Antitumor efficacy and safety of unedited autologous CD5.CAR T cells in relapsed/refractory mature T-cell lymphomas.

ABSTRACT: Despite newer targeted therapies, patients with primary refractory or relapsed (r/r) T-cell lymphoma have a poor prognosis. The development of chimeric antigen receptor (CAR) T-cell platforms to treat T-cell malignancies often requires additional gene modifications to overcome fratricide because of shared T-cell antigens on normal and malignant T cells. We developed a CD5-directed CAR that produces minimal fratricide by downmodulating CD5 protein levels in transduced T cells while retaining strong cytotoxicity against CD5+ malignant cells. In our first-in-human phase 1 study (NCT0308190), second-generation autologous CD5.CAR T cells were manufactured from patients with r/r T-cell malignancies. Here, we report safety and efficacy data from a cohort of patients with mature T-cell lymphoma (TCL). Among the 17 patients with TCL enrolled, CD5 CAR T cells were successfully manufactured for 13 out of 14 attempted lines (93%) and administered to 9 (69%) patients. The overall response rate (complete remission or partial response) was 44%, with complete responses observed in 2 patients. The most common grade 3 or higher adverse events were cytopenias. No grade 3 or higher cytokine release syndrome or neurologic events occurred. Two patients died during the immediate toxicity evaluation period due to rapidly progressive disease. These results demonstrated that CD5.CAR T cells are safe and can induce clinical responses in patients with r/r CD5-expressing TCLs without eliminating endogenous T cells or increasing infectious complications. More patients and longer follow-up are needed for validation. This trial was registered at www.clinicaltrials.gov as #NCT0308190.

LOAd703, an oncolytic virus-based immunostimulatory gene therapy, combined with chemotherapy for unresectable or metastatic pancreatic cancer (LOKON001): results from arm 1 of a non-randomised, single-centre, phase 1/2 study.

BACKGROUND: Pancreatic ductal adenocarcinoma is characterised by low immunogenicity and an immunosuppressive tumour microenvironment. LOAd703, an oncolytic adenovirus with transgenes encoding TMZ-CD40L and 4-1BBL, lyses cancer cells selectively, activates cytotoxic T cells, and induces tumour regression in preclinical models. The aim of this study was to evaluate the safety and feasibility of combining LOAd703 with chemotherapy for advanced pancreatic ductal adenocarcinoma. METHODS: LOKON001 was a non-randomised, phase 1/2 study conducted at the Dan L Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, TX, USA, and consisted of two arms conducted sequentially; the results of arm 1 are presented here. In arm 1, patients 18 years or older with previously treated or treatment-naive unresectable or metastatic pancreatic ductal adenocarcinoma were treated with standard 28-day cycles of intravenous nab-paclitaxel 125 mg/m2 plus gemcitabine 1000 mg/m2 (up to 12 cycles) and intratumoural injections of LOAd703 every 2 weeks. Patients were assigned using Bayesian optimal interval design to receive 500 µL of LOAd703 at 5 × 1010 (dose 1), 1 × 1011 (dose 2), or 5 × 1011 (dose 3) viral particles per injection, injected endoscopically or percutaneously into the pancreatic tumour or a metastasis for six injections. The primary endpoints were safety and treatment-emergent immune response in patients who received at least one dose of LOAd703, and antitumour activity was a secondary endpoint. This study was registered with ClinicalTrials.gov, NCT02705196, arm 2 is ongoing and open to new participants. FINDINGS: Between Dec 2, 2016, and Oct 17, 2019, 23 patients were assessed for eligibility, leading to 22 patients being enrolled. One patient withdrew consent, resulting in 21 patients (13 [62%] men and eight [38%] women) assigned to a dose group (three to dose 1, four to dose 2, and 14 to dose 3). 21 patients were evaluable for safety. Median follow-up time was 6 months (IQR 4-10), and data cutoff was Jan 5, 2023. The most common treatment-emergent adverse events overall were anaemia (96 [8%] of 1237 events), lymphopenia (86 [7%] events), hyperglycaemia (70 [6%] events), leukopenia (63 [5%] events), hypertension (62 [5%] events), and hypoalbuminaemia (61 [5%] events). The most common adverse events attributed to LOAd703 were fever (14 [67%] of 21 patients), fatigue (eight [38%]), chills (seven [33%]), and elevated liver enzymes (alanine aminotransferase in five [24%], alkaline phosphatase in four [19%], and aspartate aminotransferase in four [19%]), all of which were grade 1-2, except for a transient grade 3 aminotransferase elevation occurring at dose 3. A maximum tolerated dose was not reached, thereby establishing dose 3 as the highest-evaluated safe dose when combined with nab-paclitaxel plus gemcitabine. Proportions of CD8+ effector memory cells and adenovirus-specific T cells increased after LOAd703 injections in 15 (94%) of 16 patients for whom T-cell assays could be performed. Eight (44%, 95% CI 25-66) of 18 patients evaluable for activity had an objective response. INTERPRETATION: Combining LOAd703 with nab-paclitaxel plus gemcitabine in patients with advanced pancreatic ductal adenocarcinoma was feasible and safe. To build upon this novel chemoimmunotherapeutic approach, arm 2 of LOKON001, which combines LOAd703, nab-paclitaxel plus gemcitabine, and atezolizumab, is ongoing. FUNDING: Lokon Pharma, the Swedish Cancer Society, and the Swedish Research Council.

