PNC-28: The Definitive Guide

What is PNC-28?

PNC-28 is a lab-made peptide designed as an experimental cancer drug. It joins a short piece of the body's p53 protein, a well-known tumour suppressor, to a tail that helps it stick to and cross cell membranes. It has been tested only in cells and in one mouse study, and it is not approved as a medicine anywhere we checked. [1], [6], [3]

A peptide is a short chain of amino acids, the building blocks of proteins. PNC-28 is a chain of 27 of them. The first 10 copy positions 17 to 26 of p53, the exact stretch p53 uses to touch a partner protein called HDM-2 (human MDM2). The other 17 form a cell-penetrating leader that the papers call "penetratin". PNC-28 does not occur in nature; it is made by chemical synthesis. [1], [16]

Doserly

PNC-28 and PNC-27: same leader, different piece of p53

Each letter is one amino acid, in order. Structure and identity.

PNC-28 (this guide) · 27 amino acids

From p53, residues 17–26: contact HDM-2: ETFSDLWKLL. Then the cell-penetrating leader: KKWKMRRNQFWVKVQRG. About 3,509 g/mol.

PNC-27 · 32 amino acids

From p53, residues 12–26: PPLSQETFSDLWKLL. Then the same leader. About 4,032 g/mol.

PNC-27 has its own guide: PNC-27.

PNC-28 is PNC-27 without the first five p53 residues (PPLSQ); the p53 residues 17–26 and the leader are identical.

The design was first published in 2001 by a research group in New York, alongside two sibling peptides, PNC-21 and PNC-27. The same group produced almost all later PNC-28 research, and several of its members are named inventors on intellectual property covering PNC-27 and PNC-28. [1], [7]

The FDA's substance database lists PNC-28 with an identifier code. That record only tracks the substance by name and structure; it is not an approval of any product. Unlike PNC-27, PNC-28 has no entry in the US National Cancer Institute's drug vocabulary, although one dosing website says it does. [11], [17], [18]

Is PNC-28 the same as PNC-27?

No. They are close relatives from the same research group, but they are different molecules. PNC-27 carries a longer piece of p53 (positions 12 to 26) on the same leader, so it is 32 amino acids long. The developers describe PNC-28's anticancer activity as similar to PNC-27's, and no animal study has compared them head to head. [1], [19], [20] See the comparison below, and Doserly's PNC-27 guide covers the longer peptide.

What is PNC-28 not?

Three names cause confusion. A 2020 chemistry paper used "cyclic PNC-28" for the bare 10-amino-acid p53 piece, made into a ring and without the cell-penetrating leader, so the name does not always mean the same molecule. "p28" is a different peptide, a 28-amino-acid piece of a bacterial protein called azurin, which has been given to people in a small early trial; those results say nothing about PNC-28. And a 2010 study of penetratin peptides tested PNC-27, not PNC-28; its other test peptides were built from a different protein. [21], [22], [23]

Typical PNC-28 Protocols

There is no recurring pattern to report. Only one source gives a human schedule for PNC-28: a seller's page listing 2.5 mg each morning for 3–4 weeks, with no study behind it. Every study, registry, label and other website we reviewed gives no human amount, and community education groups mention PNC-28 only in passing, as a shorter relative of PNC-27. [4], [3], [5], [30]

• Titration: not established. The one listed schedule starts at its full amount, and no source describes stepping up.
• Breaks and cycles: not established. The listed schedule runs 3–4 weeks and says nothing about pauses or repeat courses.
• Units: the seller's page gives its amount in syringe units, which measure volume, not drug. With 5 mg of powder mixed into 1 mL of liquid, each mL holds 5 mg, and 50 units on a U-100 insulin syringe is 0.5 mL, or 2.5 mg. Mixing the same vial with a different volume changes what 50 units contains, so the milligram amount is what matters. The Doserly reconstitution calculator does this vial-and-syringe arithmetic; it does not make an untested amount safe. [4]
• Research units: the lab studies give PNC-28 as a concentration in a dish, in micrograms per millilitre (µg/mL). With a molecular weight of about 3,509, 40 µg/mL is about 11 micromolar. [1], [2]

This single schedule comes from a seller's page, not a study: no human amount of PNC-28 has ever been tested.

The only living-animal data come from a 2006 mouse study in which a small implanted pump released 1, 10 or 20 mg per mouse over 14 days; only 20 mg clearly slowed established tumours. Amounts in a dish or in mice are never converted into human doses (see why). [6]

Three cautions matter more than the numbers.

PNC-27 amounts do not apply. Dosing websites publish PNC-27 schedules from 100 mcg to 20 mg a day, and a 2026 public post about pancreatic cancer lists a PNC-27 schedule of 100–500 mcg a day under a title naming both peptides. Those amounts are for a different peptide, and none of them has been tested in people either. The PNC-27 guide covers them. [32], [33], [31]

It is not a replacement for cancer care. The people asking about PNC-28 in public posts and community groups are mostly facing cancer themselves or caring for someone who is. Nothing about PNC-28 has been tested in people, so it cannot stand in for treatment that has. Tell your oncology team about anything you are considering. [29], [34], [3]

Normal-cell safety is unproven. The mouse study's only safety checks were body weight and behaviour; its authors did not run blood counts or liver tests. In heart-muscle cells grown in a dish, an independent lab found more cell death with an MDM2-blocking peptide that a later review identifies as PNC-28, and warned that such drugs "may have adverse cardiac side effects". Whether that peptide was exactly PNC-28 is unconfirmed. [6], [8], [9] Read more below.

