Despite impressive progress, more than 50% of patients treated with CD19-targeting chimeric antigen receptor T cells (CAR19) experience progressive disease. Ten of 16 patients with large B cell lymphoma (LBCL) with progressive disease after CAR19 treatment had absent or low CD19. Lower surface CD19 density pretreatment was associated with progressive disease. To prevent relapse with CD19− or CD19lo disease, we tested a bispecific CAR targeting CD19 and/or CD22 (CD19-22.BB.z-CAR) in a phase I clinical trial (NCT03233854) of adults with relapsed/refractory B cell acute lymphoblastic leukemia (B-ALL) and LBCL. The primary end points were manufacturing feasibility and safety with a secondary efficacy end point. Primary end points were met; 97% of products met protocol-specified dose and no dose-limiting toxicities occurred during dose escalation. In B-ALL (n = 17), 100% of patients responded with 88% minimal residual disease-negative complete remission (CR); in LBCL (n = 21), 62% of patients responded with 29% CR. Relapses were CD19−/lo in 50% (5 out of 10) of patients with B-ALL and 29% (4 out of 14) of patients with LBCL but were not associated with CD22−/lo disease. CD19/22-CAR products demonstrated reduced cytokine production when stimulated with CD22 versus CD19. Our results further implicate antigen loss as a major cause of CAR T cell resistance, highlight the challenge of engineering multi-specific CAR T cells with equivalent potency across targets and identify cytokine production as an important quality indicator for CAR T cell potency.
Chimeric antigen receptor (CAR) T-cell therapy targeting CD19 has significantly improved outcomes in the treatment of refractory or relapsed large B-cell lymphoma (LBCL). We evaluated the long-term course of hematologic recovery, immune reconstitution, and infectious complications in 41 patients with LBCL treated with axicabtagene ciloleucel (axi-cel) at a single center. Grade 3+ cytopenias occurred in 97.6% of patients within the first 28 days postinfusion, with most resolved by 6 months. Overall, 63.4% of patients received a red blood cell transfusion, 34.1% of patients received a platelet transfusion, 36.6% of patients received IV immunoglobulin, and 51.2% of patients received growth factor (granulocyte colony-stimulating factor) injections beyond the first 28 days postinfusion. Only 40% of patients had recovered detectable CD19+ B cells by 1 year, and 50% of patients had a CD4+ T-cell count <200 cells per μL by 18 months postinfusion. Patients with durable responses to axi-cel had significantly longer durations of B-cell aplasia, and this duration correlated strongly with the recovery of CD4+ T-cell counts. There were significantly more infections within the first 28 days compared with any other period of follow-up, with the majority being mild-moderate in severity. Receipt of corticosteroids was the only factor that predicted risk of infection in a multivariate analysis (hazard ratio, 3.69; 95% confidence interval, 1.18-16.5). Opportunistic infections due to Pneumocystis jirovecii and varicella-zoster virus occurred up to 18 months postinfusion in patients who prematurely discontinued prophylaxis. These results support the use of comprehensive supportive care, including long-term monitoring and antimicrobial prophylaxis, beyond 12 months after axi-cel treatment.
Type 1 regulatory T cells suppress alloreactive immune cells after adoptive transfer in a CTLA-4 and PD-1–mediated manner.
T hymic stromal lymphopoietin (TSLP) stimulates in vitro proliferation of human fetal B-cell precursors. However, its in vivo role during normal human B lymphopoiesis is unknown. Genetic alterations that cause overexpression of its receptor component, cytokine receptor-like factor 2 (CRLF2), lead to high-risk B-cell acute lymphoblastic leukemia implicating this signaling pathway in leukemogenesis. We show that mouse thymic stromal lymphopoietin does not stimulate the downstream pathways (JAK/STAT5 and PI3K/AKT/mTOR) activated by the human cytokine in primary high-risk leukemia with overexpression of the receptor component. Thus, the utility of classic patient-derived xenografts for in vivo studies of this pathway is limited. We engineered xenograft mice to produce human thymic stromal lymphopoietin (+T mice) by injection with stromal cells transduced to express the cytokine. Control (-T) mice were produced using stroma transduced with control vector. Normal levels of human thymic stromal lymphopoietin were achieved in sera of +T mice, but were undetectable in -T mice. Patient-derived xenografts generated from +T as compared to -T mice showed a 3-6-fold increase in normal human B-cell precursors that was maintained through later stages of B-cell development. Gene expression profiles in high-risk B-cell acute lymphoblastic leukemia expanded in +T mice indicate increased mTOR pathway activation and are more similar to the original patient sample than those from -T mice. +T/-T xenografts provide a novel pre-clinical model for understanding this pathway in B lymphopoiesis and identifying treatments for high-risk B-cell acute lymphoblastic leukemia with overexpression of cytokine-like factor receptor 2.
