Method for producing active pharmaceutical ingredient of biopharmaceutical, system for producing active pharmaceutical ingredient of biopharmaceutical, and active pharmaceutical ingredient of biopharmaceutical

A system for producing an active pharmaceutical ingredient of a biopharmaceutical, the system comprising:

• a culture section where a culture step, in which cells are cultured in a culture liquid stored in a culture tank and the cells are removed from the culture liquid using a cell separation filter to obtain a culture supernatant liquid containing a product of the cells, is performed;
• a purification section where a purification step, in which the product is purified from the culture supernatant liquid to obtain an active pharmaceutical ingredient of a biopharmaceutical, is performed, the purification section including a purification step using a purification filter of a single pass tangential flow filtration method;
• a coupling line coupling the culture section and the purification section;
• and
• a sterile filter which is provided in the coupling line, has a pore diameter larger than a pore diameter of the cell separation filter, and filters the culture supernatant liquid flowing from the culture section to the purification section through the coupling line.