Theratechnologies Inc T.TH

RE:RE:RE:RE:Cell penetrating peptides

[scarlet1967]

I am not sure this is relevant to manufacturing of PDC and mixing of "uncharacteristic molecules"
but apparently FDA launched a new pilot program for drugs with novel excipients.

https://www.fda.gov/drugs/development-approval-process-drugs/novel-excipient-review-pilot-program

qwerty22 wrote:

This is well known in ADCs. The final product is a mixture of species, that's to say slightly different molecules based on how all the various parts of an ADCs comes together. This hasn't stopped ADCs getting approved. It is a less than optimal situation, the regulators don't like a drug that is a mix of uncharacterised molecules. The way it is handled though is to describe the nature of the mixture in terms of proportions of different species and then set limits to how much each species can be present. Essentially the drug has a fingerprint made up of a variety of molecules and each batch has to match that fingerprint within set limits.

Its a less than perfect scenario but one that can be controlled for. Yes it's true that generally speaking PDCs don't suffer from this problem to the same extent and it's much easier to get to a more pure final product.

 

scarlet1967 wrote: It seems due to ADC’s larger molecular size, hydrophobicity which seems to be an issue as those molecules tend to be nonpolar and prefer other neural molecules the manufacturing of these ADCs add additional layers of processing therefore they cost more to manufacture.

“An additional process development and manufacturing challenge includes the subsequent purification of the required ADC sub-population from the post conjugation reaction mixture.  The reaction mixture will include ADC variants with a range of DAR, unincorporated drug, spacer derivatives and organic solvents. Primary purification can be achieved by utilizing the size differential conferred by the mAb. Tangential flow filtration (TFF) can be used to retain the high molecular weight species whilst the underivatized reaction components can be removed by diafiltration.  This process also offers the opportunity to concentrate the ADC and reduce volume for subsequent downstream steps.  The UF/DF purification will likely require additional optimization (compared to the parent mAb process) because the addition of hydrophobic drug moieties to the mAb may result in reduced stability or solubility and an increased propensity to aggregate. Further purification can be achieved using conventional chromatography modalities, with cation exchange having the potential to resolve both mAb-derived aggregates and ADC species showing extremes of DAR.”
Antibody-Drug Conjugates: Manufacturing Challenges and Trends (adcreview.com)

 

Wino115 wrote:

This is really interesting. I couldn't get the full report and probably wouldn't understand much of it anyway.  It covers many things this board has figured out about peptides conjugates.  One thing that struck me and we gloss over is the manufacturing element. We know it costs a lot less than ADCs, but this article also states it's not an easy thing to manufacture. That may be a nice "moat" for anyone who gets to the commercializati9n stage if true.  

Also, the last peptide they discuss, LX-315, is being trialed at MD Anderson in its Phase 2.  Company is called Lytix Biopharma and it just went public in Norway (listed Euronext) with a market cap around $80mil, so quite small.  I believe you need to inject it in to the tumor.  They are doing the MD Anderson trial with Keytruda and hoping to show Keytruda delivered this way in melanoma is better than Keytruda standard.  Also have a few JVs with small companies on specific indications. Quite a different approach to TH902 but interesting to follow.  I guess you could say a peptide cancer drug that's completed P1 and has one indication is worth around $80mil. 

 

scarlet1967 wrote: This article published in August 2021 gives a good detailed overview of cell penetrating peptides and their advantages as a targeted delivery technology. They touch based on peptides lipophilicity (ability to dissolve in fat), solubility, and small molecular sizes etc. which contribute to internalization of them into cancer cells. Cancer can remodel the cell membrane resulting in less anticancer efficacy of chemotherapeutic agent however CPPs are positive charged are biodegradable and often possess low immunogenicity and low toxicity and favor the negatively charged tumor membranes over those of healthy cells which are electrically neutral. The targeted drug delivery technology  can bypass the multi drug resistance due to better selectivity, better bioaccessibility ( the fraction of the total amount of a substance that is potentially available for absorption) to the tumor cells, enhanced permeability and retention and “utilization of a homing device such as an antibody or a targeting ligand that will enable to attach to tumor cells through antigens or receptors on their surface, usually overexpressed in certain tumor types” among others. The article goes on and discuss the pros and cons of covalently or noncovalently bounds with anticancer agents and additional beneficial feature of coupling a chemotherapeutic with a CPP.
 
