Abstract 5588: T cell activation in relation to clinical responsiveness in patients with metastatic hormone-refractory prostate cancer receiving combined Prostate GVAX and anti-CTLA4 immunotherapy

Autor: N. Sacks, Thomas Harding, Helen Gall, Israel Lowy, Karin Jooss, Alfons J.M. van den Eertwegh, Petra E.T. Scholten, Winald R. Gerritsen, Saskia J. A. M. Santegoets, Rik J. Scheper, Kristen Hege, Tanja D. de Gruijl, Anita G.M. Stam, B. M. E. Von Blomberg
Rok vydání: 2010
Předmět:
Zdroj: Cancer Research. 70:5588-5588
ISSN: 1538-7445
0008-5472
DOI: 10.1158/1538-7445.am10-5588
Popis: The effects of a GM-CSF-secreting allogeneic prostate cancer vaccine (Prostate GVAX) and the anti-CTLA4 antibody Ipilimumab were investigated in a Phase I dose escalation/expansion trial of patients with metastatic, hormone-refractory prostate cancer (mHRPC). Patients received a 500 million cell GVAX priming dose on day 1 followed by 12 bi-weekly intradermal administrations of 300 million cells, while Ipilimumab was administered every 4 wks from day 1 for a total of 6 times. Initially, 12 patients were enrolled in cohorts of 3 and each cohort was assigned an escalating dose of Ipilimumab at 0.3, 1, 3 or 5 mg/kg. 16 additional patients were enrolled in the expansion cohort of 3 mg/kg Ipilimumab. Results showed that the GVAX and Ipilimumab combination was clinically active in mHRPC patients. PSA declines of more than 50% (Partial Response, PR) were observed in 5 of 22 patients in the 3-5 mg/kg Ipilimumab doses and PSA stabilizations (Stable Disease, SD) were observed in 1/3 pts in lower (0.3 and 1 mg/kg), and in 7/22 in the higher (3-5 mg/kg) dose levels. Phenotypic and functional (anti-tumor) effector T cell activation was monitored to identify changes that might predict or correlate with clinical efficacy. Most notably, pronounced and significant increases in frequencies of activated and effector CD4+ and CD8+ T cells were observed by HLA-DR and ICOS expression upon administration of high (3 and 5 mg/kg) but not of low (0.3 and 1 mg/kg) Ipilimumab doses. We also observed a significant increase of CTLA4 and PD-1 expression on CD4+ T cells compared to pre-treatment values in the 3 mg/kg Ipilimumab-administered patients. The latter might be indicative of the induction of concomitant negative feedback signaling. As an indiciation of Tumor-Associated Antigen (TAA) specific responsiveness we tested HLA-Tetramer (Tm) reactivity to NY-ESO and PSMA in HLA-A2 or -A3 positive patients. For NY-ESO, GVAX/Ipi-induced increased seroreactivity (by Western Blot or ELISA) was observed in 6/28 patients. Of these 6 patients, three could be tested for Tm reactivity and in two (1SD, 1 Progressive Disease, PD) increased NY-ESO157 rates were found concomitant with increasing serum Ab levels, whereas no Tm reactivity was detected in 8 patients without seroconversions. Whereas PSMA seroconversions were observed in a total of 12/28 patients (and of note, in 4/5 PR), no Tm positivity at any time was found in a total of 15 patients tested. Further functional Treg and CTL analyses are ongoing. So far, only early HLA-DR upregulation on CD4+ or CD8+ T cells (visit 1 versus visit 3) showed any value for response prediction, since it was observed to significant levels in patients with PR or SD, but not in patients with PD. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5588.
Databáze: OpenAIRE
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