Viral contamination in biologic manufacture and implications for emerging therapies

May combine two claims.

Current best practice relies on three pillars: selection of appropriate starting and raw materials with a low risk of adventitious virus; testing of cell banks and in-process materials to ensure they are free from detectable viruses; and incorporation of steps to remove and inactivate potential undetected adventitious and endogenous viral contaminants during purification.

“The lessons of the past have led to the current best practice, which relies on three pillars: the selection of appropriate starting and raw materials with a low risk of containing adventitious virus; testing of cell banks and in process materials to ensure they are free from detectable viruses; and finally, the incorporation of steps to remove and inactivate potential undetected adventitious and”

• cites [9] International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use. Q5A(R1). Viral Safety Evaluation Of Biotechnology Products Derived From Cell Lines Of Human Or Animal Origin (International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use, 1999).Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites [13] Grillberger, L., Kreil, T. R., Nasr, S. & Reiter, M. Emerging trends in plasma-free manufacturing of recombinant protein therapeutics expressed in mammalian cells. Biotechnol. J. 4, 186–201 (2009). sourcePartly supported

  Split into 3 atoms — 0 confirmed, 1 partially supported, 0 disputed, 0 misattributed, 2 unverifiable. Expand the claim to see per-atom verdicts.

  Experimental — accuracy not yet measured
• cites [14] Kozlowski, S. & Swann, P. Current and future issues in the manufacturing and development of monoclonal antibodies. Adv. Drug Deliv. Rev. 58, 707–722 (2006). sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

At the end of Q3 2019, more than 1,052 advanced therapy medicinal products (ATMPs) were being tested in phase I-III clinical trials and several cell and gene therapies had received regulatory approval.

“At the end of Q3, 2019, more than 1,052 advanced therapy medicinal products (ATMPs) were being tested in phase I-III clinical trials (https://alliancerm.org/publication/q3-2019-data-report/) and several cell 45 and gene 46 therapies had received regulatory approval.”

• cites https://alliancerm.org/publication/q3-2019-data-report/Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites [45] Murphy, M., Quesada, G. M. & Chen, D. Effectiveness of mouse minute virus inactivation by high temperature short time treatment technology: a statistical assessment. Biologicals 39, 438–443 (2011). sourceNot checked — no full text of the source
• cites [46] Meunier, S. M., Sasges, M. R. & Aucoin, M. G. Evaluating ultraviolet sensitivity of adventitious agents in biopharmaceutical manufacturing. J. Ind. Microbiol. Biotechnol. 44, 893–909 (2017). sourceCould not verify

  The citation is attached to the statement that cell therapies had received regulatory approval; the Q3 2019 trial count is attributed to a separate URL. The Introduction and Discussion and conclusions address contamination and UV disinfection in biopharmaceutical manufacturing, not approvals of cell therapies. Searches for approved cell therapies and regulatory approval found no supporting passage in our copy. (LLM, conf=0.76)

  Experimental — accuracy not yet measured

May combine two claims.

Four of the five viruses found to contaminate human and primate cell lines are known to be pathogenic in humans, whereas only one of the viruses found to contaminate CHO cell culture has been reported to cause disease in humans.

“In terms of safety implications, four (herpesvirus, human adenovirus type 1, parainfluenza virus type 3, and reovirus type 3) of the five viruses found to contaminate human and primate cell lines are known to be pathogenic in humans, whereas only one (Cache Valley virus) of the viruses found to contaminate CHO cell culture has been reported to cause disease in humans 36,37 .”

• cites [36] Anonymous. A united front. Nature 472, 389–390 (2011).Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites [37] Campbell, G. L. et al. Second human case of Cache Valley virus disease. Emerg. Infect. Dis. 12, 854–856 (2006). sourcePartly supported

  The Conclusions report a fatal, culture-confirmed case of Cache Valley virus encephalitis in a human, supporting the claim that this virus can cause human disease. The paper does not establish that Cache Valley virus contaminated CHO cell culture, that it was the only such contaminant reported to cause human disease, or the comparison with viruses contaminating human and primate cell lines. (LLM, conf=0.86)

  Experimental — accuracy not yet measured

May combine two claims.

