IMPROVE-BMT: A Pilot Randomized Controlled Trial of Prehabilitation Exercise for Adult Hematopoietic Stem Cell Transplant Recipients

Background: There is limited evidence on the effects of aerobic and resistance training exercise interventions to improve physical function and patient-reported outcomes prior to autologous and allogeneic hematopoietic stem cell transplant (HSCT). IMPROVE-BMT was a single-site, pilot randomized controlled trial investigating the feasibility, acceptability, and safety of a pragmatic resistance training exercise program prior to HSCT compared to usual HSCT care. Secondary aims included differences in physical function between the exercise group (EX) and usual care control group (UC). Methods: Outcome measurements were assessed: prior to HSCT, on/around day of HSCT admission, +30 days post-HSCT, and +100 days post-HSCT. The exercise intervention was a home-based exercise program that incorporated resistance-band and bodyweight exercises. Results: Acceptability among participants was 83%; exercise adherence averaged at 92%; and there were zero exercise-related adverse or serious adverse events. The average pre-transplant exercise phase was 6.28 weeks (2.71-18.29 weeks). EX (n = 36) demonstrated larger increases in the six-minute walk test distance, short physical performance battery scores, and 30-s chair stands compared to UC (n = 38) and demonstrated significant within-group improvements for the six-minute walk test, the short physical performance battery, the 30-s chair stands, and the timed up-and-go test. Conclusions: IMPROVE-BMT demonstrates that pragmatic exercise is highly feasible for HSCT recipients and can potentially lead to enhanced recovery that may not be achievable in non-exercisers.

The addition of doxycycline to fluoroquinolones for bacterial prophylaxis in autologous stem cell transplantation for multiple myeloma

BACKGROUND

Bacterial prophylaxis with a fluoroquinolone (FQ) during autologous stem cell transplant (ASCT) is common, although not standardized among transplant centers. The addition of doxycycline (doxy) to FQ prophylaxis was previously linked to reduced neutropenic fever and bacteremia in multiple myeloma (MM) patients undergoing ASCT although several confounders were present. We compared the incidence of neutropenic fever and bacteremia between MM patients variably receiving prophylaxis with FQ alone and FQ-doxy during ASCT.

METHODS

Systematic retrospective chart review of MM patients who underwent ASCT between January 2016 and December 2021. The primary objective was to determine the effect of bacterial prophylaxis on neutropenic fever and bacteremia within 30 days of ASCT. Multivariable logistic regression for neutropenic fever and univariate logistic regression for bacteremia accounted for differences in subject characteristics between groups.

RESULTS

Among 341 subjects, 121 received FQ and 220 received FQ-doxy for prophylaxis. Neutropenic fever developed in 67 (55.4%) and 87 (39.5%) subjects in the FQ and FQ-doxy groups, respectively (p = .005). Bacteremia was infrequent, with 5 (4.1%) and 5 (2.3%) cases developing in the FQ and FQ-doxy groups, respectively (p = .337). Among Gram-negative bacteremia events, 7/7 Escherichia coli strains were FQ-resistant, and 5/7 were ceftriaxone-resistant.

CONCLUSION

The FQ-doxy prophylaxis group had fewer cases of neutropenic fever than the FQ group, however, there was no significant difference in bacteremia. High rates of antibiotic resistance were observed. An updated randomized controlled trial investigating appropriate prophylaxis for ASCT in the context of current oncology standards and changing antimicrobial resistance rates is warranted.

Engraftment and Measurable Residual Disease Monitoring after Hematopoietic Stem Cell Transplantation: Comparison of Two Chimerism Test Strategies, Next-Generation Sequencing versus a Combination of Short-Tandem Repeats and Quantitative PCR

Chimerism testing supports the study of engraftment and measurable residual disease (MRD) in patients after allogeneic hematopoietic stem cell transplant. In chimerism MRD, relapse can be predicted by increasing mixed chimerism (IMC), recipient increase ≥0.1% in peripheral blood, and proliferating recipient cells as a surrogate of tumor activity. Conventionally, the combination of short-tandem repeat (STR) and quantitative PCR (qPCR) was needed to ensure assay sensitivity and accuracy in all chimerism status. We evaluated the use of next-generation sequencing (NGS) as an alternate technique. The median numbers of informative markers in unrelated/related cases were 124/82 (NGS; from 202 single-nucleotide polymorphism), 5/3 (qPCR), and 17/10 (STR). Assay sensitivity was 0.22% (NGS), 0.1% (qPCR), and 1% (STR). NGS batch (4 to 48 samples) required 19.60 to 24.80 hours and 1.52 to 2.42 hours of hands-on time (comparable to STR/qPCR). NGS assay cost/sample was $91 to $151, similar to qPCR ($99) but higher than STR ($27). Using 56 serial DNAs from six post-transplant patients monitored by the qPCR/STR, the correlation with NGS was strong for percentage recipient (y = 1.102x + 0.010; R2 = 0.968) and percentage recipient change (y = 0.892x + 0.041; R2 = 0.945). NGS identified all 17 IMC events detected by qPCR (100% sensitivity). The NGS chimerism provides sufficient sensitivity, accuracy, and economical/logistical feasibility in supporting engraftment and MRD monitoring.

