new type of her2 vaccine being developed, syngergizes w lapatinib

[Lani]

1: Int J Cancer. 2009 Oct 23. [Epub ahead of print]

Synergism from combined immunologic and pharmacologic inhibition of HER2 in vivo.

Morse MA, Wei J, Hartman Z, Xia W, Ren XR, Lei G, Barry WT, Osada T, Hobeika AC, Peplinski S, Jiang H, Devi GR, Chen W, Spector N, Amalfitano A, Lyerly HK, Clay TM.
Department of Medicine, Division of Medical Oncology, Duke University Medical Center, Durham, NC 27710.
The monoclonal antibody trastuzumab and the EGFR/HER2 tyrosine kinase inhibitor lapatinib improve the clinical outcome of patients with HER2-overexpressing breast cancer. However, the majority of metastatic cancers will eventually progress suggesting the need for other therapies. Because HER2 overexpression persists, we hypothesized that the anti-HER2 immune response induced by cancer vaccines would be an effective strategy for treating trastuzumab and lapatinib-refractory tumors. Furthermore, we hypothesized that the antibody response could synergize with lapatinib to enhance tumor inhibition. We developed a recombinant adenoviral vector expressing a kinase-inactive HER2 (Ad-HER2-ki) to use as a cancer vaccine. Vaccine-induced polyclonal HER2-specific anti-serum was analyzed for receptor internalization and signaling effects alone and in combination with lapatinib. Ad-HER2-ki vaccine induced potent T cell and antibody responses in mice and the vaccine-induced polyclonal HER2-specific anti-serum mediated receptor internalization and degradation much more effectively than trastuzumab. Our in vitro studies demonstrated that HER2-vaccine induced antibodies effectively caused a decrease in HER2 expression, but when combined with lapatinib caused significant inhibition of HER2 signaling, decreased pERK and pAKT levels, and reduced breast tumor cell proliferation. In addition, a known mechanism of resistance to lapatinib, induction of survivin, was inhibited. The combination of Ad-HER2-ki plus lapatinib also showed superior anti-tumor efficacy in vivo. Based on these results, we feel clinical studies using this approach to target HER2-overexpressing breast cancer, including trastuzumab- and lapatinib-resistant tumors is warranted. (c) 2009 UICC.
PMID: 19856307