Absolute Neutrophil Count Recovery Research Articles

Time of Attainment of Clinical Remission and Peripheral Blood Count Recovery during Induction Chemotherapy for Childhood Acute Lymphoblastic Leukemia

Background: Acute lymphoblastic leukemia(ALL) is the most common pediatric malignancy. Infection and bleeding are the leading cause of death during induction chemotherapy in childhood ALL. So, proper knowledge about anticipated infection and bleeding are very important during this period. But the duration of clinical remission and recovery of peripheral blood count during induction chemotherapy is not well reported in literature. Objective: The aim of the study was to determine the time of attainment of clinical remission and recovery of peripheral blood count after initiation of induction chemotherapy and to determine if the duration of clinical remission and peripheral blood count recovery differs between therapeutic risk groups. Methods: This prospective observational study was conducted from January 2021 to December 2021 in the Department of Paediatric Haematology and Oncology, BSMMU. Newly diagnosed admitted Eighty-Six ALL of both sexes aged 1 to 17.9 years were included. After commencing chemotherapy, physical examination was recorded every day until clinical remission and complete blood count (CBC) was recorded one to two days interval until peripheral blood count recovery. The number of packed red blood cell (PRBC) and platelet transfusions and the number of days of intravenous antibiotics were recorded. Results: Mean duration of clinical remission, complete Hemoglobin (Hb), Absolute neutrophil count(ANC) and platelet recovery was 8.4 ± 4.5 days, 25±7.9 days, 23.3±5.6 days and 21.8±6.4 days respectively (p<0.01). Time to attain partial recovery of platelet was 14.0±4.9 days in high risk and 19.2±5.3 days in standard risk group. PRBC transfusion requirement was 2.2±1.2 units in high risk group and 1.7±0.8 units in standard risk group (p<0.05). Time to attain partial recovery of ANC, number of days with I/V antibiotics and duration of treatment interruption were higher in high risk group. Conclusion: Time of clinical remission was similar between risk group. Platelet recovery occurred earlier than Hemoglobin (Hb) and absolute neutrophil count (ANC) recovery. Transfusion and supportive care requirement were more in high risk group during induction chemotherapy. So, more supportive care should be arranged up to three weeks of induction period to increase survival of high risk childhood ALL. Bangladesh Med Res Counc Bull 2023; 49: 177-182

Clonal Hematopoiesis Is Associated with Severe Cytokine Release Syndrome in Patients Treated with Chimeric Antigen Receptor T-Cell (CAR-T) Therapy

Background: Among patients receiving CD19 or B-cell maturation antigen (BCMA) CAR-T therapy, inflammation pre- and post-CAR-T infusion is attributed in the development of toxicities such as cytokine release syndrome (CRS), immune effector cell-associated neurotoxicity syndrome (ICANS), and prolonged cytopenias. Clonal hematopoiesis (CH), the clonal expansion of hematopoietic stem cells with somatic mutations, has been associated with inflammatory disorders such as rheumatoid arthritis and graft-versus-host disease, as well as clonal cytopenias of undetermined significance. In the setting of CAR-T, others have reported an association between CH and both ICANS and treatment-associated myeloid neoplasms. Herein, we examined the prevalence of pre-CAR-T CH in a predominantly transplant-naïve cohort of recipients with non-Hodgkin lymphoma (NHL) or multiple myeloma (MM), and assessed the relationship between CH and CAR-T related outcomes including CRS, ICANS, prolonged cytopenia, progression-free survival (PFS), and overall survival (OS). Methods: This study included 62 patients with NHL or MM who underwent CD19 or BCMA CAR-T therapy from 2017 to 2022 at City of Hope and had available pre-CAR-T cryopreserved peripheral blood mononuclear cells (PBMCs). DNA was isolated with QIAamp DNA Mini Kit (Qiagen) from PBMC samples (94% collected <30d of CAR-T infusion), on which we performed targeted exome sequencing (108 pre-defined gene panel with 1000x sequencing depth) to determine the presence of CH (variant allele frequency [VAF] ≥2%). Multivariable logistic regression was used to examine the association between CH (Yes/No) and absolute neutrophil count (ANC) recovery at day +60 (Y/N), maximum grade CRS and ICANS, grade <2 vs 2+, and OS and PFS at 1y. Covariables considered were age at CAR-T, baseline ANC, sex, race, CAR-HEMATOTOX (Rejeski et al. 2021), bridging therapy (Y/N), and number of prior lines of therapy. ANC recovery was defined as grade 2 or better for 3 measurements without growth factor support >2 weeks. Those without ANC recovery and who started new treatment before day +60 were excluded from that analysis. Results: Overall, the median age was 64y (range 21y-85y); 37 (60%) had de novo diffuse large B-cell lymphoma, 17 (27%) had transformed follicular lymphoma, 2 (3%) had MM, 2 (3%) had mantle cell lymphoma, and the remaining patients had other transformed indolent lymphomas. Median prior lines of therapy was 3 (1-12), and only 6% had previously undergone autologous hematopoietic cell transplantation. Systemic bridging therapy prior to CAR-T was required in 27 (44%), and 8 (13%) received radiation as bridging. All received fludarabine and cyclophosphamide for lymphodepleting chemotherapy. Axicabtagene ciloleucel was the most common (76%) CAR-T product, followed by tisagenlecleucel in 16% of patients. Overall, 51 (82%) and 29 (47%) patients experienced CRS and ICANS, respectively. had delayed ANC recovery. One-year PFS was 50% and 1y OS was 73%. Clonal hematopoiesis: 15 (24%) patients had at least one pathogenic CH mutation; 4 (6.5%) had ≥2 CH mutations. Of the 28 CH mutations identified, the most common were DNMT3A (18%), CHEK2 (11%), PMS2 (7%) and ASXL1 (7%); 29% of mutations had VAFs >10%. Outcomes after CAR-T: Patients with CH were significantly more likely to develop grade ≥2 CRS (60% vs. 28%, p=0.03) compared to those without CH (odds ratio [OR] 3.9, 95% CI 1.2-13.2; p=0.027). Accounting for baseline ANC (which was unexpectedly higher among the CH cohort and associated with delayed ANC recovery, p=0.02) patients with CH did not have a significantly different rate of delayed ANC recovery compared to those without CH (adjusted OR 0.37, 95% CI 0.09-1.5; p=0.17). There was no association between CH and ICANS, nor with 1y PFS and OS. Conclusion: CH was frequent (24%) in this cohort of CAR-T recipients and was associated with a higher risk of ≥2 CRS after CAR-T. Additional validation studies are currently underway, which may set the stage for consideration of pre-CAR-T CH as a biomarker for risk stratification towards more proactive CRS prophylaxis Acknowledgements: Funding through the CoH Hematological Malignancies Program Pilot Project Award. The authors acknowledge the work provided by CoH Center for Informatics, notably Research Informatics, and the utilization of the POSEIDON platform and the Honest Broker process.