Animal-derived raw materials, especially serum, carry a relatively higher risk of being contaminated with virus and are thus being replaced where possible throughout the industry.

“Animal-derived raw materials (ADRMs), especially serum, carry a relatively higher risk of being contaminated with virus and are thus being replaced where possible throughout the industry 1,9,13 .”

• cites [1] Merten, O. W. Virus contaminations of cell cultures — a biotechnological view. Cytotechnology 39, 91–116 (2002). sourcePartly supported

  The paper's introductory overview identifies contaminated raw materials as a route by which cell cultures acquire viruses, and its references include reports of viral contamination in calf serum. The passages retrieved do not establish that animal-derived materials pose a relatively higher risk than alternatives or that they are being replaced throughout the industry. (LLM, conf=0.73)

  Experimental — accuracy not yet measured
• cites [9] International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use. Q5A(R1). Viral Safety Evaluation Of Biotechnology Products Derived From Cell Lines Of Human Or Animal Origin (International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use, 1999).Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites [13] Grillberger, L., Kreil, T. R., Nasr, S. & Reiter, M. Emerging trends in plasma-free manufacturing of recombinant protein therapeutics expressed in mammalian cells. Biotechnol. J. 4, 186–201 (2009). sourceSupported

Probably not a substantial claim: may not pass S3 (load-bearing).

For recombinant viruses, master virus banks (MVBs) are generated and thoroughly characterized for contamination by adventitious viruses.

“For recombinant viruses, master virus banks (MVBs) are generated and thoroughly characterized for contamination by adventitious viruses 52 .”

• cites [52] Shukla, A. A. & Aranha, H. Viral clearance for biopharmaceutical downstream processes. Pharm. Bioprocess. 3, 127–138 (2015). sourcePartly supported

  The risk-assessment discussion (p. 128) says master and working cell banks are extensively tested for viral contamination. It does not say that master virus banks are generated or characterized for recombinant viruses; cell banks and virus banks are distinct. (LLM, conf=0.78)

  Experimental — accuracy not yet measured

Probably not a substantial claim: may not pass S3 (load-bearing).

HTS of viral RNA has been used to demonstrate a virus is biologically active.

“Additionally, determining if the contaminant identified in a nucleic acid based assay is biologically active may require a different method, though we would note that HTS of viral RNA has been used to demonstrate a virus is biologically active 61 .”

• cites [61] Miki, H. & Takagi, M. Design of serum-free medium for suspension culture of CHO cells on the basis of general commercial media. Cytotechnology 67, 689–697 (2015). sourceCould not verify

  The Cells and Discussion sections describe CHO cell culture and growth, not viral testing. Searches of our full-text copy for HTS of viral RNA and high-throughput sequencing of viral contaminants found no passage addressing whether viral RNA sequencing can demonstrate biological activity. No page numbers were available in the indexed passages. (LLM, conf=0.78)

  Experimental — accuracy not yet measured

May combine two claims.

For GMP production, five of eight cell cultures preceding the reactor were originally identified as contaminated; one of six concurrent seed trains and no concurrent cell cultures for different products were also found to be contaminated.

“For GMP production, five of eight cell cultures preceding the reactor were originally identified as contaminated; one of six concurrent seed trains and no concurrent cell cultures for different products were also found to be contaminated.”

May combine two claims.

The IVV assay was negative in four events and the contamination was detected by using another method.

“Despite this, the IVV assay was negative in four events and the contamination was detected by using another method (Table 3).”

May combine two claims.

Viral contaminations have been reported to lead to manufacturing interruptions with a median plant downtime of one to two months, loss of revenue, discarded batches, lawsuits against the company, a decrease in company reputation as reflected in stock value, and significant delays in product development.

“Further, viral contaminations have been reported to lead to manufacturing interruptions (with a median plant downtime of one to two months, Fig. 3), loss of revenue, discarded batches, lawsuits against the company, a decrease in company reputation as reflected in stock value, as well as significant delays in product development.”

May combine two claims.

Nine out of the 20 responding companies reported having one or more adventitious virus contaminations in mammalian cell culture operations since 1985, totaling 18 virus contamination events reported to the CAACB.