Clofarabine Preconditioning followed by Allogeneic Transplant Using TBI and Post-Transplant Cyclophosphamide for Relapsed Refractory Leukemia

Acute myeloid leukemia patients with induction failure or relapsed refractory disease have minimal chance of achieving remission with subsequent treatments. Several trials have shown the feasibility of clofarabine-based conditioning in allogeneic stem cell transplants (allo-HSCT) for non-remission AML patients. Pre-transplant conditioning with clofarabine followed by reduced-intensity allo-HSCT has also demonstrated a potential benefit in those patients with human leukocyte antigen (HLA)-identical donors, but it is not commonly used in haploidentical and mismatched transplants. In this case report, we describe our experience of seven cases of non-remission AML who received clofarabine preconditioning followed by an allo-HSCT with PTCy. The 2-year overall survival and disease-free survival was 83.3% (95% confidence interval (CI): 27.3-97.9%) and 85.7% (95% CI: 33.4-97.9%). Median days of neutrophil and platelet recovery were 16 (range of 13-23) and 28 (range of 17-75), respectively. The cumulative incidence of grade II-IV acute graft-versus-host disease (GVHD) at day 100 and chronic GVHD at 1-year showed 28.6% (95% CI: 8-74.2%) and 28.6% (95% CI: 3-63.9%), respectively. The two-year relapse rate was 14.3% (95% CI: 2.14-66.6%). One-year GVHD-free relapse-free survival (GFRS) at 1-year was 71.4% (95% CI: 25.8-92%). Our patients showed successful outcomes with clofarabine preconditioning to reduce the leukemic burden at the pre-transplant period followed by PTCy to reduce GVHD resulting in lower relapsed rate and better GFRS in these patients.

Acute Myeloid Leukemia Causes T Cell Exhaustion and Depletion in a Humanized Graft-versus-Leukemia Model

Allogeneic hematopoietic stem cell transplantation (alloSCT) is, in many clinical settings, the only curative treatment for acute myeloid leukemia (AML). The clinical benefit of alloSCT greatly relies on the graft-versus-leukemia (GVL) effect. However, AML relapse remains the top cause of posttransplant death; this highlights the urgent need to enhance GVL. Studies of human GVL have been hindered by the lack of optimal clinically relevant models. In this article, we report, the successful establishment of a novel (to our knowledge) humanized GVL model system by transplanting clinically paired donor PBMCs and patient AML into MHC class I/II knockout NSG mice. We observed significantly reduced leukemia growth in humanized mice compared with mice that received AML alone, demonstrating a functional GVL effect. Using this model system, we studied human GVL responses against human AML cells in vivo and discovered that AML induced T cell depletion, likely because of increased T cell apoptosis. In addition, AML caused T cell exhaustion manifested by upregulation of inhibitory receptors, increased expression of exhaustion-related transcription factors, and decreased T cell function. Importantly, combined blockade of human T cell-inhibitory pathways effectively reduced leukemia burden and reinvigorated CD8 T cell function in this model system. These data, generated in a highly clinically relevant humanized GVL model, not only demonstrate AML-induced inhibition of alloreactive T cells but also identify promising therapeutic strategies targeting T cell depletion and exhaustion for overcoming GVL failure and treating AML relapse after alloSCT.

CD26lowPD-1+ CD8 T cells are terminally exhausted and associated with leukemia progression in acute myeloid leukemia

Acute myeloid leukemia (AML) is a devastating blood cancer with poor prognosis. Novel effective treatment is an urgent unmet need. Immunotherapy targeting T cell exhaustion by blocking inhibitory pathways, such as PD-1, is promising in cancer treatment. However, results from clinical studies applying PD-1 blockade to AML patients are largely disappointing. AML is highly heterogeneous. Identification of additional immune regulatory pathways and defining predictive biomarkers for treatment response are crucial to optimize the strategy. CD26 is a marker of T cell activation and involved in multiple immune processes. Here, we performed comprehensive phenotypic and functional analyses on the blood samples collected from AML patients and discovered that CD26^lowPD-1⁺ CD8 T cells were associated with AML progression. Specifically, the percentage of this cell fraction was significantly higher in patients with newly diagnosed AML compared to that in patients achieved completed remission or healthy controls. Our subsequent studies on CD26^lowPD-1⁺ CD8 T cells from AML patients at initial diagnosis demonstrated that this cell population highly expressed inhibitory receptors and displayed impaired cytokine production, indicating an exhaustion status. Importantly, CD26^lowPD-1⁺ CD8 T cells carried features of terminal exhaustion, manifested by higher frequency of T_EMRA differentiation, increased expression of transcription factors that are observed in terminally exhausted T cells, and high level of intracellular expression of granzyme B and perforin. Our findings suggest a prognostic and predictive value of CD26 in AML, providing pivotal information to optimize the immunotherapy for this devastating cancer.

IMPROVE-BMT: a protocol for a pilot randomised controlled trial of prehabilitation exercise for adult haematopoietic stem cell transplant recipients

INTRODUCTION

Haematopoietic stem cell transplant (HSCT) in adults is an intensive medical procedure for a variety of haematological malignancies. Although there is a large body of evidence demonstrating the negative effects of HSCT on physical function and psychosocial parameters, there is limited evidence on the impact of HSCT on body composition and bone health. Further, aerobic and resistance-training exercise interventions aimed at improving physical function and patient-reported outcomes largely take place during the peritransplant and post-transplant period. Prehabilitative exercise, or exercise prior to medical treatment, has been successfully deployed in presurgical candidates and other tumour sites, yet there is a paucity of evidence on the effect of prehabilitation in HSCT patients. The aim of this study is to investigate the feasibility, acceptability and safety of a resistance training exercise programme in patients with haematological malignancies prior to HSCT.

METHODS AND ANALYSIS

IMpact of PRehabilitation in Oncology Via Exercise-Bone Marrow Transplant is a single-site, pilot randomised controlled trial of an exercise intervention compared with usual care. The primary aim is to assess the feasibility, acceptability and safety of the resistance-training exercise intervention prior to HSCT. Secondary aims include evaluating the differences in physical function, body composition, bone mineral density and patient-reported outcomes between the exercise group and usual care control group. Outcome measurements will be assessed: prior to HSCT, on/around day of HSCT admission, +30 days post-HSCT and +100 days post-HSCT. The exercise intervention is a home-based resistance training exercise programme that incorporates resistance band and body weight exercises. The primary outcomes will be reported as percentages and/or mean values. The secondary outcomes will be analysed using appropriate statistical methods to portray within-group and between-group differences.

ETHICS AND DISSEMINATION

The study has Penn State College of Medicine approval. Results will be disseminated through scientific publication and presentation at exercise-related and oncology-related scientific meetings.

