allo-HCT In Patients Research Articles

Cardiac events after allo-HCT in patients with acute myeloid leukemia

AbstractThis multicenter study sponsored by the GETH-TC investigates the incidence and predictors of early (first 100 days) and late cardiac events (CEs; ECEs and LCEs, respectively) after allo-HCT in patients with acute myeloid leukemia (AML) treated with anthracyclines, focusing on exploring the impact of PTCY on cardiac complications and the impact of CEs on OS and NRM. A total of 1020 patients with AML were included. PTCY was given to 450 (44.1%) adults. Overall, 94 (9.2) patients experienced CEs, with arrythmias, pericardial complications, and heart failure the most prevalent. ECEs occurred in 49 (4.8%) patients within a median of 13 days after allo-HCT, whereas LCEs were diagnosed in 45 (4.4%) patients within a median of 3.6 years after transplant. Using PTCY increased the risk for ECEs in multivariate analysis (hazard ratio [HR], 2.86; P = .007) but did not significantly affect the risk for LCEs (HR, 1.06; P = .892). The impact of variables on outcomes revealed was investigated using multivariate regression analyses and revealed that the diagnosis of CEs decreased the likelihood of OS (HR, 1.66; P = .005) and increased the likelihood of NRM (HR, 2.88; P < .001). Furthermore, despite using PTCY increased ECEs risk, its administration was beneficial for OS (HR, 0.71; P = .026). In conclusion, although the incidence of CEs was relatively low, it significantly affected mortality. Standard doses of PTCY increased ECE risk but were associated with improved OS. Therefore, protocols for preventing cardiac complications among these patients are needed.

Evaluating the Impact of Post-Transplant Cyclophosphamide and Anti-Thymocyte Globulin on CMV Reactivation Following Allogeneic Hematopoietic Stem Cell Transplantation: A Systematic Literature Review.

Anti-thymocyte globulin (ATG) and post-transplantation cyclophosphamide (PTCy) are two frequently utilised strategies in graft-versus-host disease (GvHD) prophylaxis following allogeneic hematopoietic cell transplantation (allo-HCT), currently approved for different recipient-donor settings. In addition, being efficacious in preventing GvHD owing to their T-cell depleting capacity, the employment of these two agents increases the risk of infections, including CMV reactivation, which stands as one of the most common and serious infections following allo-HCT. We performed a systematic literature review of articles published until 1 September 2023, through PubMed, MEDLINE, and Scopus, with the main endpoint being CMV reactivation after PTCy or ATG allo-HCT. The majority of the studies included in the analysis provide supporting evidence for a reduced risk of CMV reactivations following the use of PTCy compared to ATG, although not all findings reached statistical significance. Additionally, it appears that utilising a haploidentical donor leads to a higher incidence of CMV infections and clinically significant CMV infections (CS-CMVis) compared to other donor settings in PTCy allo-HCT. This study aims to compare the risk of CMV infections following allo-HCT in patients who have received either ATG or PTCy as GvHD prophylaxis and discuss other factors that could influence the infectious outcomes of patients who have undergone allo-HCT.

Outcomes of Allogeneic HSCT in Elderly Patients (70 years old and above) -a Canadian Experience

Introduction: Allogeneic hematopoietic cell transplant (alloHCT) in elderly patients is a challenge, as with increasing age, there is higher incidence of co-morbidities and pre-frail status. In our recent study on alloHCT in patients 60 years (y) or older, those who were 70y or more had worse outcome and high 2-y non-relapse mortality (NRM) of 53% (Al-Shaibani E et al. Ann Hematol, 2023, 102: 917-926). We therefore implemented a number of changes to improve outcomes in elderly patients undergoing alloHCT. In this study, we analyze transplant outcomes in patients ≥ 70 y, and compare the earlier cohort with the more recent cohort. Methods: This is a retrospective analysis of all consecutive patients 70y or older, who had an alloHCT from Jan 2015 to Dec 2022. We compared those who underwent an alloHCT from 2015-2019 (Cohort A, n=44) with those who had a transplant from 2020-2022 (Cohort B, n=40). The median age of the patients was 71y (range 70-76). The underlying diagnosis was mainly a myeloid malignancy (AML, MDS, MPN, CMML, n=82; lymphoid (ALL, TPLL, n=2). There were 54 males. Stages of disease at transplant were in CR1 (n=51), CR2 (n=4) or stable disease (n=15, MDS, MPN or CMML pts). All patients received RIC regimens for conditioning including Flu4/Bu2/TBI200 (n=73), Flu4/Treo30 (n=7) and Flu/Treo42 (n=3). The GVHD prophylaxis regimens used included ATG2/PTCy/CSA (n=32), ATG4.5/PTCy/CSA (n=35), ATG4.5/CSA/MTX (n=7), ATG2/CSA/MTX (n=3). The donors were either matched related (n=10), matched unrelated (including minor mismatch) (n=57) or haploidentical (n=16). Graft source was peripheral blood in all except one who received bone marrow. (Details in Table). The overall survival (OS), event free survival (EFS), NRM, cumulative incidence of relapse (CIR), incidence of acute and chronic GVHD, length of transplant hospitalization and the number of hospital re-admissions in first 6 months were assessed. The Kaplan Meier curves were plotted for OS and EFS for the overall sample, as well as stratified by the two eras (cohort A and B) and the differences assessed using log-rank tests. Cumulative incidence curves for NRM and CIR were generated, and differences assessed using Gray's K-sample. Results: For all patients transplanted in 2015-2022, the 1-year OS was 53%, the 1-year EFS was 45% and the 1-year NRM was 35%. The median number of days of transplant hospitalization for the whole population was 33.5 days (range 16 - 116). The incidence of grade I-II aGVHD was 32%, and grade III-IV aGVHD was 9.5%; mild to moderate cGVHD was 14% and severe cGVHD was 2%. The 1-year CIR was approximately 18%. Comparing the two cohorts A and B, the 1y OS was 45% vs 62% (p=0.10) respectively; the 1-year EFS was 37% vs 58% (p=0.07) respectively and the 1-year NRM was 45% vs 23% (p=0.04) respectively (Figures attached). The incidence of GVHD and CIR were similar in both cohorts, despite reducing the ATG dose in cohort B. Conclusions: Our study shows that there were statistically significant improvements in NRM and a trend towards improvement in the OS and EFS in the patients transplanted during 2020-2022 compared to patients undergoing alloHCT from 2015-2019. This improvement may be due to one or more changes implemented in recent years, although it is not possible to identify a single factor. These changes were (a) introduction of Frailty testing in all patients (Salas MQ et al. BMT. 2021; 56:60-69). (b) capping the CD34 cell dose in grafts (c) introduction of Treosulfan for selected indications (MDS/CMML) (Pasic I et al. Leuk Res 2023, 128: 107131). (d) Letermovir for CMV prophylaxis (e) reducing ATG dose for GVHD prophylaxis and (f) focus on diet, nutrition, exercise. While alloHCT should be offered to medically eligible elderly patients, there is a special need to minimize the risks that are part of age related vulnerabilities.