“Nine out of the 20 responding companies (i.e., almost half of the involved industry respondents), reported having one or more adventitious virus contaminations in mammalian cell culture operations since 1985, totaling 18 virus contamination events reported to the CAACB.”

• AssumptionRests on an assumption: The CAACB member-reported contamination events are comprehensive and representative of virus contaminations in mammalian cell culture biomanufacturing.

May combine two claims.

The authors are aware of only 26 virus contaminations over the past 36 years, 18 of which were reported directly as part of this study.

“These events are rare; we are aware of only 26 virus contaminations over the past 36 years (Table 1) [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] , 18 of which were reported directly as a part of this study.”

• cites [18] Burstyn, D. G. Contamination of genetically engineered Chinese hamster ovary cells. Dev. Biol. Stand. 88, 199–203 (1996).Not checked — no full text of the source
• cites [19] Rabenau, H. et al. Contamination of genetically engineered CHO-cells by epizootic haemorrhagic disease virus (EHDV). Biologicals 21, 207–214 (1993). sourceNot checked — no full text of the source
• cites [20] Garnick, R. L. Experience with viral contamination in cell culture. Dev. Biol. Stand. 88, 49–56 (1996).Not checked — no full text of the source

May combine two claims.

The number of contaminations reported to the CAACB per company does not correlate with total manufacturing volume, implying that a combination of circumstance, manufacturing controls in place, and prior lack of virus contamination disclosures may have contributed to this rate.

“However, the number of contaminations reported to the CAACB per company does not correlate with total manufacturing volume, implying that a combination of circumstance, manufacturing controls in place, and prior lack of virus contamination disclosures may have contributed to this rate.”

May combine two claims.

Only after the viral load was increased to a detectable level, through concentration or biological amplification, was the virus detected in the raw material, and then only in three events.

“Only after the viral load was increased to a detectable level, through concentration or biological amplification, was the virus detected in the raw material, and then only in three events (Fig. 1).”

May combine two claims.

Despite raw materials being determined to be the most likely source of contamination in 11 events, testing those raw materials did not necessarily detect the contaminating virus.

“Despite the fact that raw materials were determined to be the most likely source of the contamination in 11 events, testing those raw materials did not necessarily detect the contaminating virus.”

May combine two claims.

For human and primate cell lines, the manufacturing operators or the cell line itself were suspected to be the source of contamination.

“In comparison, for the human and primate cell lines, the manufacturing operators or cell line itself were suspected to be the source.”

May combine two claims.

The reported virus contaminations occurred at all stages of the product life-cycle, with three events during pre-clinical non-GMP manufacture, two during clinical cGMP manufacture, and the remaining 13 during commercial manufacture.

“The reported virus contaminations occurred at all stages of the product life-cycle, with three events occurring during pre-clinical non-GMP manufacture, two during clinical cGMP manufacture, and the remaining 13 occurring during commercial manufacture.”

May combine two claims.

Of the 20 companies completing the CAACB virus contamination survey, 45% of respondents had reported experiencing at least one virus contamination event between 1985 and 2018, which is higher than expected when the study began.

“Of the 20 companies completing the CAACB virus contamination survey, 45% of respondents had reported experiencing at least one virus contamination event between 1985 and 2018, which is higher than expected when the study began.”

May combine two claims.

In two events, there was no apparent change in cell culture performance and the contaminating virus was only detected by a virus-specific PCR assay.

“However, in two events, there was no apparent change in cell culture performance and the contaminating virus was only detected by a virusspecific PCR assay.”

May combine two claims.

Because of the current approach, recombinant DNA-produced therapeutic proteins have been safe for over 35 years, and to the authors' knowledge there has been no transmission of a contaminating virus to a patient from such a product.

“Because of this approach, these products have been safe for over 35 years, and to our knowledge, there has been no transmission of a contaminating virus to a patient from a therapeutic protein produced using recombinant DNA technology.”

• AssumptionRests on an assumption: The safety record of recombinant DNA-produced therapeutic proteins is due to the current three-pillar safety approach rather than to other factors.

May combine two claims.

