Follow-up evaluation of prostate cancer patients infused with autologous dendritic cells pulsed with PSMA peptides.
BACKGROUND
We recently conducted a phase I clinical trial administering autologous dendritic cells pulsed with prostate-specific membrane antigen (PSMA) peptides to advanced prostate cancer patients. Participants were divided into 5 groups receiving 4 or 5 infusions of peptides alone (PSM-P1 or -P2; groups 1 and 2, respectively), autologous DC (group 3), or DC pulsed with PSM-P1 or -P2 (groups 4 and 5, respectively). Seven partial responders were observed. Follow-up evaluation of these responders is presented in this report.


METHODS
Clinical monitoring for hematological studies and prostate markers was conducted up to 370 days from the start of the phase I study. Data collected include: lymphocyte, hematocrit, alkaline phosphatase, prostate-specific antigen (PSA), free PSA, and PSMA levels.


RESULTS
Groups 4 and 5 (patients infused with DC pulsed with PSM-P1 or -P2) represented 5/7 responders. The length of response was between 100 days (1 patient) to 200 days or above (6 patients). Four patients still remained responsive at the end of the period of observation.


CONCLUSIONS
The responses observed in this phase I clinical trial are significant and of long duration. Most of the responders were in treatment groups infused with DC pulsed with PSM-P1 or -P2, suggesting the requirement of both components for effective immunotherapy.
Tjoa
B A
BA
Pacific Northwest Cancer Foundation, Cancer Research Division, Northwest Hospital, Seattle, Washington 98125, USA.
Erickson
S J
SJ
Bowes
V A
VA
Ragde
H
H
Kenny
G M
GM
Cobb
O E
OE
Ireton
R C
RC
Troychak
M J
MJ
Boynton
A L
AL
Murphy
G P
GP
D000469:Alkaline Phosphatase / Q000097:blood; D000595:Amino Acid Sequence; D015415:Biomarkers / Q000097:blood; D002478:Cells, Cultured; D003713:Dendritic Cells / Q000637:transplantation*; D005500:Follow-Up Studies; D006400:Hematocrit; D006801:Humans; D007167:Immunotherapy / Q000009:adverse effects; D007262:Infusions, Intravenous; D018655:Lymphocyte Count; D008297:Male; D010446:Peptide Fragments / Q000008:administration & dosage / Q000627:therapeutic use*; D017430:Prostate-Specific Antigen / Q000008:administration & dosage / Q000627:therapeutic use*; D011471:Prostatic Neoplasms / Q000628:therapy*; D013997:Time Factors; D014182:Transplantation, Autologous
D015415:Biomarkers; D010446:Peptide Fragments; D000469:Alkaline Phosphatase; D017430:Prostate-Specific Antigen