Patient-reported outcomes in ZUMA-7, a phase 3 study of axicabtagene ciloleucel in second-line large B-cell lymphoma.

Here, we report the first comparative analysis of patient-reported outcomes (PROs) with chimeric antigen receptor T-cell therapy vs standard-of-care (SOC) therapy in second-line relapsed/refractory large B-cell lymphoma (R/R LBCL) from the pivotal randomized phase 3 ZUMA-7 study of axicabtagene ciloleucel (axi-cel) vs SOC. PRO instruments were administered at baseline, day 50, day 100, day 150, month 9, and every 3 months from randomization until 24 months or an event-free survival event. The quality of life (QoL) analysis set comprised patients with a baseline and ≥1 follow-up PRO completion. Prespecified hypotheses for Quality of Life Questionnaire-Core 30 (QLQ-C30) physical functioning, global health status/QoL, and EQ-5D-5L visual analog scale (VAS) were tested using mixed-effects models with repeated measures. Clinically meaningful changes were defined as 10 points for QLQ-C30 and 7 for EQ-5D-5L VAS. Among 359 patients, 296 (165 axi-cel, 131 SOC) met inclusion criteria for QoL analysis. At day 100, statistically significant and clinically meaningful differences in mean change of scores from baseline were observed favoring axi-cel over SOC for QLQ-C30 global health status/QoL (estimated difference 18.1 [95% confidence interval (CI), 12.3-23.9]), physical functioning (13.1 [95% CI, 8.0-18.2]), and EQ-5D-5L VAS (13.7 [95% CI, 8.5-18.8]; P < .0001 for all). At day 150, scores significantly favored axi-cel vs SOC for global health status/QoL (9.8 [95% CI, 2.6-17.0]; P = .0124) and EQ-5D-5L VAS (11.3 [95% CI, 5.4-17.1]; P = .0004). Axi-cel showed clinically meaningful improvements in QoL over SOC. Superior clinical outcomes and favorable patient experience with axi-cel should help inform treatment choices in second-line R/R LBCL. This trial was registered at www.clinicaltrials.gov as #NCT03391466.

Outcomes with low dose anti-thymocyte globulin based graft versus host disease prophylaxis after mismatched unrelated donor allogeneic hematopoietic cell transplantation.

BACKGROUND: Anti-thymocyte globulin (ATG) based graft versus host disease (GVHD) prophylaxis is widely used for mismatched unrelated donor allogeneic hematopoietic cell transplantation (HCT) although optimal dose remains unclear. Although recent literature suggested improved outcomes with PTCy-based regimens when compared to ATG-based regimens these studies used doses of ATG ≥5 mg/kg. Thus, we analyzed outcomes of HLA 9/10 MMUD allogeneic HCTs using lower-dose ATG-based regimens at our center. METHODS: We retrospectively analyzed outcomes of HLA 9/10 MMUD allogeneic HCTs using lower dose ATG-based regimens for all adults undergoing allogeneic HCT at The Ottawa Hospital from 2015 to 2022. Data regarding demographics, conditioning regimen, dose of ATG, rates of GVHD, duration of remission, and survival, were collected and analyzed. RESULTS: Seventy-seven (n = 77) patients (males 62.3%; median age 50 years) underwent allogeneic HCT from MMUD. Majority(81%; n = 63) received 2.5 mg/kg of rabbit ATG and remaining 18.2% (n = 14) received 4.5 mg/kg. Grade II-IV acute GVHD occurred in 24.7% (n = 19) while any chronic GVHD occurred in 32.5% (n = 25) patients. After a median follow-up of 21 months, relapse occurred in 28.6% of patients. Two-year OS, GRFS, CIR, and NRM were 60.6%, 45.3%, 16.9%, and 18.2% respectively. Dose of ATG (2.5 mg/kg vs. 4.5 mg/kg) was not associated with outcomes in either univariate or multivariate analyses. CONCLUSIONS: When compared to published studies using ATG doses ≥5 mg/kg, GVHD prophylaxis using lower dose ATG may potentially lead to improved outcomes in patients undergoing MMUD allogeneic HCT. Further studies are needed to directly compare lower dose ATG to PTCy-based regimens to determine ideal GVHD prophylaxis for these patients.

