Former VP at Thermo Fisher Scientific Inc
- Value proposition and utility of transfection reagents such as PEI (polyethylenimine) in C> (cell and gene therapy) workflows including in the manufacturing of viral vectors and in the transfection of cells
- Pros and cons of chemical transfection vs other transfection or transduction technologies including electroporation, LNPs (lipid nanoparticles), microfluidics and viral vectors
- Different types of transfection reagents and competitive positioning of incumbents including Polyplus, Polysciences, Mirus Bio, Thermo Fisher (NYSE: TMO) and Promega
- Demand outlook for transfection reagents and TAM expansion opportunities
Can you give a brief overview of chemical transfection reagents and what they’re used for? For example, are they used as the main driver of transfection, ie, they open up the membrane of host cells to allow naked DNA to pass through? Are they used to support other transfection methods, eg, to enhance viral transduction or to facilitate electroporation? Or are they used in the creation of viral vectors in the first instance?
My understanding is there are several types of transfection reagent, including PEI [polyethylenimine], Lipofectamine and then calcium phosphate. Can you walk me through the respective applications and relative advantages or disadvantages of those three and any additional transfection reagent you think is particularly important to discuss?
Can you elaborate on what you mean by difficult-to-transfect cell types? While PEI can be used for ex vivo transfection of HEK293 cells for viral vector manufacturing, can PEI not be used to transfect a human T cell to make a Car T, for example?
My understanding is that LVVs [lentiviral vectors] are predominantly used in the transduction of CAR T because they are integrating into the host genome. Is PEI used across AAV [adeno-associated virus] and LVVs or is it predominantly used for one or the other?
Beyond transfection efficacy, are there any other salient advantages in terms of ability to scale up, cell toxicity or yields between a lipid reagent and PEI – especially given the former involves the formation of a liposome around the nucleic acid whereas the other essentially involves cationic polymers binding to the negative DNA? For example, I’ve heard Lipofectamine does not scale linearly, unlike PEI, which does. Is there a clear advantage for the use of PEI when scaling up?
Are there any potential next-generation transfection reagents in development? My understanding is that the core concept of PEI is essentially to fit as many positively charged amine groups onto a polymer as possible, because it then binds with the negatively charged backbone of DNA. From a technical standpoint, do you see PEI being replaced with a better transfection reagent, ie, a polymer with a higher positive charge density, or is this the maximum of what we can achieve at the moment?
What market share, either by volume or value, would you say PEI has in the C> [cell and gene therapy] market relative to the lipid reagents today? Secondly, how do you see that balance evolving?
Lipid reagents are designed to form a liposome that encapsulates the nucleic acid material you’re looking to introduce into the host cell, whereas PEI is a very cationic molecule which binds to the negatively charged DNA but doesn’t necessarily form a liposome. There seems to be two different mechanisms of action. Do you see a next-generation PEI format that doesn’t involve the formation of a liposome, which could potentially compete against the traditional PEI today or the lipid reagents that seem to be taking share?
You mentioned an 80-85% split for PEI vs lipid reagents for the viral vector market today. If we look at in vivo gene therapy, the majority of these therapeutics involve the use of viral vectors, typically AAV, for the delivery of that genetic cargo. Over time, how much traction do you see LNPs [lipid nanoparticles] garnering for the in vivo delivery of gene therapies, especially in context of a player such as Intellia, which has posted robust data for the NTLA-2001.
It seems the major barrier for the use of LNPs for in vivo gene therapies remains the ability to tissue-target in a similar fashion to how the AAV vectors have different serotypes with a different tropism. I discussed the ability to tissue-target using LNPs in our recent Interview on ReCode [see Organ-targeting LNPs – ReCode Therapeutics Performance & Next-generation In-vivo Gene Therapies – 22 September 2022]. In the ex vivo C> space there seems to be a structural shift away from the use of viral vectors as they cannot deliver CRISPR-Cas9 complexes. Therefore, the market is looking for new transfection approaches to enable the use of such gene editing machinery and its derivatives, such as prime editing and base editing. How do you see the market share of PEI evolving in context of MaxCyte’s electroporation, ex vivo LNP-meditated transfection platforms, microfluidics, etc?
You mentioned you see an 80-90% share for viral vectors and therefore PEI in ex vivo CAR T applications, or ex vivo cell therapy applications more broadly, going down to 40%. What are the timelines involved there? Are we talking a horizon of five or so years, or something a bit more stretched out?
