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How Have CAR T Cells Advanced Cancer Treatment? Redirection of T-cell specificity by genetic modification of T cells with chimeric antigen receptors (CARs) has shown activity in CD19-positive malignancies, including [...]

Lymphodepletion chemotherapy with CD19-targeted chimeric antigen receptor–modified T (CAR-T)-cell immunotherapy is a novel treatment for refractory or relapsed B-cell malignancies. Infectious complications of this approach have not been systematically studied. We evaluated infections occurring between days 0 to 90 in 133 patients treated with CD19 CAR-T cells in a phase 1/2 study. We used Poisson and Cox regression to evaluate pre- and posttreatment risk factors for infection, respectively. The cohort included patients with acute lymphoblastic leukemia (ALL; n = 47), chronic lymphocytic leukemia (n = 24), and non-Hodgkin lymphoma (n = 62). There were 43 infections in 30 of 133 patients (23%) within 28 days after CAR–T-cell infusion with an infection density of 1.19 infections for every 100 days at risk. There was a lower infection density of 0.67 between days 29 and 90 (P = .02). The first infection occurred a median of 6 days after CAR–T-cell infusion. Six patients (5%) developed invasive fungal infections and 5 patients (4%) had life-threatening or fatal infections. Patients with ALL, ≥4 prior antitumor regimens, and receipt of the highest CAR–T-cell dose (2 × 107 cells per kg) had a higher infection density within 28 days in an adjusted model of baseline characteristics. Cytokine release syndrome (CRS) severity was the only factor after CAR–T-cell infusion associated with infection in a multivariable analysis. The incidence of infections was comparable to observations from clinical trials of salvage chemoimmunotherapies in similar patients. This trial was registered at www.clinicaltrials.gov as #NCT01865617.

Lymphodepletion chemotherapy followed by infusion of CD19-specific chimeric antigen receptor–modified (CAR) T cells has produced impressive antitumor responses in patients with refractory CD19+B-cell malignancies but is often associated with cytokine release syndrome (CRS). Our understanding of CRS continues to evolve, and identification of the kinetics of CRS and predictive clinical and laboratory biomarkers of severity are needed to evaluate strategies to mitigate toxicity. We report the clinical presentation of and identify biomarkers of severe CRS in 133 adult patients who received CD19 CAR T cells. CRS developed in 70% of patients, including 62.5% with grade 1 to 3 CRS (grade 1, 26%; grade 2, 32%; grade 3, 4.5%), 3.8% with grade 4, and 3.8% with grade 5. A majority of cases of grade ≥4 CRS occurred during CAR T-cell dose finding. Multivariable analysis of baseline characteristics identified high marrow tumor burden, lymphodepletion using cyclophosphamide and fludarabine, higher CAR T-cell dose, thrombocytopenia before lymphodepletion, and manufacturing of CAR T cells without selection of CD8+central memory T cells as independent predictors of CRS. Severe CRS was characterized by hemodynamic instability, capillary leak, and consumptive coagulopathy. Angiopoietin-2 and von Willebrand factor, which are biomarkers of endothelial activation, were increased during severe CRS and also before lymphodepletion in patients who subsequently developed CRS. We describe a classification-tree algorithm to guide studies of early intervention after CAR T-cell infusion for patients at high risk of severe CRS. These data provide a framework for early intervention studies to facilitate safer application of effective CD19 CAR T-cell therapy.

•High-dose anakinra (up to 12 mg/kg/day) for refractory cytokine release syndrome (CRS)/immune effector cell-associated neurotoxicity syndrome (ICANS) was safe.•Higher anakinra dose may be associated with faster CRS/ICANS resolution and was independently associated with lower treatment-related mortality.

•The median duration of response in next-generation sequencing MRD-negative responders was 53.4 months.•Prelymphodepletion maximum SUV and bulky disease, day +28 PET-CT and MRD negativity, and in vivo CAR-T cell kinetics impacted PFS

Chimeric antigen receptor (CAR)–modified T-cell therapies targeting CD19 represent a new treatment option for patients with relapsed/refractory (R/R) B-cell malignancies. However, CAR T-cell therapy fails to elicit durable responses in a significant fraction of patients. Limited in vivo proliferation and survival of infused CAR T cells are key causes of failure. In a phase 1/2 clinical trial of CD19 CAR T cells for B-cell malignancies (#NCT01865617), low serum interleukin 15 (IL-15) concentration after CAR T-cell infusion was associated with inferior CAR T-cell kinetics. IL-15 supports T-cell proliferation and survival, and therefore, supplementation with IL-15 may enhance CAR T-cell therapy. However, the clinical use of native IL-15 is challenging because of its unfavorable pharmacokinetic (PK) and toxicity. NKTR-255 is a polymer-conjugated IL-15 that engages the entire IL-15 receptor complex (IL-15Rα/IL-2Rβγ) and exhibits reduced clearance, providing sustained pharmacodynamic (PD) responses. We investigated the PK and immune cell PDs in nonhuman primates treated with NKTR-255 and found that NKTR-255 enhanced the in vivo proliferation of T cells and natural killer cells. In vitro, NKTR-255 induced dose-dependent proliferation and accumulation of human CD19 CAR T cells, especially at low target cell abundance. In vivo studies in lymphoma-bearing immunodeficient mice demonstrated enhanced antitumor efficacy of human CD19 CAR T cells. In contrast to mice treated with CAR T cells alone, those that received CAR T cells and NKTR-255 had markedly higher CAR T-cell counts in the blood and marrow that were sustained after tumor clearance, without evidence of persistent proliferation or ongoing activation/exhaustion as assessed by Ki-67 and inhibitory receptor coexpression. These data support an ongoing phase 1 clinical trial of combined therapy with CD19 CAR T cells and NKTR-255 for R/R B-cell malignancies.

