Bispecific antibodies are artificial antibodies created by joining two monoclonal antibodies or parts. The resulting antibody can have binding affinities for two or three different epitopes at the same time.
Ambrx - a San Diego-headquartered company who announced earlier this month it would raise capital in an IPO - said in a statement that “Hisun represents a strong strategic partner with the right regulatory and manufacturing expertise.” For the new collaboration, Hisun will have commercial rights to the products in China, while Ambrx will retain commercial rights outside China and will be entitled to receive royalties on sales of the products in China.
Ambrx has developed cell-based systems that can insert non-native amino acids at precisely selected sites in native proteins as they are being made within the cell. “Ambrx’s technology creates bispecific antibodies by manipulation of the conjugation chemistries of the basic 20 amino acids. It has control of where, and at what position, to conjugate the amino acid and the linker,” explained Shivani Singh, analyst with Roots Analysis.
Bispecific development
Jeremy Bender, Chief Business Officer at Sutro, a company which creates bispecifics using a cell-free system, told us bispecifics are well suited to the developed of novel cancer therapeutics because, depending on the specific ligands and epitopes in question, they can allow for better tumour targeting and tumour immunotherapy through the recruitment of T cells to tumour cells. He says Sutro’s platform has the advantage of speed and throughput.
Removab, from Fresenius Biotech and Trion Pharma, is the only bispecific antibody that has gained market approved, but 50 are under development. “Net value of bispecific antibody market is certainly small. Most of the pipeline drugs are currently in phase II trials and are expected to be approved 2015 onwards,” Singh noted.
Drug developers are focused on oncology with 64% of the industry-sponsored drugs indicated for some form of cancer. “This application in oncology is driven by the fact that cancer is a multifactorial disease, which is likely to benefit from bispecific approach. With oncology, bispecific drugs are being developed for both solid tumours as well as blood cancers. However, with 72% share of the oncological pipeline, the focus is firmly on solid tumours,” said Singh, whose company published a report entitled ‘Bispecific Antibody Therapeutics Market, 2013-2023.’
“The biggest weakness that bispecific antibodies face is that of an inefficient purification process during downstream processing. The result is a low yield and an increased cost of purification,” Singh noted.
Other companies developing bispecifics as including Sutro, Trion Pharma, Amgen/Micromet, Genentech/Roche, Covagen, Ablynx, Zymeworks and Xencor.