The distant IR risk of T1a HER2-positive breast cancer appears quite low. The distant IR risk in T1b patients, particularly those with 1.0-cm tumors, is higher. Potential risk differences for T1a and T1b, including the 1.0-cm tumors, should be considered when making treatment decisions.
Background Studies show superior outcomes for adolescent and young adult (AYA) patients with acute lymphoblastic leukemia (ALL) treated following pediatric versus adult ALL therapeutic regimens. Whether adult oncologists in the United States have adopted this approach to AYA ALL is currently unknown. We sought to provide a population-based description of AYA ALL treatment patterns over the past decade. Methods Data on AYAs 15-39 years and diagnosed with ALL during 2004-2014 while living in the Greater Bay Area were obtained from the Greater Bay Area Cancer Registry (GBACR). Treating facilities were designated as pediatric or adult centers; induction treatment regimens were abstracted from registry text data fields. Results Of 304 patients diagnosed in the GBACR catchment region, complete treatment data was available for 229 (75%). Location of care was identified for 296 (97%) patients treated at 31 unique centers. 70% of AYAs received induction therapy at an adult center. All AYAs treated at pediatric centers received pediatric ALL regimens. Among AYAs treated by adult oncologists with complete treatment data, none received a pediatric regimen prior to 2008. From 2008-2012, while the adult intergroup C10403 pediatric-inspired ALL protocol was open to accrual, 31% of AYAs treated by adult oncologists received pediatric regimens. This fell to 21% in 2013-2014. Adult facilities treating ≥2 AYA ALL GBACR patients per year were more likely to administer pediatric regimens than lower volume centers (P= 0.03). Conclusion As of 2014, only a minority of AYAs with ALL received pediatric ALL regimens at adult cancer centers.
Bleeding and thrombotic events are an emerging toxicity associated with chimeric antigen receptor (CAR) therapies. To determine their incidence, we retrospectively analyzed consecutive adult patients (n=127) with large B-cell lymphoma (LBCL) or B-cell acute lymphoblastic leukemia (B-ALL) treated between 2017-2020 with axicabtagene ciloleucel (axi-cel) (N=89) or a bispecific CD19/CD22 CAR (N=38). 12 (9.4%) and 8 (6.3%) patients developed bleeding and thrombosis within first 3 months, respectively. In the axi-cel subgroup, these occurred in 11.2% and 6.7%, respectively. Bleeding occurred between days 8-30 (median 17.5), and thrombosis between days 2-91 (median 29). Bleeding sites included genitourinary (N=6), soft tissue (N=2), intracranial (N=2), gastrointestinal (N=1), pulmonary (N=1), and were associated with features of consumptive coagulopathy. On univariate analysis, patients with bleeding were older (median 72 vs. 60 yrs, P<0.01), had lower baseline platelets (86 vs. 178 K/uL, P<0.01), lower platelet nadir after CAR-T (median 17.5 vs. 48 K/uL; P<0.01), lower fibrinogen nadir (median 122 vs. 340 ug/mL; P<0.01) and elevated LDH (P=0.01). ICANS grade ≥3 was associated with increased bleeding (50% vs. 15%; P=0.01), thrombosis (50% vs. 16%; P=0.04), PT prolongation, hypofibrinogenemia and elevated D-dimer. A paucity of events limited multivariate analysis, however low pre-treatment platelets were associated with bleeding in a multivariate logistic regression model. Patients with thrombocytopenia or severe ICANS are at increased risk of bleeding complications and should be closely monitored particularly within the first month after CAR therapy. Future studies in larger cohorts should assess risk factors for systemic coagulopathies in CAR-T therapy, including their association with neurotoxicity.
The prognosis for patients with large B-cell lymphoma (LBCL) progressing after treatment with chimeric antigen receptor (CAR) T-cell therapy targeting CD19 (CAR19) is poor. We report on the first three consecutive patients with autologous CAR19-refractory LBCL treated with a single infusion of autologous 1×106 CAR+ T-cells/kg targeting CD22 (CAR22) as part of a phase I dose escalation study. CAR22 therapy was relatively well tolerated, without any observed non-hematologic adverse events higher than grade 2. Following infusion, all three patients achieved complete remission, with all responses ongoing at the time of last follow up (mean 7.8 months, range 6-9.3). Circulating CAR22 cells demonstrated robust expansion (peak range 85.4-350 cells/µL), and persisted beyond three months in all patients with continued radiographic responses and corresponding decreases in circulating tumor DNA (ctDNA) beyond six months post-infusion. Further accrual at a higher dose level in this phase 1 dose-escalation study is ongoing and will explore the role of this therapy in patients who have failed prior CAR T-cell therapies. (Funded by the National Cancer Institute and others; ClinicalTrials.gov number, NCT04088890)
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