PNC-27 is a synthetic peptide designed in the early 2000s in New York as an “anticancer peptide”. It consists of a fragment of the human protein p53 joined to a short segment that carries the molecule across the cell membrane. In cell cultures and in mice it kills cancer cells by punching holes in their membrane while leaving normal cells alone — at least according to the work of one research group and one independent team. There is, however, not a single human study and no registered clinical trial. This review explains how PNC-27 is supposed to work, what has really been shown and why SWISS LAB deliberately does not offer it — and the most important reason is not chemical but human.
What PNC-27 is
The protein p53 is the “guardian of the genome”: it halts the division of damaged cells and triggers their death, and in most cancers it is mutated or switched off. Its natural brake is the protein HDM-2 (MDM2 in mice), which grabs p53 by its initial segment and sends it for degradation. In 2001 the team of Matthew Pincus synthesised three peptides from precisely that segment of p53 (residues 12–26, 12–20 and 17–26) and attached to the end of each the penetratin sequence — a 17-amino-acid fragment of a fruit-fly protein that “pulls” peptides into cells and stabilises their helical shape (Kanovsky et al., 2001). The peptide with residues 12–26 is PNC-27; the shorter one, with residues 17–26, was named PNC-28. In culture all three killed human cancer cells, while a control, unrelated peptide with the same penetratin did nothing. Importantly, they had no effect on normal cells, including stem cells from cord blood.
How it is supposed to work — HDM-2 in the membrane and the “hole”
The original idea — to block HDM-2 and free p53 — quickly collapsed: the peptides worked just as well on cells that had no p53 at all, and the cell death lacked the hallmarks of apoptosis (programmed, “clean” death) — the typical apoptotic proteins such as Bax and p21 were absent (Kanovsky et al., 2001). In breast-cancer cells the peptide caused rapid death resembling necrosis (bursting of the cell), and structural analysis revealed a helical, hydrophobic structure “with membrane disruptive potential” (Do et al., 2003). Work on pancreatic cancer showed the mechanism directly: after the peptide was added, cells released the enzyme LDH (a sign that the membrane had ruptured), pores in the membrane were visible under the electron microscope, and the penetratin sequence was responsible — when the same p53 fragment was introduced into cells without it, they died by apoptosis, not necrosis (Bowne et al., 2008).
Where does the selectivity come from? In 2010 the same group reported that the HDM-2 protein is present in significant amounts in the cell membranes of many cancer lines but absent from the membranes of several untransformed lines; PNC-27 adopts a shape that fits HDM-2 and binds to it precisely in the membrane. The most convincing was the reverse experiment: when the HDM-2 gene with a signal directing the protein to the membrane was introduced into normal MCF-10-2A cells, which resist PNC-27, they became susceptible (Sarafraz-Yazdi et al., 2010). The model therefore looks like this: the peptide grabs HDM-2 in the cancer cell's membrane, the complexes pair up and form a channel through the membrane, the cell spills its contents and dies. The authors named this “poptosis” (Pincus et al., 2024).
Structure and origin
PNC-27 is a chimera: 15 amino acids from p53 (PPLSQETFSDLWKLL) and 17 amino acids of penetratin (KKWKMRRNQFWVKVQRG), 32 residues in all (Kanovsky et al., 2001). Almost everything known about it comes from one milieu: the team of Pincus and Michl at SUNY Downstate in Brooklyn and their collaborators at Columbia and Drexel. The peptide also has commercial owners — in the more recent papers it is supplied by the company Oncolyze, and one of the authors is employed by NomoCan Pharmaceuticals (Wang et al., 2020; Pincus et al., 2024). That does not disqualify the results, but it needs to be borne in mind when reading the conclusions.
What was studied — cells
The list of cell lines on which PNC-27 or PNC-28 worked is long — according to the authors' review it covers “a wide variety” of solid and blood cancers: breast, pancreatic and ovarian cancer, leukaemias and others (Pincus et al., 2024); as a rule a normal line was tested alongside, and it survived. The most interesting experiment used cells from patients: primary cultures were established from two freshly removed ovarian cancers (a mucinous and a high-grade serous one), and PNC-27 inhibited their growth and killed them depending on concentration, while the control peptide PNC-29 did nothing; it also worked on chemotherapy-resistant lines (Sarafraz-Yazdi et al., 2015). This is “ex vivo” — patients' cells in a dish — not a human study. The difference is fundamental: a dish has no liver, no kidneys and no immune system.
