CD19-targeted chimeric antigen receptor T cell therapy in two patients with multiple sclerosis.

BACKGROUND: Progressive multiple sclerosis (MS) is characterized by compartmentalized smoldering neuroinflammation caused by the proliferation of immune cells residing in the central nervous system (CNS), including B cells. Although inflammatory activity can be prevented by immunomodulatory therapies during early disease, such therapies typically fail to halt disease progression. CD19 chimeric antigen receptor (CAR)-T cell therapies have revolutionized the field of hematologic malignancies. Although generally considered efficacious, serious adverse events associated with CAR-T cell therapies such as immune effector cell-associated neurotoxicity syndrome (ICANS) have been observed. Successful use of CD19 CAR-T cells in rheumatic diseases like systemic lupus erythematosus and neuroimmunological diseases like myasthenia gravis have recently been observed, suggesting possible application in other autoimmune diseases. METHODS: Here, we report the first individual treatment with a fully human CD19 CAR-T cell therapy (KYV-101) in two patients with progressive MS. FINDINGS: CD19 CAR-T cell administration resulted in acceptable safety profiles for both patients. No ICANS was observed despite detection of CD19 CAR-T cells in the cerebrospinal fluid. In case 1, intrathecal antibody production in the cerebrospinal fluid decreased notably after CAR-T cell infusion and was sustained through day 64. CONCLUSIONS: CD19 CAR-T cell administration in progressive MS resulted in an acceptable safety profile. CAR-T cell presence and expansion were observed in the cerebrospinal fluid without clinical signs of neurotoxicity, which, along with intrathecal antibody reduction, indicates expansion-dependent effects of CAR-T cells on CD19+ target cells in the CNS. Larger clinical studies assessing CD19 CAR-T cells in MS are warranted. FUNDING: Both individual treatments as well the generated data were not based on external funding.

Graft-versus-host disease and impact on relapse in myelofibrosis undergoing hematopoietic stem cell transplantation.

Allogeneic hematopoietic stem cell transplantation (alloHSCT) remains the only curative treatment for myelofibrosis (MF). Relapse occurs in 10-30% and remains a major factor for dismal outcomes. Previous work suggested that graft-versus-host disease (GVHD) might be associated with risk of relapse. This study included 341 patients undergoing their first (n = 308) or second (n = 33) alloHSCT. Anti-T-lymphocyte or antithymocyte globulin was used for GVHD prophylaxis in almost all patients. Median time to neutrophile and platelet engraftment was 13 days and 19 days, respectively. The cumulative incidence of acute GVHD grade II-IV was 41% (median, 31 days; range, 7-112). Grade III-IV acute GVHD was observed in 22%. The cumulative incidence of chronic GVHD was 61%. Liver was affected in 23% of acute GVHD cases and 46% of chronic GVHD cases. Severe acute GVHD was associated with high non-relapse mortality. The development of acute GVHD grade II and moderate GVHD was an independent factor for reduced risk for relapse after transplantation without increased risk for non-relapse mortality, while especially acute GVHD grade IV was associated with high non-relapse mortality. Last, we identified that ongoing response to ruxolitinib, accelerated-phase MF at time of transplantation and splenectomy prior to transplantation were independent predictors for relapse.

Use of ropeginterferon in inducing graft versus myelofibrosis effect in post-transplant myelofibrosis relapse.

Here, we describe a patient with post-transplant myelofibrosis with chronic graft-versus-host disease (GVHD), who showed successful molecular remission with ropeginterferon with 100% donor chimerism without any flare up of GVHD. He was initially diagnosed with polycythemia vera (PV) which progressed to myelofibrosis after 6 years. The MYSEC (Myelofibrosis Secondary to PV and ET-Prognostic Model) and MTSS (myelofibrosis transplant scoring system) scores were 13.1 and 4, respectively, and the patient was in intermediate risk group. He underwent an allogenic stem cell transplant; however, his disease gradually progressed and was administered two donor lymphocyte infusions with minimal response. A second allogeneic transplant was performed, which led to a persistent molecular remission for more than a decade, although he developed chronic skin graft-versus-host disease (GVHD). The JAK2 V617F levels started to increase 10 years post-transplant with ongoing chronic GVHD and a corresponding decrease in donor chimerism levels. He was administered ropeginterferon, which led to a decrease in JAK 2617F to undetectable levels. A graft versus myelofibrosis effect was attained with reversal to 100% donor chimerism, and he has since maintained a molecular remission with undetectable JAK 2617F levels. Chronic GVHD made him ineligible for donor lymphocyte infusions later. Thus, ropeginterferon was successful in inducing graft versus myelofibrosis effect, leading to a molecular response with no flare up of GVHD. The use of ropeginterferon needs to be further evaluated in larger cohorts of post-transplant myelofibrosis patients.