What is PNC-28 commonly used for?

PNC-28 is discussed almost only by people with cancer, or people caring for someone who does. Public posts ask about brain tumours, look for a supplier during a serious illness, or suggest it as the next thing to try if PNC-27 has not helped. Nobody in the posts we found described actually using it. [29], [34], [41]

The research points toward cancer too, but stays in the laboratory. Its developers tested it on cancer cells from the pancreas, colon, cervix, breast, lung and bone, and in one mouse model of pancreatic cancer. The sections below describe what was studied. They do not establish that PNC-28 treats any cancer, because it has never been tested in a person. [1], [6], [3]

Pancreatic cancer

Pancreatic cancer is where PNC-28 has its only animal evidence. In a dish, it killed rat pancreatic cancer cells but left their normal counterparts alive; half the cancer cells died at about 40 µg/mL (the IC50). It also killed human pancreatic cancer cells in a dish, with signs of damage within minutes. [1], [16], [19]

In a 2006 animal study, the same rat pancreatic cancer cells were transplanted into nude mice (mice with weak immune systems). PNC-28 was released continuously for 14 days from a small osmotic pump, usually placed subcutaneously (under the skin) behind a front leg, away from the tumour; in one experiment it sat in the abdominal cavity (intraperitoneal). Each group had 4 or 5 mice. The authors say each experiment was run at least twice, except the one with the pump in the abdomen, which was run once, and for at least one repeat they show only one set of mice and describe the other as "almost identical". [6]

• Cancer cells injected into the abdomen at the same time: by day 21, mice given PNC-28 had no abdominal fluid build-up or spread to the liver, whether the pump sat subcutaneously or in the abdomen. Control mice, given a control peptide or salt water, developed widespread cancer in the abdomen. The authors describe the tumours as destroyed. [6]
• Cancer cells placed subcutaneously at the same time: tumours did not grow significantly during the 14 days of treatment or for about two weeks afterwards, then grew slowly and stayed much smaller than in control mice. [6]
• Tumours already growing: when pumps went in 13 days after the cancer cells, 20 mg per mouse over 14 days shrank the tumours and slowed their regrowth, and the difference from control lasted after the pumps stopped. Lower totals of 1 and 10 mg did not slow growth significantly. [6]

The authors concluded that PNC-28 "may be effective in treating cancers especially if delivered directly to the tumor". That is a suggestion from one small mouse study using rat cancer cells, not a finding in people. [6]

Other cancer cells in a dish

In the original 2001 study, 100 µg/mL of PNC-28 for three days killed 96%, 100% and 86% of three cancer cell lines: transformed rat brain blood-vessel cells, human cervical cancer cells and human colon cancer cells with no working p53. The paper also reports, without showing the data, that lung cancer cells were wiped out and that breast and bone cancer (osteosarcoma) cells responded similarly. [1], [19]

Brain tumours

One public post asks about PNC-28 for a glioma, a type of brain tumour, "since it can break the blood brain barrier". No study has tested PNC-28 in brain tumours or measured whether it reaches the brain, and none of the research we reviewed supports that claim. [29]

As a research tool

Two independent groups used PNC-28 in other ways. One attached PNC-27 and PNC-28 to a gene-carrying particle as a tag that seeks out HDM-2 on cancer cells, which improved delivery into cancer cells in a dish. Another modelled PNC-28 variants on a computer to study how they grip MDM2. Neither is a treatment. [47], [48]

Does killing cancer cells in a dish mean it treats cancer?

No. Many substances kill cancer cells in a dish, and far fewer help people with cancer. A drug has to reach the tumour at a high enough level, avoid harming the rest of the body and work better than existing treatment, and only studies in people can show that. For PNC-28, those studies have not started. [3] See what is actually known in people.

Where do PNC-28 protocols differ?

With no human protocol to compare, the real disagreements are about what the research amounts mean, whether PNC-27 figures can stand in, and how the only animal study delivered the peptide.

What amounts appear in the research?

The mouse amounts are totals per mouse, released slowly over two weeks, not daily or single doses. The paper's text and one of its tables disagree about the amount in the first experiments (2 mg or 10 mg), and this guide shows both rather than picking one. The paper gives no amount per kilogram of body weight, and we do not calculate one. [6]

These figures describe laboratory conditions. A concentration in a dish is not a blood level, and nobody knows what blood level any human dose would produce, because PNC-28's pharmacokinetics have never been measured. Converting either set of numbers into a human dose would produce a guess, not a tested amount, and this guide does not do it. A developer patent also lists a general human range of "about 0.1 to about 20 mg per kilogram", but that is standard patent wording, not a tested dose. [46]

The cell studies also found a narrow working range: the effective concentrations spanned only about a fourfold increase, from 25 to 100 µg/mL. Below that, the peptide did little. [1]

Can PNC-27 doses be used for PNC-28?

No. PNC-27 is a different molecule with a different length and weight, and its website amounts were never tested in people either. The developers call PNC-28's activity "similar" to PNC-27's, but "similar" in a dish does not make two peptides interchangeable in a syringe. One website says not to combine the two because they would be redundant; that is an opinion, since no study has tested them together. [19], [28], [33]

Continuous release or separate injections?