Economic Evaluations of Chimeric Antigen Receptor T-Cell Therapies for Hematologic and Solid Malignancies: A Systematic Review.

OBJECTIVES: This study aimed to systematically review evidence on the cost-effectiveness of chimeric antigen receptor T-cell (CAR-T) therapies for patients with cancer. METHODS: Electronic databases were searched in October 2022 and updated in September 2023. Systematic reviews, health technology assessments, and economic evaluations that compared costs and effects of CAR-T therapy in patients with cancer were included. Two reviewers independently screened studies, extracted data, synthesized results, and critically appraised studies using the Philips checklist. Cost data were presented in 2022 US dollars. RESULTS: Our search yielded 1809 records, 47 of which were included. Most of included studies were cost-utility analysis, published between 2018 and 2023, and conducted in the United States. Tisagenlecleucel, axicabtagene ciloleucel, idecabtagene vicleucel, ciltacabtagene autoleucel, lisocabtagene maraleucel, brexucabtagene autoleucel, and relmacabtagene autoleucel were compared with various standard of care chemotherapies. The incremental cost-effectiveness ratio (ICER) for CAR-T therapies ranged from $9424 to $4 124 105 per quality-adjusted life-year (QALY) in adults and from $20 784 to $243 177 per QALY in pediatric patients. Incremental cost-effectiveness ratios were found to improve over longer time horizons or when an earlier cure point was assumed. Most studies failed to meet the Philips checklist due to a lack of head-to-head comparisons and uncertainty surrounding CAR-T costs and curative effects. CONCLUSIONS: CAR-T therapies were more expensive and generated more QALYs than comparators, but their cost-effectiveness was uncertain and dependent on patient population, cancer type, and model assumptions. This highlights the need for more nuanced economic evaluations and continued research to better understand the value of CAR-T therapies in diverse patient populations.

The impact of feedback training on prediction of cancer clinical trial results.

INTRODUCTION: Funders must make difficult decisions about which squared treatments to prioritize for randomized trials. Earlier research suggests that experts have no ability to predict which treatments will vindicate their promise. We tested whether a brief training module could improve experts' trial predictions. METHODS: We randomized a sample of breast cancer and hematology-oncology experts to the presence or absence of a feedback training module where experts predicted outcomes for five recently completed randomized controlled trials and received feedback on accuracy. Experts then predicted primary outcome attainment for a sample of ongoing randomized controlled trials. Prediction skill was assessed by Brier scores, which measure the average deviation between their predictions and actual outcomes. Secondary outcomes were discrimination (ability to distinguish between positive and non-positive trials) and calibration (higher predictions reflecting higher probability of trials being positive). RESULTS: A total of 148 experts (46 for breast cancer, 54 for leukemia, and 48 for lymphoma) were randomized between May and December 2017 and included in the analysis (1217 forecasts for 25 trials). Feedback did not improve prediction skill (mean Brier score for control: 0.22, 95% confidence interval = 0.20-0.24 vs feedback arm: 0.21, 95% confidence interval = 0.20-0.23; p = 0.51). Control and feedback arms showed similar discrimination (area under the curve = 0.70 vs 0.73, p = 0.24) and calibration (calibration index = 0.01 vs 0.01, p = 0.81). However, experts in both arms offered predictions that were significantly more accurate than uninformative forecasts of 50% (Brier score = 0.25). DISCUSSION: A short training module did not improve predictions for cancer trial results. However, expert communities showed unexpected ability to anticipate positive trials.Pre-registration record: https://aspredicted.org/4ka6r.pdf.

