Citations

The major barrier to clinical translation of αCD137 immunotherapy is separating antitumor efficacy from hepatotoxicity driven by IFN-γ–producing CD8 T cells. We propose a strategy to limit toxicity by promoting contraction of excessively expanded CD8 T cells. We identify CD11c + KLRG1 + effector CD8 T cells (CD11c + T E ) as the primary source of IFN-γ, recirculating between blood and secondary lymphoid organs (SLOs), where they undergo apoptosis during contraction. We show that lymphotoxin β receptor (LTβR) signaling restrains this contraction. Mechanistically, lymphotoxin-expressing B cells activate LTβR in fibroblastic reticular cells (FRCs), suppressing apoptosis of CD11c + T E cells in the spleen and sustaining their systemic circulation and liver infiltration. Pharmacological LTβR blockade abrogates hepatotoxicity by reducing the accumulation of IFN-γ–producing CD11c + T E cells while preserving tumor-specific CD8 T cell responses. These findings identify LTβR as a key regulator of effector CD8 T cell persistence and support the use of LTβR antagonists to improve the safety of αCD137-based immunotherapy.

Identification of a CD4 + helper T cell population providing in situ help to B and CD8 + T cells in the respiratory mucosa.

Background:Lenalidomide plus rituximab (R2) has established efficacy and a tolerable safety profile in patients with previously untreated and relapsed/refractory (R/R) indolent NHL. This includes patients with marginal zone lymphoma (MZL) who are generally treated in a similar manner to follicular lymphoma (FL).Aims:Primary results for the AUGMENT study in R/R FL grade 1–3a and MZL showed significantly improved progression‐free survival (PFS) for R2 over R/placebo in the overall population and in the subgroup analyses, with the exception of the MZL subgroup. Given the small sample size for MZL patients, post hoc analyses of baseline characteristics and univariate/multivariate analyses of PFS were conducted to examine possible explanations for these results.Methods:The phase III AUGMENT study randomized patients 1:1 to R2 (lenalidomide PO 20 mg/day (d), d1–21/28 X12 cycles plus rituximab IV 375 mg/m2 weekly in cycle 1 and d1 of cycles 2–5) or rituximab‐placebo (R/placebo; same dosing schedule). PFS by 2007 IWG (without PET) was the primary endpoint. Post hoc Cox regression models were used for univariate analysis of one risk factor and multivariate analyses including treatment arm and significant risk factors (P < 0.05) from the univariate analyses.Results:A total of 63/358 (18%) MZL patients were part of the overall study population, including n = 14/16 MALT, n = 9/6 splenic, and n = 8/10 nodal MZL subtypes for respective R2 and R/placebo arms. Numerical differences between treatment arms for baseline demographics and disease characteristics for MZL patients favoring the R/placebo arm were: fewer R2 patients had an ECOG score of 0 (55% R2 vs 72% R/placebo), and more R2 (vs R/placebo) patients were older (≥65 y: 68% vs 59%; ≥70 y: 42% vs 38%), were refractory to the last prior regimen (13% vs 3%), had Ann Arbor stage IV disease at enrollment (65% vs 41%), high‐risk MALT‐IPI score (50% vs 19%), elevated LDH (29% vs 19%), B symptoms (13% vs 3%), and high tumor burden per GELF criteria (65% vs 56%). The most common grade 3/4 AEs for MZL patients receiving R2 vs R/placebo, respectively, were neutropenia (47% vs 16%), pneumonia (3% vs 13%), and leukopenia (10% vs 0). A total of 5 deaths occurred in the R2 arm (most associated with progression of disease; 2 deaths occurred early at 3 and 13 days after randomization [one prior to receiving R2 and one 2 days after treatment initiation]) and 2 in the R/placebo arm. Despite worse prognostic features, best response was improved with R2 (vs R/placebo) with ORR = 65% vs 44% (P = 0.13) and CR = 29% vs 13% (P = 0.13), although neither were statistically significant. Improved response rates did not translate into a survival advantage for R2. Median PFS for MZL patients was 20.2 mo R2 vs 25.2 mo R/placebo (HR = 1.00; 95% CI, 0.47–2.13; P = 1.0). Univariate analyses showed that several baseline factors were prognostic for MZL patients (P < 0.05): Ann Arbor stage IV, elevated LDH, and unfit for chemotherapy (Table). Multivariate analyses adjusting for the imbalance in these 3 significant prognostic factors showed an adjusted PFS HR of 0.51 (95% CI, 0.20–1.28) favoring the R2 arm, similar to the PFS HR in the overall population (HR = 0.46; 95% CI, 0.34–0.63). The univariate and multivariate analyses suggested that the imbalance in baseline prognostic factors impacted PFS results for MZL patients.Summary/Conclusion:Overall, these findings suggest that the PFS results in MZL patients were negatively impacted by the imbalance in baseline prognostic factors and more aggressive disease in the R2 over the R/placebo arm.image

