Steve Pascolo

H-2 class I knockout, HLA-A2.1-transgenic mice: a versatile animal model for preclinical evaluation of antitumor immunotherapeutic strategies.

H‐2 class I‐negative, HLA‐A2.1‐transgenic HHD mice were used for a comparative evaluation of the immunogenicity of HLA‐A2.1‐restricted human tumor‐associated cytotoxic T lymphocyte (CTL) epitopes. A hierarchy was established among these peptides injected into mice in incomplete Freunds adjuvant which correlates globally with their capacity to bind and stabilize HLA‐A2.1 molecules. Co‐injection of a helper peptide enhanced most CTL responses. In contrast, classical HLA class I‐transgenic mice which still express their own class I molecules did not, in most cases, develop HLA‐A2.1‐restricted CTL responses under the same experimental conditions. Different monoepitope immunization strategies of acceptable clinical usage were compared in HHD mice. Recombinant Ty‐virus‐like particles, or DNA encoding epitopes fused to the hepatitis B virus middle envelope protein gave the best results. Using this latter approach and a melanoma‐based polyepitope construct, CTL responses against five distinct epitopes could be elicited simultaneously in a single animal. Thus, HHD mice provide a versatile animal model for preclinical evaluation of peptide‐based cancer immunotherapy.

Novel breast‐tumor‐associated MUC1‐derived peptides: Characterization in Db−/− × β2 microglobulin (β2m) null mice transgenic for a chimeric HLA‐A2.1/Db‐β2 microglobulin single chain

The MUC1 protein was found to be up‐regulated in a spectrum of malignant tumors. T‐cell responses to the MUC1 extracellular tandem repeat array (TRA) were observed in murine models as well as in breast‐carcinoma patients. In the present study, we evaluated the anti‐tumor potential of HLA‐A2.1‐motif‐selected peptides from non‐TRA domains of the molecule. Peptide immunogenicity was examined in the Db−/− × β2 microglobulin (β2m) null mice transgenic for a modified HLA‐A2.1/Db‐β2 microglobulin single chain (HHD mice). Our results show the existence of 3 novel HLA‐A2.1‐restricted MUC1‐derived cytotoxic T‐lymphocyte (CTL) epitopes. These peptides are processed and presented by the HHD‐transfected breast‐tumor cell line MDA‐MB‐157. Moreover, CTL induced by these 3 peptides show higher lysis of target cells pulsed with breast‐carcinoma‐derived peptides than of targets pulsed with normal breast‐tissue‐derived peptides. These data suggest an important role for non‐TRA MUC1‐derived peptides as inducers of a MHC‐restricted CTL reaction to a breast‐carcinoma cell line and patient‐derived tumor extracts. Int. J. Cancer 85:391–397, 2000. ©2000 Wiley‐Liss, Inc.