TOKYO -- With antibody treatments seen as the best weapon against COVID-19, Japan and the country's top drugmaker have turned to a type derived from the plasma of recovered patients, rather than the lab-made varieties used on U.S. President Donald Trump.
An alliance of companies and health organizations, including Takeda Pharmaceutical is working on an immunoglobulin-based coronavirus treatment, and a Phase 3 clinical trial began in October across multiple countries. Results may become available before the end of the year.
Whereas existing COVID-19 drugs like remdesivir have been repurposed from other diseases, antibody treatments are tailored specifically to the virus that causes COVID-19.
Immunoglobulins are naturally occurring antibodies taken from the plasma of recovered coronavirus patients. By contrast, the monoclonal antibodies being developed by companies such as Eli Lilly and Regeneron Pharmaceuticals are laboratory-made proteins that mimic the body's ability to fight off pathogens.
Immunoglobulins are believed to be highly effective in treating patients.
In the U.S., therapies based on monoclonal antibodies have been granted emergency use authorization to be given to patients under certain circumstances.
The Japanese government appears to envision immunoglobulin-based treatments as an initial option, followed later by the introduction of antibody treatments being developed by Eli Lilly and other drugmakers.
These developers have not conducted clinical trials for such therapies in Japan, mainly because of supply constraints. Many expect Japan to grant fast-track approval to monoclonal antibody treatments once their effectiveness is proven overseas and supply chains are in place.
Many existing coronavirus therapies originally were developed to treat other conditions, like remdesivir for Ebola. Such medications have yielded inconsistent results in coronavirus patients, and countries have adopted varying attitudes regarding their use.
Antibody treatments offer a more targeted treatment.
Nearly 20 antibody treatments are being developed worldwide. The U.S. Food and Drug Administration granted emergency use authorization on Saturday to antibody therapies by Regeneron. Though not an official approval, the products -- the same received by Trump -- now can be used on patients when no other effective treatment is available.
Clinical trials for the Regeneron therapies showed a decrease in the viral load of unhospitalized patients with light to moderate symptoms. When used together, they "were shown to reduce COVID-19-related hospitalization or emergency room visits in patients at high risk for disease progression," the FDA said in its statement.
The FDA also approved Eli Lilly's bamlanivimab for emergency use earlier this month. In the company's Phase 2 trials, just 1.6% of patients who received the drug required hospitalization or treatment in an intensive care unit.
"If you can keep the virus from multiplying inside the patient's body early on, you can minimize the risks of severe symptoms," said Shimane University professor Takeshi Urano.
But more data from antibody clinical trials is needed, and possible side effects are largely unknown. Eli Lilly and Regeneron are still conducting Phase 3 trials after the emergency use authorization.
Producing antibodies takes significant time and effort. Setting up a new production tank -- a necessary step for mass production -- can take one to two years.
Cost is another major concern. Each round of antibody therapy used against illnesses such as cancer can cost tens of thousands of dollars in Japan. Many patients may be unable to afford such treatments even after they receive official approval.
The U.S. has signed a $375 million contract with Eli Lilly for a supply of its experimental antibody treatment, which is expected to be provided for no out-of-pocket costs to patients while it qualifies for emergency use authorization.