Donor Lymphocyte Infusion and Molecular Monitoring for Relapsed Myelofibrosis After Hematopoietic Cell Transplantation.

Hematopoietic cell transplantation (HCT) is a curative approach for myelofibrosis patients, but relapse is a major cause of treatment failure. We investigated the effect of donor lymphocyte infusion (DLI) in 37 patients with molecular (n = 17) or hematological relapse (n = 20) after HCT. Patients received median of 2 (range, 1-5) cumulative DLI (total of 91 infusions). Median starting dose was 1 × 106 cells/kg, escalated by half-log ≥6 weeks if no response nor graft-versus-host disease (GvHD) occurred. Median time to first DLI was 40 weeks for molecular relapse versus 145 weeks for hematological relapse. Overall molecular complete response (mCR) at any time was 73% (n = 27) and was significantly higher for initial molecular relapse (88%) versus hematological relapse (60%; P = 0.05). The 6-year overall survival was 77% versus 32% (P = 0.03). Acute GvHD 2-4 occurred in 22% and half of the patients achieved mCR without any GvHD. All patients who relapsed from mCR achieved after first DLI could be salvaged with subsequent DLI, showing long-term survival. No second HCT was needed for molecular relapse versus 6 for hematological relapse. This comprehensive and largest study to date suggests molecular monitoring together with DLI as standard of care and a crucial approach to achieve excellent outcomes in relapsed myelofibrosis.

Impact of TP53 on outcome of patients with myelofibrosis undergoing hematopoietic stem cell transplantation.

TP53 mutations (TP53MTs) have been associated with poor outcomes in various hematologic malignancies, but no data exist regarding its role in patients with myelofibrosis undergoing hematopoietic stem cell transplantation (HSCT). Here, we took advantage of a large international multicenter cohort to evaluate the role of TP53MT in this setting. Among 349 included patients, 49 (13%) had detectable TP53MT, of whom 30 showed a multihit configuration. Median variant allele frequency was 20.3%. Cytogenetic risk was favorable (71%), unfavorable (23%), and very high (6%), with complex karyotype present in 36 patients (10%). Median survival of patients with TP53MT was 1.5 vs 13.5 years for those with wild-type TP53 (TP53WT; P < .001). Outcome was driven by multihit TP53MT constellation (P < .001), showing 6-year survival of 56% for individuals with single-hit vs 25% for those with multihit TP53MT vs 64% for those with TP53WT. Outcome was independent of current transplantation-specific risk factors and conditioning intensity. Similarly, cumulative incidence of relapse was 17% for single-hit vs 52% for multihit vs 21% for TP53WT. Ten patients with TP53MT (20%) presented as leukemic transformation vs only 7 (2%) in the TP53WT group (P < .001). Out of the 10 patients with TP53MT, 8 showed multihit constellation. Median time to leukemic transformation was shorter for multihit and single-hit TP53MT (0.7 and 0.5 years, respectively) vs 2.5 years for TP53WT. In summary, multihit TP53MT represents a very high-risk group in patients with myelofibrosis who are undergoing HSCT, whereas single-hit TP53MT alone showed similar outcome to patients with nonmutated TP53, informing prognostication for survival and relapse together with current transplantation-specific tools.

Peripheral and Portal Venous KRAS ctDNA Detection as Independent Prognostic Markers of Early Tumor Recurrence in Pancreatic Ductal Adenocarcinoma.

