Portal de Periódicos da CAPES

Abstract #3610: Assessment of circulating tumor cells in disease-free breast cancer patients vaccinated with HER2/neu peptide vaccines or immunoadjuvant GM-CSF.

2009; American Association for Cancer Research; Volume: 69; Linguagem: Inglês

1538-7445

Guy T. Clifton, Holmes Jarrod, Linda C. Benavides, Jeremy D. Gates, Suzanne Mccall, Stanley Rivera, Elizabeth A. Mittendorf, Alexander Stojadinovic, Gerald A. Merrill, Sathibalan Ponniah, George E. Peoples,

Cancer Immunotherapy and Biomarkers

AACR Annual Meeting-- Apr 18-22, 2009; Denver, CO Background: The quantity of circulating tumor cells (CTC) and post-treatment reduction predict outcome in medically treated metastatic breast cancer patients (BCa) and has previously been used to monitor the effect of vaccination with the HER2/neu peptide, E75. CTCs may be a useful early marker of therapeutic effect for vaccines in the adjuvant setting. We assessed the level of CTCs in clinically disease-free high-risk node negative (NN) and node positive (NP) BCa patients being vaccinated with immunogenic HER2/neu peptides prior to and post-vaccination. Methods: Clinically disease-free high-risk NN or NP patients were enrolled after completion of surgery and standard chemo/radiation therapy. The patients were randomized to receive one of the HER2/neu-derived peptides GP2 or AE37 with GM-CSF as an immunoadjuvant or to the control arm where they will receive only GM-CSF monthly for 6 months. The CellSearch System (Veridex, LLC Warren, NJ) was used to enumerate total CTC in 20 ml of blood from selected samples obtained from patients (n=32) prior to vaccination. If CTCs were present pre-vaccination, levels were also measured at completion and 6 months after completion of the vaccination series. Results: 12/32 patients (37.5%) had at least one CTC identified pre-vaccination. Thus far, 7 of the 12 patients have had multiple samples collected. Of those with multiple samples, 3 patients received adjuvant GM-CSF only and 4 patients received GP2 and adjuvant GM-CSF. Of the 3 in the adjuvant only arm, 33.3% (1/3) decreased after completion of the series. Of the 4 who received GP2 and adjuvant, 75% (3/4) had no detectable CTCs after completion of the vaccine series. The one GP2 patient with CTCs after completing the primary vaccine inoculations had a clinically detected cancer recurrence shortly after completion of the vaccine series. Conclusions: CTCs may be an early marker for therapeutic effect of cancer vaccines in the adjuvant setting. Initial results from our clinical trial show that patients treated with the GP2 peptide vaccine are more likely to have a decrease in the level of detectable CTCs than patients receiving GM-CSF immunoadjuvant only. These early results warrant the continued assessment of CTC in our vaccine trials. Citation Information: In: Proc Am Assoc Cancer Res; 2009 Apr 18-22; Denver, CO. Philadelphia (PA): AACR; 2009. Abstract nr 3610.