The mouse study delivered PNC-28 continuously with a pump, not by daily injections. A PNC-27 dosing page uses this study to argue for splitting PNC-27 doses through the day, but it misquotes the study as using human pancreatic cancer grafts (the cells came from rats) and bases the split on a 30-minute half-life that no study has measured. [6], [33]

The one seller's schedule takes the opposite approach: a single injection each morning. Continuous release in mice and one daily injection in people are very different exposures, and neither pattern has been compared or tested in people. [4], [6]

What the lab work does show is that timing mattered in a dish: when PNC-28 was washed off rat pancreatic cancer cells after 24 hours, only about 30% of them died, against almost all of them with continuous exposure. The authors suggested the peptide is inactivated within a day. That is a finding about cells in a dish, not a dosing schedule. [1]

Which molecule does a label mean?

Most research uses "PNC-28" for the 27-amino-acid peptide with the leader. A 2020 chemistry paper uses "cyclic PNC-28" for a ring-shaped version of the 10-amino-acid p53 piece alone, a much smaller molecule without the part the developers say is needed for the membrane effect. A product label alone cannot tell you which molecule, or how much of it, is in a vial. [21], [16]

Is PNC-28 combined with other products?

In one public PNC-27 thread, a reply suggests trying PNC-28 if PNC-27 fails, possibly with fenbendazole, an animal deworming drug. A 2026 post covering both peptides describes a plan, never carried out, to pair its PNC-27 schedule with ivermectin, an antiparasitic drug. A sourcing request lists PNC-28 alongside other experimental compounds. No study has tested PNC-28 with anything, and combining several products makes it impossible to tell which one caused a change or a side effect. [41], [31], [34]

What happens when you stop PNC-28?

There are no human data, because no one has been studied taking it. Two laboratory findings touch on the question:

• In a dish, removing PNC-28 after 24 hours cut the kill rate from almost 100% to about 30%. [1]
• In mice, distant tumours stayed blocked for the two weeks of continuous delivery and two weeks afterwards, then started to grow again, although they stayed smaller than in mice given a control peptide. Established tumours that shrank also grew back slowly. [6]

Withdrawal or rebound effects have never been studied.

How would PNC-28 be taken, and does the route matter?

Nobody knows, because no route has been tested in people. How the body absorbs, moves and removes a substance is called pharmacokinetics, and no pharmacokinetic study of PNC-28 has been published in any species. [3], [19]

• In the lab: added directly to cells in a dish. [1]
• In mice: released continuously for 14 days from an osmotic pump. The full paper places the pump subcutaneously (under the skin) behind a front leg in most experiments and in the abdominal cavity in one. An independent review describes the pump as placed subcutaneously or in the abdomen, while the developers' 2024 review mentions only the abdomen. [6], [49], [19]
• Injection: the one seller's schedule is written in insulin-syringe units, which implies injection, but it names no route. No study has tested an injection of PNC-28, and how much would reach the blood (the bioavailability) is unknown. [4]
• Oral, nasal or other forms: no data at all.

How long does PNC-28 last in the body?

Not known. Half-life is the time it takes for the level in the blood to fall by half, and it has never been measured for PNC-28. The only clue is from a dish: the effect faded when the peptide was removed after 24 hours, and the authors suggested it is inactivated within that time. A half-life would say nothing, by itself, about how long an effect lasts. [1]

Should PNC-28 be injected into or near a tumour?

No study in people has compared injection sites. The mouse study's authors suggested it may work best "if delivered directly to the tumor", based on abdominal tumours that did not develop when the peptide was released into the same space, and on the stronger effect they saw there than at subcutaneous sites. Injecting into a tumour is a medical procedure with its own risks of bleeding and infection, and it has never been tested for PNC-28. [6]

Which product is in the vial?

The research used peptide made in laboratories for the studies. Products sold online as research use only are a different matter: they are not checked by any regulator for identity, purity or sterility. In April 2026, Health Canada warned that unauthorized injectable peptides bought online can seriously harm people. It did not name PNC-28, but the warning covers products like it. [10]

How should PNC-28 be stored, and how long does it last?

Not established. No stability study of PNC-28 has been published, and sellers' pages disagree. One says to keep the sealed powder frozen at -20 °C and refrigerate it at 2–8 °C once mixed. Another says to refrigerate vials at 2–8 °C in its shipping notes but to store them at room temperature (20–25 °C) in its FAQ. Others say freezer or fridge for the powder, and fridge use within about a month once mixed. Several also say to protect vials from light and not to refreeze a mixed vial. None cites a test on PNC-28. [35], [36], [25], [37]

The one related finding is from a dish, where the peptide appeared to lose activity within a day at body temperature. Storage advice written for PNC-27 or for peptides in general has not been tested on PNC-28. [1]

This guide does not cover mixing, sterile technique or injection; the Academy note below covers practical handling basics.

What do we actually know about PNC-28 in people?

Nothing. No human trial of PNC-28 has been registered, no study has measured how the body handles it, no human dose has been tested, and we found no published report of anyone taking it. Everything that exists is preclinical: cell studies, one animal study and computer modelling. [3], [6]

Doserly

Where has PNC-28 actually been tested?

Cell, animal and human research, from most to least studied.

Cells in a dish

Rat and human cancer cells (pancreas, colon, cervix, lung, breast, bone); normal rat pancreatic cells; blood stem cells from 5 donors. Developer group; effective range 25–100 µg/mL.

Independent normal-cell test

Heart-muscle cells in a dish: more cell death. Abstract only; a 2019 review calls the peptide PNC-28, identity unconfirmed.

