Recently, the metabotropic glutamate receptor-1 (mGluR1) was shown to be a promising target for cancer therapy. At Erasmus MC, we hold a plasma sample of a unique ataxia patient with anti-mGluR1 antibodies that can block the receptor. These fully human antibodies provide a great opportunity for anti-cancer treatments because they are of very high affinity and because they have a minimal chance to evoke an anti-drug response during therapy. At present it is not possible to deduce the full length sequence of antibodies from plasma. In this project a novel mass spectrometry based antibody-sequencing pipeline will be developed to recover the amino acid sequence from antibodies in plasma.