Abstract Negative selection refers to the selective deletion of autoreactive thymocytes but its molecular events have not been well defined. In this study, we demonstrate that a cellular ligand for herpes virus entry mediator and lymphotoxin receptor (LIGHT), a newly identified member of the TNF superfamily, may play a critical role in negative selection. Using TCR transgenic mice, we find that the blockade of LIGHT signaling in vitro and in vivo prevents negative selection induced by peptide and intrathymically expressed Ags, resulting in the rescue of thymocytes from apoptosis. Furthermore, the thymi of LIGHT transgenic mice show severe atrophy with remarkably reduced CD4+CD8+ double-positive cells caused by increased apoptosis, suggesting that LIGHT can delete immature T cells in vivo. Taken together, these results demonstrate a critical role of LIGHT in thymic negative selection of the T cell repertoire.

Abstract 4-1BB, a member of the TNFR superfamily, is a costimulatory receptor primarily expressed on activated T cells. It has been shown that the administration of agonistic anti-4-1BB Abs enhances tumor immunity and allogenic immune responses. Paradoxically, we found that the administration of an agonistic anti-4-1BB mAb (2A) dramatically reduced the incidence and severity of experimental autoimmune encephalomyelitis (EAE). Adoptive transfer of T cells from such treated mice failed to induce EAE, whereas anti-4-1BB treatment following adoptive transfer of encephalitogenic T cells did not prevent EAE pathogenesis. These results suggest that anti-4-1BB treatment during the induction phase inhibits autoreactive T cell immune responses rather than preventing T cell trafficking into the CNS. This was substantiated by the observations that draining lymph node cells from anti-4-1BB-treated mice failed to respond to Ag stimulation in vitro. In addition, we found that such treatment initially promotes the activation and proliferation of Ag-specific CD4+ T cells but subsequently increases their probability of undergoing activation-induced cell death, thereby inhibiting effector T cell responses. More importantly, 2A treatment also inhibits the relapse of EAE in a clinically relevant murine model of multiple sclerosis. This study indicates that the agonistic Ab against 4-1BB can potentially be used as a novel immunotherapeutic agent for treating autoimmune diseases.

Abstract Interaction of 4-1BB (CD137) and its ligand (4-1BBL) is thought to positively regulate cell-mediated and humoral immune responses. We have prepared transgenic mouse strains that express 4-1BBL cDNA under the control of MHC class II I-Eα promoter. The 4-1BBL-transgenic mice show progressive splenomegaly and selective depletion of B220+ B cells accompanied with low levels of circulating IgG and defective humoral responses to Ag challenge. In addition, splenocytes from the transgenic mice fail to provide stimulation for allogeneic T cells in both lymphoproliferative and CTL responses in vitro, whereas their T cells remain functionally normal. Our results reveal unexpected functions of 4-1BBL in the regulation of humoral immune responses and Ag presentation.