Targeting mutant p53 - Evaluation of novel anti-p53 R175H monoclonal antibodies as diagnostic tools

Sep 23, 2026

Uploaded by Jiven

Approximately half of cancers harbor p53 mutations that disable tumor suppressor function, with p53R175H as a frequent hotspot. This study evaluates two novel anti-p53R175H monoclonal antibodies for in vitro antigen-specific binding and for in vivo molecular imaging performance. Both 125I-4H5 and 125I-7B9 show long shelf life and comparable tracer behavior, with slightly faster blood clearance for 125I-7B9. Repeated SPECT/CT, biodistribution, and ex vivo autoradiography confirm higher uptake in mut-p53-expressing tumors and favorable contrast at 48 h post-injection.

LanguageEnglish

CategoryHealthcare

FormatPDF

Pages12

Reading Time30 min

AccessFree to download

Abstract

Background

Study aims and antibodies

In vitro binding assessment

In vivo imaging design and comparisons

Imaging performance and tumor uptake

Conclusions

[www. nature.com/scientificreports](www. nature.com/scientificreports) OPEN Targeting mutant p53: Evaluation of novel anti-p53 R175H monoclonal antibodies as diagnostic tools Diana Spiegelberg1,2􀀍, Le-Ann Hwang3,4, Khian Hong Pua5, Sashwini Chandra Kumar3,4, Xin Yu Koh5, Xiao Hui Koh5, Ram Kumar Selvaraju6, Kanaga Sabapathy4, Marika Nestor1 & David Lane7 About 50% of all cancers carry a mutation in p53 that impairs its tumor suppressor function. The p53 missense mutation p53R175H (p53R172H in mice) is a hotspot mutation in various cancer types. Therefore, monoclonal antibodies selectively targeting clinically relevant mutations like p53R175H could prove immensely value. We aimed to evaluate the in vitro and in vivo binding properties of two novel antip53R175H monoclonal antibodies and to assess their performance as agents for molecular imaging. In vitro, 125I-4H5 and 125I-7B9 demonstrated long shelf life and antigen-specific binding. Our in vivo study design allowed head-to-head comparison of the antibodies in a double tumor model using repeated SPECT/CT imaging, followed by biodistribution and autoradiography. Both tracers performed similarly, with marginally faster blood clearance for 125I-7B9. Repeated molecular imaging demonstrated suitable imaging characteristics for both antibodies, with the best contrast images occurring at 48 h post-injection. Significantly higher uptake was detected in the mut-p53-expressing tumors, confirmed by ex vivo autoradiography. We conclude that molecular imaging with an anti-p53R175H tracer could bea promising approach for cancer diagnostics and could be further applied for patient stratification and treatment response monitoring of mutant p53-targeted therapeutics. Keywords Cancer diagnostics, Mutant p53, Intracellular targets, Molecular imaging p53 is the most mutated gene across all cancer types, and p53 mutations are heavily involved in carcinogenesis and the response to therapy1. About 50% of all cancers carry a mutation in p53 that impairs its tumor suppressor function, making p53 a rare, almost universal, cancer marker in an otherwise very heterogeneous landscape of oncogenes and tumor suppressor genes. Among the p53 mutations, several hotspot mutations occur frequently2. These include R175(4 .8%), G245(3 . 12%), R248 (6 .79%), R249 (2 .59%), R273 (6 .55%) and R282 (2 .59%)2,3. The location of these mutations within the DNA-binding domain suggests their importance in disrupting the normal function of the p53 protein. There are generally two types of p53 mutants based on their effects on the protein structure and function. The first type, known as contact mutants, includes mutations like R248W and R273H4. These mutations specifically affect the ability of the mutant p53 protein to bind to DNA. As a result, mutant p53 loses its ability to carry out its tumor-suppressor functions, which include regulating cell growth, inducing cell death, and preventing the formation of cancerous cells. The second type of p53 mutants are conformational mutants, such as R175H and G245S4. These mutations alter the three-dimensional structure of the DNA-binding domain, rendering it incapable of properly interacting with DNA. Overall, both conformational and contact mutants of p53 result in defective DNA binding and the loss of p53’s tumor-suppressor functions. This disruption in p53 function allows cancer cells to proliferate uncontrollably and evade normal cellular mechanisms that would normally prevent tumor formation. Furthermore, p53 mutations are involved in about 70% of Li-Fraumeni syndrome (LFS) patients, an inherited genetic disorder characterized by early onset of various types of sarcomas and carcinomas5. The p53 missense mutation (p53R175H) is one of the most common hotspot mutations of p53, and is also encountered in 1Department of Immunology, Genetics, Pathology, Uppsala University, Uppsala, Sweden. 2Department of Surgical Sciences, Uppsala University, Uppsala, Sweden. 3Divisions

FAQs

Why is targeting mutant p53, especially p53R175H, relevant for cancer diagnostics?

About 50% of cancers carry p53 mutations that impair tumor suppressor function. p53R175H is a hotspot mutation across multiple cancer types, making it clinically relevant for selective diagnostic targeting.

What did the in vitro experiments show for the two anti-p53R175H monoclonal antibodies?

In vitro assays demonstrated long shelf life and antigen-specific binding for 125I-4H5 and 125I-7B9.

How were the antibodies compared in vivo, and what imaging time point produced the best contrast?

A double tumor model enabled head-to-head comparison using repeated SPECT/CT imaging, followed by biodistribution and autoradiography. The best contrast images occurred at 48 h post-injection.

Sep 23, 2026

Uploaded by Jiven