Outcomes of Allogenic Hematopoietic Stem Cell Transplantation in Patients Aged 70 Years and Older

Background: Allogeneic hematopoietic cell transplantation (Allo-HCT) is a highly effective method of achieving prolonged disease control for many types of blood cancers. However, historically, older adults were not considered eligible candidates for Allo-HCT due to concerns about increased toxicity and mortality. This is a significant issue, as the proportion of cancer patients with comorbidities, disability, and geriatric syndromes increases by 3-5% for every 5-year increase in age beyond 65 years. This systematic review aims to address this gap in literature by analyzing survival prognosis in patients aged 70 years and above who have undergone Allo-HCT. Methods: As per the preferred reporting items for systemic reviews and meta-analysis (PRISMA) guidelines, a comprehensive literature search was performed on 3 databases (PubMed, Cochrane Register of Controlled Trials and Clinicaltrials.gov) using MeSH terms and keywords for “Hematopoietic Stem Cell Transplantation” AND “Outcome Assessment” AND “&amp;gt;70 years old” from the date of inception to Feb 13, 2023. Our research produced 101 articles. After excluding irrelevant and review articles during primary and secondary screening, six original studies reporting outcomes of Allo-HCT in patients over 70 years were included. The methodological quality of the included studies was evaluated using NIH quality assessment tool. Inter-study variance was calculated using the Der Simonian-Laird Estimator. Proportions along with 95% confidence Interval (CI) were extracted to compute pooled analysis using the ‘meta’ package by Schwarzer et al. in the R programming language (version 4.16-2). Results: A total of 2292 patients aged 70 years or more were included for this systematic review and meta-analysis. (Table 1) The median age was 71.75 (70-84) years and 67.5% (n=1547) patients were male. Median follow-up time was 22.1 (5-37.1) months. The underlying diagnosis was acute myeloid leukemia (AML) 63% (n=1445), myelodysplastic syndrome (MDS) 20.9% (n=480), non-Hodgkin lymphoma (NHL) 5% (n=115), acute lymphocytic leukemia (ALL) 4.2% (n=96), and chronic lymphocytic leukemia (CLL) 3.1 % (n=71). The source of stem cells was peripheral blood, bone marrow, and cord blood in 90.2% (n=2068), 6.2% (n=142), and 3.1% (n=70) of the patients, respectively. Myeloablative conditioning (MAC) was used in 17.8% of patients, reduced-intensity conditioning (RIC) was used in 77.4% of patients, and a non-myeloablative conditioning regimen (NMA) was used in 4.6% of patients. The Hematopoietic Cell Transplantation-specific Comorbidity Index (HCT-CI) of the included patients was 0 (25.7%), 1-2 (30.1%), and 3 or more (44.2%). The pooled overall survival (OS) at a median of 2 years (1-3) was 41.8% (95% CI 0.34-0.49, I2=88%, p&amp;lt;0.01, n=2292). The pooled progression-free survival (PFS) was 36.4% (95% CI 0.31-0.43, I2=75%, p&amp;lt;0.01, n=1979) at a median of 2 (1-2) years while the pooled incidence of relapse and non-relapse mortality (NRM) was 33.7% (95% CI 0.29-0.38, I2=69%, p&amp;lt;0.01, n=2292) and 28.7% (95% CI 0.22-0.36, I2=88%, p&amp;lt;0.01, n=2292), respectively. The pooled incidence of acute graft versus host disease (GvHD) grade II-IV at a median of 6 months (3-24) and grade III-IV at median of 4.5 months (3-24) was 25.8% (95% CI 0.20-0.31, I2=84%, p&amp;lt;0.01, n=2270) and 11.1% (95% CI 0.10-0.13, I2=2%, p=0.39, n=1979), respectively, while the pooled incidence of chronic GvHD at a median of 1.5 years (1-2) was 33.6% (95% CI 0.28-0.40, I2=84%, p&amp;lt;0.01, n=2292). Conclusion: Our meta-analysis shows that allo-HCT offers promising outcomes for elderly patients aged 70 or greater, and should be considered more frequently for those with transplant eligible disease. It also shows that age can be a restrictive factor due to co-existing comorbidities and poor performance status. Several other factors such as the availability of matched donors, conditioning regimen can play a role in the final outcome of disease progression and associated adverse effects such as GVHD.

Endothelial Activation and Stress Index in adults undergoing allogeneic hematopoietic cell transplantation with post-transplant cyclophosphamide-based prophylaxis

Background aimsPost-transplant cyclophosphamide (PTCY)-based prophylaxis is becoming widespread for allogeneic hematopoietic cell transplantation (allo-HCT) performed independently of the selected donor source. In parallel, use of the Endothelial Activation and Stress Index (EASIX)—considered a surrogate parameter of endothelial activation—for predicting patient outcomes and clinical complications is gaining popularity in the allo-HCT setting. MethodsWe first investigated whether the dynamics of EASIX after allo-HCT differ between patients receiving PTCY and patients receiving other prophylaxis. We then investigated whether the predictive capacity of EASIX persists in PTCY-based allo-HCT. A total of 328 patients transplanted between 2014 and 2020 were included, and 201 (61.2%) received PTCY. ResultsEASIX trends differed significantly between the groups. Compared with patients receiving other prophylaxis, patients receiving PTCY had lower EASIX on day 0 and higher values between day 7 and day 100. In patients receiving PTCY, higher EASIX correlated significantly with higher non-relapse mortality (NRM) and lower overall survival (OS) when measured before and during the first 180 days after allo-HCT. In addition, higher EASIX scores measured at specific time points were predictors of veno-occlusive disease (VOD), transplant-associated thrombotic microangiopathy (TA-TMA) and grade 2–4 acute graft-versus-host disease (aGVHD) risk. ConclusionsThis study demonstrates how EASIX trends vary during the first 180 days after allo-HCT in patients receiving PTCY and those not receiving PTCY and validates the utility of this index for predicting NRM, OS and risk of VOD, TA-TMA and grade 2–4 aGVHD in patients receiving PTCY.

