The present disclosure pertains to filtration methods comprising: passing a first fluid that comprises cells, cell debris and targeted product produced by the cells through a first filter thereby separating the first fluid into a first retentate comprising cells and a first permeate comprising targeted product and cell debris; combining resin beads having affinity for targeted product with the first permeate to form a second fluid containing resin beads with bound target product and cell debris; passing the second fluid through a second filter thereby separating the second fluid into a second retentate comprising resin beads with bound target product and a second permeate comprising cell debris; combining an elution buffer with the second retentate to form a third fluid that comprises a mixture of resin beads and unbound targeted product; and passing the third fluid through a third filter thereby separating resin beads from targeted product.