Human and humanized antibodies for COVID-19 protection and cancer immunotherapy

Abstract

Immunotherapy using human or humanized monoclonal antibodies (mAbs) has broad applications in various disease settings, including infectious disease and cancer. For infectious diseases, the development of specific antibodies is useful for preventing pathogen transmission or conferring therapeutic cure. For malignant cancers, antibody-based blocking agents including humanized mAbs targeting the immune checkpoint molecules have achieved remarkable clinical benefits. Due to issues of emerging infections and diverse types of cancers, I hypothesize that novel human or humanized mAbs can be discovered as potential preventive and/or therapeutic antibody drugs.

The coronavirus disease 2019 (COVID-19), emerged in December 2019, was caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This disease has quickly transformed into a pandemic for more than 18 months. Over 178 million people were infected with more than 3.8 million deaths by the end of June 2021. Many human neutralizing antibodies (HuNAbs) against SARS-CoV-2 were isolated from convalescent patients and have been developed for possible treatment of infected patients. Most HuNAbs were tested to prevent the lungs from SARS-CoV-2 infection when applied either in experimental animals or human trials. Little investigation looking into the efficacy of HuNAbs in suppressing viral replication in the upper respiratory tract (URT). I, therefore, hypothesized that HuNAb-based viral suppression in nasal turbinate is necessary for improving prophylaxis and therapeutic efficacy. To test this hypothesis, I discovered four HuNAbs from Hong Kong patients by the phage display technology. By testing the most potent HuNAb ZDY20 in the golden Syrian hamster model, I found that high viral loads and diffuse nucleocapsid protein (NP) expression were readily detected in the nasal turbinate of infected hamsters regardless ZDY20 intervention at 10mg/kg for either prophylaxis or post-exposure treatment. My findings not only revealed a mechanism underlying thousands of vaccine-breakthrough infections and re-infected cases but also promoted the need of universal masking before completing the population vaccination.

Immune checkpoint inhibitors, such as humanized programmed cell death 1 (PD1)-specific mAbs, have been extensively used for cancer immunotherapy. Besides PD1, one of alternatively spliced isoforms, namely delta42PD1, has been discovered by our group. Moreover, a delta42PD1-specific mAb, CH101 was invented by the hybridoma technology. The immune modulation effect of delta42PD1 has been demonstrated by our previous teammates, which implies delta42PD1 as a potential target for developing therapeutic antibodies. Based on the critical role of PD1 pathway in tumorigenesis of hepatocellular carcinoma (HCC), I hypothesized that blocking delta42PD1 using a humanized version of CH101 may have therapeutic benefits in slowing the progression of HCC. Through antibody engineering, I successfully obtained the first version of fully humanized CH101, namely hufrCH101, at 97.0% humanness by CDR grafting. I also determined the specificity, binding affinity, and sensitivity of hufrCH101 with delta42PD1. Our preliminary in vivo experiments revealed that the HCC progression was partially influenced by the treatment of hufrCH101 through measuring tumor growth and inflammatory cytokines released. I found that the tumor volume was restrained in the antibody treatment group. The findings imply the necessity for further optimization of both hufrCH101 and animal HCC model in future studies.