Mice

One study (2006): rat pancreatic tumours; 14-day pump, mostly under the skin; 4–5 mice per group. 1–20 mg per mouse in total; only 20 mg slowed established tumours; no blood or liver tests; never convert to a human dose.

People

No trials registered. No reports of use. PNC-27 has one case report; PNC-28 has none.

Mouse doses are study doses only and do not convert to a human dose.

Almost all of the evidence comes from cells and mice; no human trial has tested PNC-28.

The research base is also small. A PubMed search on September 26, 2026 found 7 records that mention PNC-28, against 25 for PNC-27, and PNC-28 has only one animal study, from 2006. PNC-27 has more cell work, several mouse studies and one published human case report; PNC-28 has none of the last. [6], [50], [51]

Who produced the research?

Almost all of it comes from the group that designed the peptide, whose members are named inventors on related intellectual property; one of its recent reviews also reports ties to a related company. That does not make the findings wrong, but it means they have not been independently confirmed. The only independent PNC-28 work is a gene-delivery study, a computer-modelling study, a chemistry paper and the heart-muscle-cell study described below. [7], [19], [47], [48], [21], [8]

What the mouse study can and cannot tell you

The 2006 study is the strongest evidence that exists, and its limits are large. [6]

• Rat cells in special mice. The tumours were rat cancer cells growing in mice with weak immune systems, not human cancers in people.
• Very small groups. Each group had 4 or 5 mice. The authors say most experiments were repeated at least once (the abdominal-pump experiment was not), but much of the repeat data is not shown.
• A delivery people cannot copy. The peptide was released continuously for two weeks from an implanted pump, not injected.
• Unclear amounts. For the first experiments the text says 2 mg per mouse and a table heading says 10 mg. For tumours already growing, only the highest total tested, 20 mg per mouse, had a significant effect, and the authors called it roughly the lowest amount that worked.
• Thin safety checks. Treated mice kept their weight and behaved normally. The authors state they did not measure blood counts or liver function, and no organ or toxicity testing has been published.

What would a useful result look like?

For a cancer drug, the questions are concrete: does the tumour shrink or stop growing on scans, do people live longer or better, and how does that compare with people who did not receive it? For PNC-28, none of these has been measured, and a personal impression of feeling better cannot show that a tumour responded, especially when other treatments changed at the same time.

That is why a clear record matters: exact products, doses and dates, alongside scans, blood tests, symptoms and every other treatment, give an oncology team something to interpret.

How might PNC-28 work?

All of what follows comes from cell studies, mostly by the developers. It describes a proposed model, not something shown in people.

What are p53 and HDM-2?

p53 is a protein that stops damaged cells from dividing, and HDM-2 is the protein that keeps p53 in check. Many cancers make extra HDM-2. PNC-28 carries the 10 positions of p53 (17 to 26) that directly contact HDM-2, so it is built to grip HDM-2 the way p53 does. [1]

Punching holes: the pore model

The developers propose that cancer cells carry HDM-2 in their outer membrane, while most normal cells carry little or none there. In their model, PNC-28 binds that membrane HDM-2, the pairs cluster into ring-shaped pores, and the cell's contents leak out within minutes. They call this "poptosis". Electron microscope images showed pores in human pancreatic cancer cells 15 minutes after PNC-28 was added, and a cell-damage enzyme called lactate dehydrogenase (LDH) leaked out almost at once. [19], [16]

The leader changes how cells die

A 2008 study asked what the leader does. When the 10-amino-acid p53 piece was made inside pancreatic cancer cells without the leader, the cells died by apoptosis, a tidy, programmed form of cell death, with raised p53 and the usual apoptosis markers. When PNC-28 with the leader was added from outside, the cells died by necrosis, a fast breakdown of the outer membrane, and p53 did not rise. The authors concluded that the leader is responsible for this switch. [16], [19]

Does the order of the parts matter?

It appears to. In a developer patent, a version called PNC28′, with the leader attached to the other end of the same p53 piece, killed no rat pancreatic cancer cells after two weeks at 25 to 100 µg/mL; about half of the cells instead took on a more normal shape. With the leader on its usual end, PNC-28 killed all the cells within about 4 days at 50 and 100 µg/mL. This is one cell experiment, reported in a patent rather than a peer-reviewed paper. [46]

Why it may not need working p53

Many cancers have a broken p53 gene, which blocks treatments that rely on switching p53 back on. In the 2001 study, PNC-28 killed human colon cancer cells with no p53 at all, and the usual p53-driven death proteins (Bax and p21) did not rise. That fits the membrane model rather than a p53 effect inside the cell. [1]

How selective is it for cancer cells?

The developers report that PNC-28 left normal rat pancreatic cells alive and did not change the growth of blood stem cells from five cord-blood donors at 100 µg/mL, a concentration that killed most cancer cells. [1]

Two independent findings complicate that picture:

• Heart-muscle cells. A 2006 study from a separate laboratory used a peptide inhibitor of MDM2 on isolated heart-muscle cells in a dish. It raised p53 and increased cell death, including in a lab model of heart muscle losing and then regaining its oxygen supply, as happens when blood flow is cut off and restored. The abstract does not name the peptide; a 2019 review identifies it as PNC-28. We could read only the abstract, so the peptide's exact identity, the amounts used and the species are unconfirmed, and this guide gives no numbers from it. [8], [9]
• The shared leader. A 2010 study from another independent laboratory tested PNC-27, which carries the same leader. It was only 2 to 3 times more toxic to tumour cells than to normal cells, and swapping the leader for other cell-penetrating tails removed the preference, so part of the selectivity seems to come from the leader. PNC-28 itself was not tested. [23]

The heart-cell result also differs from the developers' pancreatic cancer findings, where PNC-28 did not raise p53. Different cells, conditions, concentrations or even a different peptide may explain it. Even so, the developers' claim of "no effect on normal cells" has not been confirmed by any independent laboratory. [8], [16]

Where does the lab evidence fall short?

