GLONGHUI, May 22 | Bojian said it has agreed to buy privately held biotechnology company Human Immunology Biosciences (Hi-Bio) at a price of up to 1.8 billion US dollars to strengthen the development of rare disease drugs because demand for its older multiple sclerosis drugs is weak due to increased competition. Hi-Bio's Felzartamab has completed mid-term research on patients with a kidney disease known as primary membranous nephropathy and a disease in which antibodies produced by the immune system damage transplanted organs. The deal included $1.15 billion in advance payments and up to $650 million in potential payments. The two companies said on Wednesday that the deal is expected to close in the third quarter. Hi-bio has received support from biotechnology-focused investors such as Arch Venture Partners and Monograph Capital.