DNA vaccination controls Her-2+ tumors that are refractory to targeted therapies

Area of Science:

• Oncology
• Immunology
• Cancer Research

Background:

• Emergence of drug-resistant Her-2/neu(+) tumors challenges current therapies.
• Antibody and receptor tyrosine kinase inhibitors face resistance due to tumor heterogeneity.
• Need for alternative strategies to control refractory Her-2/neu(+) mammary tumors.

Purpose of the Study:

• To evaluate active vaccination as a strategy against drug-resistant Her-2/neu(+) tumors.
• To compare drug sensitivity and resistance mechanisms in neu(+) mouse mammary tumor models.
• To determine the efficacy of T-cell-mediated immunity in overcoming therapeutic resistance.

Main Methods:

• Comparison of gefitinib and antibody sensitivity in four neu(+) mouse mammary tumor lines.
• Spectral karyotyping to analyze chromosomal aberrations in drug-resistant tumors.
• Active immunization using plasmids encoding different domains of neu (pneuTM, pcytneu) in BALB/c mice.
• Assessment of antibody and T-cell responses, tumor rejection, and impact of T-cell depletion.

Main Results:

• Drug resistance in Her-2/neu(+) tumors is associated with chromosomal aberrations beyond neu signaling.
• Immunization with pneuTM induced antibody and T-cell responses, rejecting both drug-sensitive and drug-resistant tumors.
• T-cell-dependent rejection was crucial for resistant tumors, while T-cell-independent (antibody) rejection worked for sensitive tumors.
• Immunization with pcytneu, inducing CD8 T cells, led to rejection of all tested tumors, irrespective of drug sensitivity.

Conclusions:

• Cytotoxic T lymphocytes activated by the full neu epitope repertoire are effective against all tested Her-2/neu(+) tumors.
• Active Her-2 vaccination is a promising strategy for controlling both drug-sensitive and drug-resistant tumors.
• This approach warrants further investigation for patients with Her-2-targeted therapy resistance.