• Almost all of it comes from one research group. [7]
• Cells in a dish are exposed directly, at controlled concentrations, with no immune system, liver or kidneys involved.
• The working range in a dish was narrow, and whether any human dose could reach it in a tumour without reaching it elsewhere is unknown. [1]
• A 2026 computer re-analysis, not yet peer reviewed, points out that the leader closely matches penetratin read backwards (14 of 16 positions). That does not change the findings, but it shows the design has not been fully explained. [52]

What are the risks and unanswered questions?

Is PNC-28 safe?

Nobody knows, because it has never been studied for safety in people or formally tested for toxicity in animals. The mouse study notes that treated mice, including those given the highest total of 20 mg, kept their weight and behaved normally. No blood counts or liver tests were done. An independent lab found more heart-muscle cell death in a dish with a peptide that a later review identifies as PNC-28, though its exact identity is unconfirmed. [6], [8], [9]

What harms have been reported?

In people, none, because we found no report of anyone using PNC-28. No harm report is not the same as evidence of safety: with no users studied, harms would go unrecorded. [3], [53]

The harms that have been reported for the family belong to PNC-27: an FDA warning about contaminated products and one fatal bleeding case whose cause could not be established. They are covered in the comparison below, and they are not PNC-28 findings. [54], [51]

What could go wrong that has not been measured?

These are concerns based on how PNC-28 is meant to work and how research peptides are sold. None has been measured for PNC-28.

• Heart-muscle cells: the independent lab finding above. Whether it happens in a living body, and at what dose, is unknown. [8]
• Tumour lysis syndrome: when many cancer cells die quickly, they release potassium, phosphate and other contents into the blood, which can cause kidney failure, dangerous heart rhythms and death. It is a known emergency with effective cancer treatments. If PNC-28 did kill tumour cells rapidly in a person, this would be a risk. [55]
• Damage at an injection site: a peptide designed to punch holes in cell membranes could harm normal tissue at high local concentrations, especially with a leader whose preference for tumour cells was only partial in an independent test. [23]
• Immune reactions: the body can make antibodies against a foreign peptide (immunogenicity), and this has never been checked.
• Infection and wrong contents: unregulated injectable peptides can be contaminated or mislabelled. [10]

Could product quality change the risk?

Yes. There is no approved PNC-28 product and no official quality standard, and the name has been used for more than one molecule. Only a laboratory test of a specific batch can show what it contains, and even then it covers only the samples tested. [10], [21]

Can PNC-28 replace cancer treatment?

No evidence supports that. PNC-28 has never been compared with any cancer treatment, or given to anyone with cancer in a study. Delaying treatment that works for one that has not been tested can cost time that matters. [3]

Is PNC-28 legal? Is it FDA-approved?

Checked September 26, 2026. A "research use only" label does not make a product legal to sell or use as a medicine.

• United States. Not approved by the FDA for any use. The FDA's substance database gives it an identifier (UNII 5237P710BP), which tracks the substance but is not an approval. It is not on the FDA's list of bulk substances nominated for pharmacy compounding (May 14, 2026 update), so there is no legal compounding route. No FDA warning, recall or enforcement record names PNC-28; the 2017 FDA warning named PNC-27 only. [11], [14], [53], [54]
• Canada. Health Canada's Drug Product Database lists no PNC product. In April 2026 Health Canada warned that unauthorized injectable peptides bought online can seriously harm people; that advisory does not name PNC-28. [12], [10]
• Australia. PNC-28 is not named in the June 2026 Poisons Standard. We did not search the Australian Register of Therapeutic Goods (the list of medicines approved for supply) directly and found no report of an approved product. Not being named in the Poisons Standard does not make a substance approved or legal to sell as a medicine. [13]
• United Kingdom and European Union. Not checked for this guide; we found no report of an approval.

Is PNC-28 banned in sport?

Yes. PNC-28 is not named on the World Anti-Doping Agency (WADA) list, but it falls under class S0, "non-approved substances": any substance with no current approval by a government health authority for human use, including drugs still in preclinical development. S0 substances are banned at all times, in and out of competition. [15]

Who should be especially cautious?

None of the following groups has been studied. That is a reason for caution, not guidance on safe use.

• People with cancer on active treatment: interactions with chemotherapy, targeted drugs, immunotherapy and radiation are untested, and an unreported product can confuse the interpretation of side effects, scans and blood tests. Tell your oncology team. [3]
• People with heart disease, or treatments that strain the heart: an independent lab found more heart-muscle cell death in a dish with an MDM2-blocking peptide that a later review identifies as PNC-28, though its identity is unconfirmed. [8], [9]
• People with weakened immune systems: an unregulated injectable product carries an infection risk. [10]
• People with kidney disease or a large tumour burden: these raise the stakes of tumour lysis syndrome, a concern not measured for PNC-28. [55]
• Pregnancy, breastfeeding or trying to conceive: not studied in any species.
• Under-18s: not studied.
• Drug-tested athletes: banned at all times under S0. [15]

Has PNC-28 been tested alongside other medicines?