Long-Term Efficacy and Immune Reconstitution with Bendamustine As a Lymphodepleting Agent for Axicabtagene Ciloleucel (Axi-Cel) in Patients with Refractory or Relapsed Large B-Cell Lymphoma (LBCL)

Introduction: Lymphodepletion (LD) is crucial for the expansion and persistence of CAR T cells. Fludarabine in combination with cyclophosphamide (FC) is the LD standard regimen. A national fludarabine shortage in 2022 necessitated the exploration of alternative LD regimens. Bendamustine (benda) is a purine analog and an alkylating chemotherapy that has been used as an LD agent for tisagenlecleucel (Ghilardi et al.,2022). However, there is no data for benda LD in other commonly used CART products for relapsed or refractory non-hodgkin lymphoma (rel/ref NHL). Early safety, efficacy, and expansion kinetics data were presented previously (Bharadwaj, ASH 2022). We are now reporting long-term efficacy and immune reconstitution data. Methods: 84 consecutive patients with relapsed/refractory LBCL treated with axi-cel were included in this single-institution study. 27 patients who received Bendamustine lymphodepletion (90mg/m2 on days -4 and -3) were compared to a preceding 57-patient FC cohort. Response, survival, and cytopenia data were collected closest to the 12-month time point for all patients who had not progressed. Response was assessed using the Lugano 2014 criteria, while toxicities were evaluated using the CTCAE version 5.0 and the ASTCT grading. To reduce the influence of confounding variables in this study, a covariate balance propensity score weighting approach (IPTW) was implemented. Covariates included age, sex, presence of bridging therapy, IPI score at apheresis, number of prior therapy lines, absolute lymphocyte count at leukapheresis, prior auto SCT, and pre-lymphodepletion LDH, ALC, ANC, and platelet count. Continuous outcomes were compared using the Mann-Whitney U test, categorical outcomes using chi-square tests, and time-to-event outcomes using a log-rank test weighted in the IPTW sample. Statistical significance was considered when p < 0.05. All analyses were conducted in R 4.3.0. Results: There was no significant difference in the best complete response (CR) rate and best overall response rate (ORR) between the two groups, with a CR rate of 71.9% for FC and 74% for bendamustine (p = 0.182), and an ORR of 89.4% for FC and 85.1% for bendamustine (p = 0.502). For the FC group, 9-month progression-free survival (PFS) and overall survival (OS) were 63.16% (95% CI: 49.29% to 74.19%) and 78.95% (95% CI: 65.92% to 87.45%), respectively with a median follow-up of 15.5 months (IQR: 13.6, 16.8). 9-month PFS and OS point-estimates for the bendamustine group were 70.37% (95% CI: 49.4% to 83.94%) and 77.41% (95% CI: 56.41% to 89.18%), respectively, with a median follow-up of 9.5 months (IQR: 8.6, 9.8). No significant difference was found between groups in either 9 months PFS ( P=0.055) or 9 months OS ( P=0.6290). Median PFS and OS have not been achieved for either group [Figure 1]. Bendamustine was effective in achieving severe lymphodepletion, with a median absolute lymphocyte count (ALC) nadir of 0.11 K/ul (IQR: 0.04, 0.17) occurring within one day after axi-cel infusion. In comparison, the FC group had a lower median ALC nadir of 0.03 K/ul (IQR: 0.01, 0.06) occurring on the day of axi-cel infusion ( P=0.01). Both cohorts showed a similar pattern of lymphocyte recovery over 1, 3, and 6 months. Median ALC counts at 9-12 months post-infusion indicated better lymphocyte recovery in the bendamustine group with a median ALC of 1.55 K/ul (IQR: 1.04, 1.94) compared to 0.96 K/ul (IQR: 0.58, 1.23) in the FC group ( P=0.043) [Figure 2]. There was no significant difference in the recovery of absolute neutrophil count, hemoglobin, and platelets. Updated efficacy analysis and immune reconstitution data including T-cell, B-cell, and NK cell recovery will be reported at the time meeting, as all patients will have completed at least one year of follow-up by September 2023. Discussion: Bendamustine lymphodepletion prior to axi-cel therapy showed comparable efficacy and safety outcomes to the standard FC regimen in relapsed/refractory LBCL patients. Bendamustine demonstrated effective lymphodepletion and better lymphocyte recovery at 9-12 months post-infusion compared to FC cohort. These findings suggest that bendamustine may be an acceptable alternative lymphodepleting regimen. Prospective studies, ideally randomized control trial, are warranted.

A Randomized Phase 2 Trial of 28-Day (Arm A) Versus 14-Day (Arm B) Schedule of Venetoclax + Azacitidine in Newly Diagnosed Acute Myeloid Leukemia Patients ≥ 60 Years

Background: Treatment options for older, less fit acute myeloid leukemia (AML) patients continue to be challenging, with toxicities and limited efficacy. The combination therapy of azacitidine (Aza) and the bcl-2 inhibitor venetoclax (Ven) showed superior benefit in response rates and overall survival compared to Aza alone, leading to the combination's FDA approval in newly diagnosed AML patients ≥ 75 years and younger patients ineligible for intensive chemotherapy. While Ven-Aza is a very effective and potent therapy, the 28-day continuous dosing of Ven combined with 7 days of Aza resulted in interrupted dosing or shortened dosing schedules due to persistent cytopenias in more than 50% of treated patients in the VIALE-A trial and subsequent real-world data. Furthermore, investigation of novel agents in combination with Ven-Aza has been challenging due to prolonged cytopenias even when monotherapy with the new agent shows no myelosuppression. Given that Ven-Aza is not curative, successful integration of other agents with this standard of care remains important in AML. The growing knowledge of Ven-Aza toxicities prompted attention to developing a safer dosing regimen while maintaining similar efficacy. Our study will examine the FDA label of 28 days of Ven, versus 14 days, in combination with Aza for newly diagnosed AML patients ≥ 60 years who are not candidates for intensive chemotherapy. The primary objective of this study is to compare complete remission (CR) rates with an abbreviated schedule of Ven (14 days) versus the current package insert approved schedule (28 days). We hypothesize that reducing the dosing duration of Ven would reduce the associated toxicities while maintaining a comparable response rate. Study Design and Methods: This protocol is a sub-study of the Beat AML Master Trial (NCT03013998) in which untreated AML patients age ≥ 60 are assigned an investigational therapy based on cytogenetic and central genomic analysis. Patients are randomized onto Arm A (28-day Ven-Aza schedule) or Arm B (14-day Ven-Aza schedule) stratified by age (60-74 vs. 75+ years). The primary objective is to determine the complete remission (CR) rate of patients treated in each randomized arm for up to 2 cycles. The secondary objectives will include assessments of composite complete remission (CR, CR with hematologic improvement, CR with incomplete count recovery), duration of remission, survival, and incidence of treatment-related and non-related toxicities. Additionally, the overall incidence of febrile neutropenia, grade ≥3 infections, transfusions, days of hospitalization and time to neutrophil recovery will be determined. In both arms of the study, patients will be assessed for response at day 21-28 of cycles 1 and 2. Patients who have marrow remission (< 5% blasts) will wait for count recovery of absolute neutrophil count ≥ 0.5x10 9/L and platelets ≥ 50x10 9/L before initiating the next cycle of therapy. Patients will then be followed for survival. With the exception of the Ven dosing schedule (14 vs. 28 days), the FDA approved package insert for Ven, including dose modifications for concurrent azole therapy, will be followed in both arms. The intent of the analysis is to demonstrate that the 14-day Ven-Aza regimen is at least as effective as the standard 28-day regimen. A total of 166 patients (83 per group) will provide 80% power to detect a 10% non-inferiority margin at the one-sided 5% significance level, assuming that the CR rate is 36% for the 28-day regimen, as observed in VIALE-A, and 25% higher (45%) for the 14-day regimen. In addition to assessing the frequency of adverse events such as cytopenias, safety monitoring will include an assessment of response rates after at least 25% of patients have completed 2 cycles of treatment, with consideration for stopping the study if data suggest the 14-day regimen is inferior to the standard regimen. Correlative studies will include measurement of MRD and a focus on identifying properties of leukemic cells that respond, do not respond and become resistant to therapy.

