More than ten years ago, the first multispecific antibody drug entered the market. Now, these advanced treatments are gaining popularity as researchers and investors embrace the idea that targeting multiple disease pathways at once could be more effective for conditions like cancer and autoimmune disorders. Unlike traditional monoclonal antibodies, which target a single site, these newer drugs—including bispecifics and other multi-targeted therapies—can attack two or more sites simultaneously. The first bispecific therapy, Blincyto by Amgen, was approved by the FDA in 2014. Since then, over a dozen similar drugs have been approved, with even more complex “tri-specific” and higher-order multispecific antibodies (msAbs) in development. These next-generation treatments are attracting attention due to promising clinical results, improved safety, and better drug performance, according to a report by Back Bay Life Science Advisors. Two major success stories so far are Genentech’s Hemlibra, used for hemophilia, and Vabysmo, which treats eye diseases. However, many more are expected to reach blockbuster status—generating over a billion dollars in sales—by 2030, says Peter Bak, a managing director at Back Bay and co-author of the report. While most approved msAbs are for cancer, there’s a growing shift toward autoimmune diseases, partly due to encouraging early results from cell therapies. The market for msAbs is expanding rapidly, with 250 candidates in clinical trials, 24 of which are in late-stage testing. As of August 2025, the FDA has approved 14 msAbs, with eight of those approvals happening since 2023. Seven cancer-fighting msAbs are on track to become blockbusters by 2030. Researchers are particularly excited about lupus, where promising data has led companies to rethink their strategies. Some believe that T cell engagers—drugs that direct immune cells to attack cancer—could also be used to control overactive immune cells in autoimmune diseases. The hope is that these treatments will work similarly to CAR-T therapies but at a lower cost, making them more accessible. In some cases, msAbs could help patients who didn’t respond to other treatments. For conditions like lupus, where treatment options are limited, msAbs could become a first-line biologic therapy. This growing opportunity has attracted significant investment. In the first half of 2025, companies developing msAbs for autoimmune diseases raised $269 million more than those focusing on cancer. Deal-making has also increased, with nearly as many transactions involving msAbs as those for antibody-drug conjugates—a popular alternative approach. Several companies are testing msAbs for autoimmune conditions. Roche’s Lunsumio, already approved for lymphoma, recently completed early trials for lupus. Amgen is testing Blincyto in phase 2 trials for lupus with kidney involvement and severe rheumatoid arthritis. Cullinan Therapeutics is also testing a bispecific T-cell engager in phase 1 trials for lupus and rheumatoid arthritis, with early results expected in early 2026. Another promising candidate is MoonLake Immunotherapeutics’ bispecific drug targeting IL-17, which is in late-stage trials for hidradenitis suppurativa, a chronic skin condition. If successful, the company could seek FDA approval in mid-2026. While autoimmune research is accelerating, cancer treatments remain a key focus, including ivonescimab, a potential rival to Keytruda, developed by China-based Akeso and licensed to Summit Therapeutics. Companies are also exploring msAbs for neurological diseases, neurodegenerative conditions, and solid tumors. However, challenges remain, including manufacturing hurdles and proving that msAbs are better than other emerging treatments like radiopharmaceuticals, protein degraders, and cell therapies. In cancer, msAbs are already proving their value, with researchers optimizing dosing and delivery. For autoimmune diseases, it’s a race to bring these treatments to market as quickly as possible.