No. No study has tested PNC-28 with chemotherapy, other cancer drugs, blood thinners or any everyday medicine, in people or in animals. The only combinations in the research are laboratory constructions, such as attaching it to a gene-carrying particle. Bring a complete list of everything you take, including research peptides, to your oncologist or pharmacist. [47]

What should be monitored while using PNC-28?

There is no official monitoring guidance, because no regulator has approved PNC-28 and no human study has run. The only safety observations published from the mouse study are body weight and normal behaviour; its authors state they did not measure blood counts or liver function, and no blood or organ test results for PNC-28 have been published in any species. What can be described is which checks follow from the concerns in this guide. It is information to discuss with a clinician, not a personal testing plan. [6]

Sources for the table: [8], [9], [55], [10], [6]

None of these checks makes an untested product safe. They show what is changing, which is what a clinician needs to judge whether to continue.

What do people in public communities report?

Almost nothing about actual use. Archive searches of public Reddit communities found nine posts about PNC-28: questions, sourcing requests and general commentary. None described taking it, a dose, an outcome or a side effect. Three more threads mention it in passing. These selected posts are not a survey of everyone who has tried it. [29], [30], [34], [41], [42], [31], [43], [44], [45]

What do people ask?

• For brain tumours: one post asks whether anyone has used PNC-28 for a glioma, on the belief that it crosses into the brain. It received no remaining answers, and no study supports the belief. [29]
• For a dose: a post titled "PNC-27 (PNC-28) - Dosage?" was removed by moderators, with no replies archived. In a 2026 post, a reply asks whether a listed schedule was "daily or weekly". [30], [31]
• For a supplier: a person facing a serious diagnosis asked, in the same words across four posts, where to buy PNC-27, PNC-28 and two other experimental compounds, and found only one catalogue seller. [34]

How is it talked about next to PNC-27?

As a fallback, and sometimes as if the two were interchangeable. In a caregiver's PNC-27 thread, one reply suggests PNC-28 if PNC-27 fails. In an older thread, a commenter notes that PNC-28 exists but says they know nothing about it. [41], [42]

The clearest mix-up risk is a 2026 post about pancreatic cancer titled after both peptides. It summarizes the PNC-28 research accurately, then gives a step-up schedule from 100 to 500 mcg a day that it labels as PNC-27. The author later wrote that the family member it was meant for declined it. A reader skimming the title could easily take those amounts as PNC-28 doses; they are not, and they were never tested for either peptide. [31]

Two general commentary posts describe PNC-28 for readers interested in research. One matches the lab evidence (pores and rapid cell bursting). The other describes PNC-28 as adjusting p53 activity rather than breaking the cell membrane, which conflicts with the 2008 study, and links an article that hints at human data. No human study of PNC-28 has been registered or published. [43], [44], [16], [3]

What do community education groups say?

Very little. In lesson material, PNC-28 appears only as a passing note in a PNC-27 course, which describes it accurately as a shorter relative. In member discussions, one caregiver asked about using PNC-27, PNC-28 or both for a relative with active cancer. Replies urged caution: one member living with cancer said they had researched both and decided against them. No one described using PNC-28 or gave an amount for it.

How can you judge a cancer story?

With PNC-28 there are no stories yet, so the practical risk is borrowing someone else's. A report about PNC-27, or about a combination of products, says nothing reliable about PNC-28. For any account, ask what the diagnosis was, what else changed at the same time (surgery, chemotherapy, other products), whether scans or blood tests were checked, and whether there was a follow-up months later.

How does PNC-28 compare with PNC-27 and FOXO4-DRI?

PNC-27 is the peptide PNC-28 is most often confused with, and FOXO4-DRI is another lab-made peptide aimed at the p53 system. No study has compared any of them directly with PNC-28. The route column describes what studies used, not tested human doses.

PNC-28 and PNC-27 are the closest pair, and the difference is small but real. Both carry the same cell-penetrating leader and are proposed to kill cancer cells the same way, by binding HDM-2 in the cell membrane and forming pores. PNC-28 keeps only the 10 p53 positions that directly contact HDM-2; PNC-27 adds five more, which makes it 32 amino acids long and about 4,032 grams per mole against PNC-28's 27 and about 3,509. [1], [19], [20], [2]

Their evidence comes from parallel lab work, not a contest. Most cell studies and the leukaemia mouse study used PNC-27; the pancreatic tumour mouse study used PNC-28. The original cell tests found PNC-21, PNC-27 and PNC-28 behaved alike, and the developers call their activity similar. One dosing website says PNC-27 is "generally more potent" because it has a longer binding region; no study has tested that, so neither peptide can be called stronger. [50], [6], [1], [19], [28]

The safety records differ, but that reflects use and study, not proven chemistry. PNC-27 alone was named in the FDA's 2017 warning after the agency found bacteria in a PNC-27 product; the FDA did not test PNC-28 products. The single fatal bleeding case, whose cause could not be established, also involved PNC-27. PNC-28 has no such record, which reflects how little it has been used and studied, not a sign that it is safer. [54], [51]

No dose carries over in either direction. Even for PNC-27 there is no agreed amount: dosing websites list 100 mcg to 20 mg a day, and amounts shared in community education groups run from 10 mcg to 3 mg and contradict one another. The one seller that lists both gives them different schedules (PNC-27 at 1–2 mg three times a day for 6–24 weeks; PNC-28 at 2.5 mg once a day for 3–4 weeks). None of these amounts has been tested in people, and none should be moved from one peptide to the other. [32], [33], [4]

FOXO4-DRI also involves p53, but it works on a different protein partner and a different kind of cell, so the comparison is loose. [56]

Common questions about PNC-28

Has PNC-28 been tested in people?