Phase I Trial of Allogeneic Donor Gamma Delta T Cell Infusion Post-Hematopoietic Cell Transplantation, an Interim Safety Report

Background Patients with 2017 European LeukemiaNet (ELN) adverse risk acute myeloid leukemia (AML) are at 40% risk of relapse leading to poor survival after allogeneic hematopoietic cell transplantation (allo-HCT) (Hansen TCT 2021, Jimenez BMT 2021). Ex vivo donor-derived gamma delta T cells (GDT) expanded with artificial antigen presented calls (aAPC) are a novel therapy with potent MHC-independent antineoplastic cytotoxicity. An ongoing phase 1/1b study is evaluating the safety and potential efficacy of ex vivo expanded donor GDT after reduced-intensity conditioning (RIC) allo-HCT in patients with ELN adverse risk AML ( NCT05015426). We report on manufacturing, safety, and correlative biology of expanded donor GDT after allo-HCT in the first 5 treated patients (Table 1). Methods The primary endpoint is the maximum-tolerated dose (MTD) of allogeneic donor GDT as a single infusion at day 60 after RIC allo-HCT. Next generation sequencing was used for measurable residual disease (MRD) assessment pre-HCT and post-GDT infusion. Donor GDT collected from the same donor of the allo-HCT were enriched from non-mobilized leukapheresis product by stimulation with zoledronic acid and IL-2 for 7 days followed by alpha beta T cell depletion using the Miltenyi CliniMACS. Enriched GDT (&amp;gt;90% TCRVδ2) were then co-cultured with irradiated aAPCs in Wilson Wolf G-Rex 100MCS over 10 days (Boucher J. Immunother 2023). This single center, investigator-initiated phase 1 trial is testing 3 distinct dose cohorts of infused GDT (5 x 10 6 cells/kg, 2.5 x 10 7 cells/kg, and 1 x 10 8 cells/kg) with acceptable range of 25% margin. A Bayesian optimal interval design is used to guide dose escalation/de-escalation decisions. Results First 3 patients enrolled in dose level 1 (DL1) cohort received GDT dose of 6.25 x 10 6 cells/kg, while last 2 patients enrolled in DL2 cohort received 3.13 x 10 7 cells/kg dose. Dose-limiting toxicities (DLT) were evaluated for 42 days following GDT infusion and no DLT were observed. None of the treated patients experienced cytokine release syndrome (CRS), Immune Effector Cell-Associated Neurotoxicity Syndrome (ICANS) or graft-versus-host disease (GVHD) during DLT period. Among patients treated on DL1, patient #01 had ASXL1 AML with MRD pos (VAF 43.9%) prior to RIC haploidentical (Haplo) HCT. He is in ongoing complete remission (CR) 9 months post-HCT and has had no GVHD. Patient #02 had MRD pos (VAF 61.7%) AML with TP53 mutation/complex karyotype prior to RIC matched sibling donor allo-HCT. He is in CR and has mild chronic GVHD at 7 months post-HCT. Patient #03 with pre-HCT MRD negRUNX1 AML is in ongoing CR 7 months post-RIC Haplo HCT with no GVHD. At day 28 and day 120 post-GDT, all 3 patients were MRD neg in bone marrow and had 100% bone marrow and peripheral blood leukocyte and granulocyte chimerism. In DL2 cohort, patient #04 with RUNX1 AML and patient #05 with t(9;22) AML both were MRD neg prior to RIC Haplo HCT and remain in CR with no GVHD at 5 and 4 months post-HCT, respectively. At day 28 post-GDT, both patients were MRD neg and had 100% chimerism. Patient #05 had a fall during DLT period in a setting of orthostatic hypotension requiring hospitalization for 24 hours for hydration. This was the only grade 3 adverse event observed in this trial. Serum cytokines analyzed included IL2, IL6, IL15, IFNγ, TNFα, Angiopoietin 1&amp;2, and GM-CSF (Figure 1). We compared results prior and up to 90 days post-GDT infusion and found no significant differences, which can explain no CRS or ICANS events yet observed on this trial. Immunophenotype (TCRVδ2, TCRVδ1, PD1, CTLA4, TIGIT and CD28) of GDT was analyzed in samples of donor apheresis, pre- and post-enrichment, infused GDT product and at days 28 and 90 post-infusion. GDT (TCRVδ2) persisted at day 28 and day 90 post-infusion and expressed low levels of cell surface inhibitory receptors. Conclusion This preliminary interim report demonstrates favorable safety and tolerability of donor GDT therapy with no CRS, ICANS or GVHD in first 5 patients treated in this trial. All these patients with adverse risk AML are in ongoing MRD neg CR following RIC allo-HCT, including 2 pre-HCT MRD pos cases with TP53 AML and AXSL1 AML. Early results of this trial are promising, which provides validation for continued testing of adoptive transfer of ex vivo expanded donor GDT. Updated results of this trial will be presented at the annual conference.

Allogeneic Hematopoietic Cell Transplantation with Non-Myeloablative Conditioning and Post-Transplant Cyclophosphamide Prophylaxis in Patients with Reduced Systolic Function

Post-transplantation cyclophosphamide (PTCy) has become standard of care for graft-versus-host disease (GVHD) prophylaxis after allogeneic hematopoietic cell transplantation (alloHCT), allowing for expanded donor options. However, there is scant literature examining outcomes of patients with reduced systolic function receiving PTCy. The present study aimed to describe our experience in performing alloHCT in patients with reduced systolic function, including their nonrelapse mortality (NRM), overall survival (OS), and cumulative incidence of early cardiac events (ECEs). We performed a retrospective descriptive analysis using the Johns Hopkins Hematologic Malignancy database. From 2017 through 2021, 1118 consecutive patients underwent alloHCT with nonmyeloablative (NMA) conditioning and PTCy. Forty-three of those patients had a pretransplantation left ventricular ejection fraction (LVEF) ≤45% measured by transthoracic echocardiography. Patients whose LVEF improved on treatment prior to transplantation were also included. These 2 cohorts were stratified into 2 groups-heart failure with reduced ejection fraction (HFrEF) and heart failure with recovered ejection fraction (HFrecEF)-and subgroup analyses compared NRM, OS, and cumulative incidence of ECEs, including arrhythmia, coronary artery disease, reduction in LVEF, and pericardial effusion, within 100 days post-transplantation. The median LVEF was 40% to 45% (range, 30% to 45%) for the 31 patients undergoing transplantation with HFrEF and 35% to 40% (range, 20% to 45%) for the 12 patients with HFrecEF. The NRM for all 43 patients was 16% (95% confidence interval [CI], 5% to 27%) at 100 days and 23% (95% CI, 11% to 36%) at 2 years. The NRM was 23% (95% CI, 8% to 38%) at 100 days and 26% (95% CI, 10% to 42%) at 2 years for the HFrEF cohort and 0 at 100 days and 18% (95% CI, 0 to 41%) at 2 years for the HFrecEf cohort. The OS at 3 years was 41% (95% CI, 26% to 62%), 40% (95% CI, 25% to 65%) and 38% (95% CI, 14% to 100%) in the combined, HFrEF, and HFrecEF cohorts, respectively. The cumulative incidence of any ECE was 37.2% (95% CI, 22% to 51.9%), including 39% of HFrEF subjects and 33% of HFrecEF subjects. Grade ≥3 toxicities were seen in 56% of patients. Reduced ejection fraction was the most common ECE. One death was attributable to a cardiac etiology. Cardiac toxicities seemed to be more frequent and severe in patients with a history of systolic dysfunction, but this did not lead to worse survival outcomes. This study adds to and extends the existing literature supporting the use of NMA conditioning and PTCy in patients with systolic dysfunction.

