Abstract Oncolytic viruses (OVs) are an emerging class of bio-therapeutics that have attracted significant interest due to their inherent specificity for targeting malignant tissues in cancer immunotherapy. One of the main challenges in many OVs manufacturing processes is the dead-end sterile filtration step that is highly desirable from a safety and regulatory perspective. The primary issue is the severe membrane fouling, as indicated by a dramatic and uncontrollable transmembrane pressure (TMP) increase in constant flux experiments, and low recovery of the desired final product. While previous studies have mostly focused on selective retention or removal of viruses during the production of smaller biologics, this study is the first to obtain quantitative data for the fouling propensity of microfiltration filters and recovery of viral vectors in a sterile filtration process. The performance of four either 0.2 or 0.22 µm commercial sterile filters was evaluated in constant flux filtration tests with a promising OV candidate (Rhabdovirus Maraba). Among the tested sterile filters, two-layered sterile filters (i.e. Fluorodyne EX EDF and MiniSart Plus) demonstrated slower transmembrane pressure (TMP) increase along with a higher filtered viral volume. For all four filters, the total viral recovery was quite low (less than 25%) – this significant amount of loss of a valuable therapeutic product is of particular concern. These results provide important insights into the development of new sterile filtration membranes and processes that are critically needed for the large-scale production of OVs.

中文翻译：

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溶瘤病毒的无菌过滤：膜形态对污染和产品回收的影响分析

摘要 溶瘤病毒 (OVs) 是一类新兴的生物治疗剂，由于其在癌症免疫治疗中靶向恶性组织的固有特异性而引起了人们极大的兴趣。许多 OV 制造过程中的主要挑战之一是死端无菌过滤步骤，从安全和监管的角度来看，这是非常理想的。主要问题是严重的膜污染，如恒定通量实验中跨膜压 (TMP) 显着且无法控制的增加以及所需最终产品的低回收率所表明的。虽然之前的研究主要集中在较小生物制剂生产过程中病毒的选择性保留或去除，该研究首次获得了微滤过滤器污染倾向和无菌过滤过程中病毒载体回收的定量数据。四个 0.2 或 0.22 µm 商用无菌过滤器的性能在恒定通量过滤测试中使用有希望的 OV 候选物（弹状病毒 Maraba）进行评估。在经过测试的无菌过滤器中，两层无菌过滤器（即 Fluorodyne EX EDF 和 MiniSart Plus）表现出较慢的跨膜压 (TMP) 增加以及更高的过滤病毒量。对于所有四种过滤器，总病毒回收率非常低（低于 25%）——这种有价值的治疗产品的大量损失尤其令人担忧。