"A series of 15-mer peptides overlapping each other by 10 amino acids and a series of 9-mer peptides overlapping each other by 8 amino acids covering the HPV16 E6 protein have been described (20). To define the minimal and optimal amino acid sequences of the CD8 T-cell epitope, 8-mer, 10-mer, 11-mer, and homologous peptides (see Table 1) were synthesized as needed (CPC Scientific, Inc., San Jose, CA)."
Abstract
Human papillomavirus (HPV)-specific T-cell response to the HPV type 16 (HPV16) E6 protein has been shown to be associated with successful viral clearance. The patterns of CD8 T-cell epitopes within HPV16 E6 protein were previously studied in two women with HPV16 clearance. The goal of this study was to characterize these epitopes in terms of their minimal and optimal amino acid sequences and the human leukocyte antigen (HLA) restriction molecules. The presence of the epitope-specific memory T cells after viral clearance was also examined. In subject A, the dominant epitope was characterized to be E6 75-83 (KFYSKISEY), restricted by the HLA-B62 molecule, while that of subject B was E6 133-142 (HNIRGRWTGR), restricted by the HLA-A6801 molecule. Homologous epitopes were identified in five other high-risk HPV types for both of these epitopes, but they were not recognized by respective T-cell clone cells. An enzyme-linked immunospot assay or tetramer analysis was performed on peripheral blood mononuclear cells from blood samples collected after viral clearance but prior to isolation of the T-cell clones. The presence of epitope-specific memory T cells was demonstrated. These data suggest that HPV-specific memory T cells were generated in vivo and that they may remain in circulation many months, if not years, after viral clearance. Our findings broaden the spectrum of the CD8 T-cell epitopes of the HPV16 E6 protein. The characterization of novel T-cell epitopes and long-lasting epitope-specific memory T cells may be useful for the development of a potential epitope-based vaccine.
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CPC Scientific at DCAT 2025!
GMP Peptide Manufacturing
What an amazing time we had at DCAT 2025! It was fantastic to meet with colleagues, clients, and friends, and showcase CPC Scientific’s cutting-edge capabilities in synthetic API development and commercial production.
A heartfelt […]
We are excited to share that CPC Scientific Inc. has officially received the Good Manufacturing Practice (GMP) Certificate in accordance with the ISO 22716:2007(E) Cosmetic Guidelines.
This certification highlights our unwavering commitment to delivering the highest quality peptide ingredients for cosmetic use, guaranteeing:
- Superior Quality Control – Striving for excellence in safety, consistency, and purity.
[…]
In Part 1 of our Minimal Protection Group Strategies for SPPS, we discussed methods for eliminating sidechain protection on hydroxy-bearing amino acids such as serine, threonine, tyrosine, and hydroxyproline. By omitting t-butyl protection, we enhanced atom economy and avoided the use of hazardous solvents typically required to remove these protection groups. In Part 2, we present a new case study, expanding our approach to include the unprotected side chains of histidine, tryptophan, and arginine. We demonstrate the synthesis of a Goserelin peptide API impurity, showcasing how a convergent peptide fragment strategy can be used to eliminate the need for TFA and diethyl ether, eliminate side chain protection of Arginine, Histidine, and Tryptophan.
The synthesis of the linear RP-182 analog, bicyclo[6.1.0]non-4-yn-9-ylmethyloxycarbonyl-PEG2-Lys-Phe-Arg-Lys-Ala-Phe-Lys-Arg-Phe-Phe-Lys(azido-PEG)-NH2, was achieved using standard solid-phase peptide synthesis (SPPS) protocols. After cleaving the linear peptide from the resin, macrocyclization was performed in the liquid phase through a strain-promoted click reaction. BCN introduces extra ring strain due to its fused cyclopropane structure. The combined effect of ring strain, the selection of BCN, and copper catalysis significantly increases the macrocyclization efficiency of longer peptides like RP-182.
Nakagawa, Mayumi, Teresa Evans, Milan Bimali, Hannah Coleman, Jasmine Crane, Nadia Darwish, Jennifer L. Faulkner et al. MedRxiv (2025): 2025-01.
The vaccine consisted of four current good manufacturing production-grade synthetic peptides covering the HPV 16 E6 protein [amino acid (aa)1-45, 46-80, 81-115, and 116-158] (CPC Scientific, San Jose, CA [..]
Stapled peptides have emerged as a powerful tool in drug discovery and therapeutic development due to their ability to overcome the limitations associated with traditional peptide drugs, such as poor stability and low cell permeability. By introducing staples into the peptide backbone, researchers can stabilize peptide conformations and enhance their interactions with target proteins, resulting in improved efficacy and specificity. This approach not only addresses the challenges of peptide drug design but also opens new avenues for targeting challenging biomolecular interactions that are difficult to modulate with small molecules or antibodies. The development of stapled peptides has led to significant advancements in targeting protein-protein interactions, addressing previously intractable diseases, and enhancing the precision of therapeutic interventions.
Peptide receptor radionuclide therapy (PRRT) is a targeted therapeutic approach that utilizes peptides to deliver cytotoxic radiation to specific receptors overexpressed on cancer cells. Peptides offer several advantages as therapeutic vectors in PRRT due to their small size, favorable pharmacokinetics, high binding affinity, low immunogenicity and toxicity, and minimal off-target effects. Tumor-targeting peptides conjugated to radionuclide chelates represent a promising class of cancer therapeutics.
Singh, S.S., Calvo, R., Kumari, A., Sable, R.V., Fang, Y., Tao, D., Hu, X., Castle, S.G., Nahar, S., Li, D. and Major, E. Molecular Cancer Therapeutics (2024).
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[..] assembling the peptide on the Rink Amide resin and attaching the PEG azide moiety to the N-terminal Lys, the Dde group was removed as previously shown and coupled to the Fmoc-PEG2-acid. Removal of the Fmoc followed by simultaneously click/coupling to bicyclo[6.1.0]non-4-yn-9-ylmethyl (2,5-dioxopyrrolidin-1-yl) carbonate gave 1c which was deprotected and cleaved from the resin to give 1c.
Most proteinogenic peptides, except for certain hydrophobic sequences, can be synthesized in a linear fashion using solid-phase peptide synthesis (SPPS) methods. However, longer sequences, particularly those exceeding 70 amino acids, often require alternative techniques due to challenges like steric hindrance. Other issues, such as poor solvation of the protected peptide during synthesis and the formation of intermolecular hydrogen bonds (e.g., β-sheets) between fragments, can also result in inefficient coupling and deprotection.