BACKGROUND: KRAS circulating tumor DNA (ctDNA) has shown biomarker potential for pancreatic ductal adenocarcinoma (PDAC) but has not been applied in clinical routine yet. We aim to improve clinical applicability of ctDNA detection in PDAC and to study the impact of blood-draw site and time point on the detectability and prognostic role of KRAS mutations. METHODS: 221 blood samples from 108 PDAC patients (65 curative, 43 palliative) were analyzed. Baseline peripheral and tumor-draining portal venous (PV), postoperative, and follow-up blood were analyzed and correlated with prognosis. RESULTS: Significantly higher KRAS mutant detection rates and copy numbers were observed in palliative compared to curative patients baseline blood (58.1% vs 24.6%; P = 0.002; and P < 0.001). Significantly higher KRAS mutant copies were found in PV blood compared to baseline (P < 0.05) samples. KRAS detection in pre- and postoperative and PV blood were significantly associated with shorter recurrence-free survival (all P < 0.015) and identified as independent prognostic markers. KRAS ctDNA status was also an independent unfavorable prognostic factor for shorter overall survival in both palliative and curative cohorts (hazard ratio [HR] 4.9, P = 0.011; HR 6.9, P = 0.008). CONCLUSIONS: KRAS ctDNA detection is an independent adverse prognostic marker in curative and palliative PDAC patients-at all sites of blood draw and a strong follow-up marker. The most substantial prognostic impact was seen for PV blood, which could be an effective novel tool for identifying prognostic borderline patients-guiding future decision-making on neoadjuvant treatment despite anatomical resectability. In addition, higher PV mutant copy numbers contribute to an improved technical feasibility.

Individualized busulfan dosing improves outcomes compared to fixed-dose administration in pre-transplant minimal residual disease-positive acute myeloid leukemia patients with intermediate-risk undergoing allogeneic stem cell transplantation in CR.

Pre-transplant minimal residual disease (MRD) impacts negatively on post-transplant relapse risk in acute myeloid leukemia (AML). Therapeutic drug monitoring by calculating area under the curve (AUC) was developed to optimize busulfan (Bu) exposure. Here, we compared post-transplant outcomes after individualized versus fixed busulfan dosage in intermediate-risk AML who achieved CR prior to allograft focusing on pre-transplant flow-MRD. Eighty-seven patients (median, 56 years) with intermediate-risk AML and pre-transplant flow-MRD ("different from normal") were included. Thirty-two patients received individualized busulfan; 54 fixed dosages. Individualized dosage was adjusted in 25/32 patients: increased, n = 18/25 (72%); decreased: n = 7/25 (28%). After median follow-up of 27 months, we observed lower 3-year relapses (6%, 2%-19% vs. 35%, 23%-49% p = 0.02), improved 3-year leukemia-free survival (LFS) (78%, 54%-91% vs. 55%, 40%-70% p = 0.009) and - overall survival (OS) (82%, 60%-93% vs. 69%, 54%-81% p = 0.05) after individualized compared to fixed Bu. Non-relapsed mortality (NRM) and acute graft versus host disease (GvHD) were not different. In multivariate analysis, fixed Bu showed unfavorable impact on OS (hazard ratio [HR] 4.6, p = 0.044), LFS (HR 3.6, p = 0.018) and relapses (HR 3.6, p = 0.033). Fixed Bu also had unfavorable impact on LFS (3.6, 1.1-12.6, p = 0.041) in pre-transplant MRD-positive patients. Individualized, AUC-based, busulfan is associated with lower relapses in intermediate-risk AML patients allografted in CR and may overcome pre-transplant MRD-positivity.

Molecular monitoring of T-cell kinetics and migration in severe neurotoxicity after real-world CD19-specific chimeric antigen receptor T cell therapy.