What was studied — animals
There are two sets of in vivo data, both in mice. The first concerns the shorter PNC-28 in nude (immunodeficient) mice with transplanted pancreatic cancer: given into the peritoneal cavity for two weeks together with a tumour transplanted into the same site, it destroyed the tumours completely; when the tumour grew at a remote site, it blocked growth for the period of administration and two weeks beyond, after which the tumours regrew — more slowly than with the control peptide, but they regrew. The authors themselves pointed out that the peptide “may be effective in treating cancers especially if delivered directly to the tumor” (Michl et al., 2006).
The second, and the strongest, comes from outside the parent group — from the City of Hope centre in California, although the peptide was supplied by Oncolyze. In acute myeloid leukaemia (AML), membrane HDM-2 was present exclusively on blasts (human and mouse), including leukaemia stem cells, and not on normal blood-forming stem cells. PNC-27 bound HDM-2 in the membrane and triggered the degradation of E-cadherin, which damaged the membrane; in mice with human and mouse AML it killed both the “bulk” blasts and the leukaemia stem cells, while sparing normal blood-forming cells, with “minimal off-target hematopoietic toxicity” (Wang et al., 2020). This is an important result — and still a result in mice.
No human studies — what that means
In PubMed the term “PNC-27” yields 25 papers: cell cultures, mice, structural work and reviews — not a single human study. In the ClinicalTrials.gov registry (as of 14 September 2026) there is no trial of PNC-27 or PNC-28. Twenty-five years after the first publication the peptide has not even entered phase 1, the stage that tests safety in humans. It is therefore unknown what it does in the human body: how quickly it breaks down, whether it reaches the tumour, how the immune system reacts to a foreign fragment of a fruit-fly protein and — most importantly — whether the “selectivity” seen in the dish and in mice carries over to people.
Safety and the limits of the evidence
Two limitations. First: the mechanism destroys membranes by definition. The peptide does not “switch off” the cell, it makes a hole in it; the selectivity rests on the fact that membrane HDM-2 is found mainly on cancer cells. The authors write that normal cells express it “at most” at low levels — and “low” is not “zero”. No off-target harm was reported in mice (Wang et al., 2020; Pincus et al., 2024), but the formal toxicology studies required for drug registration have not been published, and nobody has checked this in humans. Second: almost the entire literature comes from one group with a commercial interest in it; the only independent replication (City of Hope) concerns one type of cancer and also used peptide supplied by the company.
There is one more thing that has to be said plainly. In January 2017 the US FDA warned cancer patients not to buy or use PNC-27 sold through a website as a “treatment or cure for cancer”. An FDA laboratory found the bacterium Variovorax paradoxus in a sample of “PNC-27 solution for inhalation”, and Ralstonia insidiosa in another; the product was also offered as an intravenous solution and as suppositories. The FDA reiterated that it had never evaluated or approved PNC-27 for any disease, and noted that it had received no reports of illness at that time. For a patient with a weakened immune system such contamination can do harm all by itself.
Why it is not on offer
SWISS LAB does not sell PNC-27 and does not intend to. The pharmacological reason is clear: it is a peptide whose entire action consists of puncturing membranes, and the margin between “kills cancer cells” and “damages others too” is known only from the dish and from mice. But that is not the most important reason. PNC-27 is at times offered online to people with cancer — people who are looking for hope and have the least time for mistakes. The gravest harm this compound can do is not chemical: it is the situation in which someone postpones or abandons treatment of proven efficacy — surgery, chemotherapy, radiotherapy, immunotherapy — in favour of a peptide that has never been given to any patient within a study. We judge nobody who looks for it — but we do not want to be a link in that chain. Cancer requires clinical treatment, and if someone wants to try an experimental therapy, the proper route is a clinical trial under medical supervision, not a vial from the internet. For PNC-27 no such trial exists today.
