Intestinal Candida albicans overgrowth in IgA deficiency

BACKGROUND

Secretory IgA interacts with commensal bacteria, but its impact on human mycobiota ecology has not been widely explored. In particular, whether human IgA-deficiency is associated with gut fungal dysbiosis remains unknown.

OBJECTIVES

Our goal was to study the impact of IgA on gut mycobiota ecology.

METHODS

The Fungi-Flow method was used to characterize fecal, systemic, and maternal IgA, IgM, and IgG responses against 14 representative fungal strains (yeast/spores or hyphae forms) in healthy donors (HDs) (n = 34, 31, and 20, respectively) and to also compare gut mycobiota opsonization by secretory antibodies in HDs (n = 28) and patients with selective IgA deficiency (SIgAd) (n = 12). Stool mycobiota composition was determined by internal transcribed spacer gene sequencing in HDs (n = 23) and patients with SIgAd (n = 17). Circulating CD4+ T-cell cytokine secretion profiles were determined by intracellular staining. The impact of secretory IgA, purified from breast milk (n = 9), on Candidaalbicans growth and intestinal Caco-2 cell invasion was tested in vitro.

RESULTS

Homeostatic IgA binds commensal fungi with a body fluid-selective pattern of recognition. In patients with SIgAd, fungal gut ecology is preserved by compensatory IgM binding to commensal fungi. Gut Calbicans overgrowth nevertheless occurs in this condition but only in clinically symptomatic patients with decreased TH17/TH22 T-cell responses. Indeed, secretory IgA can reduce in vitro budding and invasion of intestinal cells by Calbicans and therefore exert control on this pathobiont.

CONCLUSION

IgA has a selective impact on Calbicans ecology to preserve fungal-host mutualism.

Preexisting autoantibodies as predictor of immune related adverse events (irAEs) for advanced solid tumors treated with immune checkpoint inhibitors (ICIs)

INTRODUCTION

Immune checkpoint inhibitors (ICIs) are now standard of care in many cancers. They can generate immune-related adverse events (irAEs), but no biomarkers are available to identify patients who are more likely to develop irAEs. We assess the association between pre-existing autoantibodies and occurrence of irAEs.

PATIENTS AND METHODS

We prospectively collected data from consecutive patients receiving ICIs for advanced cancers, in a single center between May 2015 and July 2021. Autoantibodies testing was performed before ICIs initiation including AntiNeutrophil Cytoplasmic Antibodies, Antinuclear Antibodies, Rheumatoid Factor anti-Thyroid Peroxidase and anti-Thyroglobulin. We analyzed the associations of pre-existing autoantibodies with onset, severity, time to irAEs and with survival outcomes.

RESULTS

Of the 221 patients included, most had renal cell carcinoma (n = 99; 45%) or lung carcinoma (n = 90; 41%). Grade ≥2 irAEs were more frequent among patients with pre-existing autoantibodies: 64 (50%) vs. 20 (22%) patients (Odds-Ratio= 3.5 [95% CI=1.8-6.8]; p < 0.001) in the positive vs negative group, respectively. irAEs occurred earlier in the positive group with a median time interval between ICI initiation and irAE of 13 weeks (IQR = 8.8-21.6) vs. 28.5 weeks (IQR=10.6-55.1) in the negative group (p = 0.01). Twelve patients (9.4%) experienced multiple (≥2) irAEs in the positive group vs. 2 (2%) in the negative group (OR = 4.5 [95% CI: 0.98-36], p = 0.04). After a median follow-up of 25 months, median PFS and OS were significantly longer among patients experiencing irAE (p = 0.00034 and p = 0.016, respectively).

CONCLUSION

The presence of pre-existing autoantibodies is significantly associated with the occurrence of grade ≥2 irAEs, with earlier and multiple irAEs in patients treated with ICIs.

Preexisting autoantibodies as predictor of immune-related adverse events for advanced solid tumors treated with immune checkpoint inhibitors

2523

Background: Immune checkpoint inhibitors (ICIs), used alone or as a combination are standard of care in many cancers. Generally well tolerated, they can generate immune-related adverse events (irAEs). No biomarkers are available to identify patients who are more likely to develop irAEs. The aim of this study was to assess the association between preexisting autoantibodies, occurrence of irAEs and survival outcomes. Methods: We performed a prospective study including 221 patients receiving ICIs for advanced solid tumors between May 2015 and July 2021. Autoantibodies testing (anti-neutrophil cytoplasmic, anti-nuclear, thyroid peroxidase and thyroglobulin) was performed before ICIs initiation. The associations among preexisting autoantibodies, the occurrence, the severity, the delay of irAEs and the survival outcomes, including progression-free survival (PFS) and overall survival (OS) were analyzed. Statistical analyses were performed with T-test, Cox regression models, univariate and multivariate analyses and Kaplan-Meier’s method. Results: Of the 221 patients, 151 (68%) were men, the median age was 66,5 (range 21-90) years and 103 (81%) had an ECOG-PS of 0 or 1. Seventy-three percent (n=162) received an anti-PD-(L)1 in monotherapy, 27% (n=59) an anti-PD-(L)1 in combination, for a renal cell carcinoma in 45% (n=99) and a lung carcinoma in 41% (n=90). In total, 129 (58%) patients had preexisting antibodies. IrAEs were significantly more frequent in patients with preexisting autoantibodies: 64 patients (50%) in the positive group vs. 20 patients (22%) in the negative group, OR = 3.5 (95%CI=1.8 - 6.8), p=0.00002. Median time interval between ICI initiation and irAE was shorter in the positive group vs. the negative group, 13 weeks (IQR=43weeks) vs. 28.5 weeks (IQR=12weeks) respectively (p=0.01). Twelve patients (9.4%) experienced multi toxicities in the positive group vs. two (2%) in the negative group, OR=4.5 (95%CI0.98-36), p=0.04. ICIs exposure was identical in preexisting and non-preexisting autoantibodies groups. After a median follow-up of 25 months (95%CI=19-31), median PFS and OS were significantly longer among patients experiencing irAE: 12.6 months (95%CI=11-22.7) vs 5 months (95%CI=4.2-7.0), p= 0.0003 and 30 months (95%CI= 22.7-NR) vs 21 months (95%CI=15-34.6), p= 0.016. In multivariate analyses irAEs remain statistically associated with survival outcomes. Preexisting autoantibodies were not associated with survival outcomes. Conclusions: The presence of preexisting autoantibodies is significantly associated with the occurrence of irAE in patients treated with ICIs. Earlier and multiple irAEs were observed in the presence of preexisting autoantibodies. Thus, these biomarkers could help to identify patients at risk of irAEs and would prompt us to closely monitor them.