Donor-derived multiple leukemia antigen-specific T-cell therapy to prevent relapse after transplant in patients with ALL.

Hematopoietic stem cell transplant (HSCT) is a curative option for patients with high-risk acute lymphoblastic leukemia (ALL), but relapse remains a major cause of treatment failure. To prevent disease relapse, we prepared and infused donor-derived multiple leukemia antigen-specific T cells (mLSTs) targeting PRAME, WT1, and survivin, which are leukemia-associated antigens frequently expressed in B- and T-ALL. Our goal was to maximize the graft-versus-leukemia effect while minimizing the risk of graft-versus-host disease (GVHD). We administered mLSTs (dose range, 0.5 × 107 to 2 × 107 cells per square meter) to 11 patients with ALL (8 pediatric, 3 adult), and observed no dose-limiting toxicity, acute GVHD or cytokine release syndrome. Six of 8 evaluable patients remained in long-term complete remission (median: 46.5 months; range, 9-51). In these individuals we detected an increased frequency of tumor-reactive T cells shortly after infusion, with activity against both targeted and nontargeted, known tumor-associated antigens, indicative of in vivo antigen spreading. By contrast, this in vivo amplification was absent in the 2 patients who experienced relapse. In summary, infusion of donor-derived mLSTs after allogeneic HSCT is feasible and safe and may contribute to disease control, as evidenced by in vivo tumor-directed T-cell expansion. Thus, this approach represents a promising strategy for preventing relapse in patients with ALL.

Long-term follow-up for the development of subsequent malignancies in patients treated with genetically modified IECs.

Subsequent malignancies are well-documented complications in long-term follow-up of cancer patients. Recently, genetically modified immune effector (IE) cells have shown benefit in hematologic malignancies and are being evaluated in clinical trials for solid tumors. Although the short-term complications of IE cells are well described, there is limited literature summarizing long-term follow-up, including subsequent malignancies. We retrospectively reviewed data from 340 patients treated across 27 investigator-initiated pediatric and adult clinical trials at our center. All patients received IE cells genetically modified with γ-retroviral vectors to treat relapsed and/or refractory hematologic or solid malignancies. In a cumulative 1027 years of long-term follow-up, 13 patients (3.8%) developed another cancer with a total of 16 events (4 hematologic malignancies and 12 solid tumors). The 5-year cumulative incidence of a first subsequent malignancy in the recipients of genetically modified IE cells was 3.6% (95% confidence interval, 1.8% to 6.4%). For 11 of the 16 subsequent tumors, biopsies were available, and no sample was transgene positive by polymerase chain reaction. Replication-competent retrovirus testing of peripheral blood mononuclear cells was negative in the 13 patients with subsequent malignancies tested. Rates of subsequent malignancy were low and comparable to standard chemotherapy. These results suggest that the administration of IE cells genetically modified with γ retroviral vectors does not increase the risk for subsequent malignancy.

Incipient clonal hematopoiesis is accelerated following CD30.CAR-T therapy.