Fifty years of BMT: risk stratification, donor matching, and stem cell collection for transplantation.

In this review, we discuss recipient risk assessment for allo-HCT regarding comorbidities present at baseline to predict non relapse mortality. We further reviewed the incorporation of remission status and cytogenetic risk prior to allograft transplantation to predict relapse rates for hematologic malignancies. HCT-CI and DRI are tools available to physicians to assess the risk-benefit of allo-HCT in patients referred for transplantation. Next, we discuss our algorithm for donor selection and criteria for donor selection in case matched donors are not available. Finally, we discuss our approach for stem cell mobilization, especially in donors failing G-CSF, and our approach for the use of plerixafor and data supporting its use.

What Influences the Decision to Proceed to Transplant for Patients With AML in First Remission?

Although allogeneic hematopoietic cell transplantation (allo-HCT) remains the backbone of curative treatment for the majority of fit adults diagnosed with AML, there is indeed a subset of patients for whom long-term remission may be achieved without transplantation. Remarkable changes in our knowledge of AML biology in recent years has transformed the landscape of diagnosis, management, and treatment of AML. Specifically, markedly increased understanding of molecular characteristics of AML, the expanded application of minimal/measurable residual diseases testing, and an increased armamentarium of leukemia-directed therapeutic agents have created a new paradigm for the medical care of patients with AML. An attempt is herein made to decipher the decision to proceed to transplant for patients with AML in first complete remission on the basis of the current best available evidence. The focus is on factors affecting the biology and treatment of AML itself, rather than on variables related to allo-HCT, an area characterized by significant advancements that have reduced overall therapy-related complications. This review seeks to focus on areas of particular complexity, while simultaneously providing clarity on how our current knowledge and treatment strategies may, or may not, influence the decision to pursue allo-HCT in patients with AML.

Novel strategies to prevent and overcome relapse after allogeneic hematopoietic cell transplantation in acute lymphoblastic leukemia.

The outcome of B-cell acute lymphoblastic leukemia (B-ALL) has improved over time with the incorporation of multi-agent chemotherapy in the treatment landscape as well as the recent approval of immunotherapeutic agents allowing a larger proportion of patients to undergo allogeneic hematopoietic cell transplantation (allo-HCT) which is still considered a potential curative approach. However, relapse post-transplant is still occurring and constitutes a common cause of treatment failure in B-ALL. The present review aims to discuss the novel strategies and therapies used to prevent and overcome relapse post allo-HCT in patients with ALL, focusing on the role of tyrosine kinase inhibitors in Philadelphia chromosome positive B-ALL, the role of innovative agents such as blinatumomab and inotuzumab ozogamicin, and finally the role of cellular therapy.

Maintenance therapy after allogeneic hematopoietic stem cell transplantation for patients with multiple myeloma.

In the last two decades, proteasome inhibitors (PIs), immunomodulatory drugs (IMiDs), and monoclonal antibodies have greatly improved the overall survival of patients with multiple myeloma. However, multiple myeloma remains incurable, and high-risk patients have poor long-term survival. Although allogeneic hematopoietic stem cell transplantation (allo-HCT) is not considered standard therapy because of relatively high transplant-related mortality and relapse rates, the graft-versus-myeloma (GVM) effect makes it a potentially curative therapy. Therefore, allo-HCT remains a treatment option for younger patients and those with high-risk myeloma. Maintenance therapy with novel agents has recently been attempted to reduce relapse in patients undergoing allo-HCT, but its effectiveness remains unclear. This review focuses on the role of maintenance therapy after allo-HCT in patients with myeloma. Maintenance therapy using IMiDs and/or PIs after allo-HCT may be effective in reducing relapse or improving response because it may prevent early progression before achievement of the GVM effect or enhance the GVM effect. However, care must be taken to avoid complications, such as graft-versus-host disease. Further studies are necessary to determine the optimal maintenance drugs, drug combinations, dosing, start timing, and number of cycles.

Total body irradiation plus fludarabine versus busulfan plus fludarabine as a myeloablative conditioning for adults with acute myeloid leukemia treated with allogeneic hematopoietic cell transplantation. A study on behalf of the Acute Leukemia Working Party of the EBMT.

Cyclophosphamide is frequently substituted with fludarabine (Flu) in conditioning regimens before allogeneic hematopoietic cell transplantation (allo-HCT). We aimed to compare retrospectively, total body irradiation (12 Gy) plus Flu (FluTBI12) versus busulfan (Bu) plus Flu (FB4) as a myeloablative conditioning before allo-HCT in patients with acute myeloid leukemia (AML). Out of 3203 patients who met the inclusion criteria, 109 patients treated with FluTBI12 and 213 treated with FB4 were included in a final matched-pair analysis. In both groups, median patient age was 41 years, first or second complete remission (CR1/CR2) proportion was 78%/22%, allo-HCT from an unrelated donor was performed in 78% of patients. The probabilities of leukemia-free survival and overall survival at 2 years in FluTBI12 and FB4 groups were 65% vs. 60% (p = 0.64) and 70% vs. 72% (p = 0.87), respectively. The cumulative incidence of relapse was 19% vs. 29% (p = 0.11), while non-relapse mortality was 16% vs. 11%, respectively (p = 0.13). There were no statistical differences in both acute and chronic graft-versus-host disease (GVHD) incidence. The probability of GVHD-free, relapse-free survival (GRFS) was 49% for both groups. FluTBI12 and FB4 are comparable myeloablative regimens before allo-HCT in AML patients transplanted in CR1 and CR2.

Busulfan, fludarabine, and melphalan are effective conditioning for pediatric and young adult patients with myeloid malignancies underdoing matched sibling or alternative donor transplantation.