The expense of investigating a contamination, as reported to the CAACB, was in the $1-10 million range, but in the worst cases the cost of investigating a contamination, implementing corrective actions, decontaminating the facility, and other ancillary costs could be in the hundreds of millions.

“The expense of such an investigation, as reported to the CAACB, was in the $1-10 million range, but in the worst cases the cost of investigating a contamination, implementing corrective actions, decontaminating the facility, and other ancillary costs could be in the hundreds of millions.”

May combine two claims.

In 67% of reported events, the manufacturing platform was Chinese hamster ovary (CHO) cells, whereas the other 33% of events involved human or primate cell lines.

“In 67% of reported events, the manufacturing platform was Chinese hamster ovary (CHO) cells, whereas the other 33% of events involved human or primate cell lines.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

When a viral contaminant matched a PCR target, this was effective at preventing contamination of the entire manufacturing facility.

“When a viral contaminant matched a PCR target, this was effective at preventing contamination of the entire manufacturing facility.”

May combine two claims.

In the other eight contamination events, virus testing of raw materials was negative and the source of the contamination was only identified using indirect evidence.

“In the other eight contamination events, virus testing of raw materials was negative and the source of the contamination was only identified using indirect evidence.”

• AssumptionRests on an assumption: Source attributions based on indirect evidence correctly identify the raw material as the source of contamination.

Probably not a substantial claim: may not pass S4 (based). May combine two claims.

In all cases reported to the CAACB, no drug substance produced from a contaminated cell culture was ever released for human use, and all such drug substance was subsequently destroyed.

“It is important to note that in all cases reported to the CAACB no drug substance produced from a contaminated cell culture was ever released for human use, and all such drug substance was subsequently destroyed.”

May combine two claims.

The control of raw materials by direct testing had limited value, either due to virus concentrations in the raw material being below the assay detection limit, or because the contaminating virus was not homogeneously distributed in the raw material.

“Our study showed that the control of raw materials by direct testing had limited value (Fig. 1), either due to virus concentrations in the raw material being below the assay detection limit, or because the contaminating virus was not homogeneously distributed in the raw material.”

• cites Fig. 1Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

The CAACB study has identified five viruses that have been shown to contaminate CHO cell culture, and four viruses that have contaminated cell culture with human or primate cells.

“The CAACB study has identified five viruses that have been shown to contaminate CHO cell culture, and four viruses that have contaminated cell culture with human or primate cells.”

• cites Table 2Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

For 7 events, the contamination was contained in the cell culture, for 6 events the contamination was spread to downstream purification operations, and for 5 events the extent of contamination was unknown.

“Reovirus / Unknown 34 events, the contamination was contained in the cell culture, for 6 events the contamination was spread to downstream purification operations, and for 5 events the extent of contamination was unknown.”

• cites Fig. 2Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Probably not a substantial claim: may not pass S4 (based).

The work presented here represents the first comprehensive collection and analysis of previously unpublished industry wide viral contamination information.

“Whereas learning from these events has historically been a challenge, the work presented here represents the first comprehensive collection and analysis of previously unpublished industry wide viral contamination information.”

May combine two claims.

Despite the excellent safety record, viral infection of mammalian cell culture is a real risk with severe consequences.

“Despite this excellent safety record, viral infection of mammalian cell culture is a real risk with severe consequences.”

May combine two claims.

Poliovirus vaccine was contaminated with Simian Virus 40 (SV40), and the health impacts of that contamination were not fully known for many decades.

“This included the contamination of poliovirus vaccine with Simian Virus 40 (SV40) 3 , for which the health impacts were not fully known for many decades 4 .”

• cites [3] Shah, K. & Nathanson, N. Human exposure to SV40: review and comment. Am. J. Epidemiol. 103, 1–12 (1976). sourceNot checked — no full text of the source
• cites [4] Stratton, K., Alamario, D. A. & McCormick, M. C. Immunization Safety Review: SV40 Contamination of Polio Vaccine and Cancer. (National Academies Press, Washington, DC, 2003).Not checked — no full text of the source

May combine two claims.

Different host cells may require the consideration and management of different virus contamination risks, with human and primate cell lines being more susceptible to contamination from operators.

