PHP53-nb
Short answer: PHP53-nb is PHP Biotech’s lead drug candidate: according to the company, a humanized camelid nanobody that carries the 3-NAntC peptide in its binding region, intended for cancers with faulty p53 signalling such as triple-negative breast cancer.[1][2] It is investigational and preclinical, has not been tested in registered clinical trials and has not been approved by any regulator.[3][4]
What is PHP53-nb made of?
The company describes PHP53-nb as a “humanized camelid monoclonal nanobody” that expresses the 3-NAntC peptide in its paratope, the part of the antibody that binds its target, and says no chemical linkers are used.[1][5] Nanobodies are the single binding region of the “heavy-chain-only” antibodies made by camelids such as camels and llamas.[6] 3-NAntC is a synthetic peptide derived from crotoxin B, a protein found in the venom of Crotalus (rattlesnake) species.[7]
How large is PHP53-nb?
The company’s current platform and science pages give about 17 kDa, roughly a tenth of a conventional monoclonal antibody (about 150 kDa).[5][1] The company’s home page in January 2026 gave about 14 kDa.[8] The difference has not been explained and is listed as an open question.
How does the company say it works?
The company says PHP53-nb binds a receptor on tumor cells, is taken into the cell, and sets off a chain of stress responses that reactivates p53 signalling and leads to apoptosis (programmed cell death).[1] In a press release dated 18 September 2026 the company said it had identified uPAR, the urokinase plasminogen activator receptor, as the receptor through which PHP53-nb enters cells.[4] These are the company’s descriptions; this wiki found no peer-reviewed publication of the mechanism for PHP53-nb itself.
What results has the company reported?
The company reports, on its website, laboratory tests in which PHP53-nb lowered the viability of triple-negative breast cancer and pancreatic cancer cell lines over 72 hours compared with a benign breast cell line, and shows similar data for ovarian cancer cell models.[1][9] It also describes a zebrafish tumor model in which malformations appeared only at 20 times the IC50 dose, and a preliminary mouse study in which PHP53-nb remained stable for up to 24 hours.[1] None of these PHP53-nb results were found in peer-reviewed journals; the one published paper tested the 3-NAntC peptide alone.[7]
What did the published 3-NAntC study find?
In the 2024 Molecules study, 3-NAntC at 1 µg/mL for 72 hours reduced the viability of MDA-MB-231 triple-negative breast cancer cells to 49.0 ± 17.5%, compared with 98.2 ± 13.8% for normal human mammary epithelial cells.[7] The authors reported that, in these cell tests, the peptide was more active than cisplatin and similar to doxorubicin, and that it caused cell-cycle arrest and mainly apoptotic cell death.[7] The study was laboratory and zebrafish work only, and it was funded by PHP Biotech.[7]
Which cancers is it being studied for?
The company names triple-negative breast cancer as its focus and also shows data in pancreatic and ovarian cancer cell lines.[2][1][9] These are research models, not approved uses.[3]
Is PHP53-nb approved or available?
No. The company states that PHP53-nb is investigational and has not been approved by the U.S. Food and Drug Administration or any other regulatory authority.[4] No clinical trial of PHP53-nb was registered on ClinicalTrials.gov as of 4 October 2026.[3] See Development stage.
Frequently asked questions
What is PHP53-nb?
An investigational nanobody drug candidate from PHP Biotech that, according to the company, carries the crotoxin B-derived peptide 3-NAntC in its binding region.
Has PHP53-nb been tested in people?
No clinical trial was registered on ClinicalTrials.gov as of 4 October 2026. The company hopes to start clinical trials in 2027.
Is PHP53-nb made from snake venom?
Its peptide, 3-NAntC, is a synthetic peptide derived from crotoxin B, a rattlesnake venom protein. The nanobody itself is produced in cell culture, according to the company.
What is uPAR?
The urokinase plasminogen activator receptor, a cell-surface protein. PHP Biotech announced in September 2026 that it identified uPAR as the entry receptor for PHP53-nb.
See also
References
- ^ a b c d e f g “Our Science” (including the science FAQ). PHP Biotech International Inc. (phpbiotech.com). Retrieved 4 October 2026.
- ^ a b “Understanding Triple-Negative Breast Cancer (TNBC)” (blog post, 31 August 2026). PHP Biotech International Inc. (phpbiotech.com). Retrieved 4 October 2026.
- ^ a b c ClinicalTrials.gov search results for “PHP53-nb”, “PHP53”, “Pepcrotament”, “3-NAntC” and sponsor “PHP Biotech” (no studies found). U.S. National Library of Medicine, ClinicalTrials.gov. Retrieved 4 October 2026.
- ^ a b c “PHP Biotech Identifies uPAR as the Cellular Entry Receptor for Its PHP53-nb Anti-Tumor Nanobody” (Southlake, Texas, 18 September 2026). PressAdvantage newsroom (company press release). Retrieved 4 October 2026.
- ^ a b “Platform”. PHP Biotech International Inc. (phpbiotech.com). Retrieved 4 October 2026.
- ^ “What Is a Nanobody?” (blog post, 17 August 2026). PHP Biotech International Inc. (phpbiotech.com). Retrieved 4 October 2026.
- ^ a b c d e Bezerra P, Motti EF. “3-NAntC: A Potent Crotoxin B-Derived Peptide against the Triple-Negative MDA-MB-231 Breast Cancer Cell Line.” Molecules 2024;29(7):1646. doi:10.3390/molecules29071646. PMID 38611925. PubMed, U.S. National Library of Medicine. Retrieved 4 October 2026.
- ^ Archived copy of phpbiotech.com, captured 23 January 2026. Internet Archive Wayback Machine. Retrieved 4 October 2026.
- ^ a b Home page. PHP Biotech International Inc. (phpbiotech.com). Retrieved 4 October 2026.