4. Conclusions
The end-to-end continuous process
for mAb purification reported in this study has upstream and downstream
steps with pool-less direct connections and a low pH inactivation step
with automated pH adjustment performed in batch mode, which serves as a
batch demarcation and also allows for feed adjustment before and after
the low pH inactivation step. These characteristic properties make the
process amenable for continuous mAb production. Furthermore, the mAb
production experiment by the scale-down model of this report confirmed
that this continuous process results in high productivity and high
purity of mAb. The mAb was highly purified by the total flow-through
integrated polishing process in which two columns (AEX and CEX) were
directly connected to the virus filter. As a result, even with a
filtration throughput of about 1000 L/m2, filtration
pressure increases on the virus filter were extremely small,
demonstrating that high purification and extremely stable virus
filtration can be realized in the end-to-end continuous process for mAb
purification.
Regarding virus reduction, both the flow-through two column
chromatography and the virus filter showed robust virus removability for
the total flow-through integrated polishing process. While virus
filtration is usually carried out by constant pressure filtration and is
not easily incorporated into a continuous process, the hollow fiber type
virus filters tested in this study showed high virus reduction even at
very low flux and with a process pause that may be observed in
continuous processing. For very low flux of 1.5 LMH and a condition with
process pause of 60 min, both Planova BioEX and S20N showed virus LRV of
> 4, indicating that these hollow fiber type virus filters
are highly applicable for the continuous process with high filterability
and robust virus removability.