TRIAL REGISTRATION NUMBER

NCT03886909.

Post-transplant cyclophosphamide alters immune signatures and leads to impaired T cell reconstitution in allogeneic hematopoietic stem cell transplant

Despite the increased usage of post-transplant cyclophosphamide (PTCy) in allogeneic hematopoietic stem cell transplantation (allo-HSCT), our knowledge of immune reconstitution post-allo-HSCT in the setting of PTCy is limited. Adequate immune reconstitution is the key to a successful transplant. In this study, we aim to investigate the effect of PTCy on the reconstitution of each immune component; more focus was placed on the immunophenotype and functions of T cells. Using blood samples from patients who underwent allo-HSCT under regimens containing PTCy (n = 23) versus those who received no PTCy (n = 14), we examined the impact of PTCy on the post-transplant immune response. We demonstrated a distinct T cell immune signature between PTCy versus non-PTCy group. PTCy significantly delayed T cell reconstitution and affected the T cell subsets by increasing regulatory T cells (Treg) while reducing naïve T cells. In addition, we observed remarkable enhancement of multiple inhibitory receptors (TIGIT, PD-1, TIM-3, CD38, CD39) on both CD4⁺ and CD8⁺ T cells on day 30 post-transplantation in patients who received PTCy. Importantly, upregulation of PD-1 on CD8 T cells was persistent through day 180 and these T cells were less functional, manifested by reduced cytokine production upon anti-CD3/CD28 stimulation. Furthermore, we found a significant correlation of T cell immune phenotypes to clinical outcome (disease relapse and GVHD) in patients who received PTCy. Our novel findings provide critical information to understand the mechanism of how PTCy impacts immune reconstitution in allo-HSCT and may subsequently lead to optimization of our clinical practice using this treatment.

A novel clinically relevant graft-versus-leukemia model in humanized mice

The prognosis for acute myeloid leukemia (AML) relapse post allogeneic hematopoietic stem cell transplantation (alloSCT) is dismal. Novel effective treatment is urgently needed. Clinical benefit of alloSCT greatly relies on the graft-versus-leukemia (GVL) effect. The mechanisms that mediate immune escape of leukemia (thus causing GVL failure) remain poorly understood. Studies of human GVL have been hindered by the lack of optimal clinically relevant models. Here, using our large, longitudinal clinical tissue bank that include AML cells and G-CSF mobilized donor hematopoietic stem cells (HSCs), we successfully established a novel GVL model in humanized mice. Donor HSCs were injected into immune-deficient NOD-Cg-Prkdcscid IL2rgtm1Wjl /SzJ (NSG) mice to build humanized mice. Immune reconstitution in these mice recapitulated some clinical scenario in the patient who received the corresponding HSCs. Allogeneic but HLA partially matched patient-derived AML cells were successfully engrafted in these humanized mice. Importantly, we observed a significantly reduced (yet incomplete elimination of) leukemia growth in humanized mice compared with that in control NSG mice, demonstrating a functional (but defective) GVL effect. Thus, for the first time, we established a novel humanized mouse model that can be used for studying human GVL responses against human AML cells in vivo. This novel clinically relevant model provides a valuable platform for investigating the mechanisms of human GVL and development of effective leukemia treatments.

Alloantigen-activated (AAA) CD4+ T cells reinvigorate host endogenous T cell immunity to eliminate pre-established tumors in mice

BACKGROUND

Cancer vaccines that induce endogenous antitumor immunity represent an ideal strategy to overcome intractable cancers. However, doing this against a pre-established cancer using autologous immune cells has proven to be challenging. "Allogeneic effects" refers to the induction of an endogenous immune response upon adoptive transfer of allogeneic lymphocytes without utilizing hematopoietic stem cell transplantation. While allogeneic lymphocytes have a potent ability to activate host immunity as a cell adjuvant, novel strategies that can activate endogenous antitumor activity in cancer patients remain an unmet need. In this study, we established a new method to destroy pre-developed tumors and confer potent antitumor immunity in mice using alloantigen-activated CD4⁺ (named AAA-CD4⁺) T cells.

METHODS

AAA-CD4⁺ T cells were generated from CD4⁺ T cells isolated from BALB/c mice in cultures with dendritic cells (DCs) induced from C57BL/6 (B6) mice. In this culture, allogeneic CD4⁺ T cells that recognize and react to B6 mouse-derived alloantigens are preferentially activated. These AAA-CD4⁺ T cells were directly injected into the pre-established melanoma in B6 mice to assess their ability to elicit antitumor immunity in vivo.

RESULTS

Upon intratumoral injection, these AAA-CD4⁺ T cells underwent a dramatic expansion in the tumor and secreted high levels of IFN-γ and IL-2. This was accompanied by markedly increased infiltration of host-derived CD8⁺ T cells, CD4⁺ T cells, natural killer (NK) cells, DCs, and type-1 like macrophages. Selective depletion of host CD8⁺ T cells, rather than NK cells, abrogated this therapeutic effect. Thus, intratumoral administration of AAA-CD4⁺ T cells results in a robust endogenous CD8⁺ T cell response that destroys pre-established melanoma. This locally induced antitumor immunity elicited systemic protection to eliminate tumors at distal sites, persisted over 6 months in vivo, and protected the animals from tumor re-challenge. Notably, the injected AAA-CD4⁺ T cells disappeared within 7 days and caused no adverse reactions.

CONCLUSIONS

Our findings indicate that AAA-CD4⁺ T cells reinvigorate endogenous cytotoxic T cells to eradicate pre-established melanoma and induce long-term protective antitumor immunity. This approach can be immediately applied to patients with advanced melanoma and may have broad implications in the treatment of other types of solid tumors.