Comparison of Condensed to Standard Schedule of High Dose Cytarabine Consolidation for Acute Myeloid Leukemia in First Complete Remission

Background Traditionally, acute myeloid leukemia (AML) consolidation therapy for patients less than 60 years old with low to intermediate risk disease has been treated with high dose cytarabine (HDAC) cycles given on days 1, 3, and 5 (HDAC-135). However, more recent publications have assessed alternative dosing, namely administering HDAC on days 1, 2, and 3 (HDAC-123). National Comprehensive Cancer Network (NCCN) Guidelines for AML discuss this alternative dosing for HDAC and do not recommend one over another. A prospective study found that there was no cumulative hematologic toxicity and no change in survival when comparing HDAC-123 to HDAC-135 5. As a result, Northside Hospital began using HDAC-123 in patients less than 60 years old for AML consolidation therapy. The purpose of this study was to assess the safety, efficacy, and health care resource consumption associated with HDAC-135 versus the condensed HDAC-123 regimen at Northside Hospital. Methods This single-center, retrospective study included patients with AML between 18 and 60 years old who received at least one cycle of HDAC-123 or HDAC-135 at Northside Hospital Atlanta's outpatient clinic from January 1, 2018 to January 1, 2023. The primary outcome was time to hematologic recovery of white blood cell (WBC), absolute neutrophil count (ANC), and platelets. Secondary endpoints were the amount of transfusions needed, incidence of documented infections, rate of hospital admission, and length of hospital stay. Results A total of 51 patients were included. Twenty one patients received a cumulative total of 39 cycles of HDAC-123 and 30 patients received a cumulative total of 57 cycles of HDAC-135. Overall, baseline characteristics were similar between groups although hemoglobin and hematocrit were significantly lower in the HDAC-123 group. In the HDAC-123 group compared to the HDAC-135 group, the median day of WBC recovery was 15 and 24 days, respectively (p < 0.001). The median day of ANC recovery was 16 and 28 days, respectively (p < 0.001). The median day of platelet recovery was 16 and 20 days, respectively (p < 0.001). Conclusion The results of this retrospective review support the findings of other studies. HDAC-123 demonstrated a significantly reduced time to WBC, ANC, and platelet recovery compared to HDAC-135. HDAC-123 was also was associated with lower rates of microbiologically documented infections but did require more RBC transfusions. HDAC-123 may be preferred over HDAC-135 for consolidation therapy in patients less than 60 years old.

Inotuzumab Ozogamicin + Blinatumumab +/- Rituximab + Mini-Hcvd Shows Improved Tolerability with Similar Efficacy Compared to E1910 in Treatment of Philadelphia Chromosome Negative Acute Lymphoblastic Leukemia in Older Adults

CONCLUSION Philadelphia chromosome negative acute lymphoblastic leukemia (Ph- ALL) boasts contradicting survival rates given its binodal age distribution. While children and adolescents post 5-year overall survival (OS) rates of 89%, the stark contrast of 5-year OS of 20.4% in older adults greater than 65 years, makes this a challenging population to treat. Currently, there is no standard of care for the treatment of ALL with various regimens utilized dependent on age, co-morbidities, performance status, as well as physician/institute preference. One regimen that is commonly used is a combination of targeted therapies along with reduced intensity chemotherapy (inotuzumab ozogamicin, rituximab (if CD20+), blinatumomab and mini hyper fractionated cyclophosphamide, vincristine, and dexamethasone [Mini-HCVD]), which has demonstrated both improvements in survival while reducing treatment related toxicity. Another commonly accepted approach is a modified Berlin-Frankfurt-Munster (BFM) backbone (i.e., E1910). Despite the available options, there is a lack of comparison of these regimens. To answer this unanswered question, we compared the characteristics, outcomes, and toxicities of older adults with ALL treated with either Mini-HCVD or E1910 at our academic medical center. Medical records were retrospectively reviewed at Roswell Park Comprehensive Cancer Center to identify patients diagnosed with Ph- ALL treated with Mini-HCVD or E1910 between January 1 2016 - May 31 2022. Those with relapsed/refractory ALL or received E1910 in the setting of a clinical trial were excluded from the study. Demographics, disease-specific variables, and overall outcomes were collected in accordance with the institutional review board approved protocol. Primary outcome was 3-year overall survival rate, while secondary outcomes included best response in first 3 months, minimal residual disease (MRD) status at 3 months, 30-day mortality, as well as the frequency and incidence of toxicities per cycle. Best response was defined as less than 5% blasts on bone marrow biopsy with complete (CR) or incomplete (CRi) absolute neutrophil or platelet count recovery. MRD status was assessed via flow cytometry and next generation sequencing using ClonoSEQ®. Adverse events and their severity were characterized according to the National Cancer Institute Common Terminology Criteria for Adverse Events version 5.0. Differences in OS between two groups were examined by log-rank test. Propensity scores were obtained based on the baseline variables that with potentially imbalanced distributions (p<0.1). MRD status and response to treatment were compared using Fisher's exact test. Toxicities were summarized as frequencies for each treatment cycle. The incidence of grade 3-4 toxicities was defined as the number occurrence per treatment cycle and were compared using Poisson regression. 27 patients were included, with 15 (55.5%) receiving Mini-HCVD and 12 (44.5%) receiving E1910. Median age was 70 years (49-83), in Mini-HCVD arm and 63 years (47-74), in E1910 arm. Three-year OS was 61.9% for those who received Mini-HCVD (95% CI 40.2-95.3) and 28.1% for those who received E1910 (95% CI 10.9-72.9; p=0.23). In Mini-HCVD 77% and 69% of patients achieved CR/CRi and MRD negative status in the first three months, compared to 60% and 70% in E1910. Only 13% of patients in Mini-HCVD proceeded to transplant or CAR-T, compared to 58% in E1910 (p=0.0198). The most common treatment-related adverse events in both arms were cytopenias. Febrile neutropenia occurred in 47% of Mini-HCVD patients compared to 83% in E1910. There was no difference in rates of infections between arms. Mean incidence of grade 3/4 toxicity per cycle was 0.85/0.96 with Mini-HCVD and 1.03/1.65 with E1910 (p=0.0098). This retrospective single institute study demonstrates that the clinical outcomes of Mini-HCVD plus immunotherapeutic agents in older adults with Ph- ALL are similar to modified BFM backbone with reduced incidence of toxicity. While limited by small numbers, these results suggest that reduced intensity chemotherapy in combination with novel targeted agents could represent a new standard of care regimen in this historically difficult to treat patient population.