A Discussion with Dr. Natasha Kekre, Hematologist and Clinician Scientist.

[Figure: see text] Dr. Natasha Kekre has been appointed to the Department of Medicine in the Division of Hematology, within the Transplant and Cellular Therapy Program at The Ottawa Hospital since 2015. She is also a scientist within the Ottawa Hospital Research Institute and an associate professor of medicine at the University of Ottawa. She completed her Bachelor's in Science at the University of Windsor then obtained her medical degree from the University of Ottawa. She trained at the University of Ottawa in Internal Medicine and Hematology, then did fellowship in stem cell transplantation at Dana Farber Cancer Institute in Boston, MA with a Masters in Public Health from Harvard University. Her research is focused on developing early phase clinical trials and moving home grown therapeutic strategies from the lab to patients in the clinic. She has collaborated with scientists and physicians across Canada to build a Canadian CAR-T cell platform (chimeric antigen receptor T cells are immune cells engineered to kill cancer cells), bringing this exciting new therapy to Canadian patients.

HLA-haploidentical vs matched unrelated donor transplants with posttransplant cyclophosphamide-based prophylaxis.

Posttransplant cyclophosphamide (PTCy) graft-versus-host disease (GVHD) prophylaxis has enabled haploidentical (Haplo) transplantation to be performed with results similar to those after matched unrelated donor (MUD) transplantation with traditional prophylaxis. The relative value of transplantation with MUD vs Haplo donors when both groups receive PTCy/calcineurin inhibitor/mycophenolate GVHD prophylaxis is not known. We compared outcomes after 2036 Haplo and 284 MUD transplantations with PTCy GVHD prophylaxis for acute leukemia or myelodysplastic syndrome in adults from 2011 through 2018. Cox regression models were built to compare outcomes between donor types. Recipients of myeloablative and reduced-intensity regimens were analyzed separately. Among recipients of reduced-intensity regimens, 2-year graft failure (3% vs 11%), acute grades 2 to 4 GVHD (hazards ratio [HR], 0.70; P = .022), acute grades 3 and 4 GVHD (HR, 0.41; P = .016), and nonrelapse mortality (HR, 0.43; P = .0008) were lower after MUD than with Haplo donor transplantation. Consequently, disease-free (HR, 0.74; P = .008; 55% vs 41%) and overall (HR, 0.65; P = .001; 67% vs 54%) survival were higher with MUD than with Haplo transplants. Among recipients of myeloablative regimens, day-100 platelet recovery (95% vs 88%) was higher and grades 3 and 4 acute (HR, 0.39; P = .07) and chronic GVHD (HR, 0.66; P = .05) were lower after MUD than with Haplo donor transplantation. There were no differences in graft failure, relapse, nonrelapse mortality, and disease-free and overall survival between donor types with myeloablative conditioning regimens. These data extend and confirm the importance of donor-recipient HLA matching for allogeneic transplantation. A MUD is the preferred donor, especially for transplantations with reduced-intensity conditioning regimens.

Current challenges in the manufacture of clinical-grade autologous whole cell vaccines for hematological malignancies.

Autologous whole cell vaccines use a patient's own tumor cells as a source of antigen to elicit an anti-tumor immune response in vivo. Recently, the authors conducted a systematic review of clinical trials employing these products in hematological cancers that showed a favorable safety profile and trend toward efficacy. However, it was noted that manufacturing challenges limit both the efficacy and clinical implementation of these vaccine products. In the current literature review, the authors sought to define the issues surrounding the manufacture of autologous whole cell products for hematological cancers. The authors describe key factors, including the acquisition, culture, cryopreservation and transduction of malignant cells, that require optimization for further advancement of the field. Furthermore, the authors provide a summary of pre-clinical work that informs how the identified challenges may be overcome. The authors also highlight areas in which future basic research would be of benefit to the field. The goal of this review is to provide a roadmap for investigators seeking to advance the field of autologous cell vaccines as it applies to hematological malignancies.

