PD14-07 REAL-TIME IMAGING DEMONSTRATING T-CELL MEDIATED DESTRUCTION OF PROSTATIC ACID PHOSPHATASE (PAP)-EXPRESSING CELLS IN PATIENTS (PTS) TREATED WITH SIPULEUCEL-T (SIP-T)

You have accessJournal of UrologyProstate Cancer: Advanced (including Drug Therapy) II1 Apr 2018PD14-07 REAL-TIME IMAGING DEMONSTRATING T-CELL MEDIATED DESTRUCTION OF PROSTATIC ACID PHOSPHATASE (PAP)-EXPRESSING CELLS IN PATIENTS (PTS) TREATED WITH SIPULEUCEL-T (SIP-T) Brant Inman, Tuyen Vu, Evan Y Yu, Dwayne Campogan, Heather Haynes, Nadeem A Sheikh, and Daniel George Brant InmanBrant Inman More articles by this author , Tuyen VuTuyen Vu More articles by this author , Evan Y YuEvan Y Yu More articles by this author , Dwayne CampoganDwayne Campogan More articles by this author , Heather HaynesHeather Haynes More articles by this author , Nadeem A SheikhNadeem A Sheikh More articles by this author , and Daniel GeorgeDaniel George More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2018.02.793AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Sip-T is an autologous cellular immunotherapy for metastatic castrate-resistant prostate cancer (mCRPC). Sip-T is made by culturing peripheral blood mononuclear cells (PBMCs) with PA2024 antigen (PAP conjugated to GM-CSF). Evidence suggests that sip-T induces antigen-specific humoral and cytotoxic T lymphocyte (CTL) mediated immunity that correlate with survival. We sought to obtain visual evidence of CTLs in action in sip-T-treated pts. METHODS STAMP (NCT01487863) was a phase 2 trial of sip-T with abiraterone in mCRPC. Thawed PMBCs collected at baseline and post-sip-T from STAMP pts were incubated ± PAP peptide (1.2 nmol) to activate PAP-specific T cells. CD8+ T cells were purified from PBMCs with a magnetic bead-based CD8+ T cell negative selection kit (Miltenyl Biotec). Autologous monocytes, purified from PBMCs by negative cell isolation (EasySep human monocyte enrichment kit; STEMCELL Technologies), were used as targets. These cells were fluorescently stained (calcein AM), pulsed with PAP (to make them immune targets), and incubated with CD8+ T cells activated by sip-T treatment in a chamber slide system (Thermo Fisher). Non-PAP pulsed monocytes were controls. 6 h videos were acquired with a Leica CRT6500 confocal microscope (METAMORPH software). RESULTS No evidence of cell destruction was seen in controls (wk 0 and 6 non-PAP monocytes). At wk 0, there was no PAP-expressing target destruction by CD8+ T cells not yet activated by sip-T treatment. Videos documenting sip-T activated CD8+ T cells destroying PAP-expressing targets at wks 6 were captured. The figure (wk 6 data) shows still images of activated CD8+ T cells (dark grey) migrating towards (A and D) and contacting PAP-expressing targets (green) (B and E). The T cells attack the targets resulting in monocyte death (loss of green, C and F). CONCLUSIONS We provide the first video documentation of sip-T-induced, antigen-specific, CTL activity using ex vivo imaging in pt samples. This observation provides evidence that part of sip-T's mechanism of action is the induction and expansion of anti-PAP CTLs that can target and kill PAP-expressing cells in the body. © 2018FiguresReferencesRelatedDetails Volume 199Issue 4SApril 2018Page: e307 Advertisement Copyright & Permissions© 2018MetricsAuthor Information Brant Inman More articles by this author Tuyen Vu More articles by this author Evan Y Yu More articles by this author Dwayne Campogan More articles by this author Heather Haynes More articles by this author Nadeem A Sheikh More articles by this author Daniel George More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...