included. Event-free survival (EFS) and GvHD were not higher in the mismatched PT-Cy group as compared to the matched group. Moreover, despite delayed neutrophil engraftment (day +22 vs. +26, p = 0.002) and immune recovery in the mismatched PT-Cy group, this did not result in more infectious complications. Therefore, we conclude that in the absence of an HLA-identical or a matched unrelated donor, HSCT with a mismatched unrelated or haploidentical donor in combination with ATG plus PT-CY can be considered a safe and effective treatment option for pediatric hemoglobinopathy patients.

Influence of laboratory procedures on postthawing cell viability and hematopoietic engraftment after autologous peripheral blood stem cell transplantation.

The kinetics of hematopoietic recovery after autologous stem cell transplantation (ASCT) may be affected by laboratory procedures. The aim of this study was to evaluate the influence of characteristics of the cryopreserved units of peripheral blood stem cells (PBSC) on postthawing cell viability and engraftment outcomes after ASCT. This was a retrospective cohort study including individuals referred for ASCT. Cryopreservation was conducted at a single processing facility between 2014 and 2019, and patients received clinical care at six transplant centers. Covariates and outcome data were retrieved from participants' records. The study population comprised 619 patients (345 [55.7%] male). Median age was 53 years. Multiple myeloma was the most common diagnosis (62.7%). Higher preapheresis CD34+ cell count, lower nucleated cell (NC) concentration per cryobag, and composition of the cryoprotectant solution (5% dimethyl sulfoxide [DMSO] and 6% hydroxyethyl starch) were statistically significantly associated with higher postthawing cell viability. The linear regression model for time to neutrophil and platelet engraftment included the infused CD34+ cell dose and the composition of the cryoprotectant solution. Patients who had PBSC cryopreserved using 10% DMSO solution presented six times higher odds (odds ratio [OR] = 6.9; 95% confidence interval [CI]: 2.2-21.1; p = .001) of delayed neutrophil engraftment (>14 days) and two times higher odds (OR = 2.3, 95%CI: 1.4-3.7; p = .001) of prolonged hospitalization (>18 days). The study showed that mobilization efficacy, NC concentration, and the composition of the cryoprotectant solution significantly affected postthawing cell viability. In addition, the composition of the cryoprotectant solution significantly impacted engraftment outcomes and time of hospitalization after ASCT.