Chimeric antigen receptor (CAR) T-cells are an emerging therapy for refractory lymphomas. Clonal hematopoiesis (CH), the preferential outgrowth of mutated bone marrow progenitors, is enriched in lymphoma patients receiving CAR-T cells. CAR-T therapy requires conditioning chemotherapy and often induces systemic inflammatory reactions, both of which have been shown to promote expansion of CH clones. Thus, we hypothesized that pre-existing CH clones could expand during CAR-T cell treatment. We measured CH at 154 timepoints longitudinally sampled from 26 patients receiving CD30.CAR-T therapy for CD30+ lymphomas on an investigational protocol (NCT02917083). Pre-treatment CH was present in 54% of individuals and did not correlate with survival outcomes or inflammatory toxicities. Longitudinal tracking of single clones in individual patients revealed distinct clone growth dynamics. Initially small clones, defined as VAF <1%, expanded following CAR-T administration, compared with relatively muted expansions of larger clones (3.37-fold vs. 1.20-fold, P = 0.0014). Matched clones were present at low magnitude in the infused CD30.CAR-T product for all CH cases but did not affect the product's immunophenotype or transduction efficiency. As cellular immunotherapies expand to become frontline treatments for hematological malignancies, our data indicates CAR-T recipients could be enriched for CH, and further longitudinal studies centered on CH complications in this population are warranted.

Prolonged cytopenias after immune effector cell therapy and lymphodepletion in patients with leukemia, lymphoma and solid tumors.

BACKGROUND AIMS: The success of chimeric antigen receptor (CAR) T-cell therapy in treating B-cell malignancies has led to the evaluation of CAR T-cells targeting a variety of other malignancies. Although the efficacy of CAR T-cells is enhanced when administered post-lymphodepleting chemotherapy, this can trigger bone marrow suppression and sustained cytopenia after CD19.CAR T-cell therapy. Additionally, systemic inflammation associated with CAR T-cell activity may contribute to myelosuppression. Cytopenias, such as neutropenia and thrombocytopenia, elevate the risk of severe infections and bleeding, respectively. However, data on the incidence of prolonged cytopenias after immune effector therapy in the solid tumor context remain limited. OBJECTIVE: We compared the incidence of prolonged cytopenias after immune effector therapy including genetically modified T-cells, virus-specific T-cells (VSTs) and NKT-cells, as well non-gene-modified VSTs for leukemia, lymphoma, and solid tumors (ST) to identify associated risk factors. METHODS: A retrospective analysis was conducted of 112 pediatric and adult patients with relapsed and/or refractory cancers who received lymphodepleting chemotherapy followed by immune effector therapy. Patients treated with 13 distinct immune effector cell therapies through 11 single-center clinical trials and 2 commercial products over a 6-year period were categorized into 3 types of malignancies: leukemia, lymphoma and ST. We obtained baseline patient characteristics and adverse events data for each participant, and tracked neutrophil and platelet counts following lymphodepletion. RESULTS: Of 112 patients, 104 (92.9%) experienced cytopenias and 88 (79%) experienced severe cytopenias. Patients with leukemia experienced significantly longer durations of severe neutropenia (median duration of 14 days) compared with patients with lymphoma (7 days) or ST (11 days) (P = 0.002). Patients with leukemia also had a higher incidence of severe thrombocytopenia (74.1%), compared with lymphoma (46%, P = 0.03) and ST (14.3%, P < 0.0001). Prolonged cytopenias were significantly associated with disease type (63% of patients with leukemia, 44% of patients with lymphoma, and 22.9% of patients with ST, P = 0.006), prior hematopoietic stem cell transplant (HSCT) (66.7% with prior HSCT versus 38.3% without prior HSCT, P = 0.039), and development of immune effector cell-associated neurotoxicity syndrome (ICANS) (75% with ICANS versus 38% without ICANS, P = 0.027). There was no significant association between prolonged cytopenias and cytokine release syndrome. CONCLUSIONS: Immune effector recipients often experience significant cytopenias due to marrow suppression following lymphodepletion regardless of disease, but prolonged severe cytopenias are significantly less common after treatment of patients with lymphoma and solid tumors.

