Identification of Tumor Antigens in the HLA Peptidome of Patient-derived Xenograft Tumors in Mouse.

Personalized cancer immunotherapy targeting patient-specific cancer/testis antigens (CTA) and neoantigens may benefit from large-scale tumor human leukocyte antigen (HLA) peptidome (immunopeptidome) analysis, which aims to accurately identify antigens presented by tumor cells. Although significant efforts have been invested in analyzing the HLA peptidomes of fresh tumors, it is often impossible to obtain sufficient volumes of tumor tissues for comprehensive HLA peptidome characterization. This work attempted to overcome some of these obstacles by using patient-derived xenograft tumors (PDX) in mice as the tissue sources for HLA peptidome analysis. PDX tumors provide a proxy for the expansion of the patient tumor by re-grafting them through several passages to immune-compromised mice. The HLA peptidomes of human biopsies were compared with those derived from PDX tumors. Larger HLA peptidomes were obtained from the significantly larger PDX tumors as compared with the patient biopsies. The HLA peptidomes of different PDX tumors derived from the same source tumor biopsy were very reproducible, even following subsequent passages to new naïve mice. Many CTA-derived HLA peptides were discovered, as well as several potential neoantigens/variant sequences. Taken together, the use of PDX tumors for HLA peptidome analysis serves as a highly expandable and stable source of reproducible and authentic peptidomes, opening up new opportunities for defining large HLA peptidomes when only small tumor biopsies are available. This approach provides a large source for tumor antigens identification, potentially useful for personalized immunotherapy.

Factors affecting participation in group intervention in patients after adjuvant treatment for early-study breast cancer.

BACKGROUND AND PURPOSE: According to studies of patients with cancer, support groups can help in three areas: 1) improve mood; 2) introduce new, adaptive ways of handling potentially difficult situations; and 3) impart strategies for managing stress. Nevertheless, the decrease in the quality of life of cancer patients or survivors does not always translate into their utilization of available psychosocial services. The aim of the current study was to explore the factors affecting the decision of patients with breast cancer to participate in group intervention based on an enhancing-resilience approach. METHODS: One hundred eighty-nine patients who were diagnosed with early-stage breast cancer at a tertiary hospital and had completed adjuvant therapy at least three months previously were asked to enroll in the study with or without group intervention. One hundred and one (53.4%) completed the battery of psychological questionnaires, of whom 56 agreed to participate in the intervention. Sociodemographic and medical data were collected for all 189 subjects from the medical files. RESULTS: No significant differences in sociodemographic or medical data were found between intervention-group participants (N = 56) and non-participants (N = 133). Group participants reported significantly higher levels of psychological pathology. Subjects who completed the questionnaires but did not participate in the intervention reported significantly higher levels of positive cognitive emotion regulation and flexibility than participants. CONCLUSION: Low participation in group interventions may be more strongly associated with psychological characteristics than sociodemographic and medical factors. It seems that patients know to perceive whether their personal resources are inadequate for facing a life-threatening illness. Like individual therapy, group interventions should be more sensitive to perceived individual needs and to the art of tailoring suitable contents according individual needs.