No. No human trial of PNC-28 has ever been registered, and we found no published report of anyone taking it. The evidence consists of cell studies, one 2006 mouse study of rat pancreatic tumours and computer modelling. That makes it one step further from people than PNC-27, which at least has a single published human case report. Online hints of early human testing are not backed by any registered trial or published report. Everything known about PNC-28's effects comes from dishes and mice, so its benefit, safety and dose in people are all unknown. [3], [6], [44] See what is known in people.

What is the dose of PNC-28?

No human dose has ever been tested. No study, label or registered trial gives one. A single seller's page lists 50 syringe units of a 5 mg vial mixed with 1 mL (2.5 mg) every morning for 3–4 weeks, with no source and no route, and no other website we checked gives a human amount. The research used concentrations in a dish (25–100 µg/mL) and pump totals of 1 to 20 mg per mouse over 14 days, and neither can be converted into a human dose. PNC-27 amounts found online belong to a different peptide and were never tested in people either. [4], [3], [1], [6] See the protocol section.

Is PNC-28 the same as PNC-27?

No. PNC-28 is a shorter relative from the same research group. Both carry the same 17-amino-acid cell-penetrating leader, but PNC-28 keeps only p53 positions 17 to 26, while PNC-27 carries positions 12 to 26. The developers describe their activity in cells as similar, and no animal study has compared them. The two are separate products with separate evidence, and PNC-27 findings, including its FDA warning and case report, should not be assumed to apply to PNC-28. [1], [19] See the comparison.

Is PNC-27 or PNC-28 more potent?

Nobody knows. The original 2001 cell study found PNC-21, PNC-27 and PNC-28 behaved alike against rat pancreatic cancer cells, and the developers' 2024 review calls PNC-28's anticancer activity "similar to that of PNC-27". One dosing website says PNC-27 is more potent because its p53 piece is longer, but no study has compared the two head to head, in cells or in animals, at matched doses. [1], [19], [28] See the comparison.

Does PNC-28 harm normal cells?

The developers report that it does not: normal rat pancreatic cells and human blood stem cells survived concentrations that killed cancer cells. But the one independent test in normal cells found the opposite: in heart-muscle cells in a dish, a peptide a 2019 review identifies as PNC-28 raised p53 and increased cell death. A separate lab found that PNC-27, with the same leader, was only 2 to 3 times more toxic to tumour cells than to normal cells. [1], [8], [9], [23] See the selectivity evidence.

Can PNC-28 cross the blood-brain barrier?

There is no evidence that it does. The idea appears in a public post asking about brain tumours, but no study has measured whether PNC-28 reaches the brain, and none has tested it on brain tumours in animals or people. Its only animal study used tumours in the abdomen and in subcutaneous tissue, with the peptide released from a subcutaneous or abdominal pump. [29], [6] See the uses section.

Is it legal to buy PNC-28?

It is not an approved medicine in the United States or Canada, and it has no legal pharmacy compounding route in the US. Sellers label it "research use only", which does not make it legal to sell or use as a medicine. It is not named in Australia's June 2026 Poisons Standard, and we did not check the UK or EU. It is banned in sport at all times under the WADA S0 class. [11], [14], [12], [13], [15] See legal status.

Is PNC-28 the same as p28?

No. "p28" is a different anticancer peptide, a 28-amino-acid piece of azurin, a protein from bacteria, and it has been given by infusion to 15 people with advanced cancer in a first safety trial. PNC-28 is built from human p53 and a cell-penetrating leader, and none of the p28 results apply to it. Also watch for "cyclic PNC-28", which one chemistry paper used for the bare 10-amino-acid p53 piece without the leader, a different and much smaller molecule. [22], [21], [1] See what PNC-28 is not.

Glossary

Plain explanations of the route, dosing, research and regulatory terms used in this guide. Underlined terms in the text link here.

Adverse event

A harmful or unwanted medical event reported after someone used a treatment. A report alone does not prove the treatment caused it.

Amino acid

A small chemical building block. Chains of amino acids make up peptides and proteins.

Animal study

Research in animals such as mice. It shows what a substance does in a living body, but results in people can differ.

Apoptosis

A tidy, programmed form of cell death in which a cell dismantles itself from the inside. Many cancer treatments work this way.

Bioavailability

How much of a dose reaches the bloodstream in a usable form. It depends heavily on the route. It has never been measured for PNC-28.

Cell study (in vitro)

Research on cells grown in a dish. It gives early clues about biology, but it is far from proof of benefit in people.

Cell-penetrating peptide

A short, usually positively charged chain of amino acids that helps a molecule stick to or cross cell membranes. PNC-28's 17-amino-acid leader is one.

Compounding

When a pharmacy prepares a customized medicine from individual ingredients. In the US, federal lists control which bulk ingredients pharmacies may use.

Controlled trial

A study that compares people who receive a treatment with a similar group who do not. No controlled trial of PNC-28 exists.

Course and cycle

A course is one continuous stretch of use; a cycle is a course followed by a planned break. No course length or cycle has been studied for PNC-28.