Clinical effects of administering leukemia-specific donor T cells to patients with AML/MDS after allogeneic transplant.

Relapse after allogeneic hematopoietic stem cell transplantation (HCT) is the leading cause of death in patients with acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS). Infusion of unselected donor lymphocytes (DLIs) enhances the graft-versus-leukemia (GVL) effect. However, because the infused lymphocytes are not selected for leukemia specificity, the GVL effect is often accompanied by life-threatening graft-versus-host disease (GVHD), related to the concurrent transfer of alloreactive lymphocytes. Thus, to minimize GVHD and maximize GVL, we selectively activated and expanded stem cell donor-derived T cells reactive to multiple antigens expressed by AML/MDS cells (PRAME, WT1, Survivin, and NY-ESO-1). Products that demonstrated leukemia antigen specificity were generated from 29 HCT donors. In contrast to DLIs, leukemia-specific T cells (mLSTs) selectively recognized and killed leukemia antigen-pulsed cells, with no activity against recipient's normal cells in vitro. We administered escalating doses of mLSTs (0.5 to 10 × 107 cells per square meter) to 25 trial enrollees, 17 with high risk of relapse and 8 with relapsed disease. Infusions were well tolerated with no grade >2 acute or extensive chronic GVHD seen. We observed antileukemia effects in vivo that translated into not-yet-reached median leukemia-free and overall survival at 1.9 years of follow-up and objective responses in the active disease cohort (1 complete response and 1 partial response). In summary, mLSTs are safe and promising for the prevention and treatment of AML/MDS after HCT. This trial is registered at www.clinicaltrials.com as #NCT02494167.

EBV/LMP-specific T cells maintain remissions of T- and B-cell EBV lymphomas after allogeneic bone marrow transplantation.

Autologous T cells targeting Epstein-Barr virus (EBV) latent membrane proteins (LMPs) have shown safety and efficacy in the treatment of patients with type 2 latency EBV-associated lymphomas for whom standard therapies have failed, including high-dose chemotherapy followed by autologous stem-cell rescue. However, the safety and efficacy of allogeneic donor-derived LMP-specific T cells (LMP-Ts) have not been established for patients who have undergone allogeneic hematopoietic stem-cell transplantation (HSCT). Therefore, we evaluated the safety and efficacy of donor-derived LMP-Ts in 26 patients who had undergone allogeneic HSCT for EBV-associated natural killer/T-cell or B-cell lymphomas. Seven patients received LMP-Ts as therapy for active disease, and 19 were treated with adjuvant therapy for high-risk disease. There were no immediate infusion-related toxicities, and only 1 dose-limiting toxicity potentially related to T-cell infusion was seen. The 2-year overall survival (OS) was 68%. Additionally, patients who received T-cell therapy while in complete remission after allogeneic HSCT had a 78% OS at 2 years. Patients treated for B-cell disease (n = 10) had a 2-year OS of 80%. Patients with T-cell disease had a 2-year OS of 60%, which suggests an improvement compared with published posttransplantation 2-year OS rates of 30% to 50%. Hence, this study shows that donor-derived LMP-Ts are a safe and effective therapy to prevent relapse after transplantation in patients with B cell- or T cell-derived EBV-associated lymphoma or lymphoproliferative disorder and supports the infusion of LMP-Ts as adjuvant therapy to improve outcomes in the posttransplantation setting. These trials were registered at www.clinicaltrials.gov as #NCT00062868 and #NCT01956084.

Aggressive utilization of liver allografts: Improved outcomes over time.

BACKGROUND: Aggressive acceptance of liver allografts has driven utilization of marginal allografts. Our aim was to assess the impact of the aggressive phenotype on transplant center outcomes over time. METHODS: We used a cohort of 148 361 candidates from the Organ Procurement and Transplantation Network for liver transplantation between 2002 and 2016 in 134 centers. Using the Discard Risk Index, we designated high probability discard allografts by the top 10th percentile for likelihood of discard. Aggressive phenotype was defined by usage of high probability discard (HPD) allografts (top 10th percentile). Our analysis of survival on waitlist and graft survival after transplantation included a comprehensive list of center level covariates across three equal time periods (2002-2006, 2007-2011, and 2012-2016). RESULTS: After adjusting for recipient and center-level factors, aggressive centers had improving graft survival over time. Aggressive vs non-aggressive centers: 2002-2006 HR 1.12 (1.05-1.19), 2007-2011 HR 1.13 (1.05-1.22), 2012-2016 HR 0.99 (0.89-1.10). Aggressive centers had improved waitlist survival compared with non-aggressive centers after adjusting for allograft disparity. CONCLUSIONS: Aggressive phenotype had a positive impact on waitlist survival, and graft survival in aggressive centers have improved to benchmark levels over time. These findings serve as justification for aggressive utilization of allografts.