Use of CRISPR/Cas9 gene editing to improve chimeric antigen-receptor T cell therapy: A systematic review and meta-analysis of preclinical studies.

BACKGROUND: Chimeric antigen-receptor T (CAR-T) cells represent great promise in cancer treatment. CRISPR/Cas9 gene editing in preclinical studies has enabled the development of enhanced CAR-T products with improved function and reduced toxicity. METHODS: A systematic review of preclinical animal studies was conducted to determine the efficacy and safety of this approach. RESULTS: 3753 records were identified (to September 9, 2020), with 11 studies using CRISPR/Cas9 gene editing in combination with CAR-T therapy against human cells in animal models of acute leukemia (four studies), glioma (two studies), melanoma (two studies), and other cancers (three studies). Compared with unedited controls, gene-edited CAR-T cells reduced tumor volume in treated animals and improved survival. No adverse side effects were reported. Use of allogeneic "third-party" CAR-T cells appears feasible. Improved efficacy was achieved through both knock-in and knockout gene editing of various targets implicated in immune function. Targeting multiple genes also appears feasible. Significant heterogeneity in study design and outcome reporting was observed, and potential bias was identified in all studies. CONCLUSION: CRISPR/Cas9 gene editing enables manufacturing of CAR-T cells with improved anti-cancer effects. Future studies should reduce unintentional bias and heterogeneity of study designs and strive to augment long-term persistence of edited cells. PROTOCOL REGISTRATION: PROSPERO; registration number CRD42020220313 registered November 30, 2020.

Building a Platform for Meaningful Patient Partnership to Accelerate "Bench-to-Bedside" Translation of Promising New Therapies.

Engaging patients as partners in the design and execution of early-phase clinical trials offers a unique opportunity to ensure patient perspectives are considered. Here we describe our experience partnering with four individuals with lived experience of blood cancer to co-develop documents and services to support participants of an early-phase trial. Through regular team meetings, patient partners co-developed a visual informed consent document and a non-technical summary of the informed consent document to facilitate participant understanding of trial procedures. Overall, patient partners highlighted important trial components that would not have been identified without their input.

Safety and efficacy of autologous whole cell vaccines in hematologic malignancies: A systematic review and meta-analysis.

Autologous cell vaccines use a patient's tumor cells to stimulate a broad antitumor response in vivo. This approach shows promise for treating hematologic cancers in early phase clinical trials, but overall safety and efficacy remain poorly described. We conducted a systematic review assessing the use of autologous cell vaccination in treating hematologic cancers. Primary outcomes of interest were safety and clinical response, with secondary outcomes including survival, relapse rate, correlative immune assays and health-quality related metrics. We performed a search of MEDLINE, Embase and the Cochrane Register of Controlled Trials including any interventional trial employing an autologous, whole cell product in any hematologic malignancy. Risk of bias was assessed using a modified Institute of Health Economics tool. Across 20 single arm studies, only 341 of 592 enrolled participants received one or more vaccinations. Primary reasons for not receiving vaccination included rapid disease progression/death and manufacturing challenges. Overall, few high-grade adverse events were observed. One death was reported and attributed to a GM-CSF producing allogeneic cell line co-administered with the autologous vaccine. Of 58 evaluable patients, the complete response rate was 21.0% [95% CI, 10.4%-37.8%)] and overall response rate was 35.8% (95% CI, 24.4%-49.0%). Of 97 evaluable patients for survival, the 5-years overall survival rate was 64.9% (95% CI, 52.6%-77.2%) and disease-free survival was 59.7% (95% CI, 47.7%-71.7%). We conclude that, in hematologic malignancies, based on limited available data, autologous cell vaccines are safe and display a trend towards efficacy but that challenges exist in vaccine manufacture and administration.

Autologous Hematopoietic Stem Cell Transplantation for Chronic Inflammatory Demyelinating Polyradiculoneuropathy.