TBI-Containing with T-Cell Replete Full Haplotype Mismatched Hematopoietic Stem Cell Transplantation in Adult Patients with De Novo Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is the 2nd most frequent developing hematologic malignancy with deep heterogeneity, but unfortunately the majority of patients relapse even after allogeneic hematopoietic stem cell transplantation (HSCT) in complete remission (CR). We have developed allogeneic HSCT from familial mismatched/haploidentical donors (FMT) in adult patients with a single disease entity of AML lacking of both HLA-identical siblings and well-matched unrelated donors (WMUD) from the mid 1990s. Previously, several pilot studies of FMT performed with various total body irradiation (TBI)-based conditioning regimens (2~12 gray) with or without post-transplant cyclophosphamide (PT-Cy) as a graft-versus-host disease (GvHD) prophylaxis were reported. Here, we demonstrate about the encouraging outcomes of FMT using unmanipulated peripheral blood donor stem cells (PBSCs) and de-escalated dose of TBI (4~8 gray) containing conditioning regimen without T-cell depletion manner. Although PT-Cy as a specific GvHD prophylaxis regimen is increasingly used for both adult and pediatric FMT, our group investigated the clinical outcomes in adult patients with de novo AML who received full haplotype mismatched HSCT after TBI containing preparation regimen consisted of fractionated TBI (total 4 gray for elderly and 8 gray for <60 years old), fludarabine (150 mg/m 2/day), busulfex (6.4mg/kg/day), and anti-thymocyte globulin (ATG). For GvHD prophylaxis, rabbit ATG (thymoglobulin, Genzyme, 1.25mg/kg/day for 4 days at D-4 to D-1) and a combination of tacrolimus and short-term methotrexate was used. G-CSF mobilized unmanipulated PBSCs were used with a median CD34+ dose of 6.5 x 10 6/kg (1~25.6). From 2008 to the end of 2022, total 429 adult patients were enrolled, and data demonstrated that our trial of intermediate-dose of ATG and reduced toxicity of TBI-containing conditioning regimen to reduce graft-failure even for high levels of donor-specific antibody titer, early transplant-related mortality, critical cytomegalovirus (CMV) disease, and emerging post-transplant lymphoproliferative disease with rapid immune recovery has shown very successful outcomes. Briefly, the median absolute neutrophil count recovery was 12 days (10~26) and the platelet of 14 days (5~38). There was no either primary or secondary graft-failures at all. With a median follow-up of 36.5 months (2~242) for survivors, overall survival rate (OS) and relapse-free survival (RFS) for patients in any CR (n=338) and relapse/refractory status (n=91) were 62.9% vs. 34.3% and 59.5% vs. 32.2%, respectively. Although there was no significant difference in the subgroup analysis, de novo and young aged patients in any CR showed the best OS 73% (Figure 1). Cumulative incidences of acute GvHD and chronic GvHD were 66% (59-73), 70% (63-76), respectively. The incidences of moderate to severe acute GvHD and chronic GvHD were 16.1%, 30.5%, respectively. By univariate and multivariate analyses, patient's age <54 (p=0.043), pre-HSCT CR1 (p <0.001), absence of mod to severe chronic GvHD (p <0.001), and use of post-transplant iron-chelating agent (p=0.001) were the statistically significant in the study. The GvHD-free and relapse-free survival rate in CR1 was 62.4% for younger patients (age <54) and 47.9% for older patients (p=ns). The non-relapse mortality rate was 27.2% for all enrolled patients and 16% for CR patients. The rapidity of immune recovery was also compared with our old control cohort when we performed T-cell depletion using the CliniMACS system, and it showed a significant reconstitution of CD4+ cells (>300/ul) at 3 months post-FMT compared to the much delayed T-cell depleted FMT. Of note, CMV DNAemia was relatively higher (76.9%) than reported in other studies, likely due to the use of ATG and the endemic region of our country. Therefore, we suggest that the strategic reduction of fractionated TBI 4~8 gray-based conditioning with unmanipulated PBSCs graft without PT-Cy seems feasible with favorable outcomes for adult patients with de novo AML undergoing FMT in CR, especially even in a certain subgroup of elderly patients with AML.

ALLO-647 for Lymphodepletion in the Allogeneic CAR T Setting: Safety Experience with ALLO-501/501A in Patients (Pts) with Relapsed/Refractory (r/r) Large B-Cell and Follicular Lymphomas

Background: While breakthroughs in hematologic malignancies with autologous CAR T-cell therapies have been met with growing clinical interest due to impressive outcomes, limitations in logistics/manufacturing, quality consistency, and product availability persist. Allogeneic CAR T-cell therapies may circumvent such challenges by providing an off-the-shelf therapeutic option derived from healthy donors. For allogeneic CAR T cells to be successful, there must be a safe and effective way to control host lymphocyte rejection of allogeneic CAR T cells (allo-rejection). ALLO-501 and ALLO-501A are allogeneic anti-CD19 CAR T-cell products that use Cellectis technologies' TALEN® gene editing to disrupt both the TCRα constant ( TRAC) and CD52 genes. CD52 disruption specifically permits use of ALLO-647, an anti-CD52 antibody, for the transient and selective depletion of host lymphocytes that enables ALLO-501 and ALLO-501A to proliferate after infusion without rapid allo-rejection. Updated phase 1 data for ALLO-501 (ALPHA; NCT03939026) and ALLO-501A (ALPHA2; NCT04416984) showed that administration of anti-CD19 allogeneic CAR T product following use of lymphodepletion that includes ALLO-647 plus fludarabine and cyclophosphamide provided durable responses and an acceptable safety profile in CAR T-cell-naive pts with r/r large B-cell lymphoma (LBCL; Locke FL, et al. ASCO 2023; #2517). Herein, we provide safety results of ALLO-647 in pts with r/r LBCL and follicular lymphoma (FL). Methods: Pts with r/r LBCL and FL enrolled in ALPHA and ALPHA2 studies received a 3 to 5-day lymphodepletion regimen consisting of fludarabine 30 mg/m 2 and cyclophosphamide 300-500 mg/m 2 (FC) and 39, 60, or 90 mg of ALLO-647 in divided doses. ALLO-501/ALLO-501A were administered after the completion of lymphodepletion. Incidence rates of grade ≥3 cytopenias (neutropenia, thrombocytopenia, anemia and pancytopenia) were assessed at 3 timepoints (Study Day 28, Day 56, and Month 4). Pts underwent weekly cytomegalovirus (CMV) monitoring. Leukocyte reconstitution was evaluated following lymphodepletion and CAR T-cell infusion. Results: As of April 20, 2023, 87 pts with r/r LBCL (n=61) and FL (n=26) were treated with ALLO-647 and included in the analysis (median age, 64 years; median number of prior regimens, 3). In total, 11 (13%), 39 (45%), and 37 (43%) pts received 39, 60, and 90 mg ALLO-647, respectively. Among the LBCL pts, 33 were CAR T-cell-naive and treated with product manufactured using the Phase 2 process. Median follow-up was 29.5 months (range, 6.8-47.5). The most common treatment-emergent adverse events (TEAEs), assessed from the time of first dose of lymphodepletion, included neutropenia (79%), anemia (61%), infusion-related reactions (IRRs, 55%), and thrombocytopenia (53%). The most common grade ≥3 TEAEs included neutropenia (74%), anemia (38%), and thrombocytopenia (38%). The proportion of pts experiencing grade ≥3 cytopenias decreased over time from Day 28 (29%) to Day 56 (20%) to Month 4 (15%), which was consistent across all lymphoma pt subgroups. ALLO-647 IRRs were typically low grade, except for 5 (6%) grade 3 events; all IRRs were managed with supportive care measures. After treatment with ALLO-501/501A, 20 pts (23%) experienced cytokine release syndrome events, which were low grade except for 1 (1%) grade 3 event. No GvHD, grade ≥3 immune effector cell-associated neurotoxicity syndrome events, or progressive multifocal leukoencephalopathy were reported. Any grade and grade ≥3 infections were reported in 50 pts (58%) and 18 pts (21%), respectively. Two pts had (2%) fatal infectious events (COVID-19 pneumonia and pneumonia, n=1 each) as previously reported. The most common infection was CMV reactivation (any grade, n=22 [25%]; grade 3, n=8 [9%]). Following lymphodepletion, the median time to absolute neutrophil count and absolute lymphocyte count recovery to grade <4 was 7 days and 28 days, respectively. T-cell counts exhibited a steady increase over time, with the majority of pts achieving full T-cell recovery (return to baseline levels) by Month 6. Detailed pharmacokinetics and pharmacodynamics data will be presented. Conclusions: These data suggest allogeneic CAR T-cell products administered following lymphodepletion consisting of FC and ALLO-647 can provide a safe and tolerable alternative to autologous CAR T-cell therapy.