“The implication is that different host cells may require the consideration and management of different virus contamination risks, with human and primate cell lines being more susceptible to contamination from operators.”

May combine two claims.

Current manufacturing controls used to prevent the spread of a potential contaminant within manufacturing facilities are effective, as no cross-contamination of other concurrent manufacturing operations was reported.

“Data collected as a part of the CAACB study indicate that current manufacturing controls used to prevent the spread of a potential contaminant within manufacturing facilities are effective as no cross-contamination of other concurrent manufacturing operations was reported.”

• AssumptionRests on an assumption: The absence of reported cross-contamination in the CAACB data indicates that cross-contamination controls are effective.

May combine two claims.

CHO cells are the most commonly used host cells by the recombinant biologic industry, with published reports indicating that approximately 70% of approved biotech products are manufactured using CHO.

“This result is not unexpected as CHO cells are the most commonly used host cells by the recombinant biologic-industry with published reports indicating that approximately 70% of approved biotech products are manufactured using CHO 12 .”

• cites [12] Walsh, G. Biopharmaceutical benchmarks 2014. Nat. Biotechnol. 32, 992–1000 (2014). sourceNot checked — no full text of the source

May combine two claims.

The IVV assay takes 14 to 28 days, which is much too long to assess the reactor for contamination prior to processing downstream for purification.

“The IVV assay also takes 14 to 28 days-much too long to assess the reactor for contamination prior to processing downstream for purification.”

Classified as probably not a substantial claim.

The in vitro virus (IVV) assay is a cell-based assay used to test harvest cell culture samples for potential viral contaminants.

“The in vitro virus (IVV) assay is a cell-based assay used to test harvest cell culture samples for potential viral contaminants 38 .”

• cites [38] Sexton, D. J. et al. Life-threatening Cache Valley virus infection. N. Engl. J. Med. 336, 547–549 (1997). sourceNot checked — no full text of the source

May combine two claims.

Minute virus of mice is especially challenging as a potential contaminant because it is shed from ever-present wild mouse populations, may not be detectable even with established rodent control, and can persist in the environment and in raw materials long after being shed.

“Minute virus of mice is especially challenging as a potential contaminant.It is shed from ever present wild mouse populations, may not be detectable even with established rodent control, and can persist in the environment and in raw materials long after being shed.”

Probably not a substantial claim: may not pass S2 (checkable).

The safety of biologic products should not rely on testing alone, including orthogonal methods, but should be assured by multiple controls including prevention, detection, and viral clearance throughout the process.

“These data imply that the safety of biologic products should not rely on testing alone (including orthogonal methods) but be assured by multiple controls (including prevention, detection, and viral clearance) throughout the process.”

May combine two claims.

For living cell-based therapies, viral clearance would be required to remove or inactivate viruses in the cell culture supernatant and to separate or destroy infected cells from uninfected cells.

“In the case of living cell-based therapies, viral clearance would be required to remove or inactivate viruses in the cell culture supernatant as well as separating or destroying infected cells, which harbor virus, from any cells not infected with virus.”

May combine two claims.

The three main risks for viral contamination in cell culture for therapeutic production are cell sources, materials utilized in cell culture, and exposure of the cell culture process stream to the operator/environment.

“The three main risks for viral contamination in cell culture for therapeutic production are cell sources, materials utilized in cell culture, and exposure of the cell culture process stream to the operator/environment.”

May combine two claims.

Due to the scale of their manufacture, ATMPs may rely much more on open cell culture transfers than recombinant proteins and vaccines, resulting in an increased possibility of virus contamination from open operations for these types of products.

“However, due to the scale of their manufacture, ATMPs may rely much more on open cell culture transfers than recombinant proteins and vaccines.The result is an increased possibility of virus contamination from open operations for these types of products.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Some animal- or human-derived materials may be sensitive to heat, radiation, or UV exposure, which may ultimately affect cell growth and performance.

“Despite the effectiveness of treating raw materials, we note that some animal-or human-derived materials may be sensitive to heat, radiation, or UV exposure, which may ultimately affect cell growth and performance.”

