Tumor-associated antigen-based personalized dendritic cell vaccine in solid tumor patients

Abstract

Tumor-associated antigens (TAAs) have been tested in various clinical trials in cancer treatment but the patterns of specific T cell response to personalized TAA immunization remains to be fully understood. We report antigen-specific T cell responses in patients immunized with dendritic cell vaccines pulsed with personalized TAA panels. Tumor samples from patients were first analyzed to identify overexpressed TAAs. Autologous DCs were then transfected with pre-manufactured mRNAs encoding the full-length TAAs, overexpressed in the patients' tumors. Patients with glioblastoma multiforme (GBM) or advanced lung cancer received DC vaccines transfected with personalized TAA panels, in combination with low-dose cyclophosphamide, poly I:C, imiquimod and anti-PD-1 antibody. Antigen-specific T cell responses were measured. Safety and efficacy were evaluated. A total of ten patients were treated with DC vaccines transfected with personalized TAA panels containing 3-13 different TAAs. Among the seven patients tested for anti-TAA T cell responses, most of the TAAs induced antigen-specific CD4⁺ and/or CD8⁺ T cell responses, regardless of their expression levels in the tumor tissues. No Grade III/IV adverse events were observed among these patients. Furthermore, the treated patients were associated with favorable overall survival when compared to patients who received standard treatment in the same institution. Personalized TAA immunization-induced-specific CD4⁺ and CD8⁺ T cell responses without obvious autoimmune adverse events and was associated with favorable overall survival. These results support further studies on DC immunization with personalized TAA panels for combined immunotherapeutic regimens in solid tumor patients.Trial registration ClinicalTrials.gov, NCT02709616 (March, 2016), NCT02808364 (June 2016), NCT02808416 (June, 2016).

Keywords: CD4+ T cell response; CD8+ T cell response; DC vaccine; Glioblastoma multiforme; Non-small cell lung cancer; Personalization; Tumor-associated antigen.

Fig. 1

Heatmap of mRNA expression of TAAs and TME immunosuppressive factors in serial tumor samples from patients BT001 and BT030. The mRNAs of the indicated TAA and TME immunosuppressive factors in tumor samples from lung and brain were assayed by qPCR in triplicates. Lung para-tumor tissue from biopsy was used as the control for comparison for patient BT001 and pooled normal brain tissues were used as controls for comparison for patient BT030. The mRNA expression levels of the measured genes were expressed as mean fold changes. a Expression of TAAs in tumor samples from patient BT001. Three tumor samples are from lung (Lung lesion), vertebral metastasis (metastasis 1 and 2) at day 376, 682, 701 after diagnosis. b Expression of TAAs in tumor samples from patient BT030. Four tumor samples are from newly diagnosed GBM and recurrences at day 0, 326, 453, 584 after diagnosis. c Expression of TME immunosuppressive factors in tumor samples from patient BT001 as in (a). d Expression of TME immunosuppressive factors in tumor samples from patient BT030 as in (b). Color bar and number represent fold changes

Fig. 2

TAA-specific T cell responses from patients BT077 (NSCLC) and BT057 (GBM). PBMCs collected at the indicated time were stimulated with autologous DCs transfected with the corresponding TAA-mRNAs for 12 days and restimulated for 6 h. T cells were stained for intracellular expression of TNFα and IFNγ. Mock represents DCs without antigen transfection as background for T cell stimulation. a FACS profiles of antigen-specific CD8⁺ T cell responses after 2- or 4-doses of TAA-pulsed DC vaccination in patient BT077. b Kinetics of antigen-specific CD4⁺ and CD8⁺ T cell responses against TAAs after DC immunization in patient BT077. c FACS profiles of CD8⁺ T cell responses after the 3 immunizations of TAA-pulsed DC cells in patient BT057. d Kinetics of antigen-specific CD4⁺ and CD8⁺ T cell responses against TAAs after DC immunization in patient BT057. Mock represents mock-transfected DCs as a control. Two-way ANOVA with Bonferroni test: ***P < 0.001, **P < 0.01, *P < 0.05

Fig. 3

Overall survival of patients in NSCLC with brain metastases and GBM. Kaplan–Meier curves showing survival for patients with TAA-mDC vaccination or standard treatment. a Lung cancer with brain metastases patients. b GBM patients. P value (P) was calculated using Cox regression analysis