Targeting of HPV oncoproteins using novel antibody therapeutics - PROJECT SUMMARY Human papillomaviruses (HPVs) cause a range of anogenital malignancies and are the major drivers of a current head and neck cancer (HNC) epidemic, which is expected to exceed 30,000 annual US cases by 2030. The dependence of HPV+ HNC on the continuous dysregulation of the tumor suppressors p53 and Rb by the viral oncoproteins E6 and E7, respectively, renders these viral proteins ideal therapeutic targets. Of note, the targeting of E6 and E7 oncoprotein expression and/or function has been demonstrated to yield substantial anti-cancer effects. However, clinical therapeutics targeting these indispensable viral proteins are lacking, highlighting the need to evaluate novel approaches to target HPV oncoproteins. Recently, the targeting of mutated oncoproteins with dimeric immunoglobulin A (IgA) molecules was reported to result in mutated oncoprotein expulsion and subsequent growth retardation of epithelial cancers. The anti-tumor effect of oncoprotein-targeting IgA requires the transcytosis of dimeric IgA through the target cell, a process that is initiated by binding to pIGR on the cell surface. Our preliminary data show that the vast majority HPV+ HNC express PIGR, suggesting that IgA-based targeting of viral oncoproteins might be an attractive and innovative treatment avenue for this malignancy. Importantly, we recently pioneered the generation of HPV-specific human monoclonal antibodies (hmAbs) from intratumoral B cells of patients with HPV+ HNC, yielding a unique set of recombinant hmAbs specific for the viral oncoprotein E6. Overall, this puts us in the unique position to generate HPV oncoprotein-targeting dimeric IgA antibodies and assess their anti-cancer activity in HPV+ HNC. Our central hypothesis is that that dimeric IgA molecules targeting the oncoproteins E6 and E7 will efficiently inhibit the growth of HPV+ HNC. Our main objectives in this proposal are (i) to generate HPV E6- and E7-targeting dimeric IgA therapeutics using our recombinant hmAb platform, (ii) to define their anti-tumor activity against various HPV+ HNC cell lines, (iii) to measure the expression of pIGR, the receptor initiating IgA transcytosis, at the protein level in primary HPV+ HNC to determine whether IgA-based treatment approaches could be broadly applicable for the treatment of HPV+ HNC, and (iv) to identify proinflammatory signals that can upregulate pIGR in HPV+ HNC and thus sensitize cancer cells for dimeric IgA therapies. Together, these aims will address whether IgA-based therapeutics can be leveraged to target viral oncoproteins in HPV+ HNC, and will provide the necessary preliminary data for a subsequent R01 application. Overall, our study has thus the potential to guide the development of a new class of HPV-specific therapeutics that would allow for improved and gentler therapies for patients with HPV+ HNC.
