In vivo Therapeutic Synergism of Anti–Epidermal Growth Factor Receptor and Anti-HER2 Monoclonal Antibodies against Pancreatic Carcinomas

Abstract

Purpose: Pancreatic carcinoma is highly resistant to therapy. Epidermal growth factor receptor (EGFR) and HER2 have been reported to be both dysregulated in this cancer. To evaluate the in vivo effect of binding both EGFR and HER2 with two therapeutic humanized monoclonal antibodies (mAb), we treated human pancreatic carcinoma xenografts, expressing high EGFR and low HER2 levels. Experimental Design: Nude mice, bearing xenografts of BxPC-3 or MiaPaCa-2 human pancreatic carcinoma cell lines, were injected twice weekly for 4 weeks with different doses of anti-EGFR (matuzumab) and anti-HER2 (trastuzumab) mAbs either alone or in combination.The effect of the two mAbs, on HER receptor phosphorylation, was also studied in vitro by Western blot analysis. Results: The combined mAb treatment significantly inhibited tumor progression of the BxPC-3 xenografts compared with single mAb injection (P = 0.006) or no treatment (P = 0.0004) and specifically induced some complete remissions. The two mAbs had more antitumor effect than 4-fold greater doses of each mAb. The significant synergistic effect of the two mAbs was confirmed on the MiaPaCa-2 xenograft and on another type of carcinoma, SK-OV-3 ovarian carcinoma xenografts. In vitro, the cooperative effect of the two mAbs was associated with a decrease in EGFR and HER2 receptor phosphorylation. Conclusions: Anti-HER2 mAb has a synergistic therapeutic effect when combined with an anti-EGFR mAb on pancreatic carcinomas with low HER2 expression. These observations may open the way to the use of these two mAbs in a large panel of carcinomas expressing different levels of the two HER receptors.The incidence of pancreatic cancer has steadily increased over the past four decades, and its prognosis is still dismal, despite all efforts in early diagnosis and therapy. Even with a complete surgical resection, the 5-year survival rate is <20% (1).Conventional therapies associating surgery and radiotherapy often in combination with chemotherapy show modest efficacy in local control and palliation and no real progress in patient survival (2 -4). Thus, novel approaches to human pancreatic carcinoma therapy are urgently needed.Among the numerous biochemical and genetic abnormalities that were found to be associated with this malignancy (3), we were interested by the fact that two receptors of the HER tyrosine kinase family epidermal growth factor receptor (EGFR; ErbB1 or HER1) and HER2 (ErbB2) are expressed in a significant percentage of cases ranging from 45% to 95% for EGFR (5, 6) and 43% to 69% for HER2 (7,8). The levels of HER2 expression, however, were low in the majority of tumors. Furthermore, the overexpression of EGFR and HER2 receptors is often caused by encoding gene amplification (9).EGFR and HER2 are known to play an essential role in regulating cell proliferation and differentiation. They have a strong tendency to assemble with other HER receptors into homodimers and/or heterodimers on extracellular growth factor binding, which results in various forms of signal transd...

Inhibition of pancreatic carcinoma by homo- and heterocombinations of antibodies against EGF-receptor and its kin HER2/ErbB-2

“…The other strategy combined two antibodies, one to EGFR and the other to HER2, in similarity to reports by Azria, Pelegrin, and coworkers, who combined two antibodies (24) and also added a third agent, namely a tyrosine kinase inhibitor (25). Here, we compare the two types of antibody combinations and also highlight potential mechanisms of the synergy observed in animals bearing human PDAC xenografts.…”

“…2 A and B). Importantly, BXPC3 cells express ∼10-fold higher levels of EGFR relative to HER2 (24). Nevertheless, in complete analogy to anti-EGFR antibodies ( Fig.…”

“…In light of the ability of EGFR and HER2 to form stable heterodimers (26,27), and the observed antitumorigenic effects of our anti-EGFR and anti-HER2 antibodies, we assumed that mixtures comprising one of our antibodies to EGFR and another to HER2 would synergistically inhibit PDAC xenografts. Notably, a mixture of the humanized mAbs matuzumab (anti-EGFR) and trastuzumab (anti-HER2) displayed synergistic effects in animals (24), raising the possibility that synergy can be obtained with several distinct antibody mixtures. To test this prediction, we used several different mixtures: (i) mAb 565 (to EGFR) combined with mAb 12 (to HER2), (ii) mAb 565 and either mAb 431 or mAb 26 (both to HER2), and (iii) the mAbs 111 (to EGFR) and 431.…”

Effects of the combined blockade of EGFR and ErbB-2 on signal transduction and regulation of cell cycle regulatory proteins in breast cancer cells

“…We and others have demonstrated that gefitinib and trastuzumab have a synergistic anti-tumor effect in breast cancer cells that express both receptors. Synergism of anti-EGFR and anti-ErbB-2 agents has also been demonstrated in cells derived from tumors of different histological type, such as ovarian, non-small-cell lung and pancreatic carcinomas [28][29][30].…”

Association d’anticorps anti-EGFR et anti-HER2

“…La co-expression de ces deux récepteurs dans un même tissu est moins documentée mais semble associée à un plus mauvais pronostic dans les cancers du sein [5] et du côlon [6]. Par ailleurs, certaines conséquences de l'interaction d'EGFR avec HER2 telles que l'inhibition de l'endocytose de EGFR Efficacité thérapeutique in vivo de l'association de deux anticorps monoclonaux dirigés contre l'EGFR et HER2 dans le traitement du cancer du pancréas L'association trastuzumab-matuzumab a été évaluée chez des souris immunodéficientes porteuses de carcinomes pancréatiques humains [14]. Le traitement a consisté en l'injection par voie intrapéritonéale, deux fois par semaine …”