Machine Learning-Based Time-Series Clustering Identifies Archetypal Trajectories of Hematotoxicity after CAR T-Cell Therapy

BACKGROUND Severe hematotoxicity has been reported in a subset of patients (pts) after chimeric antigen receptor (CAR) T-cell therapy, leading to severe infections, transfusion dependency, and worse outcomes. Early identification of pts at risk for severe hematotoxicity could inform the consideration of an autologous stem cell boost, allogeneic HCT, and/or additional infectious prophylaxis. While distinct archetypal trajectories of blood count recovery have been proposed (e.g., quick vs. intermittent vs. aplastic), manual trajectory classification is subjective and labor-intensive. To address these limitations, we automated the identification of distinct trajectories of hematotoxicity by applying time-series clustering to longitudinal absolute neutrophil count (ANC) data from >400 pts treated with CAR T-cell therapy. Next, we sought to identify factors associated with the identified trajectories and to assess the predictive ability of the CAR-HEMATOTOX score (Rejeski, Blood 2021). STUDY DESIGN AND METHODS Adults ≥18 years of age who received their first infusion of CAR T cells for hematologic malignancies with commercial or investigational products at the Fred Hutchinson Cancer Center (2013-2023) were included. ANC trajectories were clustered using non-supervised longitudinal k-means based on Euclidean distances using the latrend and kml packages in R 4.1.3. We applied logistic regression to pre-lymphodepletion (pre-LD) variables to predict poor/very poor ANC recovery. Sensitivity and specificity were computed using a probability threshold based on the Youden criteria. RESULTS A total of 509 pts were identified; 106 were excluded due to insufficient data, with 403 pts included for the analysis. The most common disease types were aggressive NHL (n = 161; 40%), indolent NHL (n = 82; 20%), and ALL (n = 74; 18%). CAR T-cell products were axi-cel, n= 101 (25%); brexu-cel, n = 24 (6%); cilta-cel, n = 21 (5%); liso-cel, n = 46 (11%); ide-cel, n = 25 (6%); tisa-cel, 12 (3%); and investigational CD19 or CD20 CAR T-cell products, n = 174 (43%). As shown in Figure 1A, the ANC longitudinal data clustered into four distinct trajectories as follows: 1) high nadir followed by rapid recovery (“very good recovery”), n = 294 (73%); 2) low nadir followed by rapid recovery (“good recovery”), n = 87 (22%); 3) low nadir followed by intermittent recovery (“poor recovery”), n = 13 (3%); 4) aplastic phenotype (“very poor recovery”), n = 9 (2%). In univariate logistic regression, ALL (reference: aggressive NHL; OR = 5.43, 95% CI, 1.71-20.6, p = 0.006), pre-LD lower ANC (OR = 3.33 per log 10 , 95% CI, 1.82-6.25, p < 0.001), lower pre-LD platelet count (OR = 10 per log 10, 95% CI, 3.70-33.3), p < 0.001), and higher pre-LD disease burden as measured by lactate dehydrogenase (LDH) were associated with poor/very poor ANC recovery (OR = 16.6 per log 10, 95% CI, 4.79-59.3, p < 0.001). Next, we assessed the predictive ability of CAR-HEMATOTOX to identify poor/very poor ANC recovery in n = 356 pts with a calculable score. The CAR-HEMATOTOX score high/low showed modest discrimination (C-index: 0.65), which improved when used as a continuous variable (C-index: 0.85). As previously reported, these models had high sensitivity (>90%) but low specificity (high/low: 31%, continuous: 58%). To improve risk prediction of poor/very poor ANC recovery, we built a logistic regression model using restricted cubic splines - allowing for non-linear effects - including pre-LD ANC, platelet, Hb, LDH, CRP, and ferritin, which showed higher discrimination (C-index: 0.91), high sensitivity (88%), and higher specificity (79%) ( Figure 1B). CONCLUSION We introduce an automated, scalable, and disease-agnostic framework to analyze hematologic toxicity after CAR T-cell therapy. K-means clustering of longitudinal ANC data categorized pts into archetypal trajectories of hematologic recovery. A logistic regression model using pre-LD ANC, platelet, Hb, LDH, CRP, and ferritin showed improved discrimination and sensitivity compared to CAR-HEMATOTOX in our training set, but both models had low specificity (poor ability to “rule in” pts at risk of severe hematotoxicity) and thus low clinical utility at this time. We plan to further improve our predictive models by incorporating post-infusion biomarkers of systemic inflammation that we have previously shown to be associated with delayed count recovery after CAR T-cell therapy (Juluri, Blood Advances 2022).

Outcomes of Children Discharged Prior to Absolute Neutrophil Count Recovery After Admission for Febrile Neutropenia.

Febrile neutropenia (FN) management in pediatric oncology patients traditionally necessitates inpatient admission until evidence of bone marrow recovery. Discharge before count recovery may be a way to safely reduce the length of hospitalizations for select patients. A chart review was conducted of patients admitted for FN at one tertiary care children's hospital, where the standard is to discharge well-appearing patients after 48 hours of negative cultures if afebrile for at least 24 hours, irrespective of absolute neutrophil count (ANC). Patients with ANC <500 at discharge were identified as early discharges, and data were collected with respect to rates of readmission and infectious complications in this cohort. Among 1230 FN encounters, 765 (62%) were early discharges. 122 patients (15.9%) were readmitted within 7 days. Patients with acute myeloid leukemia and ANC <100 at discharge were more likely to be readmitted. Of the early discharges, only 10 (1.31%) were readmitted with positive blood cultures and 5 (0.7%) were admitted to the pediatric intensive care unit within 24 hours of readmission. Routine discharge before ANC recovery allows for short hospital stays with low rates of readmission, infectious complications, and critical illness for pediatric oncology patients. This safe and beneficial policy should be considered at other institutions.

Safety of Procalcitonin Guided Early Discontinuation of Antibiotic Therapy among Children Receiving Cancer Chemotherapy and Having Low-Risk Febrile Neutropenia: A Randomized Feasibility Trial (ProFenC Study)

In low-risk febrile neutropenia (LR-FN), the safety of early discontinuation of empiric antibiotics without marrow recovery is not well established. This study aimed to evaluate the safety of procalcitonin (PCT) guided early discontinuation of antibiotics in LR-FN. In this trial, children with LR-FN with an afebrile period of at least 24 h, sterile blood culture, and negative/normalized PCT were randomized at 72 h of starting antibiotics into two groups: intervention arm and standard arm. The antibiotics were stopped in the intervention arm regardless of absolute neutrophil count (ANC), while in the standard arm, antibiotics were continued for at least 7 days or until recovery of ANC (>500/mm3). The primary objective was to determine the treatment failure rates, and the secondary objective was to compare the duration of antibiotics and all-cause mortality between the two arms. A total of 46 children with LR-FN were randomized to either the intervention arm (n = 23) or the standard arm (n = 23). Treatment failure was observed in 2/23 (8.7%) of patients in the intervention arm compared to 1/23 (4.3%) in the standard arm [RR: 2 (95% CI: 0.19–20.6); p = 0.55]. The median duration of antibiotics in the intervention arm and standard arm were 3 days vs 7 days (P= <0.001). There was no mortality in this study. PCT-guided early discontinuation of empirical antibiotics in LR-FN is feasible. There was no significant difference observed in treatment failure between the early discontinuation of antibiotics vs standard therapy. The total duration of antibiotic exposure was significantly lesser in the discontinuation arm. Further, larger multicenter studies are needed to confirm the finding of this study.

