Recent clinical trials have demonstrated that advanced melanoma can be treated with a combination of nonmyeloablative chemotherapy and autologous adoptive T cell immunotherapy ?:AIT?;to achieve a 50% clinical response rate. Such clinical responses are not, however, consistently durable. Cytotoxic T cells ?:CTL?;are shortlived in the absence of T cell help ?:Th?;, with limited persistence after infusion. Furthermore, antigen ?:Ag?;negative variants develop after infusion of CD8?E predominant tumor specific T cell lines, suggesting tumors readily escape from focused therapy. Our goal is to optimize and extend AIT to advanced breast cancer by providing functionally characterized, tumor Ag-specific CD4?E Th1 cells as a central component of the infused product. Tumor Ag-specific CD4?E Th1 cells can home to tumor and secrete inflammatory cytokines, modulating the microenvironment to enhance the function of local antigen presenting cells ?:APC?;. The resultant increased processing of endogenous tumor cells results in epitope spreading. By providing a robust CD4?E Th1 immune response, tumor Ag-specific CD8?E T cells will be elicited, and the response generated will be long lived.
We aim to promote tumor-specific, epitope spreading, Th1-type CD4?E responses as an essential component of effective AIT. This strategy has been validated by our own vaccine trials for Stage III/IV patients with HER-2/neu ?:HER2?;- overexpressing breast cancer. Patients vaccinated with MHC Class II-binding HER2-derived peptides evidenced a significant survival advantage if they achieved not only enhanced CD4?E T cell responses to vaccine peptides, but also T cell responses to additional HER2 epitopes expressed by their tumors but absent from the vaccine. In animal studies we observe that the inclusion of autologous dendritic cells ?:DCs?;during T cell culture can markedly improve T cell therapeutic performance at the time of re-infusion. Moreover, appropriately activated DCs can promote the expansion of T cells with higher functional avidity, including CD8?E cytolytic T cells that can directly lyse MHC-restricted tumors. We propose to develop a clinically relevant method to expand HER2 specific T cells ex vivo, using optimally activated autologous DC generated simultaneously in the same cultures as the T cells to be activated. ompared to pre-culture or to culture without IL-12, we calculate that this degree of enrichment may still remain suboptimal for purposes of AIT. We hypothesize that maximal therapeutic responses to AIT will occur after T cell propagation is optimized to (1) provide dually T1- and T17-biased CD4+ and CD8+ T cell responses;(2) maximize Ag-specific proliferation and frequency;(3) enhance T functional cell avidity for tumor targets;and (4) preserve and amplify intramolecular and intermolecular epitope spreading which had already occurred in patients during the prior vaccination.
Our aims are as follows: A.1. We will investigate the mechanisms by which natural DC constituents within PBMC cultures can be activated to optimize propagation of HER2-specific T cells for AIT. Our Preliminary Data demonstrate that timely culture-activation of IL12p70-producing DC precursors can tremendously enhance the Ag-specific proliferation of CD4+ and CD8+ T cells to recall Ags. We have also demonstrated that such IL-12 induction allows the generation of higher avidity T1-type T cells even against tolerogenic self-Ags such as HEthe co-propagation of CD4+ T cells during CD8+ CTL expansion.3 This advance was predicted by many prior animal and clinical AIT studies which had demonstrated the limited efficacy of CD8+ CTLs in the absence of CD4+ T cells, even when combined with nonmyeloablative chemotherapy and IL-2.3-9 Moreover, we and others recently observed that AIT which includes Ag-specific IL-17 secreting (Th17) CD4+ T cetients'extended survival, and that such epitope spreading can be further propagated in vitro by optimizing DC Ag-presenting function within PBMC cultures. Since these epitopes may also be expressed by HER2neg breast cancers, these investigations may provide novel immune targets relevant to HER2neg patients as well. Work under each Aim has been accelerated to achieve important benchmarks within a 2 year timeframe of stimulus funding: To accomplish these goals within the condensed 2 year timeframe and within budget, subaim 1.2 will be performed using newly leukapheresed vaccinated patient PBMCs rather than archived samples, facilitating coordination with subaim 1.3, and the number of clones screened under Subaim 2.1 may be reduced by up to 25%. We still anticipate that IND preparation will be initiated at the end of the 2 year funding period. The submitted 2 year budget will result in the hiring of a new research scientist (UW), a new post-doctoral fellow (Mayo), and a new technologist (Mayo). It will also provide increased hours of employment for a project scientist (UW). Furthermore, the new technology which will be developed and optimized for clinical use has a major potential to create additional jobs as it evolves into a standard of care. We already have many elements of this work in promising clinical trials. We therefore believe that this 2 year proposal is consonant with Recovery Act goals by promoting job creation, economic development, and accelerating the pace and achievement of scientific research.
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