BACKGROUND: Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) refractory to conventional therapy can lead to marked disability and represents a therapeutic challenge. OBJECTIVE: To report five cases of treatment-refractory disabling CIDP treated with autologous hematopoietic stem cell transplantation (AHSCT). METHODS: This was a retrospective cohort study from a tertiary care referral center for both neuromuscular disease and AHSCT. Patients with CIDP treated with AHSCT between 2008 and 2020 were included. All patients had major persistent and disabling neuropathic deficits despite combinations of intensive immunosuppressive therapy. The primary outcome measures were: Medical Research Council sum score, Overall Neuropathy Limitations Scale and requirement for ongoing CIDP immunotherapy after transplantation. We also analyzed safety outcomes by documenting all severe AHSCT-related complications. RESULTS: Five patients with refractory CIDP underwent AHSCT. Three were classified as manifesting a typical syndrome, two were classified as the multifocal Lewis Sumner variant. The mean age at time of CIDP diagnosis was 33.4 years (range 24-46 years), with a median delay of 46 months (range 21-135 months) between diagnosis and AHSCT. The median follow-up period was 41 months. All five patients were able to wean off CIDP-related immunotherapy. Marked improvements in Medical Research Council scale and overall Neuropathy Limitations Scale were noted in 4/5 patients. One patient with longstanding neurogenic atrophy showed no improvement in disability scales. There were no treatment-related deaths or critical illnesses. CONCLUSIONS: AHSCT can achieve marked sustained clinical improvement of refractory CIDP and may allow for weaning off long-term complex immunotherapies.

Does Lymphocyte Count Impact Dosing of Anti-Thymocyte Globulin in Unrelated Donor Stem Cell Transplantation?

Anti-thymocyte globulin (ATG) is used to reduce the incidence and severity of graft-versus-host disease (GVHD) with hematopoietic cell transplantation, yet optimum dosing has yet to be determined. We have previously demonstrated that 2.5 mg/kg ATG in conditioning can reduce the incidence of GVHD in unrelated donor transplants. Recent literature has suggested that ATG dosing based on absolute lymphocyte count (ALC) could lead to more optimum exposure of the drug. We sought to determine if ALC at the time of transplant could impact clinical outcomes. We conducted a retrospective single-center study analyzing all consecutive patients at The Ottawa Hospital who received a matched unrelated donor stem cell transplant with ATG between 2009 and 2014. Patients received rabbit ATG (thymoglobulin) at 0.5 mg/kg on day -2 and 2.0 mg/kg on day -1. Univariate and multivariate analyses were used to determine if any patient- or transplant-related factors, including weight, ALC, and total ATG dose given, impacted GVHD, relapse, or mortality. In total, 111 patients met inclusion, with a median age of 50 years (range, 19 to 70). The most common diagnoses were acute myelogenous leukemia (43%), Myelodysplasia/myeloproliferative neoplasms (13%), and lymphoma (12%). The median weight at time of conditioning was 80.3 kg (range, 45 to 216). The median ALC on the first day of ATG administration was 0.1 × 109/L (range, 0 to 190). The median total dose of ATG received was 201 mg (range, 112 to 540 mg). The incidence of acute and chronic GVHD was 35.1% and 21.6%, respectively. In the multivariate model, the actual dose of ATG given to patients was not associated with GVHD (hazard ratio [HR], 1.11; 95% confidence interval [CI], 0.99 to 1.25; P = .07), relapse (HR, 1.13; 95% CI, 0.98 to 1.30; P = .1), or mortality (HR, 1.09; 95% CI, 0.92 to 1.28; P = .32). Similarly, the pretransplant ALC was not associated with GVHD (HR, 1; P = .82), relapse (HR, 1; P = .90), or mortality (HR, 1; P = .39). If patients had received ALC-based dosing according to previously published work (Admiraal et al., Lancet Haematol 2017), the mean total dose of ATG received would have been 1205 mg, more than 5 times the mean dose that was actually given based on weight. With GVHD outcomes being similar to that published by Admiraal et al. and ALC not independently associated with outcomes in our study, further studies are still needed to compare standard weight-based dosing to ALC-based dosing of ATG in matched unrelated donor stem cell transplant.

