Inhibition of MDM2 by RG7388 confers hypersensitivity to X-radiation in xenograft models of childhood sarcoma
Open accessAbstract
Background: Curative therapy for childhood sarcoma presents challenges when complete resection is not possible. Ionizing radiation (XRT) is used as a standard modality at diagnosis or recurrence for childhood sarcoma; however, local recurrence is still problematic. Most childhood sarcomas are TP53 wild type at diagnosis, although approximately 5–10% have MDM2 amplification or overexpression. Procedures: The MDM2 inhibitor, RG7388, was examined alone or in combination with XRT (20Gy given in 2 Gy daily fractions) to immune‐deficient mice bearing Rh18 (embryonal) or a total of 30 Gy in 2 Gy fractions to mice bearing Rh30 (alveolar) rhabdomyosarcoma xenografts. RG7388 was administered by oral gavage using two schedules (daily ×5; schedule 1 or once weekly; schedule 2). TP53‐responsive gene products (p21, PUMA, DDB2, and MIC1) as well as markers of apoptosis were analyzed. Results: RG7388 showed no significant single agent antitumor activity. Twenty Grays XRT induced complete regressions (CR) of Rh18 with 100 percent tumor regrowth by week 7, but no tumor regrowth at 20 weeks when combined with RG7388. RG7388 enhanced time to recurrence combined with XRT in Rh30 xenografts compared to 30 Gy XRT alone. RG7388 did not enhance XRT‐induced local skin toxicity. Combination treatments induced TP53 responsive genes more rapidly and to a greater magnitude than single agent treatments. Conclusions: RG7388 enhanced the activity of XRT in both rhabdomyosarcoma models without increasing local XRT‐induced skin toxicity. Changes in TP53‐responsive genes were consistent with the synergistic activity of RG7388 and XRT in the Rh18 model. Pediatr Blood Cancer 2015;62:1345–1352. © 2015 Wiley Periodicals, Inc.
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Temozolomide was previously shown to act synergistically with RG7112.
“For example, temozolomide was previously shown to act synergistically with RG7112 [37].”
From Preclinical Efficacy of the MDM2 Inhibitor RG7112 in <i>MDM2</i> -Amplified and <i>TP53</i> Wild-type Glioblastomas (2016) · cites this paper as [37]
The Discussion reports that previous studies found synergy between MDM2–TP53 inhibitors and cytotoxic chemotherapy in hematopoietic cells in vitro. It does not identify temozolomide or say that RG7112 specifically acted synergistically with it; a search for temozolomide found no such passage in our copy. (LLM, conf=0.75)
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References 47 · Cited by 27
- Authors
- Phelps, D., Bondra, K., Seum, S., Chronowski, C., Leasure, J., Kurmasheva, R. T., Middleton, S., Wang, D., Mo, X., & Houghton, P. J.
- Affiliations
- Nationwide Children's Hospital (US)
- The Ohio State University Comprehensive Cancer Center – Arthur G. James Cancer Hospital and Richard J. Solove Research Institute (US)
- Hoffmann‐La Roche, Inc. New York
- Rush University Medical Center (US)
- The Ohio State University (US)
- Corresponding author
- Houghton, Peter J.
- Venue
- Pediatric Blood & Cancer
- Publisher
- Wiley
- Published
- 2015-04
- Volume
- 62
- Issue
- 8
- Pages
- 1345-1352
- ISSN
- 1545-5009 (ISSN-L)
- 1545-5017
- PMC
- PMC4563820
- OpenAlex
- W1763522509
- Cited by
- 27
- References
- 47
- Citations by year
- 2026: 1 · 2024: 2 · 2023: 1 · 2022: 2 · 2021: 3 · 2020: 4 · 2019: 3 · 2018: 4 · 2017: 3 · 2016: 2 · 2015: 2
- FWCI
- 1.60
- Type
- journal article
- Language
- en
- Open access
- green
- www.ncbi.nlm.nih.gov
- Locations
- Pediatric Blood & Cancer (publishedVersion)
- PubMed (publishedVersion)
- PubMed Central (acceptedVersion)
- Funders
- Hoffmann-La Roche Inc.
- NCI (CA165995 and CA169368)
- Topics
- Health Sciences › Medicine › Oncology › Cancer-related Molecular Pathways
- Health Sciences › Medicine › Pulmonary and Respiratory Medicine › Sarcoma Diagnosis and Treatment
- Health Sciences › Medicine › Genetics › Glioma Diagnosis and Treatment
- Keywords
- RG7388, MDM2 inhibitors, rhabdomyosarcoma, pediatric sarcoma, X-rays, radiosensitization, alveolar rhabdomyosarcoma, embryonal rhabdomyosarcoma, p21, PUMA, DDB2, MIC-1, apoptosis, local recurrence, skin toxicity, xenograft models
- MeSH terms
- Animals, Child, Child, Preschool, DNA-Binding Proteins, Female, Humans, Mice, Nude, Neoplasm Recurrence, Local, Pyrrolidines, Radiation-Sensitizing Agents, Rhabdomyosarcoma, Tumor Suppressor Protein p53, Apoptosis, Xenograft Model Antitumor Assays, Tumor Suppressor Proteins, Cyclin-Dependent Kinase Inhibitor p21, Apoptosis Regulatory Proteins, Mice, Proto-Oncogene Proteins c-mdm2, Growth Differentiation Factor 15, para-Aminobenzoates
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