Antibiotic practice and stewardship in the management of neutropenic fever: A survey of US institutions

Background: Neutropenic fever management decisions are complex and result in prolonged duration of broad-spectrum antibiotics. Strategies for antibiotic stewardship in this context have been studied, including de-escalation of antibiotics prior to resolution of neutropenia, with unclear implementation. Here, we present the first survey study to describe real-world neutropenic fever management practices in US healthcare institutions, with particular emphasis on de-escalation strategies after initiation of broad-spectrum antibiotics. Methods: Using REDCap, we conducted a survey of US healthcare institutions through the SHEA Research Network (SRN). Questions pertained to antimicrobial prophylaxis and supportive care in the management of oncology patients and neutropenic fever management (including specific antimicrobial choices and clinical scenarios). Hematologic malignancy hospitalization (2020) and bone-marrow transplantation (2016–2020) volumes were obtained from CMS and Health Resources &amp; Services Administration databases, respectively. Results: Overall, 23 complete responses were recorded (response rate, 35.4%). Collectively, these entities account for ~11.0% of hematologic malignancy hospitalizations and 13.3% bone marrow transplantations nationwide. Of 23 facilities, 19 had institutional guidelines for neutropenic fever management and 18 had institutional guidelines for prophylaxis, with similar definitions for neutropenic fever. Firstline treatment universally utilized antipseudomonal broad-spectrum IV antibiotics (20 of 23 use cephalosporin, 3 of 23 use penicillin agent, and no respondents use carbapenem). Fluoroquinolone prophylaxis was common for leukemia induction patients (18 of 23) but was mixed for bone-marrow transplantation (10 of 23). We observed significant heterogeneity in treatment decisions. For stable neutropenic fever patients with no clinical source of infection identified, 13 of 23 respondents continued IV antibiotics until ANC (absolute neutrophil count) recovery. The remainder had criteria for de-escalation back to prophylaxis prior to this (eg, a fever-free period). Respondents were more willing to de-escalate prior to ANC recovery in patients with identified clinical sources (14 of 23 de-escalations in patients with pneumonia) or microbiological sources (15 of 23 de-escalations in patients with bacteremia) after dedicated treatment courses. In free-text responses, several respondents described opportunities for more systemic de-escalation for antimicrobial stewardship in these scenarios. Conclusions: Our results illustrate the real-world management of neutropenic fever in US hospitals, including initiation of therapy, prophylaxis, and treatment duration. We found significant heterogeneity in de-escalation of empiric antibiotics relative to ANC recovery, highlighting a need for more robust evidence for and adoption of this practice.Disclosures: None

Outcomes of 3- versus 5-day administration schedule of consolidation cytarabine in adults with acute myeloid leukemia (AML).

7014 Background: Consolidation therapy with intermediate to high-dose cytarabine is critical to prevent relapse in AML. Cytarabine is typically administered every 12 hours on days 1, 3, 5. Two large studies have examined a condensed 3-day administration schedule in patients &lt;60 years and demonstrated a shorter time to absolute neutrophil count (ANC) recovery without compromising long term outcomes. However, use of this regimen in patients ≥60 years has not been evaluated. Here we report our experience with the condensed administration schedule compared with the standard schedule in patients over and under 60 years. Methods: All patients with AML in first complete remission (CR) following intensive induction chemotherapy receiving consolidation at our institution between 1/1/2020 to 12/31/2021 were included in the study. Patients received cytarabine every 12 hours on days 1, 3, 5 (AC135) from 1/1/2020 – 12/31/2020 and cytarabine every 12 hours on days 1, 2, 3 (AC123) from 1/1/2021 – 12/31/2021. All patients received peg-filgrastim support. Data was collected to determine time to ANC recovery &gt;1,000/µL, hemoglobin (Hb) &gt;8g/dL, and platelets &gt;75,000/µL. Comparison of continuous variables between two groups was done using multiple t-tests. Results: Between 1/1/2020 - 12/31/2021, 91 patients received at least one cycle of consolidation with 212 individual encounters. 38 patients received all cycles with AC135, 45 received AC123, and 8 received at least one cycle each of AC123 and AC135. Median age of the AC123 cohort was 50.2 years (range 19-72 years) and 54.3 years for the AC135 cohort (range 22-72 years). For patients ≥60 years of age, 33% (71/213) of the encounters were in the AC123 cohort and the rest in AC135 cohort. Median dose of cytarabine was 5,100 mg/dose in AC123 and 4,600 mg /dose in AC135 (p=0.02). Median time to ANC recovery, hemoglobin, and platelets as well as hospital-related outcomes are described in the table. In patients ≥60 years, median time to ANC recovery was 16.5 vs. 18.6 days (p = 0.03) and platelet recovery was 17.4 vs. 19.7 (p = 0.0008) in AC123 vs AC135 respectively. No neurotoxicity events were noted. Complication rates were similar in both arms. Conclusions: Our study demonstrates that AC123, as compared to AC135, is safe and leads to earlier hematopoietic recovery in adults under and over 60 years. AC123 should be considered the preferred schedule of consolidation therapy administration. [Table: see text]

Venetoclax plus cyclophosphamide and cytarabine as induction regimen for adult acute myeloid leukemia.

The efficacy of induction chemotherapy (IC) for acute myeloid leukemia (AML) has improved significantly with the application of targeting drugs. Our previous study showed that a 4-day IC regimen of cyclophosphamide (CTX) and Ara-C [CA (4+3)] achieved similar complete remission (CR) rate (80%) compared with the traditional 7-day regimen, and the survival rate appeared to be better. In this pilot study, we further shortened the CA regimen to 3 days, added low-dose venetoclax (VEN, 200 mg/day) (VCA), and reported the efficacy and safety here. Twenty-five newly diagnosed adult AML patients were enrolled in this study and evaluated for the remission rate after one cycle of the VCA regimen. The CR/Cri was 92%, and all these patients had undetectable minimal residual disease (MRD-). The estimated overall survival at 12 months was 79.3%. The median time for both platelet recovery and absolute neutrophil count recovery was 16 days, faster than that of traditional IC. Compared with the previous CA (4+3) regimen, a higher CR rate (92% vs. 80%, P < 0.01) and a deeper degree of remission (CRMRD- rate, 92% vs. 45%, P < 0.01) were found in the VCA group. This study showed that the 3-day CTX and Ara-C regimen is highly effective in newly diagnosed AML patients, and the addition of VEN to the CA regimen achieves higher and deeper one-course remission.

