Antibody drug DXP-604 approved to fight coronavirus, expert tells Shanghai forum

Ti Gong

A new neutralizing antibody treatment has been used on 14 COVID-19 patients in Beijing, according to renowned biophysical chemist Xie Xiaoliang, also known as Sunny Xie.

It is widely believed that DXP-593 and DXP-604 are two major SARS-CoV-2 (the virus that causes COVID-19) neutralizing antibody drug candidates. Recently, Xie's lab at Peking University "discovered something we didn't know."

"DXP-604 is actually really good in a special way," the winner of the 2015 Albany Prize in Medicine told the "WLA Panel Session: Reflections on the Pandemic and Public Health."

Experiments show the hyper-contagious Delta strain escaped DXP-593, but not DXP-604, Xie said, giving a summation.

"As a potentially new drug, we discovered DXP-604, a 'full spectrum' SARS-CoV-2 neutralizing antibody, which has not been escaped by current variants, and is less likely to be escaped by further variants."

He revealed that DXP-604 has been approved at Beijing Ditan Hospital for expanded access, also called compassionate use, an option to treat patients with serious diseases or immediately life-threatening conditions with investigational medical products outside of clinical trials when there are no comparable or satisfactory alternatives.

Fourteen patients have received DXP-604, he said, adding that his team is planning to promote it to the world.

Also, the vaccine is another powerful weapon against COVID-19, in particular the third booster dose, Xie told the session.

Ti Gong

"The good news is that vaccines are largely effective. But the bad news is new virus variants keep emerging, which compromises the vaccines' efficiency, causing breakthrough infection cases," he said. "But the efficiency of vaccines can be reinforced by a third booster shot."

He explained with a chart showing the titer of the neutralizing antibodies in vaccinees' blood – the degree of dilution at which more than half of the cells would not be infected. The higher the titer, the stronger the neutralizing power generated by the vaccine.

Experiments show the current Delta variant reduces the effective titer of neutralizing antibodies in the blood after the previous two doses of vaccine, causing breakthrough infections. But the immune memory is still there, and can be awakened by a third booster shot within seven days, he said.

"So, we recommend the best time for the third booster dose is six months after the second dose, and the booster can last for nine months," he added.

The session was held on Wednesday night as part of this year's World Laureates Forum held in Shanghai.

Apart from Xie, Nobel laureates Randy Schekman, Peter Agre, Harvey Alter and Joachim Frank also attended the session. They discussed the spread and prevention of diseases, joint efforts by governments and scientists in the fight against the pandemic, and other challenges to public health.