The adoptive transfer of donor T cells that have been genetically modified to recognize leukemia could prevent or treat leukemia relapse after allogeneic HSCT (allo-HSCT). However, adoptive therapy after allo-HSCT should be performed with T cells that have a defined endogenous TCR specificity to avoid GVHD. Ideally, T cells selected for genetic modification would also have the capacity to persist in vivo to ensure leukemia eradication. Here, we provide a strategy for deriving virus-specific T cells from CD45RA−CD62L+CD8+central memory T (TCM) cells purified from donor blood with clinical grade reagents, and redirect their specificity to the B-cell lineage marker CD19 through lentiviral transfer of a gene encoding a CD19-chimeric Ag receptor (CAR). Virus-specific TCMwere selectively transduced by exposure to the CD19 CAR lentivirus after peptide stimulation, and bi-specific cells were subsequently enriched to high purity using MHC streptamers. Activation of bi-specific T cells through the CAR or the virus-specific TCR elicited phosphorylation of downstream signaling molecules with similar kinetics, and induced comparable cytokine secretion, proliferation, and lytic activity. These studies identify a strategy for tumor-specific therapy with CAR-modified T cells after allo-HSCT, and for comparative studies of CAR and TCR signaling.

Type 17 programmed CD161hiCD8α+T cells contribute to mucosal immunity to bacteria and yeast. In early life, microbial colonization induces proliferation of CD161hicells that is dependent on their expression of a semi-invariant Vα7.2+TCR. Although prevalent in adults, CD161hiCD8α+cells exhibit weak proliferative and cytokine responses to TCR ligation. The mechanisms responsible for the dichotomous response of neonatal and adult CD161hicells, and the signals that enable their effector function, have not been established. We describe acquired regulation of TCR signaling in adult memory CD161hiCD8α+T cells that is absent in cord CD161hicells and adult CD161locells. Regulated TCR signaling in CD161hicells was due to profound alterations in TCR signaling pathway gene expression and could be overcome by costimulation through CD28 or innate cytokine receptors, which dictated the fate of their progeny. Costimulation with IL-1β during TCR ligation markedly increased proinflammatory IL-17 production, while IL-12–induced Tc1-like function and restored the response to TCR ligation without costimulation. CD161hicells from umbilical cord blood and granulocyte colony stimulating factor-mobilized leukaphereses differed in frequency and function, suggesting future evaluation of the contribution of CD161hicells in hematopoietic stem cell grafts to transplant outcomes is warranted.

Most HIV+individuals require lifelong highly active antiretroviral therapy (HAART) to suppress HIV replication, but fail to eliminate the virus in part because of residual replication in gut-associated lymphoid tissues (GALT). Naturally elicited HIV-specific CD8+T cells generated in the acute and chronic infectious phases exhibit antiviral activity, but decrease in number after HAART. Therapeutic vaccines represent a potential strategy to expand cellular responses, although previous efforts have been largely unsuccessful, conceivably because of a lack of responding HIV-specific central-memory CD8+T cells (Tcm). To determine whether patients receiving HAART possess CD8+T cells with Tcm qualities that are amenable to augmentation, HIV-specific CD8+T-cell clones were derived from HIV-reactive CD28+CD8+T-cell lines isolated from 7 HIV+HAART-treated patients, expanded ex vivo, and reinfused into their autologous host. Tracking of the cells in vivo revealed that clones could persist for ≥ 84 days, maintain expression and/or re-express CD28, up-regulate CD62L, secrete IL-2, proliferate on cognate Ag encounter and localize to the rectal mucosa. These results suggest some infused cells exhibited phenotypic and functional characteristics shared with Tcm in vivo, and imply that more effective therapeutic vaccination strategies targeting CD8+Tcm in patients on HAART might provide hosts with expanded, long-lasting immune responses not only systemically but also in GALT. This study is registered at www.clinicaltrials.govas NCT00110578.