Daily total

All the amounts given in one day, added together. For example, 250 mcg twice a day is a 500 mcg daily total.

Dose (amount each time)

The amount given on one occasion. A protocol lists both the dose and how often it is given. No human dose of PNC-28 exists.

Half-life

The time it takes for the measured level of a substance in the blood to fall by half. It is not the same as how long an effect lasts.

HDM-2 (MDM2)

A protein that keeps the tumour suppressor p53 in check. HDM-2 is the human version; MDM2 is the name for the mouse version and is often used for both. PNC-28 is designed to bind it.

Heart-muscle cell (cardiomyocyte)

The cells that make the heart contract. Researchers can grow them in a dish to test how substances affect them.

IC50

The concentration of a substance that kills or blocks half of the cells in a test. A lower IC50 means a stronger effect in that test.

Immunogenicity

The tendency of a substance to provoke an immune response, such as antibodies or an allergic reaction. Not studied for PNC-28.

Intraperitoneal (IP)

Delivered into the abdominal cavity, the space around the gut. One experiment in the PNC-28 mouse study placed the pump there; people do not use this route.

Investigational

Still being studied and not approved by a regulator, such as the FDA, to treat any condition.

Loading phase

A short period of higher or more frequent doses at the start of a course. None has been described for PNC-28.

mcg and mg

Micrograms and milligrams. 1 mg equals 1,000 mcg, so 500 mcg is half a milligram.

Micromolar (µM)

A measure of concentration that counts molecules rather than weight. For PNC-28, 40 micrograms per millilitre is about 11 micromolar.

Necrosis

A fast, uncontrolled form of cell death in which the cell's outer membrane fails and its contents leak out.

Osmotic minipump

A small capsule implanted in a lab animal that releases a drug slowly and steadily for days or weeks, instead of separate injections.

p53

A protein that helps stop damaged cells from dividing, often called a tumour suppressor. Its gene is changed in many cancers.

Peptide

A short chain of amino acids. PNC-28 is a chain of 27.

Pharmacokinetics

How the body absorbs, moves, breaks down and removes a substance. No pharmacokinetic study of PNC-28 has been published.

Placebo

An inactive dummy treatment given to a comparison group so that real effects can be told apart from expectation and chance. The PNC-28 mouse study used a control peptide or salt water instead.

Preclinical research

Studies done before research in people: cell studies and animal studies.

Reconstitution

Mixing a freeze-dried powder with a liquid so it can be measured. The amount of liquid sets how much peptide each unit holds.

Research use only

A label on products sold for laboratory research. It does not mean a product is approved, tested for human use or legal to sell as a medicine.

Subcutaneous (SC)

Injected into the fatty layer just under the skin. It has never been studied in people for PNC-28; the only mouse study released it continuously from a pump placed under the skin.

Syringe units

Markings on an insulin syringe that measure volume. On a U-100 syringe, 100 units equal 1 mL. The amount of drug per unit depends on the vial's concentration.

Titration

Adjusting a dose in steps, usually starting lower and increasing. No titration has been described for PNC-28.

Trial registry

A public database, such as ClinicalTrials.gov, where studies are recorded before they run. No PNC-28 study is registered.

Tumour lysis syndrome

A medical emergency in which many cancer cells break down quickly and flood the blood with potassium, phosphate and other contents, which can damage the kidneys and heart.

UNII

Unique Ingredient Identifier: a code the FDA assigns to a substance so it can be tracked in its databases. Having one is not an approval.

WADA

The World Anti-Doping Agency, which publishes the list of substances banned in sport. Its class S0 covers substances with no human approval.

Withdrawal and rebound

Withdrawal effects are symptoms caused by stopping a substance. A rebound is a problem returning worse than before. Neither has been studied for PNC-28.

Explore more of the research

Across this guide, the citations include 12 original scientific papers and reports. 7 of them tested or described PNC-28 itself (cell, animal, chemistry and computer-modelling work); the rest are about PNC-27, the shared leader or a related peptide and are used for comparison. The optional library below summarizes 8 of them, grouped by question. Paper counts are not counts of independent research teams: most PNC-28 papers come from the group that designed the peptide. Reviews, registry searches, regulatory documents, websites and public posts are counted separately.

How this guide was researched

This guide is built from a thorough review of the sources cited throughout it: published scientific studies, trial-registry searches, regulatory and anti-doping documents, identity databases and published protocol pages. We also reviewed public online forums and community education groups where people discuss PNC peptides.

The guide cites 60 sources, including 12 original scientific papers and reports. Each type of source answers a different question. Studies show what researchers measured. Protocol pages show what is being claimed about use. Public posts show what people are asking. Every numbered citation links to its entry below, labeled by source type. Reviews, including the developers' 2024 overview of the pore mechanism, helped locate studies but are not counted as independent confirmation. [19], [58], [59], [60]

How this guide was made

Research and drafting were AI-assisted. Every cited source was checked against the original, and the guide was reviewed and edited by Doserly before publication. It has not had an independent clinical review, and Doserly does not currently have medical reviewers. Doserly makes a medication and health-tracking app and runs Doserly Academy, both of which are promoted in this guide. Read our editorial policy for how guides are researched, updated and corrected.

This guide is for educational purposes. It summarizes what the reviewed sources report so the research is easier to understand; it is not medical advice. For a deeper dive, or to check any point for yourself, go straight to the cited sources.

Explore the sources