The FDA released draft guidance on developing bispecific antibodies to target multiple disease-modifying molecules with a single drug.

The guidance includes advice on the data needed to gain approval for bispecific antibodies—defined as engineered proteins that can simultaneously bind to two different antigens.

Regulations for fixed-combination prescription drugs don’t apply to bispecific antibodies because they are “single molecules,” the agency says. The antibodies can come in many different formats with unique quality and manufacturing considerations—such as stability and production yields—but their manufacturing processes should generally align with standard practices for monoclonal antibodies, the guidance says.

In certain cases, the agency will request a comparison of the bispecific antibody to an approved monospecific product targeted against the same antigens.