We investigated the potential role of an immune reaction in mediating the dominant engraftment of 1 cord blood unit in 14 patients who received a double-unit cord blood transplantation (CBT). In 10 patients, dominant engraftment of a single donor unit emerged by day 28 after CBT. In 9 of these 10 patients, a significant subset of CD8+CD45RO+/−CCR7−T cells, present in peripheral blood mononuclear cells and derived from the engrafting cord blood unit, produced interferon-γ (IFN-γ) in response to the nonengrafting unit. No significant population of IFN-γ–secreting cells was detectable when posttransplantation peripheral blood mononuclear cells were stimulated against cells from the engrafted unit (P< .001) or from a random human leukocyte antigen disparate third party (P= .003). Three patients maintained persistent mixed chimerism after CBT, and no significant IFN-γ–secreting cells were detected after similar stimulations in these patients (P< .005). Our data provide the first direct evidence in human double-unit CBT recipients that immune rejection mediated by effector CD8+T cells developing after CBT from naive precursors is responsible for the failure of 1 unit to engraft. Future investigations based on these findings may result in strategies to predict a dominant unit and enhance graft-versus-leukemia effect.

CD19-targeted chimeric antigen receptor-engineered (CD19 CAR) T cells are novel therapies showing great promise for patients with relapsed or refractory (R/R) aggressive B-cell non-Hodgkin lymphoma (B-NHL). Single-arm studies showed significant variations in outcomes across distinct CD19 CAR T-cell products. To estimate the independent impact of the CAR T-cell product type on outcomes, we retrospectively analyzed data from 129 patients with R/R aggressive B-NHL treated with cyclophosphamide and fludarabine lymphodepletion followed by either a commercially available CD19 CAR T-cell therapy (axicabtagene ciloleucel [axicel] or tisagenlecleucel [tisacel]), or the investigational product JCAR014 on a phase I/II clinical trial (NCT01865617). After adjustment for age, HCT-CI, LDH, largest lesion diameter, and ALC, CAR T-cell product type remained associated with outcomes in multivariable models. JCAR014 was independently associated with lower CRS severity compared to axicel (adjusted OR [aOR], 0.19; 95%CI, 0.08-0.46), with a trend towards lower CRS severity with tisacel compared to axicel (aOR, 0.47; 95%CI, 0.21-1.06; p=0.07). Tisacel (aOR, 0.17; 95%CI, 0.06-0.48) and JCAR014 (aOR, 0.17; 95%CI, 0.06-0.47) were both associated with lower ICANS severity compared to axicel. Lower odds of complete response (CR) were predicted with tisacel and JCAR014 compared to axicel. Although sensitivity analyses using either PET or CT-based response criteria also suggested higher efficacy of axicel over JCAR014, the impact of tisacel versus axicel became undetermined. Higher preleukapheresis LDH, largest lesion diameter, and lower ALC were independently associated with lower odds of CR. We conclude that CD19 CAR T-cell product type independently impacts toxicity and efficacy in R/R aggressive B-NHL patients.

Changes in blood dendritic cell (BDC) counts (CD123hiBDC and CD11c+BDC) and expression of CD62L, CCR7, and CD49d were analyzed in healthy donors, multiple myeloma (MM), and non-Hodgkin lymphoma (NHL) patients, who received granulocyte-colony stimulating factor (G-CSF) containing peripheral blood stem cell (PBSC) mobilization protocols. Low-dose G-CSF in healthy donors (8-10 μg/kg/d subcutaneously) and high-dose G-CSF in patients (30 μg/kg/d) increased CD123hiBDC (2- to 22-fold, mean 3.7 × 106/L-17.7 × 106/L and 1.9 × 106/L-12.0 × 106/L) in healthy donors and MM but decreased CD11c+BDC (2- to 10-fold, mean 5.7 × 106/L-1.6 × 106/L) in NHL patients, on the day of apheresis, compared with steady state. After apheresis, CD123hiBDC counts remained high, whereas low CD11c+BDC counts tended to recover in the following 2-5 days. Down-regulation of CD62L and up-regulation of CCR7 on CD123hiBDC were found in most healthy donors and MM patients. CD49d expression was unchanged. Thus, PBSC mobilization may change BDC counts by altering molecules necessary for BDC homing from blood into tissues.

Background:Autologous T cells engineered to express a CD19 or BCMA-specific chimeric antigen receptor (CAR) have shown high overall response rates in treatment-refractory B-cell non-Hodgkin lymphoma (NHL) and BCMA +multiple myeloma (MM), respectively. However, most patients will eventually relapse, and thus strategies are needed to further improve the efficacy and durability of CAR-T cell products. NKTR-255 is an investigational polyethylene glycol-modified recombinant human IL-15 (rhIL-15) receptor agonist designed to engage the IL-15 pathway to stimulate and expand natural killer (NK) cells and promote the survival and expansion of memory CD8 +T cells. Preclinical data in B-cell lymphoma xenograft models have shown that NKTR-255 enhanced expansion, survival, and anti-tumor activity of human CD19 CAR-T cells. Furthermore, clinical studies have validated that IL-15 augments anti-tumor activity and promotes a stem-cell memory subset in tumor-specific T cells. Here we report pharmacodynamic (PD) analysis of CAR-T cells from relapsed/refractory (R/R) NHL or MM patients who had prior CAR-T therapy and were subsequently enrolled in an ongoing Phase 1 study of NKTR-255.