[The coronavirus disease 2019 (COVID-19) and hematologic oncology or BMT practice at our center in US]

The coronavirus disease 2019 (COVID-19) pandemic has exerted a considerable impact in our region; thus, we have been performing only emergency transplants in March 2020. At present, all inpatients and surgical patients are being tested and screened for COVID-19. If they are found to be positive, they are transferred to the COVID-19 ward, where a specialized team manages them. Team-based care allows the hematology/oncology teams to perform their regular duties. In particular, for post-transplant patients, treatment decisions are made through discussion with infectious disease specialists, and in principle, the patients are treated using the same protocol as that used for the general COVID-19 infected patients. Currently, vaccination is being promoted at a rapid pace based on the Centers for Disease Control and Prevention Guidelines (CDC) guidelines. At our institution, when a situation of suspected nosocomial COVID-19 infection occurred, all healthcare workers were tested. Thereafter, all hospitalized patients were tested every week for COVID-19, and we were able to overcome the situation. Although definitive measures for COVID-19 are yet to be established, signs of an end to the infection are beginning to appear with a wider availability of vaccines.

Graft-versus-host disease depletes plasmacytoid dendritic cell progenitors to impair tolerance induction

Graft-versus-host disease (GVHD) causes failed reconstitution of donor plasmacytoid dendritic cells (pDCs) that are critical for immune protection and tolerance. We used both murine and human systems to uncover the mechanisms whereby GVHD induces donor pDC defects. GVHD depleted Flt3-expressing donor multipotent progenitors (MPPs) that sustained pDCs, leading to impaired generation of pDCs. MPP loss was associated with decreased amounts of MPP-producing hematopoietic stem cells (HSCs) and oxidative stress-induced death of proliferating MPPs. Additionally, alloreactive T cells produced GM-CSF to inhibit MPP expression of Tcf4, the transcription factor essential for pDC development, subverting MPP production of pDCs. GM-CSF did not affect the maturation of pDC precursors. Notably, enhanced recovery of donor pDCs upon adoptive transfer early after allogeneic HSC transplantation repressed GVHD and restored the de novo generation of donor pDCs in recipient mice. pDCs suppressed the proliferation and expansion of activated autologous T cells via a type I IFN signaling-dependent mechanism. They also produced PD-L1 and LILRB4 to inhibit T cell production of IFN-γ. We thus demonstrate that GVHD impairs the reconstitution of tolerogenic donor pDCs by depleting DC progenitors rather than by preventing pDC maturation. MPPs are an important target to effectively bolster pDC reconstitution for controlling GVHD.

Unexpected Short-Tandem-Repeat Patterns in Posttransplant Chimerism Testing: Investigation of 3 Cases with Help from Forensic Science

Chimerism testing by short tandem repeats (STRs) is used to monitor engraftment after allogeneic hematopoietic stem cell transplantation (HSCT). Generally, STR alleles are stable and transferred from parent to child or from donor to recipient. However, 3 cases did not follow this norm. Additional work-up with help from forensic literature solved these mysteries. In case 1, the patient received HSCT from his son. The son shared STR alleles in 22/23 loci except Penta E, which was explained by repeat expansion in the son. In case 2, the patient had been in remission for 14 years after HSCT for lymphoma and developed repeat expansion in CSF1PO in granulocytes. In case 3, a pre-HSCT patient demonstrated 3 alleles, with 2 peaks taller than the third, in the FGA locus (chromosome 4). A combination of a triallelic variant and leukemia-associated trisomy 4 explained the finding. STR number variants are rare and clinically inconsequential but can overlap malignancy-associated, clinically significant changes.

[Transplant conditioning revisited]

Treatment of acute leukemia has evolved rapidly over the past 10 years. Moreover, the role of hematopoietic stem cell transplantation (HSCT) in such treatments has been changing. With the refinement of molecular-targeted therapy and other new modalities, HSCT is no longer the only curative option for leukemia. Nowadays, HSCT is being incorporated into the comprehensive scheme of leukemia treatment and is being compared to other treatment options. This was made possible through the effort to decrease nonrelapse mortality associated with HSCT to levels comparable with those of other modalities. In this review, we will particularly focus on transplantation in patients with aggressive leukemia and graft failure and discuss the role of conditioning regimens for HSCT in the new era of targeted therapy.

Multi-dimensional analysis identifies an immune signature predicting response to decitabine treatment in elderly patients with AML

Decitabine is a DNA‐hypomethylating agent that has been widely applied for the treatment of acute myeloid leukaemia (AML) patients who are elderly or unfit for intensive therapy. Although effective, the complete response rate to decitabine is only around 30% and the overall survival remains poor. Emerging data support that regulation of DNA methylation is critical to control immune cell development, differentiation and activation. We hypothesize that defining how decitabine influences the immune responses in AML will facilitate the development of novel immune‐based leukaemia therapeutics. Here, we performed phenotypic and functional immune analysis on clinical samples from AML patients receiving decitabine treatment and demonstrated a significant impact of decitabine on the immune system. T‐cell expression of inhibitory molecules was upregulated and the ability of CD8 T cells to produce cytokines was decreased upon decitabine treatment. Importantly, in an unbiased comprehensive analysis, we identified a unique immune signature containing a cluster of key immune markers that clearly separate patients who achieved complete remission after decitabine from those who failed to do so. Therefore, this immune signature has a strong predictive value for clinical response. Collectively, our study suggests that immune‐based analyses may predict clinical response to decitabine and provide a therapeutic strategy to improve the treatment of AML.