Assuming electroporation is going to take majority share of the 50pp delta, what does that mean for the use of transfection reagents? Are transfection reagents used as part of the electroporation process itself?
You mentioned MaxCyte, which indeed has been considered as the market leader for a time now, certainly due to the first-mover advantage and having that FDA Master File, but there is competition catching up. We hear there is Lonza’s Nucleofector and then Thermo Fisher’s Neon in the mix, the latter of which seems to be a hybrid electroporation and microfluidic device. How are you thinking about the sustainability of MaxCyte’s first-mover advantage and the threat of the Nucleofector, the Neon or any other electroporation device?
Could you quantify the market share MaxCyte has today, either as a percentage of the pipeline therapies in total or as a percentage of the pipeline therapies using electroporation as the transfection method of choice?
Last we heard, Lonza was still working on its FDA Master File and the fact that MaxCyte had one represented a significant advantage, especially when it came to off-the-shelf protocols and getting to the regulator as fast as possible. Are you aware of whether Lonza has the FDA Master File yet?
My understanding is that the Thermo Fisher Neon incorporates both electroporation and microfluidics. How rapidly do you see the Neon taking share from MaxCyte or driving down the percentage share for PEI more broadly?
You mentioned the MaxCyte royalty rate. Based on conversations with MaxCyte customers, the company seems to maintain fairly egregious contracts with customers, demands a percentage of on-market sales, which typically goes against the norm in this market, certainly from the perspective of a life sciences tools provider. Can you elaborate on what you meant by the company having had to modify its pricing terms?
We’ve talked about the threat from novel transfection technologies to the use of PEI in viral vectors across ex and in vivo applications. I also want to dig into the threat of stable producer cell lines vs the current transient transfection method for viral vectors. You mentioned that PEI has 80-85% of the market for the manufacturing of viral vectors, but we’re hearing that the creation of recombinant AAV-producing cells that have integrated into their genome all the elements required for AAV assembly, as well as the ITR [inverted terminal repeat] flanks transgene, is starting to be commercialised. Should we have stable producer cell lines, there’ll be no need for constant transient transfection of HEK293 cells using transfection reagents. We also hear PEI is not suitable for stable cell lines, due to cell toxicity. Cevec Pharmaceuticals, for example, has a commercial stable producer cell line called Elevecta on the market. Do you see stable producer cell lines dramatically disrupting the viral vector manufacturing market? If so, what does that mean for PEI, given it doesn’t seem to have any application here?
What are the timelines involved before mass adoption of stable packaging and stable producing cell lines, respectively?
You mentioned that for the viral vector manufacturing market, PEI had 80-85% share, going down to 70% over the coming years. In that calculation, were you baking in the impact of stable packaging and producer cell lines or not?
We’ve highlighted how the demand for PEI is likely to drop fairly significantly over the coming years, due to the ever-changing nature of the C> manufacturing market. Where do you see demand growing for PEI? Do you see any ex-C> applications for these transfection reagents? Do you see a TAM expansion opportunity?
I want to shift gears and talk about the transfection reagent competitive landscape. Key players include Thermo Fisher, Polyplus, Polysciences, Mirus Bio, Promega, Merck MilliporeSigma, etc. Can you walk me through the major suppliers of PEI in some of the other transfection reagents we’ve been discussing?
Based on previous Interviews, it seems Polyplus’s PEI patents expired in 2015. How aggressively have other players started offering PEI-based transfection reagents? Why does it seem Polyplus has been able to hold onto that market share?
Why haven’t other competitors such as Thermo successfully come out with PEI at GMP [Good Manufacturing Practice] quality at large scale?
Who else offers GMP-quality PEI at scale today? Is it just Polyplus and Polysciences, or are players such as Thermo, Mirus Bio, Promega and MilliporeSigma starting to enter the market?
Other experts have noted up to a 30x price delta between Polyplus and Polysciences. Can you confirm that was the case? How do you see that pricing delta evolving, given the demand dynamics we’ve discussed?
How do you see prices trending? As demand shifts from research to therapeutic applications, coupled with the extremely high price point of the finished in vivo or ex vivo C>, is it reasonable to assume that GMP-quality PEI pricing could continue to rise despite the demand dynamics we discussed?
What regulatory guidance is provided by agencies such as the FDA in terms of the quality requirement for transfection reagents, given the use of these transfection reagents is at least two steps removed from the actual finished product itself? Is there clear language defining and stipulating what CGMP [Current GMP] transfection reagents are and how they’re supposed to be used?
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