CD19-specific chimeric antigen receptor (CD19-CAR) T-cell therapies mediate durable responses in late-stage B-cell malignancies, but can be complicated by a potentially severe immune effector cell-associated neurotoxicity syndrome (ICANS). Despite broad efforts, the precise mechanisms of ICANS are not entirely known, and resistance to current ICANSdirected therapies (especially corticosteroids) has been observed. Recent data suggest that inflammatory cytokines and/or targeting of cerebral CD19-expressing pericytes can disrupt the blood-brain barrier and facilitate influx of immune cells, including CAR T cells. However, specific tools for CD19-CAR T-cell analysis within often minute samples of cerebrospinal fluid (CSF) are not broadly available. Here, we applied our recently developed digital polymerase chain reaction assays to monitor CD19-CAR T-cell kinetics in CSF and blood in real-world patients with neurotoxicity. Consistently, we observed a CAR T-cell enrichment within CSF in ICANS patients with further progressive accumulation despite intense corticosteroid- containing immuno-chemotherapies in a subset of patients with prolonged and therapy-resistant grade 3-4 neurotoxicity. We used next-generation T-cell receptor-b sequencing to assess the repertoire of treatment-refractory cells. Longitudinal analysis revealed a profound skewing of the T-cell receptor repertoire, which at least partly reflected selective expansion of infused T-cell clones. Interestingly, a major fraction of eventually dominating hyperexpanded T-cell clones were of non-CAR T-cell derivation. These findings hint to a role of therapy-refractory T-cell clones in severe ICANS development and prompt future systematic research to determine if CAR T cells may serve as 'door openers' and to further characterize both CAR-positive and non-CAR T cells to interrogate the transcriptional signature of these possibly pathologic T cells.

High Molecular and Cytogenetic Risk in Myelofibrosis Does Not Benefit From Higher Intensity Conditioning Before Hematopoietic Cell Transplantation: An International Collaborative Analysis.

There is no direct evidence to recommend specific conditioning intensities in myelofibrosis undergoing allogeneic hematopoietic cell transplantation, especially in the molecular era. We aimed to compare outcomes of reduced intensity (RIC) or myeloablative conditioning (MAC) transplantation in myelofibrosis with molecular information. The study included 645 genetically annotated patients (with at least driver mutation status available), of whom 414 received RIC and 231 patients received MAC. The median follow-up time from transplantation was 6.0 years for RIC and 9.4 years for MAC. The 6-year overall survival rates for RIC and MAC were 63% (95% confidence interval [CI], 58%-68%) and 59% (95% CI, 52%-66%; P = 0.34) and progression-free survival was 52% (95% CI, 47%-57%) and 52% (95% CI, 45%-59%; P = 0.64). The 2-year cumulative incidence of nonrelapse mortality was 26% (95% CI, 21%-31%) for RIC and 29% (95% CI, 23%-34%) for MAC (P = 0.51). In terms of progression/relapse, the 2-year cumulative incidence was 10% (95% CI, 5%-19%) for RIC and 9% (95% CI, 4%-14%) for MAC (P = 0.46). Higher intensity conditioning did not seem to improve outcomes for higher-risk disease, according to mutational, cytogenetic, and clinical profile. In contrast, patients with reduced performance status, matched unrelated donors, and ASXL1 mutations appeared to benefit from RIC in terms of overall survival.

Population Pharmacokinetics of Busulfan and Its Metabolite Sulfolane in Patients with Myelofibrosis Undergoing Hematopoietic Stem Cell Transplantation.

For patients with myelofibrosis, allogeneic hematopoietic stem cell transplantation (allo-HSCT) remains the only curative treatment to date. Busulfan-based conditioning regimens are commonly used, although high inter-individual variability (IIV) in busulfan drug exposure makes individual dose selection challenging. Since data regarding the IIV in patients with myelofibrosis are sparse, this study aimed to develop a population pharmacokinetic (PopPK) model of busulfan and its metabolite sulfolane in patients with myelofibrosis. The influence of patient-specific covariates on the pharmacokinetics of drug and metabolite was assessed using non-linear mixed effects modeling in NONMEM®. We obtained 523 plasma concentrations of busulfan and its metabolite sulfolane from 37 patients with myelofibrosis. The final model showed a population clearance (CL) and volume of distribution (Vd) of 0.217 L/h/kg and 0.82 L/kg for busulfan and 0.021 L/h/kg and 0.65 L/kg for its metabolite. Total body weight (TBW) and a single-nucleotide polymorphism of glutathione-S-transferase A1 (GSTA1 SNP) displayed a significant impact on volume of distribution and metabolite clearance, respectively. This is the first PopPK-model developed to describe busulfan's pharmacokinetics in patients with myelofibrosis. Incorporating its metabolite sulfolane into the model not only allowed the characterization of the covariate relationship between GSTA1 and the clearance of the metabolite but also improved the understanding of busulfan's metabolic pathway.

