Lung cancer accounts for >25% of cancer-related deaths in both men and women, making it the largestsource of cancer-related mortality. Despite advancements in surgical intervention, radiation, chemotherapy,and immunotherapy, the 5-year survival rate for all types of lung cancer is 19%. The advent of immunecheckpoint inhibitor therapy is associated with remarkable efficacy is some patients with lung cancers, but>75% of patients do not achieve meaningful clinical responses. Currently, T-regulatory (Treg) T cells areregarded as one of the major obstacles to the successful clinical application of tumor immunotherapy. Tregscontribute to the early establishment and progression of tumors, dampen effector cell responses by variousmechanisms, and promote and support pro-tumoral myeloid-derived suppressor cell development andfunction. Tregs are thereby key to the immunosuppressive state of the tumor microenvironment thatprevents effective anti-tumor immune responses. Pre-clinical studies show targeting of Tregs, by theirdepletion or functional modulation, can have significant therapeutic benefit, alone or in combination withother immunomodulatory approaches. We and others have described the significant accumulation ofintratumoral Treg in lung cancer patients, and their increased intratumoral numbers correlate with poorprognosis in many types of cancers.Tregs are defined by their expression of the transcription factor FOXP3, which controls Treg development,stability, and function. FOXP3 is the key element of multiple Treg-associated molecular complexes thatregulate the Treg-specific gene network and mechanisms of Treg-mediated immune regulation. FOXP3 islocated intracellularly, and previous efforts to target Tregs using their CD25 surface marker haveunintentionally co-targeted CD25+ activated T effector cells, causing a lack of robust anti-tumoralefficiency in pre-clinical and clinical studies, along with severe adverse effects and toxicity. On the otherhand, Foxp3-specific depletion of Treg using tumor bearing DEREG transgenic mice, in combination withanti-tumor vaccine therapy, resulted in robust antitumor immunity and an absence of overt autoimmunity.Thus, there is an urgent and unmet need for therapies that can selectively target Treg cells, allowing thebody to mount its normal defenses against the cancer, without negative influences on the rest of the immunesystem.We have developed third generation FANA antisense oligonucleotides (FANA ASOs) that selectivelyinhibit Tregs by knockdown of FOXP3 expression. This next generation of ASO differs from theirpredecessors by chemical modifications that allow their efficient (gymnotic) self-delivery, even to restingcells, and make them resistant to degradation by endogenous nucleases. In preliminary studies, anti-Foxp3FANA ASOs reduced Foxp3 expression and suppressive functions of murine Tregs, and in 50% ofsyngeneic mice bearing lung tumors, daily injection of FANA ASOs showed complete destruction of thetumors as compared to scrambled controls and without overt toxicity. We now propose validation of newlydeveloped human FOXP3 FANAs, alone or in conjunction with anti-PD-1 monoclonal antibody therapy.Aim 1 will assess their ability to knockdown FOXP3 and promote anti-tumor immunity in humanized micein vivo. Aim 2 will evaluate their activity against actual human lung cancer associated Treg cells.
Public Health Relevance Statement: PROJECT NARRATIVE
The goal of this project is to develop a new approach for lung cancer immunotherapy by using chemically
modified antisense oligonucleotides (ASO). Lung cancer survival is significantly affected by the infiltration
of FOXP3+ T-regulatory (Treg) cells into the lung tumor microenvironment, as Tregs strongly suppress
the anti-tumor immune response mediated by CD8+ T-effector (Teff) cells and may also promote resistance
to checkpoint inhibition. Self-delivering FANA ASO targeting the key Treg transcription factor, FOXP3,
offer a means of selectively inhibiting Tregs and thereby restore anti-tumor immunity and treat lung cancer.
We will undertake in vitro and in vivo studies using our newly developed human anti-FOXP3 FANAs,
alone or in conjunction with anti-PD-1 monoclonal antibody, as first steps towards filing an IND
application.
Project Terms: 