Efficacy and Safety of Decitabine Combined with Modified EIAG Regimen in the Treatment of Patients with Relapsed/Refractory Acute Myeloid Leukemia and High-risk Myelodysplastic Syndrome

To investigate the efficacy, prognosis and safety of decitabine combined with modified EIAG regimen in the treatment of patients with relapsed/refractory acute myeloid leukemia (AML) and high-risk myelodysplastic syndrome (MDS). The clinical data of 44 patients with relapsed/refractory AML and high-risk MDS admitted to our hospital from January 2017 to December 2020 were analyzed retrospectively. The patients were equally divided into D-EIAG group (decitabine combined with EIAG regimen) and D-CAG group (decitabine combined with CAG regimen) according to clinical treatment regimen. The complete response (CR), CR with incomplete hematologic recover (CRi), morphologic leukemia-free state (MLFS), partial response (PR), overall response rate (ORR), modified composite complete response (mCRc), overall survival (OS) time, 1-year OS rate, myelosuppression and adverse reactions between the two groups were compared. In D-EIAG group, 16 patients (72.7%) achieved mCRc (CR+CRi+MLFS), 3 patients (13.6%) achieved PR, and ORR (mCRc+PR) was 86.4%. In D-CAG group, 9 patients (40.9%) achieved mCRc, 6 patients (27.3%) achieved PR, and ORR was 68.2%. Difference was observed in mCRc rate between the two groups (P=0.035), but not in ORR (P>0.05). The median OS time of D-EIAG group and D-CAG group was 20 (2-38) months and 16 (3-32) months, and 1-year OS rate was 72.7% and 59.1%, respectively. There was no significant difference in 1-year OS rate between the two groups (P>0.05). After induction chemotherapy, the median time for absolute neutrophil count recovery to 0.5×109/L in D-EIAG group and D-CAG group was 14 (10-27) d and 12 (10-26) d, for platelet count recovery to 20×109/L was 15 (11-28) d and 14 (11-24)d, the median red blood cell suspension transfusion volume was 8 (6-12) U and 6 (6-12) U, and the median apheresis platelet transfusion volume was 4 (2-8) U and 3 (2-6) U, respectively. There were no statistically significant differences in comparison of the above indicators between the two groups (P>0.05). The hematological adverse reactions of patients were mainly myelosuppression. Grade III-IV hematological adverse events occurred in both groups (100%), with no increase in the incidence of non-hematological toxicities such as gastrointestinal reactions or liver function damage. Decitabine combined with EIAG regimen in the treatment of relapsed/refractory AML and high-risk MDS can improve remission rate, provide an opportunity for subsequent therapies, and have no increase in adverse reactions compared with D-CAG regimen.

Safety and Efficacy of BCMA CAR-T Cell Therapy in Older Patients With Multiple Myeloma

Risks of B-cell maturation antigen (BCMA) chimeric antigen receptor T-cell (CAR-T) therapy for patients with multiple myeloma (MM) include cytokine release syndrome (CRS), immune effector cell-associated neurotoxicity syndrome (ICANS), cytopenias, and infections. The efficacy and safety of BCMA CAR-T therapy in the geriatric setting, including complications such as falls and delirium, which may be more prevalent in older patients, have not been fully analyzed. We wanted to analyze the efficacy and safety of BCMA CAR-T therapy among older patients (age ≥70 at infusion) versus younger patients with MM. We analyzed all patients with MM who received any autologous BCMA CAR-T therapy over a 5-year period at our institution. Key endpoints included CRS, ICANS incidence, days to absolute neutrophil count (ANC) recovery, incidence of hypogammaglobulinemia (IgG < 400 mg/dL), infections within 6 months, progression-free survival (PFS), and overall survival (OS). Of 83 analyzed patients (age range 33-77), 22 (27%) were aged ≥70 at infusion. The older cohort had lower creatinine clearances (median 67.3 versus 91.9 mL/min, P < .001) and a higher proportion of patients with performance status ≥1 (59% versus 30%, P = .02) but were otherwise similar. Rates of any-grade CRS, any-grade ICANS, and days to ANC recovery were similar between groups. Rates of baseline hypogammaglobulinemia were 36% in older patients and 30% in younger patients (P = .60), whereas post-infusion hypogammaglobulinemia occurred in 82% versus 72%, respectively (P = .57). Infections occurred in 36% (n = 8) of the older cohort versus 52% (n = 32) of the younger cohort (P = .22). There were no statistically significant differences between the older and younger cohorts in terms of documented falls (9% versus 15%, P = .72) or non-ICANS delirium (5% versus 7%, P = 1.0). Median PFS was 13.1 months in older patients (95% confidence interval [CI], 9.2-not reached [NR]) versus 12.5 months in younger patients (95% CI 11.3-22.5, P = .42. Median OS was not reached in the older cohort (95% CI, NR-NR) versus 31.4 months in the younger cohort (95% CI, 24.8-NR) with P = .04. However, age ≥70 was not a significant predictor of OS after adjusting for high-risk cytogenetics, triple-class refractoriness, extramedullary disease, and bone marrow plasma cell burden. Although limited by small sample size and unmeasured confounders, our retrospective analysis did not demonstrate significant increases in CAR-T toxicity among older patients. This included toxicities associated with geriatric populations such as falls and delirium. Our paradoxical finding of borderline better OS among patients aged ≥70, which was not significant in regression modeling, may have been due to selection bias in favor of disproportionately healthy CAR-T candidates in the geriatric population. Overall, BCMA CAR-T remains a safe and effective option for older patients with MM.

Assessing deviations for HPCs obtained during COVID-19 (ADHOC): Evaluating impact of the COVID-19 pandemic on cellular therapy products and processes, the BEST collaborative study.

The success of allogeneic hematopoietic stem cell transplantation is dependent on a world-wide network of collection centers providing donations that predominantly have been infused as fresh cells. The logistics chain that supports the just-in-time delivery model for stem cell and immunotherapy products was severely stressed by the COVID pandemic, and in early 2020 a number of national and international bodies recommended that cells should be cryopreserved at the collection or transplant center to avoid interruptions in their acquisition or delivery to patients who had started conditioning. To assess the potential consequences of such pandemic-related deviations to normal practice, we surveyed nine international laboratories to determine if the characteristics or transplant outcomes of allogeneic stem cell donations differed in the immediate periods before and after the switch to routine cryopreservation. Nine centers on two continents provided data for 72 HSC donations just before, and 71 just after, switching to cryopreservation for allogeneic HSC products. No statistically significant differences between the period before and after cryopreservation were noted for time from product collection to receipt, product temperature at receipt, or CD34+ cell viability at receipt. There was an indication of slower absolute neutrophil count recovery after cryopreservation was required (mean time of 15 vs. 17.6 days). While there were no apparent changes to most parameters studied, there was an indication of slower neutrophil engraftment that will need to be examined in larger, longer term studies.

Deep-learning-based personalized prediction of absolute neutrophil count recovery and comparison with clinicians for validation

Neutropenia and its complications are major adverse effects of cytotoxic chemotherapy. The time to recovery from neutropenia varies from patient to patient, and cannot be easily predicted even by experts. Therefore, we trained a deep learning model using data from 525 pediatric patients with solid tumors to predict the day when patients recover from severe neutropenia after high-dose chemotherapy. We validated the model with data from 99 patients and compared its performance to those of clinicians. The accuracy of the model at predicting the recovery day, with a 1-day error, was 76%; its performance was better than those of the specialist group (58.59%) and the resident group (32.33%). In addition, 80% of clinicians changed their initial predictions at least once after the model’s prediction was conveyed to them. In total, 86 prediction changes (90.53%) improved the recovery day estimate.