Alternative donor transplantation for acute myeloid leukemia in patients aged ≥50 years: young HLA-matched unrelated or haploidentical donor?

We sought to study whether survival after haploidentical transplantation is comparable to that after matched unrelated donor transplantation for 822 patients aged 50-75 years with acute myeloid leukemia in first or second complete remission. One hundred and ninety-two patients received grafts from haploidentical donors (sibling 25%; offspring 75%) and 631 patients from matched unrelated donors aged 18-40 years. Patients' and disease characteristics of the two groups were similar except that recipients of matched unrelated donor transplantation were more likely to have poor risk cytogenetics and more likely to receive myeloablative conditioning regimens. Time from documented remission to transplant did not differ by donor type. Five-year overall survival was 32% and 42% after haploidentical and matched unrelated donor transplant, respectively (P=0.04). Multivariable analysis showed higher mortality (hazard ratio 1.27, P=0.04) and relapse (hazard ratio 1.32, P=0.04) after haploidentical transplantation, with similar non-relapse mortality risks. Chronic graft-versus-host disease was higher after matched unrelated donor compared to haploidentical transplantation when bone marrow was the graft (hazard ratio 3.12, P<0.001), but when the graft was peripheral blood, there was no difference in the risk of chronic graft-versus-host disease between donor types. These data support the view that matched unrelated donor transplant with donors younger than 40 years is to be preferred.

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.

Effect of Donor Age and Donor Relatedness on Time to Allogeneic Hematopoietic Cell Transplantation in Acute Leukemia.

Relapse after allogeneic hematopoietic cell transplantation (HCT) for acute leukemia can be reduced when pursued early after first complete remission. The impact of donor age and donor relatedness on the time from diagnosis to transplant in patients with acute leukemia was examined to clarify the design of future prospective studies that can address optimal donor choice. Files of 100 consecutive patients undergoing transplantation for leukemia were reviewed. Recipients of related donors (RDs) and unrelated donors (UDs) were not significantly different in terms of recipient gender, age, underlying diagnosis, disease risk index, graft source, or donor HLA match. UDs were significantly younger than RDs (median age, 29 versus 51, P < .001). Multivariate linear regression revealed that when controlling for age of donor and recipient, the time from diagnosis to transplant was 35% longer with UDs compared with RDs (P = .018). No significant correlation was observed between donor and recipient age on length of time to transplant (P = .134 and P = .850, respectively), when controlling for other variables. The steps in UD procurement that contribute most to the longer time to transplant relate to activating the donor workup and scheduling the donor workup before cell collection. Understanding sources of delay in the transplant process will help transplant centers and UD registries reduce the time to transplant for patients with acute leukemia and will provide necessary insight for the design of prospective controlled studies that can address optimal donor choice.

Natural Killer Cell IFNγ Secretion is Profoundly Suppressed Following Colorectal Cancer Surgery.

