Preliminary observations on soluble programmed cell death protein-1 as a prognostic and predictive biomarker in patients with metastatic melanoma treated with patient-specific autologous vaccines

Blood samples obtained during a randomized trial in patients with metastatic melanoma were tested from 22 patients treated with a tumor cell vaccine and 17 treated with a dendritic cell vaccine.

Among DCV-treated patients, these sPD-1 criteria appropriately classified 8/10 of 3-year survivors, and 6/7 of patients who did not survive three years.

Dr. Robert O. Dillman from AIVITA Biomedical, Inc. in Irvine, CA, USA said, "PD-1 (CD279) was first described by Tasuku Honjo and colleagues at Kyoto University in 1992."

The purpose of this study was to determine the possible use of sPD-1 as an immune marker in patients with metastatic melanoma who were enrolled in a randomized phase II trial testing autologous dendritic cell vaccines and autologous tumor cell vaccines.

Figure 1: Changes in sPD-1 between week-0 and week-4 for individual patients. (A) shows all 39 patients by treatment arm - dendritic cell vaccine (DCV) or tumor cell vaccine (TCV); (B) shows the 23 patients who survived less than three years by treatment arm (DCV or TCV); and (C) shows the 16 patients who survived more than three years by treatment arm (DCV or TCV).

The authors asked the following questions:

• Was baseline sPD-1 prognostic for survival in these patients with metastatic melanoma, or for either of the two treatment-defined cohorts;
• Within each treatment-defined cohort, was either vaccine efficacious in patients with very low sPD-1 levels and/or very high sPD-1 levels;
• If there was a change in sPD-1 from week-0, one week before the first of three weekly vaccine injections, to week-4, one week after the third injection, was this predictive of survival for all patients or in either treatment-defined cohort; and
• Could sPD-1 be used to define cohorts that were prognostic or predictive of survival.

The AIVITA Research Team concluded that they believe the levels of sPD-1 and changes in sPD-1 are a reflection of Th1 immune responses and their suppression by the PD-1/PD-L1 axis.

Full text - https://doi.org/10.18632/oncotarget.27164

Correspondence to - Robert O. Dillman - robert.dillman55@gmail.com

Keywords - programmed cell death protein-1 (PD-1), dendritic cell vaccines, metastatic melanoma