The alternative complement pathway activation product Ba as a marker for transplant-associated thrombotic microangiopathy.

BACKGROUND: Transplant-associated thrombotic microangiopathy (TA-TMA) occurs after hematopoietic stem cell transplantation (HSCT) and is characterized by microvascular thrombosis and end-organ injury particularly of the kidneys. TA-TMA is challenging to diagnose and treat, which can lead to long-term complications and death in patients with severe disease. Studies have shown that genetic abnormalities of the alternative complement pathway (AP) are associated with TA-TMA. We hypothesized that patients with TA-TMA may generate elevated levels of the AP activation product, Ba, compared with HSCT patients without TA-TMA. PROCEDURE: We longitudinally measured plasma levels of complement activation products C3a, Ba, and C5a in 14 HSCT patients: 7 with TA-TMA and 7 without TA-TMA. We assessed renal function by calculating estimated glomerular filtration rate (eGFR) and correlated the extent of AP activation with renal dysfunction in both patient populations. RESULTS: The median days from HSCT to study enrollment were 154 (39-237) in the TA-TMA group and 84 (39-253) in the HSCT group without TA-TMA. Median Ba levels (ng/mL) at enrollment were 1096.9 (826.5-1562.0) in the TA-TMA group and 725.7 (494.7-818.9) in the HSCT group without TA-TMA (P = 0.007). Over the study duration, Ba levels inversely correlated with eGFR. There were no differences in C3a, C5a, or sC5b9 levels between the two populations at any measured interval. CONCLUSIONS: We conclude in this preliminary study that Ba protein may serve as a marker for TA-TMA, and furthermore, that components generated in the early phase of AP activation may be involved in the pathogenesis of renal endothelial injury in TA-TMA.

Therapeutic Plasma Exchange does not Improve Renal Function in Hematopoietic Stem Cell Transplantation-Associated Thrombotic Microangiopathy: An Institutional Experience.

Transplantation-associated thrombotic microangiopathy (TA-TMA) is a complication of hematopoietic stem cell transplant (HSCT) that causes severe multiorgan injury. The kidneys are almost universally affected. There is no proven therapy, but therapeutic plasma exchange (TPE) is commonly used to treat TA-TMA at Texas Children's Hospital (TCH). To date, there have been no studies assessing the long-term efficacy of TPE in preventing the development of chronic kidney disease (CKD) in TA-TMA patients. In this study we retrospectively analyzed the incidence of CKD in TA-TMA pediatric patients treated with TPE to determine if this treatment modality improves renal morbidity. We reviewed records between January 2007 and June 2017 of pediatric HSCT patients diagnosed with TA-TMA, identified through an internal database maintained at TCH. To be included patients must have completed a course of TPE per the "TPE in TA-TMA" institutional protocol at TCH. CKD was defined as kidney damage for at least 3 months and stratified into stages 1 through 5 according to estimated glomerular filtration rate. Stages 4 and 5 were considered "severe CKD." In the 10-year timeframe 15 patients with TA-TMA completed a course of TPE per our institutional protocol and were subsequently followed for a median of 963 days. Fourteen patients developed CKD, and 5 of these 14 patients developed severe CKD. The cumulative incidence of severe CKD development was 33% (95% confidence interval. 11% to 57%). 6 patients required dialysis, and 2 patients received a renal transplant. 5 patients received eculizumab in addition to TPE. In our patients a TPE course of at least 7 weeks (and up to 25 weeks) was not effective in the prevention of CKD. Our data indicate a need for alternative therapeutic measures to prevent the development of CKD in TA-TMA patients.