BACKGROUND: Surgical stress results in a significant reduction in natural killer (NK) cell cytotoxicity (NKC), which has been linked to postoperative cancer metastases. However, few studies have measured the impact of surgical stress upon NK cell IFNγ secretion (NKA), a cytokine with essential roles in controlling infection and metastases. The objective of this study was to investigate the impact of surgical stress on NKA in colorectal cancer (CRC) surgery patients. METHODS: Peripheral blood was collected from CRC surgery patients (n = 42) preoperatively and on postoperative day (POD) 1, 3, 5, 28, and 56. Healthy donor blood (n = 27) was collected for controls. We assessed NKA by production of IFNγ following whole blood cytokine stimulation, NKC by 51Cr-release assay, and immune cell profiling by flow cytometry. RESULTS: The mean reduction in NKA on POD1 compared with baseline was 83.1% (standard deviation 25.2%; confidence interval 75-91), and therefore the study met the primary endpoint of demonstrating a > 75% decrease in a cohort of CRC surgery patients (p < 0.0001). The profound and universal suppression of NKA persisted with 65.5% (19/29) and 33.3% (4/12) of patients with levels measuring < 75% of baseline on POD28 and POD56 respectively. The NKC was significantly reduced on POD1, but the degree was less pronounced (24.6%, p = 0.0024). Immune cell profiling did not reveal differences in the absolute number of NK cells (CD3-CD56+) or the ratio of CD56dim-to-CD56bright subsets. CONCLUSIONS: NKA is significantly suppressed for up to two months following surgery in CRC patients, a degree of surgery-induced immunosuppression far worse than previously reported.

Low-Dose Antithymocyte Globulin for Graft-versus-Host-Disease Prophylaxis in Matched Unrelated Allogeneic Hematopoietic Stem Cell Transplantation.

Graft-versus-host disease (GVHD) is a leading cause of morbidity and mortality in allogeneic hematopoietic stem cell transplantation (alloHCT). Prophylactic in vivo T cell depletion with antithymocyte globulin (ATG) has been associated with decreased GVHD rates in many alloHCT settings. Despite decades of clinical study, optimal ATG dosing has not been established. Understanding that higher rates of GVHD are observed with matched unrelated donor (MUD) versus matched related donor (MRD) alloHCT, at our institution MUD alloHCT recipients have historically had low-dose Thymoglobulin (total dose, 2.5 mg/kg; Genzyme-Sanofi, Cambridge, MA) added to our standard MRD GVHD prophylaxis regimen. In this retrospective cohort study we assessed post-HCT the effectiveness of our uniquely low-dose ATG strategy by comparing ATG exposed (MUD) and unexposed (MRD) alloHCT recipients for GVHD and other clinical HCT outcomes. This retrospective single-center study included all HCT patients transplanted for any malignant indication at The Ottawa Hospital from 2009 to 2014. MUD patients received rabbit ATG (Thymoglobulin) at a total dose of 2.5 mg/kg given over 2 days (.5 mg/kg on day -2; 2.0 mg/kg on day -1 before stem cell infusion) in addition to standard GVHD prophylaxis. Primary outcomes assessed were incidence of acute and chronic GVHD, defined as new-onset GVHD requiring systemic immunosuppressive therapy at less or more than 100 days, respectively. Secondary outcomes included disease relapse and survival. There were 110 and 77 patients in the ATG exposed (MUD) and unexposed (MRD) cohorts, respectively. At baseline there were no significant differences in median age at transplant, sex, disease indication or risk index, graft source, conditioning regimen, or intensity between cohorts. A higher proportion of 7/8 mismatched donor transplants (13% versus 3%, P = .02) and a higher median CD34+ dose (7.9 versus 4.9 × 108 cells; P < .01) was observed in the ATG exposed cohort. No differences were noted in platelet engraftment. ATG exposed patients had significantly shorter time to neutrophil engraftment than the unexposed cohort (16 versus 19 days, respectively; P < .01). ATG exposed patients had significantly lower rates of GVHD than ATG unexposed patients (57% versus 79%; P = .01), with differences predominantly in rates of chronic GVHD (18% versus 44%, P < .01). At median follow-up of 28 (range, 3 to 69) and 25 (range, 2 to 73) months for survivors in ATG exposed and unexposed cohorts, respectively, no significant differences in overall survival (median overall survival not met for either cohort), relapse incidence (26% versus 29%, P = .73), or relapse-free survival (RFS) (not met in ATG exposed and 26 months in ATG unexposed, P = .22) were observed between groups. The ATG exposed cohort had significantly higher GVHD-free RFS (GRFS) with a 2-year GRFS of 23% versus 3% (P = .003). There were no significant differences between cohorts in proportion of patientswith post-HCT infectious episodes or intensive care unit admissions. Here we report significantly lower rates of chronic GVHD and significant improvement in GRFS in an ATG exposed MUD alloHCT cohort compared with an ATG unexposed MRD cohort. These findings were observed without differences in relapse, survival, infectious complications, or intensive care unit admissions. Our findings highlight the association of unconventionally low-dose ATG with improved GVHD outcomes and suggest a need for prospective study of ATG use in lower doses.

