Despite the knowledge of many genetic alterations present in osteosarcoma, the complexity of this disease precludes placing its biology into a simple conceptual framework. Cytotoxic T-lymphocyte antigen-4 (CTLA-4) plays important roles in downregulating T-cell activation, thereby attenuating anti-tumor responses and increasing cancer susceptibility. Polymorphisms in the CTLA-4 gene are associated with different autoimmune diseases and cancers. The current study evaluated the association of four CTLA-4 gene mutations, -1661A/G (rs4553808), -318C/T (rs5742909), +49G/A (rs231775), and CT60A/G (rs3087243), with osteosarcoma in the Chinese population. CTLA-4 polymorphisms were detected by polymerase chain reaction-restriction fragment length polymorphism in 267 osteosarcoma patients and 282 age-matched healthy controls. Results showed that the CTLA-4 gene +49 AA genotype, +49 A allele, and GTAG haplotype were significantly more frequent in osteosarcoma patients than in controls (odds ratio [OR] 2.20, 95% confidence interval [CI] 1.23-2.95, p = 0.007; OR 1.32, 95% CI 1.03-1.69, p = 0.029, and OR = 1.47, 95% CI 1.03-2.09, p = 0.033, respectively). The CTLA-4 +49G/A polymorphism and GTAG haplotype are associated with increased risk of osteosarcoma.

Glypican-3 is a promising target for immunotherapy for hepatocellular carcinoma, but limited data exist regarding its immunogenicity in patients with diverse HLA types, immunogenicity for CD4+ T-cells, and the impact of inhibitory co-stimulation on glypican-3-specific T-cells. Using a 15mer overlapping peptide library for glypican-3, PBMC from patients with HCC were assessed ex vivo and after short-term in vitro expansion for tumor antigen-specific T-cell responses with and without blockade of PD-1/PD-L1 and CTLA-4 signaling. Glypican-3-specific T-cells were undetectable ex vivo, but primarily IFNγ+ TNFα+ CD4+ T-cells expanded with short-term in vitro stimulation in 10/19 (52%) patients. Glypican-3-specific CD8+ T-cells predominantly produced TNFα, but did not secrete IFNγ nor degranulate. CTLA-4 and PD-1 blockade minimally impacted the cytokine secretion and proliferation of glypican-3-specific T-cells. These data suggest that CD8+ T-cell-directed tumor vaccines in HCC may have limited potential for efficacy unless optimal co-stimulation conditions can be identified but CD4+-directed vaccines merit consideration.