No Gains in Long-term Survival After Liver Transplantation Over the Past Three Decades.

OBJECTIVE: The aim of this study was to assess improvements in long-term survival after liver transplant by analyzing outcomes in transplant recipients who survived beyond 1 year. SUMMARY OF BACKGROUND DATA: Gains in short-term survival following liver transplantation have been gratifying. One-year survival in 1986 was 66% improved to over 92% in 2015. However, little is known about why long-term has not seen similar success. METHODS: We analyzed 111,568 recipients from 1987 to 2016 using the Kaplan-Meier method for time-to-event analysis and multivariable Cox regression. RESULTS: There were no significant gains in unadjusted long-term outcomes among 1-year survivors over the past 30 years. Only the time periods of 1987 to 1990 [hazard ratio (HR) 1.35, confidence interval CI) 1.28-1.42] and 1991 to 1995 (HR 1.17, CI 1.13-1.21) had a minor increase in risk compared with the period 2011 to 2016. Cause of death analysis suggests malignancy after transplantation is a growing problem and preventing recurrent hepatitis C with direct-acting antivirals (DDAs) may only have a limited impact. Furthermore, rejection leading to graft failure and death had a rare occurrence (1.7% of long-term deaths) especially when compared with the sequelae of long-term immunosuppression: malignancy (16.4%), nonrejection graft failure (9.8%), and infection (10.5%) (P < 0.001). CONCLUSION: In stark contrast to short-term survival, there have been no appreciable improvements in long-term survival following liver transplantation among 1-year survivors. Long-term sequelae of immunosuppression, including malignancy and infection, are the most common causes of death. This study highlights the need for better long-term immunosuppression management.

c-MPL provides tumor-targeted T-cell receptor-transgenic T cells with costimulation and cytokine signals.

Adoptively transferred T-cell receptor (TCR)-engineered T cells depend on host-derived costimulation and cytokine signals for their full and sustained activation. However, in patients with cancer, both signals are frequently impaired. Hence, we developed a novel strategy that combines both essential signals in 1 transgene by expressing the nonlymphoid hematopoietic growth factor receptor c-MPL (myeloproliferative leukemia), the receptor for thrombopoietin (TPO), in T cells. c-MPL signaling activates pathways shared with conventional costimulatory and cytokine receptor signaling. Thus, we hypothesized that host-derived TPO, present in the tumor microenvironment, or pharmacological c-MPL agonists approved by the US Food and Drug Administration could deliver both signals to c-MPL-engineered TCR-transgenic T cells. We found that c-MPL+ polyclonal T cells expand and proliferate in response to TPO, and persist longer after adoptive transfer in immunodeficient human TPO-transgenic mice. In TCR-transgenic T cells, c-MPL activation enhances antitumor function, T-cell expansion, and cytokine production and preserves a central memory phenotype. c-MPL signaling also enables sequential tumor cell killing, enhances the formation of effective immune synapses, and improves antileukemic activity in vivo in a leukemia xenograft model. We identify the type 1 interferon pathway as a molecular mechanism by which c-MPL mediates immune stimulation in T cells. In conclusion, we present a novel immunotherapeutic strategy using c-MPL-enhanced transgenic T cells responding to either endogenously produced TPO (a microenvironment factor in hematologic malignancies) or c-MPL-targeted pharmacological agents.

In Vivo Fate and Activity of Second- versus Third-Generation CD19-Specific CAR-T Cells in B Cell Non-Hodgkin's Lymphomas.

Second-generation (2G) chimeric antigen receptors (CARs) targeting CD19 are highly active against B cell malignancies, but it is unknown whether any of the costimulatory domains incorporated in the CAR have superior activity to others. Because CD28 and 4-1BB signaling activate different pathways, combining them in a single third-generation (3G) CAR may overcome the limitations of each individual costimulatory domain. We designed a clinical trial in which two autologous CD19-specific CAR-transduced T cell products (CD19.CARTs), 2G (with CD28 only) and 3G (CD28 and 4-1BB), were infused simultaneously in 16 patients with relapsed or refractory non-Hodgkin's lymphoma. 3G CD19.CARTs had superior expansion and longer persistence than 2G CD19.CARTs. This difference was most striking in the five patients with low disease burden and few circulating normal B cells, in whom 2G CD19.CARTs had limited expansion and persistence and correspondingly reduced area under the curve. Of the 11 patients with measurable disease, three achieved complete responses and three had partial responses. Cytokine release syndrome occurred in six patients but was mild, and no patient required anti-IL-6 therapy. Hence, 3G CD19.CARTs combining 4-1BB with CD28 produce superior CART expansion and may be of particular value when treating low disease burden in patients whose normal B cells are depleted by prior therapy.