Comparison of High Doses of Total Body Irradiation in Myeloablative Conditioning before Hematopoietic Cell Transplantation

Malignancy relapse is the most common cause of treatment failure among recipients of hematopoietic cell transplantation (HCT). Conditioning dose intensity can reduce disease relapse but is offset by toxicities. Improvements in radiotherapy techniques and supportive care may translate to better outcomes with higher irradiation doses in the modern era. This study compares outcomes of recipients of increasing doses of high-dose total body irradiation (TBI) divided into intermediate high dose (IH; 13-13.75 Gy) and high dose (HD; 14 Gy) with standard dose (SD; 12 Gy) with cyclophosphamide. A total of 2721 patients ages 18 to 60 years with hematologic malignancies receiving HCT from 2001 to 2013 were included. Cumulative incidences of nonrelapse mortality (NRM) at 5 years were 28% (95% confidence interval [CI], 25% to 30%), 32% (95% CI, 29% to 36%), and 34% (95% CI, 28% to 39%) for SD, IH, and HD, respectively (P = .02). Patients receiving IH-TBI had a 25% higher risk of NRM compared with those receiving SD-TBI (12 Gy) (P = .007). Corresponding cumulative incidences of relapse were 36% (95% CI, 34% to 38%), 32% (95% CI, 29% to 36%), and 26% (95% CI, 21% to 31%; P = .001). Hazard ratios for mortality compared with SD were 1.06 (95% CI, .94 to 1.19; P = .36) for IH and .89 (95% CI, .76 to 1.05; P = .17) for HD. The study demonstrates that despite improvements in supportive care, myeloablative conditioning using higher doses of TBI (with cyclophosphamide) leads to worse NRM and offers no survival benefit over SD, despite reducing disease relapse.

Association of Antiepileptic Medications with Outcomes after Allogeneic Hematopoietic Cell Transplantation with Busulfan/Cyclophosphamide Conditioning

High-dose busulfan (BU) followed by high-dose cyclophosphamide (CY) before allogeneic hematopoietic cell transplantation (HCT) has long been used as treatment for hematologic malignancies. Administration of phenytoin or newer alternative antiepileptic medications (AEMs) prevents seizures caused by BU. Phenytoin induces enzymes that increase exposure to active CY metabolites in vivo, whereas alternative AEMs do not have this effect. Lower exposure to active CY metabolites with the use of alternative AEMs could decrease the risk of toxicity but might increase the risk of recurrent malignancy after HCT. Previous studies have not determined whether outcomes with alternative AEMs differ from those with phenytoin in patients treated with BU/CY before allogeneic HCT. We studied a cohort of 2155 patients, including 1460 treated with phenytoin and 695 treated with alternative AEMs, who received BU/CY before allogeneic HCT between 2004 and 2014. We found no differences suggesting decreased overall survival or relapse-free survival or increased risks of relapse, nonrelapse mortality, acute or chronic graft-versus-host disease, or regimen-related toxicity associated with the use of alternative AEMs compared with phenytoin. The risk of dialysis was lower in the alternative AEM group than in the phenytoin group. Alternative AEMs are safe for prevention of seizures after BU administration and can avoid the undesirable toxicities and drug interactions caused by phenytoin.

A phase II study of myeloablative allogeneic hematopoietic stem cell transplantation (aHSCT) for acute lymphoblastic leukemia (ALL) in older patients using fludarabine and total body irradiation (Flu/TBI)

TPS7069

Background: Older adults with ALL have poor survival outcomes. Although aHSCT can be curative when used as consolidation after complete remission (CR), advanced age, limited performance status, and comorbidities are risk factors for increased non-relapse mortality (NRM) after myeloablative aHSCT. The 1-year disease free survival (DFS) for patients ≥ 40 years who receive an aHSCT for ALL is often estimated to be 40-50%. Previous studies have demonstrated the efficacy of TBI-based regimens in adults with ALL when combined with cyclophosphamide (Cy). Reduced intensity conditioning for ALL patients has fallen out of favor due to high relapse rate forfeiting the benefit of reduced NRM. High-dose Cy is, however, associated with cardiac, hemorrhagic and hepatic toxicities. Fludarabine (Flu) has emerged as a safer substitute of Cy (e.g. Flu/Bu replacing Bu/Cy) with favorable toxicity profile. Given the efficacy of TBI-based regimens in ALL, we hypothesized that a myeloablative regimen of Flu/TBI (12 Gy) is almost as effective as Cy/TBI 12 Gy in older adults with ALL undergoing aHSCT, but with less NRM confering survival benefit over Cy/TBI 12 Gy. Methods: This study is a single center, single-arm phase II clinical trial of Flu 40 mg/m2 IV daily (days -7 to -4) and TBI 2 Gy X2 (days -3 to -1) as myeloablative conditioning for older adults (≥40 years old) or younger adults with significant comorbidities with ALL. Patients aged 40-65 years with ALL in CR, KPS ≥ 70, adequate organ function, and having HLA-matched sibling or unrelated donor will be eligible. The primary endpoint of the study is 1-year DFS post-transplant. Secondary endpoints include 1-year overall survival (OS), incidence and severity of acute and chronic GVHD, immune reconstitution and regimen related toxicity. The study has just finished accrual (January 2019) enrolling a total of 16 patients. This number of patients was pre-determined to give a probability ≤ 0.05 of concluding that the 1-year DFS rate exceeds 45%, and a probability of at least 0.80 of concluding that the 1-year DFS rate exceeds 45% (expecting 1-year DFS of 75%). Clinical trial information: NCT01991457.

Dendritic Cell Regulation of Graft-Vs.-Host Disease: Immunostimulation and Tolerance

Graft-vs.-host disease (GVHD) remains a significant cause of morbidity and mortality after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Significant progresses have been made in defining the dichotomous role of dendritic cells (DCs) in the development of GVHD. Host-derived DCs are important to elicit allogeneic T cell responses, whereas certain donor-types of DCs derived from newly engrafted hematopoietic stem/progenitor cells (HSPCs) can amply this graft-vs.-host reaction. In contrast, some DCs also play non-redundant roles in mediating immune tolerance. They induce apoptotic deletion of host-reactive donor T cells while promoting expansion and function of regulatory T cells (Treg). Unfortunately, this tolerogenic effect of DCs is impaired during GVHD. Severe GVHD in patients subject to allo-HSCT is associated with significantly decreased number of circulating peripheral blood DCs during engraftment. Existing studies reveal that GVHD causes delayed reconstitution of donor DCs from engrafted HSPCs, impairs the antigen presentation function of newly generated DCs and reduces the capacity of DCs to regulate Treg. The present review will discuss the importance of DCs in alloimmunity and the mechanism underlying DC reconstitution after allo-HSCT.