Venous thromboembolism is associated with graft-versus-host disease and increased non-relapse mortality after allogeneic hematopoietic stem cell transplantation.

Although venous thromboembolism rates and risk factors are well described in patients with cancer, there are limited data on the incidence, risk factors and outcomes of thrombosis after allogeneic stem cell transplantation, a curative therapy for patients with hematologic malignancies. We aimed to determine the incidence and risks associated with venous thrombosis in allogeneic stem cell transplants. We studied 2276 recipients of first transplant between 2002-2013 at our institution with a median follow up of 50 months (range 4-146). Using pharmacy records and subsequent chart reviews, 190 patients who received systemic anticoagulation for venous thrombosis were identified. The 1-and 2-year cumulative incidence of all venous thrombotic events were 5.5% (95% confidence interval (CI) 4.6-6.5%) and 7.1% (95% CI 6.1-8.2%), respectively. There was no difference in age, sex, body mass index, diagnosis, disease risk index, conditioning intensity, donor type or graft source between transplant recipients with and without subsequent thrombosis. In multivariable models, both acute and chronic graft-versus-host disease were independently associated with thrombosis occurrence (Hazard ratio (HR)=2.05, 95% CI 1.52-2.76; HR=1.71, 95% CI 1.19-2.46, respectively). Upper extremity thrombosis differed from all other thromboses in terms of timing, risk factors and clinical impact, and was not associated with non-relapse mortality (HR=1.15; 95% CI 0.69-1.90), unlike all other thromboses which did increase non-relapse mortality (HR=1.71; 95% CI 1.17-2.49). In subgroup analysis evaluating conventional thrombosis predictors by comparing patients with and without thrombosis, a history of prior venous thrombosis was the only significant predictor. Venous thromboembolism has a high incidence after allogeneic stem cell transplant and is associated with graft-versus-host disease and non-relapse mortality.

Effect of antithymocyte globulin source on outcomes of bone marrow transplantation for severe aplastic anemia.

For treatment of severe aplastic anemia, immunosuppressive therapy with horse antithymocyte globulin results in superior response and survival compared with rabbit antithymocyte globulin. This relative benefit may be different in the setting of transplantation as rabbit antithymocyte globulin results in more profound immunosuppression. We analyzed 833 severe aplastic anemia transplants between 2008 and 2013 using human leukocyte antigen (HLA)-matched siblings (n=546) or unrelated donors (n=287) who received antithymocyte globulin as part of their conditioning regimen and bone marrow graft. There were no differences in hematopoietic recovery by type of antithymocyte globulin. Among recipients of HLA-matched sibling transplants, day 100 incidence of acute (17% versus 6%, P<0.001) and chronic (20% versus 9%, P<0.001) graft-versus-host disease were higher with horse compared to rabbit antithymocyte globulin. There were no differences in 3-year overall survival, 87% and 92%, P=0.76, respectively. Among recipients of unrelated donor transplants, acute graft-versus-host disease was also higher with horse compared to rabbit antithymocyte globulin (42% versus 23%, P<0.001) but not chronic graft-versus-host disease (38% versus 32%, P=0.35). Survival was lower with horse antithymocyte globulin after unrelated donor transplantation, 75% versus 83%, P=0.02. These data support the use of rabbit antithymocyte globulin for bone marrow transplant conditioning for severe aplastic anemia.