Variants at the OCA2/HERC2 locus affect time to first cutaneous squamous cell carcinoma in solid organ transplant recipients collected using two different study designs

BACKGROUND

Variants at the oculocutaneous albinism 2 (OCA2)/HECT and RLD domain containing E3 ubiquitin protein ligase 2 (HERC2) locus have been associated with pigmentation phenotypes and risk of developing several types of skin cancer.

OBJECTIVES

To evaluate OCA2/HERC2 locus variants for their impact on time to develop cutaneous squamous cell carcinoma (cSCC) in organ transplant recipients (OTRs) who are at elevated risk of developing cSCC.

METHODS

Participants were solid OTRs ascertained from two centres (n = 125 and 261) with an average of 13·1 years of follow-up post-transplant. DNA was available for genotyping for all participants, in addition to medical records and questionnaire data. The Ohio State University study had a case-control design with prospective follow-up, and the University of California San Francisco study was a national cross-sectional survey with retrospective chart review.

RESULTS

OCA2 variants rs12913832 and rs916977 were significantly associated with time to first cSCC post-transplant. OTRs homozygous for the brown-eye alleles of rs916977 (GG) and rs12913832 (AA) had significant delays of time to first cSCC post-transplant compared with individuals homozygous for the blue-eye alleles (hazard ratio 0·34, P < 0·001 and hazard ratio 0·54, P = 0·012, respectively). Both variants were highly associated with eye colour in the combined studies (P < 0·001).

CONCLUSIONS

This study is the first to show an association between OCA2/HERC2 variants and time to first cSCC post-transplant. This may impact dermatological screening recommendations for high-risk populations.

Differential mutation frequencies in metastatic cutaneous squamous cell carcinomas versus primary tumors

BACKGROUND

Exome and targeted sequencing studies have identified potential driver mutations for a variety of tumor types. Cutaneous squamous cell carcinoma (cSCC) is one of the most highly mutated cancers but typically is associated with low rates of metastasis and high survival rates. Nevertheless, metastatic cSCC is a significant health threat; up to 8800 individuals die each year of this disease.

METHODS

Because it is difficult to predict which cSCCs are more likely to metastasize, and because to the best of the authors' knowledge there are no targeted therapies specifically designated for patients with metastatic cSCC, exome and/or targeted sequencing of 18 metastatic and 10 primary cSCCs was performed to identify mutations that were more frequent in metastatic tumors and might be targeted for therapeutic benefit. The authors compared their results with published sequencing results of an additional 223 primary tumors and 68 metastatic cSCCs.

RESULTS

The authors identified genes demonstrating higher mutation frequencies in metastatic cSCC compared with primary tumors, including the chromatin remodeling gene lysine methyltransferase 2D (KMT2D) and the classic skin tumor suppressor tumor protein p53 (TP53), which was found to be mutated in 54% of primary tumors compared with 85% of metastatic tumors (P<.0001).

CONCLUSIONS

These studies appear to uncover potential pathways that are important in metastatic cSCC and that broaden understanding of the biology contributing to aggressive tumor behavior. These results may lead to new therapeutic strategies. Cancer 2017;123:1184-1193. © 2016 American Cancer Society.