Post-Transplantation Day +100 Minimal Residual Disease Detection Rather Than Mixed Chimerism Predicts Relapses after Allogeneic Stem Cell Transplantation for Intermediate-Risk Acute Myelogenous Leukemia Patients Undergoing Transplantation in Complete Remission.

Chimerism and minimal residual disease (MRD) are suggested to be prognostic for post-transplantation relapse in patients with acute myelogenous leukemia (AML). Nevertheless, the predictive value of both approaches in homogeneous populations remains underinvestigated. Here we suggest that MRD may have greater predictive value for relapse than mixed chimerism (MC) in intermediate-risk AML patients. Seventy-nine patients with intermediate-risk AML (40 males; median age, 57 years [range, 19 to 77 years]) were included. MRD detection on day +100 was performed in bone marrow via multiparameter flow cytometry (MFC) and quantitative real-time PCR (qPCR) for patients with an NPM1 mutation. Chimerism analysis was performed in peripheral blood. MC was defined as the persistence of <99.9% of donor alleles. The area under the receiver operating characteristic curve was highest for qPCR-MRD (.93), followed by MFC-MRD (.80) and MC (.65). The highest rate of relapse at 3 years was observed in day +100 qPCR-MRD-positive patients (100%), followed by MFC-MRD-positive patients (55%; P < .001). No patients with MC and without detectable MRD experienced relapse. The median 3-year overall survival (OS) and leukemia-free survival (LFS) for patients with MC without detectable MRD were both 86% (range, 61% to 96%), significantly higher than the values in day +100 MFC-MRD-positive patients (OS, 61% [range, 36% to 84%]; LFS: 30% [range, 11% to 59%]) and with day +100 qPCR-MRD-positive patients (OS: 17% [range, 3% to 56%], P = .001; LFS: 0%, P < .001). In patients with intermediate-risk AML, the qPCR-MRD on day +100 was highly predictive for relapse and long-term survival after allogeneic stem cell transplantation, followed closely by MFC-MRD. In contrast, chimerism status had limited predictive potential. Thus, molecular and flow cytometry MRD monitoring rather than MC in the first several months post-transplantation can identify patients at increased risk of relapse who may benefit from early post-transplantation preemptive intervention.

Comparison of single copy gene­based duplex quantitative PCR and digital droplet PCR for monitoring of expansion of CD19­directed CAR T cells in treated patients.

Chimeric antigen receptor (CAR) T cell therapy with axicabtagene ciloleucel, tisagenlecleucel and brexucabtagen ciloleucel has been adopted as the standard of care for patients with refractory and/or relapsed CD19­positive lymphoid malignancies. Monitoring of kinetics of CAR T cells after administration is crucial for patient follow­up and important to guide clinical decisions for patients subjected to CAR T cell therapy. Information of transgene copies within a CAR T cell product prior to administration, i.e. vector copy numbers, is of high importance to warrant patient safety. However, experimental assays for quantitative CAR T cell monitoring in the open domain are currently lacking. Several institutions have established in­house assays to monitor CAR T cell frequencies. In the present study, the quantitative (q)PCR assay established at the Heidelberg University Hospital (Heidelberg, Germany), i.e. single copy gene­based duplex qPCR, was compared with the digital droplet PCR assay established at the University Medical Center Hamburg­Eppendorf (Hamburg, Germany). Both methods that were independently developed enable accurate and comparable CAR T cell frequency assessment and are useful in the clinical setting.

Reduced intensity hematopoietic stem cell transplantation for accelerated-phase myelofibrosis.