Probably not a substantial claim: may not pass S3 (load-bearing).

New detection technologies, such as high-throughput sequencing (HTS), have detected adventitious viral contaminants in the presence of virus product.

“Additionally, new detection technologies, such as high-throughput sequencing (HTS), have detected adventitious viral contaminants in the presence of virus product 54 and are being explored for use in the industry 55,56 .”

• cites [54] Wirth, T., Parker, N. & Ylä-Herttuala, S. History of gene therapy. Gene 525, 162–169 (2013). sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

Media are filter sterilized before use, typically with 0.1 μm rated sterilizing-grade filters through which most viruses will pass.

“These are filter sterilized before use, typically with 0.1µm rated sterilizing-grade filters through which most viruses will pass.”

May combine two claims.

Tests to assure that autologous cell therapy-derived cells are free of adventitious virus generally cannot be completed prior to initiating cell therapy manufacturing, and the process generally proceeds at risk.

“Tests to assure that the derived cells are free of adventitious virus generally cannot be completed prior to initiating cell therapy manufacturing and the process generally proceeds at risk.”

Probably not a substantial claim: may not pass S4 (based). May combine two claims.

For a previously unknown emerging virus, such as SARS-CoV-2, the capacity of the virus to infect production cell lines or be detected in existing assays is not initially known.

“This is never more true than when faced with a previously unknown emerging virus, such as SARS-CoV-2, where the capacity of the virus to infect production cell lines or be detected in existing assays is not initially known.”

May combine two claims.

Animal-derived and human-derived components, such as serum and growth factors, carry a higher risk of virus contamination than other media components and are commonly added to media for ATMP production.

“Animalderived (Table 2) and human-derived components (e.g., serum, growth factors), which carry a higher risk of virus contamination than other media components 47 , are commonly added to media for ATMP production 48 .”

• cites [47] Mundt, W. et al. Virus filtration of cell culture media. Patent WO2013192009A1 (2003).Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites [48] Mullard, A. Second anticancer CAR T therapy receives FDA approval. Nat. Rev. Drug Discov. 16, 818 (2017). sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S3 (load-bearing).

Developing media formulations that do not require animal- or human-sourced raw materials can be a challenge for some ATMPs, especially those where nutrient requirements are not well understood, such as primary cell cultures, or which may have variable starting cells, such as autologous cell therapies.

“This can be a challenge for some ATMPs, especially those where nutrient requirements are not well understood, such as primary cell cultures, or which may have variable starting cells, such as autologous cell therapies.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Cell culture processes employed for the manufacture of biopharmaceutical products and ATMP products all utilize a variety of basal media formulations comprised of a mixture of more than 50 essential nutrients and other chemicals.

“Cell culture processes employed for the manufacture of biopharmaceutical products and ATMP products all utilize a variety of basal media formulations comprised of a mixture of more than 50 essential nutrients (e.g., amino acids, vitamins, trace elements) and other chemicals.”

Probably not a substantial claim: may not pass S3 (load-bearing).

High-throughput sequencing is seeing widespread interest from the vaccine and recombinant protein industry.

“High-throughput sequencing provides a greater breadth of detection than PCR and is seeing widespread interest from the vaccine and recombinant protein industry 56 .”

• cites [56] US Food and Drug Administration. Guidance for Industry: Characterization and Qualification of Cell Substrates and Other Biological Materials Used in the Production of Viral Vaccines for Infectious Disease Indications (US Food and Drug Administration, 2010).Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Probably not a substantial claim: may not pass S3 (load-bearing).

Viral-vectored gene therapy products utilize plasmids or recombinant viruses to initiate production.

“Viral-vectored gene therapy products utilize plasmids or recombinant viruses to initiate production 51 .”

• cites [51] Brindley, D. A. et al. Peak serum: implications of serum supply for cell therapy manufacturing. Regen. Med. 7, 7–13 (2012). sourceNot checked — no full text of the source

May combine two claims.

Virus-risk mitigation for biopharmaceutical manufacturing uses three complementary approaches: preventing virus entry by selecting low-risk starting and raw materials and utilizing manufacturing controls; testing of in-process materials to ensure they are free of virus and enable lot rejection; and clearance of virus by inactivation and/or removal from the product.

