This invention relates to a solid phase method of synthesising biomolecule-drug- conjugates. In particular, this invention relates to a solid phase method of synthesising antibody-drug-conjugates (ADCs). This invention also relates to intermediate methods of producing immobilised, chemically modified biomolecules, e.g. antibodies. The invention also relates to various uses of capture resins and to biomolecule-drug-conjugates, intermediate products and compositions of the methods of the invention.
