Summary
Background
The updated American Joint Committee on Cancer (AJCC) staging criteria for melanoma remain unable to identify high‐risk stage I tumour subsets.
Objectives
To determine the utility of epidermal autophagy and beclin 1 regulator 1 (AMBRA1)/loricrin (AMLo) expression as a prognostic biomarker for AJCC stage I cutaneous melanoma.
Methods
Peritumoral AMBRA1 expression was evaluated in a retrospective discovery cohort of 76 AJCC stage I melanomas. AMLo expression was correlated with clinical outcomes up to 12 years in two independent powered, retrospective validation and qualification cohorts comprising 379 AJCC stage I melanomas.
Results
Decreased AMBRA1 expression in the epidermis overlying primary melanomas in a discovery cohort of 76 AJCC stage I tumours was associated with a 7‐year disease‐free survival (DFS) rate of 81·5% vs. 100% survival with maintained AMBRA1 (P < 0·081). Following an immunohistochemistry protocol for semi‐quantitative analysis of AMLo, analysis was undertaken in validation (n = 218) and qualification cohorts (n = 161) of AJCC stage I melanomas. Combined cohort analysis revealed a DFS rate of 98·3% in the AMLo low‐risk group (n = 239) vs. 85·4% in the AMLo high‐risk cohort (n = 140; P < 0·001). Subcohort multivariate analysis revealed that an AMLo hazard ratio (HR) of 4·04 [95% confidence interval (CI) 1·69–9·66; P = 0·002] is a stronger predictor of DFS than Breslow depth (HR 2·97, 95% CI 0·93–9·56; P = 0·068) in stage IB patients.
Conclusions
Loss of AMLo expression in the epidermis overlying primary AJCC stage I melanomas identifies high‐risk tumour subsets independently of Breslow depth.
What's already known about this topic?
There is an unmet clinical need for biomarkers of early‐stage melanoma.
Autophagy and beclin 1 regulator 1 (AMBRA1) is a proautophagy regulatory protein with known roles in cell proliferation and differentiation, and is a known tumour suppressor.
Loricrin is a marker of epidermal terminal differentiation.
What does this study add?
AMBRA1 has a functional role in keratinocyte/epidermal proliferation and differentiation.
The combined decrease/loss of peritumoral AMBRA1 and loricrin is associated with a significantly increased risk of metastatic spread in American Joint Committee on Cancer (AJCC) stage I tumours vs. melanomas, in which peritumoral AMBRA1 and loricrin are maintained, independently of Breslow depth.
What is the translational message?
The integration of peritumoral epidermal AMBRA1/loricrin biomarker expression into melanoma care guidelines will facilitate more accurate, personalized risk stratification for patients with AJCC stage I melanomas, thereby facilitating stratification for appropriate follow‐up and informing postdiagnostic investigations, including sentinel lymph node biopsy, ultimately resulting in improved disease outcomes and rationalization of healthcare costs.
Resistance of melanoma to trametinib has been associated with the induction of prosurvival autophagy, but it is unclear how stem-cell markers, such as CD271 contribute to the transitionary phase of drug resistance.
The heterogeneity of the RCTs included in this study makes it difficult to make a direct comparison of the outcomes measured. High-quality evidence demonstrating a beneficial effect of the use of perioperative antibiotics to prevent SSI following excision of ulcerated skin cancers is lacking. In the absence of an evidence base, we propose that a well-designed multicentre RCT could evaluate the effect of perioperative antibiotics following excision of ulcerated tumours, and potentially reduce inappropriate antibiotic prescription.
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