“As noted above, virus-risk mitigation for biopharmaceutical manufacturing uses three complementary approaches: 1) preventing virus entry by selecting low risk starting and raw materials and utilizing manufacturing controls, 2) testing of in process materials to ensure they are free of virus and enable lot rejection and 3) clearance of virus (inactivation and/or removal) from the product 9,14 .”

• cites [9] International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use. Q5A(R1). Viral Safety Evaluation Of Biotechnology Products Derived From Cell Lines Of Human Or Animal Origin (International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use, 1999).Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites [14] Kozlowski, S. & Swann, P. Current and future issues in the manufacturing and development of monoclonal antibodies. Adv. Drug Deliv. Rev. 58, 707–722 (2006). sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S4 (based).

A delay in administering treatment, such as due to contamination of a production process, could negatively impact patients, possibly leading to their death.

“A delay in administering treatment, such as due to contamination of a production process, could negatively impact patients, possibly leading to their death.”

Probably not a substantial claim: may not pass S2 (checkable).

These differential clearance strategies, coupled with an understanding of the most likely viral risks, potential sources of virus, and the host cell line susceptibility to those viruses, could enable the development of a virus removal strategy.

“These differential clearance strategies, coupled with an understanding of the most likely viral risks, potential sources of virus, and the host cell line susceptibility to those viruses, could enable the development of a virus removal strategy.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

ATMP manufacturing is often more challenging for environmental control as there are more open manipulations that provide opportunity to introduce an environmental contaminant and many small lots may be manufactured at once.

“This is often more challenging in ATMP manufacturing as there are more open manipulations that provide opportunity to introduce an environmental contaminant and many small lots may be manufactured at once.”

Probably not a substantial claim: may not pass S3 (load-bearing).

New detection technologies, such as HTS, are being explored for use in the industry.

“Additionally, new detection technologies, such as high-throughput sequencing (HTS), have detected adventitious viral contaminants in the presence of virus product 54 and are being explored for use in the industry 55,56 .”

• cites [55] US Food and Drug Administration. Draft Guidance for Industry: Chemistry, Manufacturing, and Control (CMC) Information for Human Gene Therapy Investigational New Drug Applications (INDs) (US Food and Drug Administration, 2018).Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites [56] US Food and Drug Administration. Guidance for Industry: Characterization and Qualification of Cell Substrates and Other Biological Materials Used in the Production of Viral Vaccines for Infectious Disease Indications (US Food and Drug Administration, 2010).Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Classified as probably not a substantial claim.

Virus contamination during ATMP cell-culture manufacturing processes by environmental sources can be avoided by the use of functionally closed systems, which often employ single-use, disposable equipment.

“Virus contamination during ATMP cell-culture manufacturing processes by environmental sources must be strictly avoided and can be done so by the use of functionally closed systems, which often employ single-use, disposable equipment.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Approaches to develop successful virus tests have been developed and used.

“While challenging to test for adventitious viruses in the presence of recombinant viral stocks, approaches to develop successful virus tests have been developed and used 53 .”

• cites [53] Ye, G. J. et al. Herpes simplex virus clearance during purification of a recombinant adeno-associated virus serotype 1 vector. Hum. Gene Ther. Clin. Dev. 25, 212–217 (2014). sourceNot checked — no full text of the source

May combine two claims.

Current HTS sample preparation approaches and bioinformatic pipelines are not as rapid as PCR and can take 7-10 days.

“However, current HTS sample preparation approaches and bioinformatic pipelines are not as rapid as PCR and can take 7-10 days 55 .”

• cites [55] US Food and Drug Administration. Draft Guidance for Industry: Chemistry, Manufacturing, and Control (CMC) Information for Human Gene Therapy Investigational New Drug Applications (INDs) (US Food and Drug Administration, 2018).Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

Many of the virus clearance unit operations used during purification of therapeutic proteins are not suitable for use with, or have not been widely applied to, ATMPs.

“Many of the virus clearance unit operations used during purification of therapeutic proteins described earlier are not suitable for use with, or have not been widely applied to, ATMPs.”