Allogeneic hematopoietic cell transplantation (allo-HCT) remains a curative option for patients with high-risk myeloid malignancies. We present our 10-year experience (October 2012 to October 2021) of consecutive allo-HCT in patients with myeloid malignancies treated on the pediatric HCT service and conditioned with myeloablative targeted dose-busulfan (BU), fludarabine (FLU), and melphalan (MEL). Twenty-three children, adolescents, and young adult patients (CAYA) (median age 15.4years) with acute myeloid leukemia (AML, n = 17), myelodysplastic syndrome (MDS, n = 4), or chronic myeloid leukemia (CML, n = 2) underwent allo-HCT post-BU-FLU-MEL. Four patients had treatment-related AML/MDS. Donor/stem cell source was matched sibling donor (MSD) PBSC (n = 7), matched unrelated donor (MUD) PBSC (n = 2), umbilical cord blood (UCB) (n = 3), or haploidentical-BMT (n = 11). Risk stratification was low (n = 2), intermediate (n = 15), high (n = 3), and very high risk (n = 1). The two patients with CML had failed tyrosine kinase inhibitor therapies. With a median follow-up of 41.6months, the relapse rate is only 4.5% with an overall survival (OS) 100%, progression-free survival (PFS) 95.5%, and graft-versus-host-free-relapse-free survival (GRFS) 67.8%. The donor source and the acute graft-versus-host disease (GvHD) prophylaxis regimen significantly impacted grade II-IV aGvHD 66.7% versus 19.2% (p = .039) and chronic graft-versus-host-disease (cGvHD) 66.7% versus 0% (p = .002) in the patients receiving MSD or MUD PBSC compared to haplo-BMT, respectively, resulting in improved GRFS in haplo-BMT, 83.3% compared to 40% matched donor peripheral blood stem cell transplant (PBSCT) (p = .025). Our results demonstrate that BU-FLU-MEL is efficacious conditioning for disease control in young patients with myeloid malignancies undergoing MSD or alternative donor allo-HCT, but in the setting of PBSC grafts with cyclosporine A-methotrexate (CSA-MTX) GvHD prophylaxis, it results in an unacceptably high incidence of GvHD.

Allogeneic Hematopoietic Cell Transplantation in Patients with Relapsed or Refractory Acute Leukemia

Introduction: Current guidelines support allogeneic hematopoietic cell transplantation (allo-HCT) in patients with acute leukemia who achieve complete remission (CR) and are at high risk for relapse. Patients with primary refractory disease or those refractory to re-induction therapy after relapse have a poor prognosis in the absence of allo-HCT. While several studies have addressed the role of allo-HCT in those settings, the measurable benefit of allo-HCT has not been defined in such patients. Most previous studies have included patients who received myeloablative conditioning and did not address the possible impact of molecular genetic risk factors. Objective: The present study assessed outcomes of allo-HCT in patients with refractory or relapsed (R/R) acute leukemia receiving myeloablative (MAC) or reduced intensity conditioning (RIC) regimens. Our goal was to identify novel risk factors associated with improved outcomes to aid patient selection in the setting of R/R acute leukemia. Methods: Patients with R/R acute leukemia undergoing allo-HCT at Memorial Sloan Kettering Cancer Center (MSK) between 2009 and 2020 were included. Patients had a marrow blast count of 5% or more at the time of allo-HCT and were classified into one of the following categories: primary induction failure (PIF), at least 2 lines of induction therapy; not in CR (NCR), no more than one line of induction therapy; untreated relapse (UR); and refractory relapse (RR), no remission after at least one line of re-induction therapy for relapse. Results: We identified 101 patients with acute myeloid leukemia (AML; n=94), acute lymphoblastic leukemia (ALL; n=3), biphenotypic acute leukemia (n=2), and plasmacytoid dendritic cell leukemia (n=2). Table 1 depicts patient and transplant characteristics. Median blast count at the time of allo-HCT was 8% (IQR, 5%,15%). 37 patients had at least one genomic alteration, and 30 patients had circulating blasts at the time of transplant. Grafts were from HLA-identical siblings in 30 patients, from HLA-matched unrelated donors in 51 patients and from HLA-mismatched or HLA-haploidentical donors in 20 patients. 61 and 40 patients received MAC and RIC, respectively. Graft source was unmodified bone marrow (n=8), unmodified peripheral blood stem cells (PBSC; n=80), or CD34+ cellselected peripheral blood stem cells (n=7). Overall survival (OS) at 4 years was 25% (95% CI: 18%, 35%). In univariate analysis, RIC (HR 1.71, p=0.035), presence of circulating blasts (HR 2.21, p=0.002), and high pre-transplant ferritin levels (HR 1.43, p=0.049) were associated with inferior OS. In multivariate analysis, RIC was associated with reduced OS. The 4-year cumulative incidence of relapse/disease progression and non-relapse mortality (NRM) was 54% (95% CI: 43%, 63%) and 24% (CI, 16%, 33%) respectively. In univariate analysis, RIC, presence of circulating blasts, and elevated pre-transplant ferritin levels were associated with increased NRM. In multivariate analysis, RIC and elevated pre-transplant ferritin levels were associated with high NRM. The cumulative incidence of acute graft-vs-host disease (aGVHD) was 45% (95% CI: 35%, 54%) at day 100. There was no statistically significant effect of genomic and molecular parameters on NRM and OS. However, high risk molecular mutations (TP53, RUNX1, ASXL1 or FLT3-ITD) had borderline association with relapse/disease progression (HR 1.7, p=0.073). Conclusion: Allo-HCT provides durable remission in a select group of patients with relapsed or refractory acute leukemia with an OS of 25% at 4 years. The presence of circulating blasts and elevated ferritin levels at the time of allo-HCT was associated with increased NRM and inferior OS in this retrospective analysis. Known high-risk gene mutations did not affect outcomes in this population. The impact of these parameters should be evaluated in a larger cohort of patients. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Measurable Residual Disease Conversion Rate with Consolidation Chemotherapy in Acute Myeloid Leukemia