 
“The ability to permeabilize in the membrane and gain access to the cytosolic compartment is largely dependent on the physicochemical qualities of the therapeutic entities including the most relevant such as lipophilicity (ability to dissolve in fat…), polarity (positive and negative charges at the ends of the molecule) and molecular size. Among them, a fairly but not excessively hydrophobic (water insoluble) character is most conducive to the drug transport; very large, polar hydrophilic molecules are being poorly internalized similarly as extremely hydrophobic (the former ones will fail to enter the membrane, the latter will enter readily but may have difficulty in leaving it). At the cellular level, most anticancer drugs act on membrane surface receptors or have intracellular targets. In the latter case, a drug must cross the cellular membrane that constitutes an additional barrier for it. A further complication for drug traversing the cellular membranes is their remodeling induced by cancer itself, which brings about complex changes in the membrane structure and composition. They lead to a drop in anticancer drug efficacy manifested by simultaneous cancer cell proliferation, avoidance of apoptosis and development of cellular resistance.
Generally, anticancer therapy bears a high incidence of toxicity due to a low therapeutic index of the drugs and the simultaneous necessity for the usage of high doses in order to produce the clinical effect. An explanation for these unfavorable parameters of the anticancer therapy is lack of drug selectivity (they damage not only cancerous cells but also healthy rapidly growing ones) and poor bioaccessibility to the tumor cells. Another shortcoming of this therapy is multidrug resistance (MDR), which constitutes one of the dominant reasons for its failure.
An attractive application of the EPR (enhanced permeability and retention) effect in tumor chemotherapy comprises therapeutics in the form of liposomes, polymers or micelles. This effect has also been utilized by experimental technologies based on cell-penetrating peptides coupled with diverse types of cargoes (low molecular weight anticancer drugs).
CPPs are a class of diverse short sequence peptides (usually <30 amino acids) of natural (protein-derived or chimeric) or synthetic origin.
 
Internalization mechanisms of CPPs

According to the available data, CPPs are internalized by two possible main pathways, i.e. endocytosis (energy dependent) and/or direct translocation (energy independent).
 
The role of CPPs in cancer treatment (CPPs as vectors for anticancer drug delivery).
 
The interaction of a CPP with cancerous cells should be considered in light of the current concept of cancer-induced modifications within the cell membrane itself. They concern both its heteropolysaccharide (They are compounds that are made up of two or more different types of monomer. Made up of the same repeating unit. As a rule, they are overexpressed in cancerous membranes) and lipid components (Also, the lipid component contributes to the anionic character of the cancerous membrane due to the exposition of the negatively charged phosphatidylserine in its outer leaflet which correlates with a more acidic pH of their external media as well), ensuring the uncontrolled growth, progression and invasiveness of the tumor cells.
Generally, the CPPs possessing mostly cationic nature due to arginine and lysine residues favor the negatively charged tumor membranes over those of healthy cells, which are electrically neutral.
 
Improvement of anticancer selectivity of CPPs
 
The most characteristic feature of them is that they are able not only to distinguish between cancer and normal cells but also target specific tumor cell types.
Another method of increasing the tumor cell selectivity of CPPs is utilization of a homing device such as an antibody or a targeting ligand that will enable to attach to tumor cells through antigens or receptors on their surface, usually overexpressed in certain tumor types.
 
Conjugation of CPPs with a cargo – two different strategies
The association of the CPPs with their cargo may be divided into covalently or noncovalently bound. Both formulation approaches have pros and cons. The advantage of the covalent one (chemical cross-linking between the CPP and cargo) is obtaining a final product with a well-defined chemical structure and reproducibility of the procedure.
On the other hand, noncovalent interaction, i.e. physical complexation involves a simple bulk-mixing procedure of the compounds (CPP and cargo with or without a linker). This strategy, in comparison to the above-described one, is more simple and much easier to perform. Furthermore, it enables the usage of versatile cargos (with the preservation of their functionality) and low concentrations for induction of the biological response. However, the difficulty to control the final ratio and orientation of the peptide and cargo remains an important limitation of this method.
 
The anticancer activity improvement of the standard chemotherapeutics by CPPs
 
Recently, it has been found that the pharmacological properties of the chemotherapeutics may be improved by conjugating them with the CPPs, and this results in an increased efficacy of the transported drugs. Thanks to the presence of the CPP in the conjugate, the drug internalization is promoted with the consequence of high concentrations within the tumorous cells.
It is noteworthy that the improved pharmacokinetics is not the only factor that impacts the activity profile of the conjugate. There is also evidence for possible pharmacodynamic interactions between its constituents since certain CPPs possess anticancer action. An additional beneficial feature of coupling a chemotherapeutic with a CPP is overcoming MDR, which frequently occurs after repeated exposure of tumor cells to the same drug.
 
Conclusions
 
Concerning CPPs

 

1. As potential vectors for cellular delivery of small molecule drugs, they indicate a certain level of selectivity to cancer cells, called passive selectivity.
2. Besides drug transporting activity, certain peptides possess anticancer activity per se, accomplished mainly by membrane lytic effect, proapoptotic activity, or both actions.
3. Among the anticancer peptides, the most promising are p28 and LTX-315. Of great interest is particularly the latter one, the first locally acting oncolytic agent that reorganizes the tumor microenvironment. It entered several settings of phase I and II clinical trials.”

 
https://pubmed.ncbi.nlm.nih.gov/34402743/