Latent Epstein-Barr virus (EBV) infection is associated with nasopharyngeal carcinoma (NPC), whichexpresses the EBV antigens LMP1 and LMP2, both potential targets for immunotherapy. Clinical studies withEBV-specific cytotoxicT cells (EBV-CTLs) in NPC have already yielded promising results, including somecomplete responses, but their efficacy is limited because the EBV-CTL generated by standard methods are1) dominated by T-cell clones not reactive to the EBV proteins LMP1 and LMP2 expressed in NPC, 2)cannot expand significantly after infusion, 3) are sensitive to immune evasion strategies employed by NPCssuch as downregulation of MHC class I expression and the presence of regulatory T cells (Tregs) in thetumor environment, and 4) are dysfunctional in areas of hypoxia within NPC deposits. Our central hypothesisis that overcoming these limitations will enhance the antitumor activity of infused CTLs and improvetreatment outcome. Thus, we will prepare EBV-LMP1 and LMP2-specific CTLs (LMP-CTLs) and evaluatethree strategies to enhance their activity using a clinical trial or a xenograft model.
Aim 1 extends our currentPhase I clinical trials in NPC by combining LMP-CTL with lymphodepleting CD45 monoclonal antibodies toaugment CTL expansion in vivo and improve disease response rates.
In Aim 2, we will express a chimericantigen receptor (CAR) specific for CD70 in LMP-CTLs. CD70 is overexpressed in EBV-positive NPCs, andthe modified CTLs should thus be able to kill NPC cells through both MHC class l-restricted and unrestrictedpathways, increasing their therapeutic effectiveness in our xenograft model. Moreover, we will incorporatesignaling endodomains from costimulatory molecules in the CAR and test whether these modifications makethe CAR-LMP-CTL resistant to Tregs present in NPC.
In Aim 3, we will exploit our previous observationsshowing that expression of the IL-2 gene regulated by the hypoxia inducible factor (HIF-IL2) can render CTLresistant to hypoxia. We will measure cellular persistence, proliferation and function of HIF-IL2 expressingLMP-CTL in hypoxic areas within NPC tumors, and determine, if they produce enhanced antitumor activity.
These aims complement but do not overlap with those in projects 1-3, such that advances emerging from ourresearch could be rapidly assimilated into strategies being tested in other tumors within this program andvice versa. Lav Summary: The body's immune defenses against cancers often fail because themalignancies do not induce or actively inhibit immunity. We will try to counteract these limitations byengineering killer T cells to recognize structures on cancer cells (LMP1 and LMP2) and to resist thedefenses imposed by the tumor cell environment. The effects of the T cells will then be tested in patients withnasopharyngeal carcinoma (NPC).
Showing the most recent 10 out of 217 publications
