Continuous manufacturing process for bispecific antibody products

A continuous upstream manufacturing process for the production of a bispecific antibody product comprising at least a first and a second binding domain, wherein the first binding domain binds to a different target than the second binding domain, wherein the bispecific antibody product is a non-full length bispecific antibody construct, and wherein the bispecific antibody product is a bispecific T-cell engager antibody construct, the process comprising the steps, in order, of:

• (i) providing a liquid cell culture medium comprising at least one mammalian cell culture in a perfusion bioreactor, wherein the mammalian cell culture is expressing the bispecific antibody product, and wherein the cells have a concentration of at least 0.4×106 cells/mL at inoculation in the perfusion bioreactor,
• (ii) growing the mammalian cell culture by applying a perfusion rate (D) to exchange the liquid cell culture medium in a continuous manner, without removing the cells from bioreactor, wherein the perfusion rate initially corresponds to at least 0.4 vessel volume per day (vvd) and is then increased continuously, gradually or incrementally to at least 2 vvd reaching a biomass set-point, wherein the biomass set-point equals to a viable cell density (VCD) of at least 35×106 cells/mL,
• (iii) maintaining perfusion culture by applying the perfusion rate (D) to continuously or incrementally exchange the liquid cell culture medium, wherein the perfusion rate in step (iii) is in the range from 2 to 6.4 vvd, and wherein the perfusion rate (D) is a cell-specific perfusion rate (CSPR) in the range of 0.01 to 0.15 nL per cell per day (nL/cell/day), and
• (iv) bleeding extra cells from the bioreactor to maintain the biomass set-point, wherein the bispecific antibody product concentration in the bioreactor is kept below 0.3 g/L by continuously harvesting the bispecific antibody product from the liquid cell culture medium throughout steps (ii) to (iv).