Prospective characterisation of SARS-CoV-2 infections among children presenting to tertiary paediatric hospitals across Australia in 2020: a national cohort study

OBJECTIVE

To present Australia-wide data on paediatric COVID-19 and multisystem inflammatory syndromes to inform health service provision and vaccination prioritisation.

DESIGN

Prospective, multicentre cohort study.

SETTING

Eight tertiary paediatric hospitals across six Australian states and territories in an established research surveillance network-Paediatric Active Enhanced Disease (PAEDS).

PARTICIPANTS

All children aged <19 years with SARS-CoV-2 infection including COVID-19, Paediatric Inflammatory Multisystem Syndrome Temporally Associated with SARS-CoV-2 (PIMS-TS) and Kawasaki-like disease TS infection (KD-TS) treated at a PAEDS site from 24 March 2020 to 31 December 2020.

INTERVENTION

Laboratory-confirmed SARS-CoV-2 infection.

MAIN OUTCOME

Incidence of severe disease among children with COVID-19, PIMS-TS and KD-TS. We also compared KD epidemiology before and during the COVID-19 pandemic.

RESULTS

Among 386 children with SARS-CoV-2 infection, 381 (98.7%) had COVID-19 (median 6.3 years (IQR 2.1-12.8),53.3% male) and 5 (1.3%) had multisystem inflammatory syndromes (PIMS-TS, n=4; KD-TS, n=1) (median 7.9 years (IQR 7.8-9.8)). Most children with COVID-19 (n=278; 73%) were Australian-born from jurisdictions with highest community transmission. Comorbidities were present in 72 (18.9%); cardiac and respiratory comorbidities were most common (n=32/72;44%). 37 (9.7%) children with COVID-19 were hospitalised, and two (0.5%) required intensive care. Postinfective inflammatory syndromes (PIMS-TS/KD-TS) were uncommon (n=5; 1.3%), all were hospitalised and three (3/5; 60%) required intensive care management. All children recovered and there were no deaths. KD incidence remained stable during the pandemic compared with prepandemic.

CONCLUSIONS

Most children with COVID-19 had mild disease. Severe disease was less frequent than reported in high prevalence settings. Preventative strategies, such as vaccination, including children and adolescents, could reduce both the acute and postinfective manifestations of the disease.

Inter- and intrapatient heterogeneity of indoleamine 2,3-dioxygenase expression in primary and metastatic melanoma cells and the tumour microenvironment

AIMS

Indoleamine 2,3-dioxygenase (IDO), an immunomodulatory enzyme, facilitates immune escape by tumours and promotes tumour progression. IDO inhibitors with and without additional anti-PD-1 therapy have been evaluated in recent and ongoing melanoma clinical trials, but IDO expression in melanoma tumours, and therefore its potential role as a predictive biomarker remains unknown. This study sought to evaluate IDO expression in immunotherapy-naive metastatic melanoma patients in order to determine patterns of expression in corresponding primary melanomas, locoregional metastases and distant metastases.

METHODS AND RESULTS

Here, we evaluated IDO expression using immunohistochemistry in 99 melanoma tumour samples from 43 immunotherapy-naive patients with metastatic melanoma to determine patterns of expression in primary melanomas (n = 29), locoregional metastases (n = 36) and distant metastases (n = 34). Thirty-seven per cent of patients demonstrated tumour IDO expression in at least one specimen. Twelve of 35 patients (34%) with longitudinal specimens (i.e. two or more separate specimens from different disease stages in the same patient) displayed heterogeneous IDO staining between samples. Tumour IDO expression positively correlated with tumour-infiltrating lymphocyte (TIL) score as well as the number of IDO-expressing mononuclear cells in the primary melanoma (P < 0.0001 and P = 0.0011, respectively) and nodal metastases (P = 0.049 and P = 0.037, respectively), but not in distant metastases. Furthermore, tumour IDO expression correlated positively with PD-L1 expression by melanoma cells among all specimens (P = 0.0073).

CONCLUSIONS

Therefore, while assessment of tumour IDO expression warrants evaluation in melanoma patient cohorts treated with IDO inhibitors dosed at levels proven to inhibit the target by pharmacodynamic assessment, its utility as a biomarker may be limited by intertumoral heterogeneity.