Background Patients with acute myeloid leukemia (AML) who achieve complete remission (CR) following induction therapy but continue to have measurable residual disease (MRD) have inferior outcomes following allogeneic hematopoietic cell transplant (alloHCT). Determining the historical rate of MRD clearance in response to standard consolidative therapy is needed as an initial step in developing a new therapeutic strategy to clear MRD prior to alloHCT. Methods A multi-institution retrospective analysis was performed on consecutively treated AML patients in morphologic CR with detectable MRD post-induction therapy who received standard chemotherapy consolidation from January 2016 to December 2021. MRD was measured by multiparametric flow cytometry (MPFC, sensitivity 0.01-0.1%), next generation sequencing (NGS, sensitivity 1-5%), real-time quantitative PCR (qPCR, sensitivity 1:100,000-0.5%), and/or fluorescence in situ hybridization (FISH)/karyotype (sensitivity 1-5%). Any detectable disease-related abnormalities were considered to be evidence of MRD for the purpose of this study. Results Eighty-three patients met inclusion criteria for this analysis, with a median age at diagnosis of 51 years (IQR 43-63). Adverse-risk disease by ELN 2017 criteria was observed in 36 patients (43%). The majority received induction therapy with "7+3" (cytarabine + idarubicin or daunorubicin, 77 patients, 93%), and most (71 patients, 86%) required only 1 line of therapy to achieve CR. At the time of CR following induction therapy, 35 patients (42%) had MRD detected by MPFC, 38 patients (46%) had MRD detected by NGS, 10 patients (12%) had MRD detected by qPCR, and 32 patients (39%) were found to have an abnormal FISH or karyotype. Twenty-eight patients had MRD detected by more than 1 method. Consolidation therapy consisted of intermediate-dose cytarabine (defined as <3 g/m2, 41 patients, 49%) or high-dose cytarabine (defined as 3 g/m2, 39 patients, 47%) in all patients, except for 3 who received daunorubicin and cytarabine (liposomal) consolidation. The number of cycles of cytarabine consolidation were 1 cycle (36 patients, 43%), 2 cycles (23 patients, 28%), 3 cycles (15 patients, 18%), and 4 cycles (9 patients, 11%), respectively. Sixteen patients received cytarabine consolidation in combination with another agent including sorafenib (1 patient), midostaurin (10 patients), gilteritinib (1 patient), enasidenib (1 patient), and gemtuzumab (3 patients). In response to consolidation therapy, 27 of the 83 patients with measurable disease converted to MRD-negative (33%) after all given cycles of consolidation cytarabine. Of the 35 patients whose AML had MRD detected by MPFC prior to consolidation, 17 converted to MRD-negative (49%). Of the 38 patients whose AML had MRD detected by NGS prior to consolidation, 6 converted to MRD-negative (16%). Of the 10 patients whose AML had MRD detected by qPCR prior to consolidation, 6 converted to MRD-negative (60%). Of the 32 patients whose AML had MRD detected by FISH or karyotype prior to consolidation, 13 converted to MRD-negative (41%). Of note, 22 patients developed progressive disease following consolidation therapy (and therefore also did not achieve MRD-negativity). Multivariable logistic regression was performed to assess potential associations with MRD conversion during consolidation chemotherapy. Older age decreased the odds of conversion of AML to MRD-negative (OR = 0.96, 95% CI 0.92-1.00, p = 0.04). Higher ELN risk category, higher dose of cytarabine, and more cycles of consolidation did not affect the likelihood of conversion of AML to MRD-negative. Fifty-five patients received alloHCT following consolidation therapy. Thirty-one of these patients had AML with MRD detected post-consolidation, of whom 14 had MRD measured by MPFC. With a median follow-up time of 437 days post-transplant (IQR 151-914), two-year progression-free survival post-transplant was 57% in AML patients with MRD detected post-consolidation compared to 71% in AML patients with no MRD (p = 0.28). Conclusions The rate of MRD eradication with standard consolidation chemotherapy in AML is suboptimal. Combined with the known poor outcomes after alloHCT in patients with AML and detectable MRD pre-transplant, this demonstrates an unmet need to develop a new therapeutic strategy for eradicating MRD after induction therapy. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Efficacy of a Second Allogeneic Hematopoietic Cell Transplant in Relapsed Acute Myeloid Leukemia: Results of a Systematic Review and Meta-Analysis

Allogeneic hematopoietic cell transplantation (allo-HCT) remains the only known treatment modality that can offer the possibility of cure for acute myeloid leukemia (AML). Unfortunately, relapse and disease progression still occur in more than one third of cases even when patients are allografted in complete hematologic remission (CR). Treatment of AML relapsing after a first allo-HCT is particularly challenging. A second allo-HCT is offered to patients considered fit for the procedure, but reported outcomes have been conflicting. To perform a systematic review and meta-analysis to assess the totality of evidence on the role of a second allo-HCT in patients with AML, we performed a comprehensive literature search using PUBMED/MEDLINE and EMBASE on August 25, 2021, and extracted clinical outcome data relating to benefits (CR, overall survival [OS], and progression-free/disease-free survival [PFS/DFS]) and harms (acute and chronic graft-versus-host disease, non-relapse mortality [NRM], and relapse). The search identified 821 studies. Only 20 studies (n = 2772 patients) met our inclusion criteria. A second allo-HCT resulted in pooled CR, OS, PFS/DFS, NRM and relapse rates of 67%, 34%, 30%, 27%, and 51%, respectively. OS was 2-fold higher when the second allo-HCT was performed in CR (38% versus 17%) and 3-fold higher in patients who had a later relapse from the first allo-HCT (34% versus 10%). There was no apparent difference in pooled OS (hazard ratio = 1.01; 95% confidence interval, 0.78-1.31; P = .94) whether the same original donor or a different one was used. Notwithstanding several limitations apart from the high heterogeneity among included studies, this analysis shows that a second allo-HCT is a reasonable treatment option for relapsed AML. The procedure appears to be more effective when performed in CR and in patients who had a later relapse from the first allo-HCT. The high pooled relapse rates exceeding 50%, even when receiving the second allo-HCT in CR is worrisome and emphasizes the need to incorporate new therapies whether as post-transplantation maintenance or consolidation to mitigate relapse risk. This analysis was limited to patients receiving a second allo-HCT for the sole purpose of treating AML relapse. Accordingly, we caution against extrapolating these findings to other indications such as treatment of graft failure, poor graft function, or mixed donor chimerism.

P1318: THE IMPACT OF MELPHALAN DOSING IN COMBINATION WITH FLUDARABINE IN CLINICAL OUTCOMES OF PATIENTS WITH ACUTE MYELOID LEUKEMIA AND MYELODYSPLASTIC SYNDROMES RECEIVING ALLO-HCT