Outcomes after Allogeneic Transplant in Patients with Wiskott-Aldrich Syndrome.

Wiskott-Aldrich syndrome (WAS) is a rare X-linked disorder characterized by a triad of immunodeficiency, eczema, and thrombocytopenia. Currently, hematopoietic stem cell transplantation (HSCT) is the most reliable curative treatment with excellent results for patients with HLA-matched family or unrelated donors. However, even after fully myeloablative preparative regimens, mixed donor chimerism is a potential concern. We performed a retrospective chart review of 12 children who underwent allogeneic HSCT for WAS to report our experience. The median age at transplant was 10.5 months (range, 3 to 39). The median nucleated cell dose from the marrow was 4.55 × 109/kg (range, .3 to 7.9). The median times to neutrophil and platelet engraftment were 19 days (range, 13 to 27) and 18.5 days (range, 12 to 31), respectively. The rate of overall survival was 92% with median follow-up of 67 months (range, 3 to 146). Two patients developed grade IV acute graft-versus-host disease, and 1 died on day +99. Five of 12 patient's (42%) had mixed donor chimerism (range, 12% to 85%) at day +180. None of the pretransplant patient parameters was predictive of mixed chimerism. Nonetheless, of these 5 patients, 2 had normalization of the platelet count despite the mixed chimerism, 2 had full donor chimerism after receiving a second transplant with the same donor, and 1 remains transfusion dependent awaiting a second transplant. Hence, even with a significant rate of mixed chimerism, HSCT provides substantial benefit to WAS patients, with excellent overall survival.

High Incidence of Autoimmune Disease after Hematopoietic Stem Cell Transplantation for Chronic Granulomatous Disease.

There is a lack of consensus regarding the role and method of hematopoietic stem cell transplantation (HSCT) on patients with chronic granulomatous disease (CGD). Long-term follow-up after HSCT in these patient population is essential to know its potential complications and decide who will benefit the most from HSCT. We report the outcome of HSCT and long-term follow-up in 24 patients with CGD, transplanted in our center from either related (n = 6) or unrelated (n = 18) donors, over a 12-year period (2003 to 2015), using high-dose alemtuzumab in the preparative regimen. We evaluated the incidence and timing of adverse events and potential risk factors. We described in detailed the novel finding of increased autoimmunity after HSCT in patients with CGD. At a median follow-up of 1460 days, 22 patients were full donor chimeras, and 2 patients had stable mixed chimerism. All assessable patients showed normalization of their neutrophil oxidative burst test. None of the patients developed grades II to IV acute graft-versus-host disease, and no patient had chronic graft-versus-host disease. Twelve of 24 patients developed 17 autoimmune diseases (ADs). Severe ADs (cytopenia and neuropathy) occurred exclusively in the unrelated donor setting and mainly in the first year after HSCT, whereas thyroid AD occurred in the related donor setting as well and more than 3 years after HSCT. Two patients died due to infectious complications after developing autoimmune cytopenias. One additional patient suffered severe brain injury. The remaining 21 patients have long-term Lansky scores ≥ 80. The outcome of HSCT from unrelated donors is comparable with related donors but might carry an increased risk of developing severe AD. A lower dose of alemtuzumab may reduce this risk and should be tested in further studies.

Characterization and Functional Analysis of scFv-based Chimeric Antigen Receptors to Redirect T Cells to IL13Rα2-positive Glioma.