The wider context — membrane-puncturing peptides
PNC-27 is not the only peptide that kills through pores in the membrane — that is how the whole family of natural antimicrobial peptides works, including the human cathelicidin we describe in our article on LL-37; the difference lies in what the peptide recognises as its target. A separate lesson from the FDA story concerns quality: a bacterially contaminated “solution for inhalation” is exactly what a certificate of analysis is meant to guard against — how to read one is explained in our guide on CoA certificates.
Summary
PNC-27 is a 32-amino-acid chimera of a p53 fragment and penetratin which, in culture, kills cancer cells through pores in the membrane by exploiting the HDM-2 present in cancer-cell membranes; in mice the shorter analogue held back pancreatic tumours, and PNC-27 itself destroyed acute myeloid leukaemia cells while sparing normal blood formation. The literature comes almost entirely from one group with a commercial interest, and after 25 years there is not a single human study and no registered clinical trial. The state of the evidence: a promising mechanism at the level of cells and mice, zero data on safety and efficacy in humans — and a real risk that the compound reaches patients instead of treatment.
Sources
- Wang H, Zhao D, Nguyen LX, et al. Targeting cell membrane HDM2: A novel therapeutic approach for acute myeloid leukemia. Leukemia. 2020;34(1):75–86. PMID: 31337857. PMCID: PMC7951797. DOI: 10.1038/s41375-019-0522-9. pubmed.ncbi.nlm.nih.gov/31337857
- Michl J, Scharf B, Schmidt A, et al. PNC-28, a p53-derived peptide that is cytotoxic to cancer cells, blocks pancreatic cancer cell growth in vivo. International Journal of Cancer. 2006;119(7):1577–1585. PMID: 16688716. DOI: 10.1002/ijc.22029. pubmed.ncbi.nlm.nih.gov/16688716
- Kanovsky M, Raffo A, Drew L, et al. Peptides from the amino terminal mdm-2-binding domain of p53, designed from conformational analysis, are selectively cytotoxic to transformed cells. Proceedings of the National Academy of Sciences of the United States of America. 2001;98(22):12438–12443. PMID: 11606716. PMCID: PMC60072. DOI: 10.1073/pnas.211280698. pubmed.ncbi.nlm.nih.gov/11606716
- Do TN, Rosal RV, Drew L, et al. Preferential induction of necrosis in human breast cancer cells by a p53 peptide derived from the MDM2 binding site. Oncogene. 2003;22(10):1431–1444. PMID: 12629507. DOI: 10.1038/sj.onc.1206258. pubmed.ncbi.nlm.nih.gov/12629507
- Sarafraz-Yazdi E, Bowne WB, Adler V, et al. Anticancer peptide PNC-27 adopts an HDM-2-binding conformation and kills cancer cells by binding to HDM-2 in their membranes. Proceedings of the National Academy of Sciences of the United States of America. 2010;107(5):1918–1923. PMID: 20080680. PMCID: PMC2836618. DOI: 10.1073/pnas.0909364107. pubmed.ncbi.nlm.nih.gov/20080680
- Bowne WB, Sookraj KA, Vishnevetsky M, et al. The penetratin sequence in the anticancer PNC-28 peptide causes tumor cell necrosis rather than apoptosis of human pancreatic cancer cells. Annals of Surgical Oncology. 2008;15(12):3588–3600. PMID: 18931881. DOI: 10.1245/s10434-008-0147-0. pubmed.ncbi.nlm.nih.gov/18931881
- Sarafraz-Yazdi E, Gorelick C, Wagreich AR, et al. Ex vivo Efficacy of Anti-Cancer Drug PNC-27 in the Treatment of Patient-Derived Epithelial Ovarian Cancer. Annals of Clinical and Laboratory Science. 2015;45(6):650–658. PMID: 26663795. pubmed.ncbi.nlm.nih.gov/26663795
- Pincus MR, Silberstein M, Zohar N, Sarafraz-Yazdi E, Bowne WB. Poptosis or Peptide-Induced Transmembrane Pore Formation: A Novel Way to Kill Cancer Cells without Affecting Normal Cells. Biomedicines. 2024;12(6):1144. PMID: 38927351. PMCID: PMC11201261. DOI: 10.3390/biomedicines12061144. pubmed.ncbi.nlm.nih.gov/38927351
For in-vitro laboratory research only. It is not a human medicine and is not for treatment.