Background: Allogenic hematopoietic cell transplant (allo-HCT) is the only curative treatment option for many adults with acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS). Fludarabine (Flu) and melphalan (Mel) reduced intensity conditioning (RIC) regimen is frequently used for older patients and those with comorbidities. Mel dosing based on body surface area raised concerns for patient under- or overdosing in prior report. Aims: Here we studied the impact of Mel dose per kilogram of actual body weight (mg/kg) on clinical outcomes of allo-HCT. Methods: We retrospectively evaluated patients with AML or MDS who underwent allo-HCT from an 8/8 HLA matched donor and received Flu/Mel (Mel dose of 100-140 mg/m2). The objectives were to compare overall survival (OS), relapsed free survival (RFS), non-relapse mortality (NRM), relapse, grade II-IV acute graft vs host disease (aGVHD), chronic GVHD (cGVHD), mucositis and gastrointestinal (GI) toxicity based on Mel mg/kg dosing. We calculated the median Mel mg/kg dose and compared the outcomes of patients receiving median and above versus below median dose. Results: From January 2008 to December 2020, 345 patients underwent allo-HCT with Flu/Mel, all patients received peripheral blood graft, 209 patients transplanted for AML and 136 for MDS. Patient characteristics are presented in Table 1. Median dose of Mel was 3.28 mg/kg (range, 1.61-6.21 mg/kg);173 patients received Mel ≥ 3.28 mg/kg and 172 patients received Mel < 3.28 mg/kg. Median follow up time for the entire study cohort was 36.5 months. For the Mel ≥ 3.28 mg/kg vs. Mel < 3.28 mg/kg groups, median OS was 57.5 months (95% CI: 39.5 – N.E) vs. 46.6 months (95% CI: 28.2 – 109.5, p=0.49) and median RFS was 51.4 months (95% CI: 30.7 – 70.4) vs. 29.7 months (95% CI: 18.1 – 98.0, p=0.36). Similarly, there were no significant differences between the Mel ≥ 3.28 mg/kg and Mel < 3.28 mg/kg groups in 2-year rates of relapse (19.9% vs. 23.8%, p=0.3) and NRM (20.9% vs. 25.4%, p=0.94; Figure 1D). The cumulative incidences of day 100 grade II-IV aGVHD (39.9% vs. 39.0%, p=0.86), grade III-IV aGVHD (9.2% and 9.3%, p=0.99) and moderate/severe cGVHD (67.6% vs.58.4%, p=0.19) were also similar for patients receiving Mel ≥ 3.28 mg/kg vs. Mel < 3.28 mg/kg. On multivariable analysis, the Mel dose/kg had no independent impact on OS, RFS, relapse, NRM, acute and chronic GVHD outcomes. OS was worse with KPS ≤ 80 (HR, 1.51, p=0.014) and HCT-CI ≤ 3 (HR, 1.68, p=0.004), while RFS was worse with KPS ≤ 80 (HR, 1.5, p=0.012), HCT-CI ≥ 3 (HR, 1.72, p=0.002) and high/very high DRI (HR, 1.36, p=0.046). KPS ≤ 80 (HR1.75, p=0.006) and HCT-CI ≥ 3 (HR,1.67, p=0.023) were also associated with higher NRM. Cumulative incidence of any grade mucositis for Mel ≥ 3.28 mg/kg vs. Mel < 3.28 mg/kg was 33.5% vs. 29.1% (p=0.37) and of grade III mucositis was 12.1% vs. 24.0%. None of the study patients experienced grade IV mucositis. Incidence of GI toxicity with non-infectious diarrhea following Flu/Mel chemotherapy of any grade was 65.3% vs. 60.5%, (p=0.35) and of grade III was 16.8% vs. 19.2% for patients received Mel ≥ 3.28 mg/kg vs. Mel < 3.28 mg/kg, respectively. We observed no grade IV GI toxicity on our study patients. Image:Summary/Conclusion: Our study showed no significate influence of Mel mg/kg dose on clinical outcomes of allo-HCT in patients with AML and MDS receiving Flu/Mel RIC. Similarly, mucositis and GI toxicities were not affected by the Mel mg/kg dose. These findings support Mel dosing based on body surface area when combined with Flu as RIC regimen used for allo-HCT.

Outcomes of Allogeneic Hematopoietic Cell Transplantation in T Cell Prolymphocytic Leukemia: A Contemporary Analysis from the Center for International Blood and Marrow Transplant Research

T cell prolymphocytic leukemia (T-PLL) is a rare, aggressive malignancy with limited treatment options and poor long-term survival. Previous studies of allogeneic hematopoietic cell transplantation (alloHCT) for T-PLL are limited by small numbers, and descriptions of patient and transplantation characteristics and outcomes after alloHCT are sparse. In this study, we evaluated outcomes of alloHCT in patients with T-PLL and attempted to identify predictors of post-transplantation relapse and survival. We conducted an analysis of data using the Center for International Blood and Marrow Transplant Research database on 266 patients with T-PLL who underwent alloHCT between 2008 and 2018. The 4-year rates of overall survival (OS), disease-free survival (DFS), relapse, and treatment-related mortality (TRM) were 30.0% (95% confidence interval [CI], 23.8% to 36.5%), 25.7% (95% CI, 20% to 32%), 41.9% (95% CI, 35.5% to 48.4%), and 32.4% (95% CI, 26.4% to 38.6%), respectively. In multivariable analyses, 3 variables were associated with inferior OS: receipt of a myeloablative conditioning (MAC) regimen (hazard ratio [HR], 2.18; P < .0001), age >60 years (HR,1.61; P=.0053), and suboptimal performance status, defined by Karnofsky Performance Status (KPS) <90 (HR,1.53; P=.0073). Receipt of an MAC regimen also was associated with increased TRM (HR,3.31; P < .0001), an elevated cumulative incidence of grade II-IV acute graft-versus-host disease (HR,2.94; P=.0011), and inferior DFS (HR,1.86; P=.0004). Conditioning intensity was not associated with relapse; however, stable disease/progression was correlated with increased risk of relapse (HR,2.13; P=.0072). Both in vivo T cell depletion (TCD) as part of conditioning and KPS <90 were associated with worse TRM and inferior DFS. Receipt of total body irradiation had no significant effect on OS, DFS, or TRM. Our data show that reduced-intensity conditioning without in vivo TCD (ie, without antithymocyte globulin or alemtuzumab) before alloHCT was associated with long-term DFS in patients with T-PLL who were age ≤60 years or who had a KPS>90 or chemosensitive disease.

Primary Central Nervous System Involvement at Initial Diagnosis Remains an Independent Risk Factor for Relapse in Acute Lymphoblastic Leukemia after Allogeneic Hematopoietic Cell Transplantation in CR1