Immunotherapy with T cells expressing chimeric antigen receptors (CARs) is an attractive approach to improve outcomes for patients with glioblastoma (GBM). IL13Rα2 is expressed at a high frequency in GBM but not in normal brain, making it a promising CAR T-cell therapy target. IL13Rα2-specific CARs generated up to date contain mutated forms of IL13 as an antigen-binding domain. While these CARs target IL13Rα2, they also recognize IL13Rα1, which is broadly expressed. To overcome this limitation, we constructed a panel of IL13Rα2-specific CARs that contain the IL13Rα2-specific single-chain variable fragment (scFv) 47 as an antigen binding domain, short or long spacer regions, a transmembrane domain, and endodomains derived from costimulatory molecules and CD3.ζ (IL13Rα2-CARs). IL13Rα2-CAR T cells recognized IL13Rα2-positive target cells in coculture and cytotoxicity assays with no cross-reactivity to IL13Rα1. However, only IL13Rα2-CAR T cells with a short spacer region produced IL2 in an antigen-dependent fashion. In vivo, T cells expressing IL13Rα2-CARs with short spacer regions and CD28.ζ, 41BB.ζ, and CD28.OX40.ζ endodomains had potent anti-glioma activity conferring a significant survival advantage in comparison to mice that received control T cells. Thus, IL13Rα2-CAR T cells hold the promise to improve current IL13Rα2-targeted immunotherapy approaches for GBM and other IL13Rα2-positive malignancies.

Long-term outcome after haploidentical stem cell transplant and infusion of T cells expressing the inducible caspase 9 safety transgene.

Adoptive transfer of donor-derived T lymphocytes expressing a safety switch may promote immune reconstitution in patients undergoing haploidentical hematopoietic stem cell transplant (haplo-HSCT) without the risk for uncontrolled graft versus host disease (GvHD). Thus, patients who develop GvHD after infusion of allodepleted donor-derived T cells expressing an inducible human caspase 9 (iC9) had their disease effectively controlled by a single administration of a small-molecule drug (AP1903) that dimerizes and activates the iC9 transgene. We now report the long-term follow-up of 10 patients infused with such safety switch-modified T cells. We find long-term persistence of iC9-modified (iC9-T) T cells in vivo in the absence of emerging oligoclonality and a robust immunologic benefit, mediated initially by the infused cells themselves and subsequently by an apparently accelerated reconstitution of endogenous naive T lymphocytes. As a consequence, these patients have immediate and sustained protection from major pathogens, including cytomegalovirus, adenovirus, BK virus, and Epstein-Barr virus in the absence of acute or chronic GvHD, supporting the beneficial effects of this approach to immune reconstitution after haplo-HSCT. This study was registered at www.clinicaltrials.gov as #NCT00710892.

Outcomes after Second Hematopoietic Stem Cell Transplantations in Pediatric Patients with Relapsed Hematological Malignancies.

Relapse of hematological malignancies after hematopoietic stem cell transplantation (HCT) is associated with poor prognosis. A second HCT represents one of the few therapeutic options for these high-risk patients. For children undergoing second HCT, the outcome data are particularly limited. We, therefore, conducted a retrospective single-institution study and report the outcomes and prognostic variables associated with overall survival (OS) and relapse in 43 pediatric patients who underwent a second HCT between 2000 and 2013. Eleven of the 43 patients who underwent transplantation remain alive and disease-free at a median follow-up of 49 months (range, 5 to 127 months). The 5-year probability of OS for the entire cohort was 24%. Patients who had early relapse (<6 months) after first HCT had significantly worse OS than those who relapsed late (>6 months), with 5-year OS at 11% versus 34%, respectively (hazard ratio [HR], 2.24; 95% confidence interval [CI], 1.21 to 4.93; P = .013). Active disease at time of second HCT was also associated with a significantly increased risk of relapse (subdistribution hazard ratio [SHR], 2.36; P = .049) for the entire cohort and relapse was the most frequent cause of death (23 of 32; 72%). On subgroup analysis for the 34 patients with leukemia alone, presence of active disease was associated both with a significant decrease in OS (SHR, 2.28; 95% CI, 1.02 to 5.09; P = .044) and significant increase in the rate of relapse (SHR, 2.46; P = .046). By contrast, underlying disease, donor source, conditioning regimen, or development of GVHD did not modify OS or rate of relapse. Hence, a second HCT appears to be a useful therapeutic option in children with relapsed hematological malignancies that is most likely to benefit those individuals with late onset of relapse and with low disease burden at the time of transplantation.