Accelerated-phase myelofibrosis, currently defined by circulating blasts 10% to 19%, usually confers very high risk for progression and poor outcome. The outcome of hematopoietic stem cell transplantation for accelerated-phase myelofibrosis has not been evaluated yet. We analyzed the outcome of 349 clinically and genetically annotated patients with primary or secondary myelofibrosis undergoing reduced intensity transplantation, of whom 35 had accelerated-phase myelofibrosis. In comparison with chronic-phase (<10% blasts) myelofibrosis, median leukocyte counts were higher, more patients had constitutional symptoms, and RAS mutations were detected more frequently in the accelerated-phase group. After a median follow-up of 5.9 years, estimated 5-year overall survival was 65% (95% confidence interval [CI], 49% to 81%) vs 64% (95% CI, 59% to 69%) for the chronic-phase group (P = .91), and median overall survival was not reached. In terms of relapse-free survival, estimated 5-year outcome for the accelerated-phase group was 49% (95% CI, 32% to 67%) vs 55% (95% CI, 50% to 61%) for the chronic-phase group (P = .65). Estimated 5-year nonrelapse mortality was 20% (95% CI, 8% to 33%) for the accelerated-phase group vs 30% (95% CI, 24% to 35%; P = .25) for the chronic-phase group. In terms of relapse, 5-year incidence was 30% (95% CI, 14% to 46%) for the accelerated-phase group vs 15% (95% CI, 11% to 19%) for the chronic-phase group (P = .02). Results were confirmed in multivariable analysis and propensity score matching. In conclusion, reduced intensity transplantation showed excellent survival but higher relapse for accelerated-phase myelofibrosis.

Post-Transplantation Multicolored Flow Cytometry-Minimal Residual Disease Status on Day 100 Predicts Outcomes for Patients With Refractory Acute Myeloid Leukemia.

Patients with relapsed/refractory acute myeloid leukemia (AML) have a dismal prognosis. Allogeneic stem cell transplantation (allo-SCT) provides a curative approach; however, the overall survival (OS) remains low (20% to 40%). In this setting, although some effective approaches have been evaluated in recent years, the management of such patients still remains challenging. In this study we evaluated the predictive role of post-transplant day 100 minimal residual disease (MRD) detection for post-transplantation outcomes for patients with refractory AML. Fifty-six adult patients with refractory AML (median age 58, range 20-76; male, 61%) who underwent allo-SCT were included in this retrospective monocentric study. Twenty-nine patients (52%) received fludarabine, amsacrine, and cytarabine (FLAMSA)-based conditioning. MRD was assessed using multicolored flow cytometry (MFC) according to European Leukemia Net guidelines ("different from normal" and leukemia-associated phenotype). The sensitivity of the method was 10-4 to 10-5. The median marrow blast count at allo-SCT was 25% (range 6% to 91%). At day 100 after transplantation, 40 patients (71%) experienced MFC-MRD negativity, and 16 patients (29%) were MRD positive. All included patients survived at least 100 days after transplantation without relapse. Univariate and multivariate analysis based on Kaplan-Meier and Cox proportional hazards method were performed. The median follow-up was 16 months (range 3 to 66). The post-transplantation day 100 MRD-negative patients instead received 2 allografts (27% versus 6%, P = .08). In multivariate analysis, day 100 MRD status (negative versus positive) (OS: 0.23 [0.1 to 0.54], P =0.001; relapses: 0.20 [0.1 to 0.49], P = .0005) and FLAMSA versus other regimens (0.34 [0.1 to 0.83], P = .018; relapses: 0.43 [0.17 to 1.1], P = .07) independently impacted post-transplantation survival. We suggest that post-transplantation day 100 MFC-MRD detection plays predictive role in refractory AML patients and may help to define possible candidates for early post-transplantation interventions aiming to decrease the relapse risk and improve survival.

Digital PCR to quantify ChAdOx1 nCoV-19 copies in blood and tissues.

Vaccination with the adenoviral-vector-based AstraZeneca ChAdOx1 nCov-19 (Vaxzevria) vaccine is efficient and safe. However, in rare cases vaccinated individuals developed life-threatening thrombotic complications, including thrombosis in cerebral sinus and splanchnic veins. Monitoring of the applied vector in vivo represents an important precondition to study the molecular mechanisms underlying vaccine-driven adverse effects now referred to as vaccine-induced immune thrombotic thrombocytopenia (VITT). We previously have shown that digital PCR (dPCR) is an excellent tool to quantify transgene copies in vivo. Here, we present a highly sensitive dPCR for in situ quantification of ChAdOx1 nCoV-19 copies. Using this method, we quantified vector copies in human plasma 24, 72, and 168 h post vaccination and in a variety of murine tissues in an experimental vaccination model 30 min post injection. We describe a method for high-sensitivity quantitative detection of ChAdOx1 nCoV-19 with possible implications to elucidate the mechanisms of severe ChAdOx1 nCov-19 vaccine complications.