Eomes+T-betlow CD8+ T Cells Are Functionally Impaired and Are Associated with Poor Clinical Outcome in Patients with Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is a devastating blood cancer with poor prognosis. Immunotherapy targeting inhibitory pathways to unleash the antileukemia T-cell response is a promising strategy for the treatment of leukemia, but we must first understand the underlying molecular mechanisms. Eomesodermin (Eomes) and T-bet are both T-box transcription factors that regulate CD8⁺ T-cell responses in a context-specific manner. Here, we examined the role of these transcription factors in CD8⁺ T-cell immunity in AML patients. We report that the frequency of Eomes⁺T-bet^low CD8⁺ T cells increased in newly diagnosed AML. This cell subset produced fewer cytokines and displayed reduced killing capacity, whereas depletion of Eomes by siRNA reversed these functional defects. Furthermore, Eomes bound the promoter of T-cell immunoglobulin and ITIM domain (TIGIT) and positively regulated the expression of this inhibitory receptor on patient-derived T cells. A high frequency of Eomes⁺T-bet^low CD8⁺ T cells was associated with poor response to induction chemotherapy and shorter overall survival in AML patients. These findings have significant clinical implications as they not only identify a predictive and prognostic biomarker for AML, but they also provide an important target for effective leukemia therapeutics. SIGNIFICANCE: These findings reveal that a high frequency of Eomes⁺T-bet^low CD8⁺ T cells predicts poor clinical outcome in AML and that targeting Eomes may provide a therapeutic benefit against AML.

Effect of Conditioning Regimen Dose Reduction in Obese Patients Undergoing Autologous Hematopoietic Cell Transplantation

Data are limited on whether to adjust high-dose chemotherapy before autologous hematopoietic cell transplant (autoHCT) in obese patients. This study explores the effects of dose adjustment on the outcomes of obese patients, defined as body mass index (BMI) ≥ 30 kg/m². Dose adjustment was defined as a reduction in standard dosing ≥20%, based on ideal, reported dosing and actual weights. We included 2 groups of US patients who had received autoHCT between 2008 and 2014. Specifically, we included patients with multiple myeloma (MM, n = 1696) treated with high-dose melphalan and patients with Hodgkin or non-Hodgkin lymphomas (n = 781) who received carmustine, etoposide, cytarabine, and melphalan conditioning. Chemotherapy dose was adjusted in 1324 patients (78%) with MM and 608 patients (78%) with lymphoma. Age, sex, BMI, race, performance score, comorbidity index, and disease features (stage at diagnosis, disease status, and time to transplant) were similar between dose groups. In multivariate analyses for MM, adjusting for melphalan dose and for center effect had no impact on overall survival (P = .894) and treatment-related mortality (TRM) (P = .62), progression (P = .12), and progression-free survival (PFS; P = .178). In multivariate analyses for lymphoma, adjusting chemotherapy doses did not affect survival (P = .176), TRM (P = .802), relapse (P = .633), or PFS (P = .812). No center effect was observed in lymphoma. This study demonstrates that adjusting chemotherapy dose before autoHCT in obese patients with MM and lymphoma does not influence mortality. These results do not support adjusting chemotherapy dose in this population.

VISTA is highly expressed on MDSCs and mediates an inhibition of T cell response in patients with AML

Treatment of acute myeloid leukemia (AML) remains challenging. Enhancement of anti-tumor responses by blocking negative immune regulators is a promising strategy for novel effective leukemia therapeutics. V-domain Ig suppressor of T-cell activation (VISTA) is a recently defined negative regulator mediating immune evasion in cancer. To investigate the effect of VISTA on anti-leukemia immune response in AML, we initiated a study using clinical samples collected from AML patients. Here we report that VISTA is highly expressed on myeloid-derived suppressor cells (MDSCs) in the peripheral blood of AML patients. Both the frequency and intensity of VISTA expression on MDSCs are significantly higher in newly diagnosed AML than in healthy controls. Importantly knockdown of VISTA by specific siRNA potently reduced the MDSCs-mediated inhibition of CD8 T cell activity in AML, suggesting a suppressive effect of VISTA on anti-leukemia T cell response. Furthermore, we observed a strong positive association between MDSC expression of VISTA and T cell expression of PD-1 in AML. These results support the strategy of VISTA-targeted treatment for AML and underscore the strong potential for combined blockade of VISTA and PD-1 pathways in effective leukemia control.

Myeloablative Autologous Stem-Cell Transplantation for Severe Scleroderma

BACKGROUND

Despite current therapies, diffuse cutaneous systemic sclerosis (scleroderma) often has a devastating outcome. We compared myeloablative CD34+ selected autologous hematopoietic stem-cell transplantation with immunosuppression by means of 12 monthly infusions of cyclophosphamide in patients with scleroderma.

METHODS

We randomly assigned adults (18 to 69 years of age) with severe scleroderma to undergo myeloablative autologous stem-cell transplantation (36 participants) or to receive cyclophosphamide (39 participants). The primary end point was a global rank composite score comparing participants with each other on the basis of a hierarchy of disease features assessed at 54 months: death, event-free survival (survival without respiratory, renal, or cardiac failure), forced vital capacity, the score on the Disability Index of the Health Assessment Questionnaire, and the modified Rodnan skin score.