Background: A recent study from the Acute Leukemia Working Party of EBMT demonstrated that outcomes of allogeneic hematopoietic cell transplantation (allo-HCT) for adults with acute lymphoblastic leukemia (ALL) have improved significantly over time and that total body irradiation (TBI) should be considered as the preferable type of myeloablative conditioning (MAC). This study, however, did not compare outcomes of allo-HCT in patients with CNS involvement (CNS-pos) vs. those without CNS disease (CNS-neg).Study population: Here, we evaluate post allo-HCT outcomes of 547 patients (CNS-pos at initial presentation=96, CNS-neg=451) who underwent the procedure in first complete remission (CR1) between 2009 and 2019 at an EBMT participating transplant center. The distribution of ALL subtypes were as follows: CNS-pos (Ph-neg B ALL=28%, Ph-pos B ALL=27%, and T-cell ALL=45%) and for CNS-neg (Ph-neg B ALL=21%, Ph-pos B ALL=44%, and T-cell ALL=35%), p=0.01. The primary endpoint was leukemia-free survival (LFS).Results: The median follow up was not statistically different between the CNS-pos (78.7 months) and the CNS-neg group (67.2 months), p=0.58. Patients in the CNS-pos group were younger (median age 31.3 vs. 39.7 years, p=0.004), received the procedure more recently (median year 2012 vs. 2010, p=0.003), were less likely to have a Karnofsky score of equal or higher than 90 (70.8% vs. 81.9%, p=0.017), or to have received peripheral blood stem cells (PBSC) (61.5% vs. 72.7%, p=0.028). The groups did not differ in regards to donor source (URD, 50% vs. 56.5%, p=0.24) or the intensity of the preparative regimen (MAC, 82.3% vs. 85.6%, p=0.41). In multivariate analysis, CNS-pos were associated with higher cumulative incidence of relapse (HR=1.58 (95%CI=1.06-2.35), P=0.025) and a trend for an inferior leukemia-free survival (LFS) (HR=1.38 (95%CI=0.99-1.92), p=0.057), but did not adversely impact overall survival (OS) (HR=1.28 (95%CI=0.89-1.85), p=0.18). A subgroup multivariate analysis limited to patients with CNS-pos showed that prescribing a TBI MAC regimen (vs. others) results in a lower cumulative incidence of relapse (HR=0.35 (95%CI=0.15-0.79), p=0.012) and better LFS (HR=0.43 (95%CI=0.22-0.83), p=0.01) and OS (HR=0.44 (95%CI=0.21-0.92), p=0.03). Use of PBSC (vs. BM) was also independently associated with better OS (HR=0.53 (95%CI=0.29-0.99), p=0.046).Conclusion: Notwithstanding the inherent limitations of registry data, particularly ascertaining the absence of CNS involvement in the CNS-neg group, our results show CNS involvement as an independent risk factor for relapse following allo-HCT. Our data support, nonetheless, the choice of a TBI-based MAC regimen in this group of patients but stresses the need for close monitoring of relapse after allo-HCT. DisclosuresLabopin: Jazz Pharmaceuticals: Honoraria. Bazarbachi: Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Hikma: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Astra Zeneca: Membership on an entity's Board of Directors or advisory committees. Mielke: Immunicum: Other: Data safety monitoring board; DNA Prime SA: Speakers Bureau; Gilead/KITE: Other: Travel support, Expert panel ; Miltenyi: Other: Data safety monitoring board; Novartis: Speakers Bureau; Celgene/BMS: Speakers Bureau. Socie: Alexion: Research Funding. Huynh: Jazz Pharmaceuticals: Honoraria. Yakoub-Agha: Jazz Pharmaceuticals: Honoraria. Giebel: Janssen: Honoraria, Speakers Bureau; Pfizer: Consultancy, Honoraria, Speakers Bureau; Novartis: Consultancy, Honoraria, Speakers Bureau; Amgen: Consultancy, Honoraria, Speakers Bureau. Peric: Therakos, Servier, MSD, Astellas, Novartis, Abbvie, Pfizer: Honoraria. Mohty: Sanofi: Honoraria, Research Funding; Pfizer: Honoraria; Novartis: Honoraria; Takeda: Honoraria; Jazz: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Gilead: Honoraria; Celgene: Honoraria, Research Funding; Bristol Myers Squibb: Honoraria; Astellas: Honoraria; Amgen: Honoraria; Adaptive Biotechnologies: Honoraria.

Outcomes of Allogeneic Hematopoietic Stem Cell Transplantation in Secondary Central Nervous System Lymphoma

Introduction:Aggressive non-Hodgkin's lymphoma (aNHL) with secondary central nervous system (sCNS) involvement has a poor prognosis. Studies have reported a response to induction treatment as low as 35%, leaving less than half of patients eligible for autologous stem cell transplant (ASCT). Outcomes of patients in these clinical scenarios are dismal and treatment is ill-defined. Small case series suggest chimeric antigen receptor (CAR)-T cell therapy may play a role in the management of relapsed/refractory (R/R) B-cell lymphoma (BCL) with sCNS involvement, but follow-up is limited and response duration is uncertain. Allogeneic hematopoietic stem cell transplant (alloHCT) offers a durable remission for a subset of patients with R/R systemic aNHL primarily mediated through a graft versus lymphoma (GVL) effect, but it is unclear if GVL properties include the immune-privileged CNS. The present study aims to describe outcomes of a cohort of patients with R/R aggressive B- and T-cell NHL with sCNS involvement who underwent alloHCT at a single academic institution.Methods:This is a retrospective analysis that includes all patients with R/R aNHL with sCNS involvement who underwent alloHCT at the University of California, Los Angeles from 2005-2020. The UCLA Institutional Board Review approved this study. Relevant clinical data was extracted from medical records. Hematopoietic cell transplantation comorbidity index (HCT-CI) and time to neutrophil and platelet engraftment were measured according to Center for International Blood and Marrow Transplant Research criteria.Results:Ten patients were included (3 females, 7 males). Histologic subtypes included anaplastic BCL (1), mantle cell lymphoma (1), blastic natural killer-cell lymphoma (1), peripheral T-cell lymphoma, not otherwise specified (1), primary mediastinal BCL (1), and diffuse large B-cell lymphoma (DLBCL) (non-germinal center=3, germinal center-like=2). Two DLBCL patients had histologic transformed lymphoma (follicular lymphoma =1, chronic lymphocytic lymphoma = 1). Four patients had sCNS involvement at the time of initial diagnosis or during frontline treatment; the remaining 6 patients developed sCNS lymphoma at relapse. sCNS lymphoma was identified in the parenchymal (n=4), leptomeningeal (n=3), or both (n=3) compartments.The median age at the time of alloHCT was 49.5 (range 28-68), and 1 patient was ˃ 60. At the time of alloHCT, 1 patient had residual disease in the CNS and the remaining 9 patients were in a complete remission. Eight patients received ˃ 3 prior lines of therapy, and 3 patients failed prior ASCT. HCT-CI scores were 0 (n=1), 1 (n=2), 2 (n=3), 3 (n=1), and unknown (n = 3). Donor types included 10/10 matched related (3), 10/10 matched unrelated (4), 9/10 mismatched related (1), and double umbilical cord blood (2). Graft source was peripheral blood in 8 patients and cord blood in 2 patients. Conditioning regimens included myeloablative, reduced intensity and non-myeloablative in 6, 3 and 1 patient(s), respectively. Six patients received total body irradiation-containing conditioning. The average time to neutrophil engraftment was 18 days (range 11-29), and the average time to platelet engraftment was 26.5 days (range 18-59). One patient had primary graft failure.Of the 6 patients with day 100 disease reassessment (CR at time of alloHCT=5, PR in CNS at time of alloHCT=1), all were in CR. With a median follow-up of 341 days, 2 patients relapsed (CNS=1 and systemic = 1), and 6 patients died. Cause of death included infection (n=3), lymphoma (n=1), primary graft failure (n=1), and organizing pneumonia (n=1). Six patients developed acute graft versus host disease (GVHD) (grade 1-2, n=1; grade 3, n=5), and 4 patients developed chronic GVHD (score 1-2, n= 2; score 3, n=2). The median overall and progression-free survival for the entire cohort was 341 days (range 23-4825) and 268.5 days (range 23-4825), respectively.Conclusions:AlloHCT in patients with R/R aNHL with sCNS involvement is feasible and may provide a durable response in a subset of patients. Four patients remained alive and free of disease one year post-alloHCT and one patient converted from a PR to a CR in the CNS 100 days post-alloHCT, suggesting effective donor immune surveillance within the CNS. Transplant-related morbidity and mortality limits the widespread application of this therapeutic modality and less toxic approaches are urgently needed. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.