Alphamab Oncology shares closed at HK$13.50 apiece, up 32.4% from their issue price of HK$10.20 per share on Dec. 12, their first day of trading in Hong Kong.
Analysts said the stock's gains could be attributed to investor confidence in the company's drug development pipeline.
The Suzhou, China-based drugmaker sold 179,403,000 shares to raise approximately HK$ 1.71 billion, after deducting underwriting fees and commissions and expenses.
Alphamab had previously planned to price its stock between HK$9.10 and HK$10.20 apiece, according to the company's filing to the Hong Kong stock exchange in December.
The company is listed under a revised biotech IPO scheme, which allows early-stage biotech companies that have not generated any profit to list on the Hong Kong stock exchange.
The public debut gains suggest investors are confident the company has strong research and development capabilities, Ke Yan, Singapore-based co-head of research at Aequitas Research, said.
Alphamab has eight cancer drug candidates in its pipeline, with four undergoing clinical studies.
Its lead drug candidate, KN046, belongs to a class of drugs known as bispecific monoclonal antibody, which is a type of protein that can bind to two different types of foreign elements and trigger an immune response in the body.
The intravenous therapy is currently undergoing phase 2 trials for non-small cell lung cancer, esophagus cancer and breast cancer, as a sole therapy and as a combination treatment with chemotherapy or other drugs.
So far, there are no bispecific antibody drugs in the market targeting solid tumors such as lung or liver cancer, Ke said, adding that very few drugmakers have succeeded in bringing bispecific antibody therapies to mid-stage clinical trials.
KN046 aims to treat cancer by boosting the body's immune system through targeting PD-L1, a protein found on some cancer cells, and CTLA-4, a protein found on some T cells, a type of immune cell.
Shanghai-based Macquarie Research analyst Gao Xiang also said Alphamab is one of the few Chinese companies with a research platform to test various bispecific antibody candidates.
He added that bispecific antibody is a hot research area in the hunt to find new and more powerful cancer drugs.
Alphamab plans to submit a marketing application for KN046 in 2021 as a third or fourth-line therapy for nasopharyngeal carcinoma, a rare type of head and neck cancer, which means the drug may be used after other treatments fail.
The company is also developing a subcutaneously injectable PD-L1 drug KN035 in collaboration with Shanghai-based 3DMed. The two companies plan to file a marketing application for this therapy in 2020.
Net proceeds from the offering will be used for key drug development programs, building new manufacturing and research facilities in Suzhou, working capital as well as general corporate purposes.
The company's research and development expenses totaled 55.75 million yuan for the first six months of 2019, compared to 26.58 million yuan for the same period in 2018.
Morgan Stanley Asia Ltd., CLSA Capital Markets Ltd. and Jefferies Hong Kong Ltd. acted as joint sponsors for the offering.
As of Dec. 11, US$1 was equivalent to about 7.04 Chinese yuan.