RESULTS

In the intention-to-treat population, global rank composite scores at 54 months showed the superiority of transplantation (67% of 1404 pairwise comparisons favored transplantation and 33% favored cyclophosphamide, P=0.01). In the per-protocol population (participants who received a transplant or completed ≥9 doses of cyclophosphamide), the rate of event-free survival at 54 months was 79% in the transplantation group and 50% in the cyclophosphamide group (P=0.02). At 72 months, Kaplan-Meier estimates of event-free survival (74% vs. 47%) and overall survival (86% vs. 51%) also favored transplantation (P=0.03 and 0.02, respectively). A total of 9% of the participants in the transplantation group had initiated disease-modifying antirheumatic drugs (DMARDs) by 54 months, as compared with 44% of those in the cyclophosphamide group (P=0.001). Treatment-related mortality in the transplantation group was 3% at 54 months and 6% at 72 months, as compared with 0% in the cyclophosphamide group.

CONCLUSIONS

Myeloablative autologous hematopoietic stem-cell transplantation achieved long-term benefits in patients with scleroderma, including improved event-free and overall survival, at a cost of increased expected toxicity. Rates of treatment-related death and post-transplantation use of DMARDs were lower than those in previous reports of nonmyeloablative transplantation. (Funded by the National Institute of Allergy and Infectious Diseases and the National Institutes of Health; ClinicalTrials.gov number, NCT00114530 .).

Hematopoietic stem cell transplantation in the era of molecular targeted therapy

Recent developments in the field of molecular targeted therapy are certainly remarkable. However, the role of hematopoietic stem cell transplantation (HSCT) cannot be the same in this trend of targeted therapy. In the past, HSCT was the sole and ultimate treatment for refractory hematological malignancies, mainly because the conditioning regimens were strong and administering any additional therapy was impossible. In recent years, the conditioning regimens have become less intensive, thus enabling the use of additional therapies post-transplantation. In this review, we have discussed the use of each targeted therapy, such as TKIs for Philadelphia chromosome positive disease, Flt3 inhibitors, checkpoint inhibitors, monoclonal antibodies, and hypomethylating agents, in the context of using them with HSCT. Furthermore, we have discussed the importance of the intensity of chemotherapy and conditioning for HSCT and whether the depth of remission and the time of achieving deep remission are important. MRD tests can help to further delineate this point. Molecular targeted therapy will be more prevalent in the near future in the treatment of hematological malignancies where each new agent may impact the GVHD/GVL effect. Thus, clinical trials in the next decade will mostly focus on the role of HSCT and on the methods of combining it with targeted agents to provide the best therapeutic option to patients.

Outcomes of G-CSF alone vs G-CSF with upfront plerixafor vs G-CSF/chemotherapy for collection of autologous stem cells in patients with multiple myeloma

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Background: Strategies for optimizing the collection of peripheral blood stem cells (PBSC) for autologous stem cell transplant (ASCT) in patients with multiple myeloma (MM) vary among transplant centers, and include the use of G-CSF alone or in combination with plerixafor, or mobilization chemotherapy + G-CSF. In 2010, we started using “upfront” plerixafor, given on the day before the PBSC collection. Methods:We retrospectively analyzed the outcomes of 423 consecutive MM patients who underwent PBSC collections at the Penn State Hershey Cancer Institute. PBSC were collected after mobilization chemotherapy + G-CSF 5 mcg/Kg/day (group A, 91 pts), G-CSF alone, 10-16 mcg/Kg/day (group B, 72 pts), and G-CSF with “upfront” plerixafor 0.16-0.24 mg/Kg on the day before the stem cell collection (group C, 245 pts). Fifteen patients were excluded from the analysis because they collected with chemotherapy + plerixafor, received pegylated G-CSF, or plerixafor “on demand”, i.e., after failure to achieve an adequate number of stem cells on the first day of collection. We compared yields, number of days required for apheresis, clinical outcomes, and adverse events among these groups. Results: The median number of PBSC collected was 16.4 (range, 0.1-134), 4.2 (range, 0-12), and 6.2 (range, 0.2-41.2) million CD34+ cells/Kg in group A, B, and C, respectively (p<0.001). The mean number of days to collect PBSC was 1.5, 1.5, and 1.3 in group A, B, and C, respectively (p=0.033). Collection failure, defined as a yield <2 million CD34+cells/Kg, was observed in 5 (5.5%), 9 (12.5%), and 15 (6.1%) patients of group A, B, and C, respectively (p<0.001). Twenty patients in group A developed neutropenic fever requiring hospital admission, and 1 of them died of septic shock, whereas no mortality was observed in groups B or C. No difference in the rapidity of PBSC engraftment, progression-free survival, and overall survival was observed among the 3 groups. Conclusions:In patients with MM, the upfront use of plerixafor with G-CSF provided the best collection strategy: it avoided the morbidity and mortality associated with the mobilization chemotherapy, and it provided higher yields than G-CSF alone.

Late-Onset Cerebral Toxoplasmosis After Allogeneic Hematopoietic Stem Cell Transplantation

BACKGROUND Toxoplasmosis is an uncommon but potentially fatal complication following allogeneic hematopoietic stem cell transplantation (HCT). Post-transplant toxoplasmosis is often a reactivation of prior infection and typically occurs within the first 6 months of transplant. Herein, we report that cerebral toxoplasmosis may occur 22 months after allogeneic hematopoietic stem cell transplantation. CASE REPORT We describe a case of cerebral toxoplasmosis that occurred 22 months after an allogeneic HCT while the patient was on aerosolized pentamidine for Pneumocystis jiroveci pneumonia (PCP) prophylaxis. The disease was only diagnosed after brain biopsy because of atypical MRI appearance of the cerebral lesion and negative Toxoplasma gondii IgG antibody test result in the cerebrospinal fluid (CSF). The patient received pyrimethamine and sulfadiazine treatment, with dramatic improvement after several months. The patient is alive 2 years after infection diagnosis, with no evidence of disease and is off Toxoplasma prophylaxis. CONCLUSIONS Cerebral toxoplasmosis can occur late after allogeneic HCT while patients are on immunosuppression therapy, with atypical features on imaging studies and negative Toxoplasma gondii IgG antibody test result in the CSF. Pre-transplant serologic screening for T. gondii antibodies in allogeneic transplant candidates is warranted. Brain biopsy can be a helpful diagnostic tool for cerebral lesions.

