Dysregulation of CD4+ and CD8+ resident memory T, myeloid, and stromal cells in steroid-experienced, checkpoint inhibitor colitis

BACKGROUND

Colitis caused by checkpoint inhibitors (CPI) is frequent and is treated with empiric steroids, but CPI colitis mechanisms in steroid-experienced or refractory disease are unclear.

METHODS

Using colon biopsies and blood from predominantly steroid-experienced CPI colitis patients, we performed multiplexed single-cell transcriptomics and proteomics to nominate contributing populations.

RESULTS

CPI colitis biopsies showed enrichment of CD4+resident memory (RM) T cells in addition to CD8+ RM and cytotoxic CD8+ T cells. Matching T cell receptor (TCR) clonotypes suggested that both RMs are progenitors that yield cytotoxic effectors. Activated, CD38+ HLA-DR+ CD4+ RM and cytotoxic CD8+ T cells were enriched in steroid-experienced and a validation data set of steroid-naïve CPI colitis, underscoring their pathogenic potential across steroid exposure. Distinct from ulcerative colitis, CPI colitis exhibited perturbed stromal metabolism (NAD+, tryptophan) impacting epithelial survival and inflammation. Endothelial cells in CPI colitis after anti-TNF and anti-cytotoxic T-lymphocyte-associated antigen 4 (anti-CTLA-4) upregulated the integrin α4β7 ligand molecular vascular addressin cell adhesion molecule 1 (MAdCAM-1), which may preferentially respond to vedolizumab (anti-α4β7).

CONCLUSIONS

These findings nominate CD4+ RM and MAdCAM-1+ endothelial cells for targeting in specific subsets of CPI colitis patients.

Fluctuations in plasma adrenocorticotropic hormone concentration may predict the onset of immune checkpoint inhibitor-related hypophysitis

Immune checkpoint inhibitor (ICI)-related hypophysitis (RH) is a common immune-related adverse event. The early detection of ICI-RH prevents life-threatening adrenal insufficiency. However, good predictors of secondary adrenal insufficiency in ICI-RH have not yet been reported. We hypothesized that fluctuations in serum adrenocorticotropic hormone (ACTH) and cortisol levels occur similarly to those in thyroid-stimulating hormone and thyroid hormone (thyroxine and triiodothyronine) levels in ICI-related thyroiditis. Here, we sought to test this hypothesis. Patients who used ICI and had a history of measurement of serum ACTH and cortisol concentrations were retrieved from electronic medical records, and those with a history of glucocorticoid use were excluded from the analysis. We evaluated fluctuations in serum ACTH and cortisol concentrations and the development of ICI-RH. For patients with ICI-RH, data at three points (before ICI administration (pre), maximum ACTH concentration (peak), and onset of ICI-RH) were analyzed to evaluate hormone fluctuations. A total of 202 patients were retrieved from the medical record. Forty-three patients were diagnosed with ICI-RH. Twenty-six out of 43 patients had sufficient data to evaluate fluctuations in serum ACTH and cortisol concentrations and no history of glucocorticoid use. ACTH concentrations changed from 37.4 (29.9-48.3) (pre) to 64.4 (46.5-106.2) (peak) pg/mL (1.72-fold increase, p=0.0026) in the patients with ICI-RH before the onset. There were no differences in cortisol concentrations between the pre and peak values in patients with ICI-RH. We also evaluated the fluctuations in serum ACTH and cortisol levels in patients who did not receive ICI-RH (62 cases). However, elevation of serum ACTH levels was not observed in patients without ICI-RH, suggesting that transient elevation of serum ACTH levels is a unique phenomenon in patients with ICI-RH. In conclusion, serum ACTH levels were transiently elevated in some patients with ICI-RH before the onset of secondary adrenal insufficiency. Monitoring the ACTH levels and their fluctuations may help predict the onset of ICI-RH.

Systemically administered low-affinity HER2 CAR T cells mediate antitumor efficacy without toxicity

BACKGROUND

The paucity of tumor-specific targets for chimeric antigen receptor (CAR) T-cell therapy of solid tumors necessitates careful preclinical evaluation of the therapeutic window for candidate antigens. Human epidermal growth factor receptor 2 (HER2) is an attractive candidate for CAR T-cell therapy in humans but has the potential for eliciting on-target off-tumor toxicity. We developed an immunocompetent tumor model of CAR T-cell therapy targeting murine HER2 (mHER2) and examined the effect of CAR affinity, T-cell dose, and lymphodepletion on safety and efficacy.

METHODS

Antibodies specific for mHER2 were generated, screened for affinity and specificity, tested for immunohistochemical staining of HER2 on normal tissues, and used for HER2-targeted CAR design. CAR candidates were evaluated for T-cell surface expression and the ability to induce T-cell proliferation, cytokine production, and cytotoxicity when transduced T cells were co-cultured with mHER2+ tumor cells in vitro. Safety and efficacy of various HER2 CARs was evaluated in two tumor models and normal non-tumor-bearing mice.

RESULTS

Mice express HER2 in the same epithelial tissues as humans, rendering these tissues vulnerable to recognition by systemically administered HER2 CAR T cells. CAR T cells designed with single-chain variable fragment (scFvs) that have high-affinity for HER2 infiltrated and caused toxicity to normal HER2-positive tissues but exhibited poor infiltration into tumors and antitumor activity. In contrast, CAR T cells designed with an scFv with low-affinity for HER2 infiltrated HER2-positive tumors and controlled tumor growth without toxicity. Toxicity mediated by high-affinity CAR T cells was independent of tumor burden and correlated with proliferation of CAR T cells post infusion.

CONCLUSIONS

Our findings illustrate the disadvantage of high-affinity CARs for targets such as HER2 that are expressed on normal tissues. The use of low-affinity HER2 CARs can safely regress tumors identifying a potential path for therapy of solid tumors that exhibit high levels of HER2.