Axicabtagene ciloleucel in vivo expansion and treatment outcome in aggressive B-cell lymphoma in a real-world setting.

Data on the association between chimeric antigen receptor (CAR)-T-cell kinetics and patient outcome in the nontrial setting are missing, mainly due to the lack of broadly available CAR-T-cell diagnostic quantification tools. We performed prospective quantification of axicabtagene ciloleucel (axi-cel) in 21 patients treated for aggressive B-cell lymphoma at our clinic. Median peak CAR-T-cell count was 16.14 CAR-T cells/µL. Patients with 16.14/µL or higher peak CAR-T cells (strong expanders) had more day-30 objective responses (91% vs 40%, P = .02). In univariate analysis, peak CAR-T cell ≥ 16.14 (P < .001), normal platelet counts at start of lymphodepletion (P < .001), no prior stem cell transplant (P = .04), and peak CAR-T cells as continuous variable (P = .03) were associated with better progression-free survival (PFS). After adjusting for platelet counts and prior stem cell transplantation, peak CAR-T cells below median was still associated with shorter PFS (relative risk, 0.15, 95% confidence interval, 0.04-0.59, P = .007). Low platelet counts also maintained significant impact on PFS. Our data demonstrate association of axi-cel levels and outcome in a nontrial setting and for the first time use a cutoff to segregate weak and strong expanders with respective outcomes.

Enhanced Immune Reconstitution of γδ T Cells after Allogeneic Stem Cell Transplantation Overcomes the Negative Impact of Pretransplantation Minimal Residual Disease-Positive Status in Patients with Acute Myelogenous Leukemia.

Minimal/measurable residual disease (MRD) before allogeneic stem cell transplantation (allo-SCT) in patients with acute myelogenous leukemia (AML) is a poor risk factor for outcome. γδ T cells represent a unique minority lymphocyte population that is preferentially located in peripheral tissues, can recognize antigens in a non-MHC-restricted manner, and plays a "bridging" role between the innate and adaptive immune systems. In this study, we investigated a potential graft-versus-leukemia effect of γδ T cell reconstitution post-transplantation in AML patients with pretransplantation positive MRD status (MRD+). MRD assessment was performed in 202 patients using multicolored flow cytometry ("different from normal" strategy); 100 patients were deemed MRD+. Analysis for absolute concentrations of CD3+, CD4+, CD8+, natural killer, and γδ T cells were performed by flow cytometry according to an internal protocol at day +30 and +100 post-transplantation. Differences between categorical and continuous variables were determined using the chi-square and Student t test, respectively. The Mann-Whitney U test was used to compare medians of continuous variables. Spearman's correlation was used for nonparametric assessment of correlation between different cell subsets during immune reconstitution. Kaplan-Meier survival analysis and Cox regression analysis were used to investigate the associations between immune reconstitution and survival outcomes. Gray's analysis was used to compute incidences of relapse, nonrelapse mortality, and graft-versus-host disease (GVHD). The median follow-up of survivors was 28 months (range 3 to 59 months). Younger age (≤58 years) of recipient and donor (<30 years), sex mismatch, use of a matched donor, cytomegalovirus reactivation, and administration of antithymocyte globulin were associated with a faster γδ T cell reconstitution. In multivariable analysis for MRD+ patients, a higher than median level of γδ T cells on days +30 and +100 resulted in significantly improved leukemia-free survival (hazard ratio [HR], 0.42 [P = .007] and 0.42 [P = .011], respectively) and overall survival (HR, 0.44 [P = .038] and 0.33 [P = .009], respectively). Furthermore, a higher γδ T cell level on day +30 was associated with a significantly reduced risk of relapse (HR, 0.36; P = .019). No impact of γδ T cell level on relapse at days +30 and +100 could be seen in MRD-negative patients, and no correlation with occurrence of GVHD was observed. Our data indicate that enhanced immune reconstitution of γδ T cells post-transplantation may overcome the higher relapse risk of pretransplantation MRD+ status in patients with AML.