There is substantial evidence that the mainly tumour-restricted aberrant expression of the highly immunogenic cancer-testis (CT) antigens across several different cancer types makes them attractive cancer diagnostic and predictive biomarkers. Therefore, we aimed to measure differences in CT antigen-specific antibody repertoires between colorectal cancer patient samples, and assess whether these could identify novel diagnostic, therapeutic or prognostic biomarkers, which could aid in the detection and management of cancer.
In order to detect and quantify cancer-specific antibodies circulating in the serum or plasma of cancer patients, we developed a novel cancer-restricted antigen microarray platform. This array represents a high-throughput means of profiling antibody repertoires against over 100 cancer-restricted antigens (including CT antigens) in a highly reproducible manner with high sensitivity (detection limit: 10-100pg/ml) and specificity. In addition, it provides a significant advantage over tissue-based approaches, due to the ease of sample access without the need for invasive procedures.
We carried out a retrospective serological study of antibody titres across a cohort of sixty-two colorectal cancer patients (15% stage I, 36% stage II, 45% stage III and 4% stage IV) undergoing pre- or post-operative chemotherapy or radiotherapy, using our recently developed and validated novel custom protein microarray platform.
We successfully identified significant (>1000 RFU) antibody titres in all sixty-two patients (n=62/62, 100%), with abundant titres seen towards fourteen leading antigens. These included SILV/gp100 (n=19/62, 31%) and a p53 mutant (n=13/62, 21%), previously reported as a potential cancer therapeutic target for cellular immune responses, and a cancer prognostic marker, respectively. Furthermore, healthy individuals showed no detectable cancer-specific antibody titres, therefore highlighting the specificity of this tool in a cancer setting.
In conclusion, we showed that our novel protein microarray platform represents a sensitive, high-throughput and customizable means to detect and quantify the presence of large panels of cancer-specific human antibodies in serum, obtaining consistently robust, high quality and reproducible data, and demonstrating its potential feasibility and inferred biological significance.