Comparable Survival Following Allogeneic Haematopoietic Stem Cell Transplant Utilising HLA-Matched Versus Alternative Donors: A Single-Centre Retrospective, Consecutive Cohort Analysis

Introduction: Allogeneic haematopoietic stem cell transplant (alloHCT) is a potentially curative therapy for many serious haematological disorders. The advent of alternative donor alloHCT, such as umbilical cord blood unit (CBU) and haploidentical (HAPLO), greatly widened the donor pool for recipients without HLA (human leukocyte antigen)-matched donor (MD), providing near universal donor availability. Although survival outcome of MD and alternate donor is considered to be similar, there is ongoing debate about preference of CBU and HAPLO (Wagner et al Blood Adv 2021; Wieduwilt et al Blood Adv 2022). Increased relapse after HAPLO versus increased non-relapse mortality with CBU makes selection of alternative donors difficult, with minimal supporting evidence. Hence, we compared single-centre outcomes of MD versus alternative donor alloHCT. Method: We performed a retrospective, consecutive cohort review of all patients who underwent alloHCT between 1st Jan 2010 and 30th Jun 2021 at our centre. Donors matched with recipients at HLA-A, HLA-B, HLA-C and HLA-DRB1, HLA-DQB1 loci (10/10) were considered MD, HAPLO (5/10) and CBU matched (5 - 6/8). Graft versus Host Disease (GVHD) prophylaxis for MD and CBU was calcineurin inhibitor, whereas HAPLO utilised post-HCT cyclophosphamide. Unrelated MD recipients also received rabbit anti-thymoglobulin (rATG) for in vivo T cell depletion. Neutrophil engraftment was defined as first of three consecutive days of absolute neutrophil count (ANC) > 0.5x109/L. Platelet (PLT) engraftment was defined as first of three consecutive days of PLT count > 20x109/L, unsupported for ≥7 days. Overall survival (OS) was assessed by Kaplan Meier (KM) method. Cumulative incidence (CI) of GVHD and relapse (REL) were estimated as competing events. Univariate and multivariate analysis (U/MVA) was conducted via Cox regression model. Statistical significance was defined as P<0.05. Results: Four-hundred and sixteen alloHCT were performed at our centre: 354 (85.10%) MD (41% related and 59% unrelated), 44 (10.58%) CBU and 18 (4.33%) HAPLO. Median follow up was 65.12 months. CBU recipients were significantly younger than other MD or HAPLO (median age 52 vs 45 vs 61 years, respectively: P=0.0001). Primary indication for transplant of total cohort was myeloid malignancy (64%) with majority in complete remission (68%) at transplant - there was no significant difference between donor groups. MD alloHCT utilised myeloablative conditioning significantly more than CBU and HAPLO (57% vs 23% vs 11%, respectively: P<0.0001). Median CD34 dose infused was 5.02 (4.28 - 5.98), 0.29 (0.24 - 0.36) and 4.98 (4.37 - 5.00) x106/kg for MD, CBU and HAPLO, respectively (P=<0.0001). There was no difference in ANC recovery (median D+19 vs 19 vs 25 for MD, CBU and HAPLO, respectively: P=0.2) between donor groups. PLT recovery was significantly faster for MD than CBU and HAPLO (median D+23 vs 41 vs 38, respectively: P=0.0139). Cumulative incidence of Grade II - IV acute GVHD (aGVHD) by D+100 was significantly higher in CBU than MD (48.46% vs 23.06%: P<0.001) and HAPLO (48.46% vs 34.81%: P=0.001). There was no difference of aGVHD CI between MD and HAPLO (P=0.2). Cumulative incidence of relapse was significantly higher following HAPLO versus CBU (3yr CI 52% vs 23%: P=0.025). However, there was no difference in REL between MD and CBU (32% vs. 23%; P=0.1) or MD and HAPLO (32% vs. 52%; P=0.3). Median and 3-year OS in our total cohort was 40.1 months and 51.8% (95% CI 0.570), respectively. We did not observe OS difference according to donor groups. Three-year OS was 51%, 63% and 45% for MD, CBU and HAPLO, respectively (P=0.4). UVA did not identify OS difference between donor groups. However, UVA revealed significant difference in other variables that were reassessed by MVA, per Table 1. Interestingly, MVA demonstrated significantly lower OS in fresh versus cryopreserved (cryo) alloHCT (HR fresh vs cryo 0.33, 0.15 - 0.72, P=0.005). Conclusion: Overall, we observed higher rates of aGVHD with CBU, versus higher rates of REL for HAPLO. However, the overall survival was comparable. Our results demonstrate that with careful patient selection and optimal management, alternative donor alloHCT have comparable outcomes to MD. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Safety and Efficacy of BCMA-Targeted CAR-T Therapy in Geriatric Patients with Multiple Myeloma

Introduction: Risks of B-cell maturation antigen (BCMA) chimeric antigen receptor (CAR-T) therapy for patients with multiple myeloma (MM) include cytokine release syndrome (CRS), immune effector-cell associated neurotoxicity syndrome (ICANS), and infections. Geriatric patients with MM are at higher risk of infections (Blimark 2015), and pre-existing comorbidities may complicate CRS and ICANS in older patients. While progression-free survival (PFS) was similar in older vs younger patients in the KarMMa trial of idecabtagene vicleucel (Berdeja 2020), BCMA CAR-T outcomes in the geriatric setting - including the risks of prolonged cytopenias, hypogammaglobulinemia, and infections - have not yet been analyzed. Methods: We analyzed all patients with MM who received any autologous BCMA CAR-T therapy from January 2017 - June 2022 at our institution. Key endpoints included CRS and ICANS incidence (American Society for Transplantation and Cellular Therapy criteria), days to absolute neutrophil count (ANC) recovery, incidence of hypogammaglobulinemia (IgG < 400 mg/dL), confirmed infections within 30 days of CAR-T infusion, response rates, time to measurable residual disease (MRD) negativity, PFS, and overall survival (OS). Characteristics were compared between older patients (age ≥70 at infusion) and younger patients using Fisher's & Kruskal-Wallis tests as appropriate. PFS and OS were compared using log-rank tests. Results: Of 77 analyzed patients (age range 33-77), 19 (25%) were aged ≥70. Gender, weight, performance status, years since diagnosis, presence of extramedullary disease, bone marrow plasma cell burden, high-risk cytogenetics, prior lines of therapy, and triple-class refractory status were similar between older and younger patients. Despite similar weights, older patients had lower Cockcroft-Gault creatinine clearances (median 69.2 vs 92.5 mL/min, p<0.001) and were more likely to receive reduced-dose fludarabine as part of lymphodepletion (53% vs 17%, p<0.01). Rates of any-grade CRS (79% vs 79%), rates of any-grade ICANS (11% vs 10%), and median days to ANC recovery (14.0 vs 13.5) were similar between older and younger patients. Rates of baseline hypogammaglobulinemia were 32% in older patients vs 28% in younger patients (p=0.77), while post-infusion hypogammaglobulinemia occurred in 84% vs 71%, respectively (p=0.36). Six infections occurred before Day +30, all in the younger cohort: rhinovirus (n=2), Staphylococcus epidermidis (n=2), CMV reactivation (n=1), and COVID-19 (n=1). There were two deaths before Day +100, both due to progressive MM in younger patients. Overall response rates (84% vs 90%) were similar between older and younger patients. Median PFS (Figure 1A) was not reached (NR) in older patients (95% CI 10.6-NR) vs 13.1 months in younger patients (95% CI 9.4-33.1), with p=0.19. Median OS (Figure 1B) was NR in older patients (95% CI NR-NR) vs 30.0 months (95% CI 24.8-NR) in younger patients, with p=0.05. Two-year survival probabilities were 93% vs 66%, respectively. Discussion: While limited by small sample size and unmeasured confounders, our retrospective analysis did not demonstrate significant increases in CAR-T toxicity among patients aged ≥70. Differences in rates of hypogammaglobulinemia between older and younger patients did not reach statistical significance. Fludarabine dose reductions during lymphodepletion (as expected with age-adjusted creatinine clearances) did not impair CAR-T efficacy among geriatric patients. Older patients paradoxically had a significantly better OS compared to younger patients, which may have been due to selection bias in favor of disproportionately healthy geriatric patients with regard to CAR-T candidacy. Overall, our data suggest that BCMA CAR-T is a safe and effective option for older patients with MM. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal