Anti-PD-1 therapy has improved the outcome of advanced melanoma patients with a 5-year survival rate of about 40-45%. However, biomarkers predictive of response to immune checkpoint blockade therapy are lacking. There is limited data on the utility of host germline human leucocyte antigen (HLA) genotype as a predictor of response to anti-PD-1 therapy in advanced melanoma. Here, we investigate the prognostic value of HLA in predicting survival outcomes of patients with unresectable locally advanced, metastatic melanoma on anti-PD-1 therapy. Methods: Blood was collected from 113 metastatic melanoma patients who were treated with anti-PD-1 therapy at two major oncology centres in Western Australia. High quality DNA was extracted from white blood cells and subsequently HLA-I and HLA-II typed using clinically validated assay. Univariate analyses were conducted using Cox regression model correlating homozygosity at HLA-I and HLA-II loci with overall survival (OS). HLA-A and HLA-B were classified into 12 supertypes and correlated with OS. Multivariate analyses were performed while controlling for age, gender, prior therapy, BRAF mutation status, ECOG performance status and presence of liver and brain metastases. Results: Homozygosity at HLA-I or HLA-II loci was not associated with OS. However, the absence of HLA-B62 supertype was associated with a trend towards improved OS (HR: 0.53 [95% CI:0.25-1.10]; P = 0.09) as reported previously. Notably, the absence of HLA-B27 supertype was associated with improved OS which was statistically significant (HR: 0.45 [95% CI:0.24-0.85]; P = 0.01). In multivariate analyses, the prognostic value of HLA-B27 supertype (HR: 0.38 [95% CI:0.19-0.76]; P = 0.006) was maintained, whereas the prognostic value of HLA-B62 supertype significantly improved (HR: 0.42 [95% CI:0.19-0.94]; P = 0.03). Conclusions: Our results suggest a limited role of HLA homozygosity in predicting survival of melanoma patients treated with anti-PD-1 therapy. However, we identified that the absence of HLA-B62 and HLA-B27 supertype is associated with improved survival benefit. Therefore, HLA-B27 and HLA-B62 supertype may be used as adjunct biomarkers of response to anti-PD-1 therapy in patients with melanoma in addition to PD-L1 status, pending validation in prospective randomised clinical trials.
|Number of pages||2|
|Journal||Journal of Clinical Oncology|
|Publication status||Published - 20 May 2021|
|Event||2021 ASCO Annual Meeting I - , Virtual|
Duration: 4 Jun 2021 → 9 Jun 2021