In Vitro Pre-Clinical Validation of Suicide Gene Modified Anti-CD33 Redirected Chimeric Antigen Receptor T-Cells for Acute Myeloid Leukemia

Background

Approximately fifty percent of patients with acute myeloid leukemia can be cured with current therapeutic strategies which include, standard dose chemotherapy for patients at standard risk of relapse as assessed by cytogenetic and molecular analysis, or high-dose chemotherapy with allogeneic hematopoietic stem cell transplant for high-risk patients. Despite allogeneic hematopoietic stem cell transplant about 25% of patients still succumb to disease relapse, therefore, novel strategies are needed to improve the outcome of patients with acute myeloid leukemia.

Methods and findings

We developed an immunotherapeutic strategy targeting the CD33 myeloid antigen, expressed in ~ 85–90% of patients with acute myeloid leukemia, using chimeric antigen receptor redirected T-cells. Considering that administration of CAR T-cells has been associated with cytokine release syndrome and other potential off-tumor effects in patients, safety measures were here investigated and reported. We genetically modified human activated T-cells from healthy donors or patients with acute myeloid leukemia with retroviral supernatant encoding the inducible Caspase9 suicide gene, a ΔCD19 selectable marker, and a humanized third generation chimeric antigen receptor recognizing human CD33. ΔCD19 selected inducible Caspase9-CAR.CD33 T-cells had a 75±3.8% (average ± standard error of the mean) chimeric antigen receptor expression, were able to specifically lyse CD33⁺ targets in vitro, including freshly isolated leukemic blasts from patients, produce significant amount of tumor-necrosis-factor-alpha and interferon-gamma, express the CD107a degranulation marker, and proliferate upon antigen specific stimulation. Challenging ΔCD19 selected inducible Caspase9-CAR.CD33 T-cells with programmed-death-ligand-1 enriched leukemia blasts resulted in significant killing like observed for the programmed-death-ligand-1 negative leukemic blasts fraction. Since the administration of 10 nanomolar of a non-therapeutic dimerizer to activate the suicide gene resulted in the elimination of only 76.4±2.0% gene modified cells in vitro, we found that co-administration of the dimerizer with either the BCL-2 inhibitor ABT-199, the pan-BCL inhibitor ABT-737, or mafosfamide, resulted in an additive effect up to complete cell elimination.

Conclusions

This strategy could be investigated for the safety of CAR T-cell applications, and targeting CD33 could be used as a ‘bridge” therapy for patients coming to allogeneic hematopoietic stem cell transplant, as anti-leukemia activity from infusing CAR.CD33 T-cells has been demonstrated in an ongoing clinical trial. Albeit never performed in the clinical setting, our future plan is to investigate the utility of iC9-CAR.CD33 T-cells as part of the conditioning therapy for an allogeneic hematopoietic stem cell transplant for acute myeloid leukemia, together with other myelosuppressive agents, whilst the activation of the inducible Caspase9 suicide gene would grant elimination of the infused gene modified T-cells prior to stem cell infusion to reduce the risk of engraftment failure as the CD33 is also expressed on a proportion of the donor stem cell graft.

Update on stem cell transplantation for acute leukemias

The treatment strategies for acute leukemia are undergoing very rapid change. Particularly for last 10 years, due to the rapid development of molecular targeted therapy and cell/gene therapies, the role of HSCT in the treatment scheme of acute leukemia has been changing. In the author's view, these recent changes should secure the role of HSCT in the comprehensive treatment scheme of acute leukemia. By appropriately combining the new agents with HSCT, therapy for acute leukemia is anticipated to become more effective. HSCT will provide the centerpiece for the treatment scheme, by setting up the "platform" for further interventions. Keeping these changes in mind, transplant physicians should now be exploring new areas of research such as interactions between these new agents and GVHD/GVL.

Efficacy of Pharmacokinetics-Directed Busulfan, Cyclophosphamide, and Etoposide Conditioning and Autologous Stem Cell Transplantation for Lymphoma: Comparison of a Multicenter Phase II Study and CIBMTR Outcomes

Busulfan, cyclophosphamide, and etoposide (BuCyE) is a commonly used conditioning regimen for autologous stem cell transplantation (ASCT). This multicenter, phase II study examined the safety and efficacy of BuCyE with individually adjusted busulfan based on preconditioning pharmacokinetics. The study initially enrolled Hodgkin lymphoma (HL) and non-Hodgkin lymphoma (NHL) patients ages 18 to 80 years but was amended due to high early treatment-related mortality (TRM) in patients > 65 years. BuCyE outcomes were compared with contemporaneous recipients of carmustine, etoposide, cytarabine, and melphalan (BEAM) from the Center for International Blood and Marrow Transplant Research. Two hundred seven subjects with HL (n = 66) or NHL (n = 141) were enrolled from 32 centers in North America, and 203 underwent ASCT. Day 100 TRM for all subjects (n = 203), patients > 65 years (n = 17), and patients ≤ 65 years (n = 186) were 4.5%, 23.5%, and 2.7%, respectively. The estimated rates of 2-year progression-free survival (PFS) were 33% for HL and 58%, 77%, and 43% for diffuse large B cell lymphoma (DLBCL; n = 63), mantle cell lymphoma (MCL; n = 29), and follicular lymphoma (FL; n = 23), respectively. The estimated rates of 2-year overall survival (OS) were 76% for HL and 65%, 89%, and 89% for DLBCL, MCL, and FL, respectively. In the matched analysis rates of 2-year TRM were 3.3% for BuCyE and 3.9% for BEAM, and there were no differences in outcomes for NHL. Patients with HL had lower rates of 2-year PFS with BuCyE, 33% (95% CI, 21% to 46%), than with BEAM, 59% (95% CI, 52% to 66%), with no differences in TRM or OS. BuCyE provided adequate disease control and safety in B cell NHL patients ≤ 65 years but produced worse PFS in HL patients when compared with BEAM.