The MDM2-p53 Axis in Osteosarcoma: Current Understanding of Regulatory Mechanisms and Targeted Therapeutic Strategies
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe review titled "The MDM2-p53 Axis in Osteosarcoma: Current Understanding of Regulatory Mechanisms and Targeted Therapeutic Strategies" has some lacunae that needs to be addressed.
Although the authors tried to touch upon many topics I find the figures need critical introspection, particularly fig 2 is totally superficial.
In Fig 3 authors should mention the different physiological mutant isoforms with example.
In the tables authors should include physiological effect of the drug like apoptosis, cell cycle arrest etc.
Author Response
Comments 1: Although the authors tried to touch upon many topics I find the figures need critical introspection, particularly fig 2 is totally superficial.
Response 1: We sincerely thank the reviewer for this constructive critique. We completely agree that the original Figure 2 was overly conceptual. To address this, we have critically redesigned Figure 2 to provide a detailed, mechanism-driven visual summary. The revised figure now intricately illustrates the upstream stress-induced activation (e.g., ATM/ATR) and the multidimensional downstream regulatory network of p53. Specifically, we have incorporated the key molecular effectors responsible for cell cycle arrest and apoptosis (e.g., p21, PUMA, Bax/Bak), metabolic reprogramming and ferroptosis (e.g., TIGAR, SCO2, SLC7A11), and tumor microenvironment modulation (e.g., the cGAS-STING pathway). We believe this thoroughly updated figure now perfectly complements the molecular depth discussed in our main text.
Comments 2: In Fig 3 authors should mention the different physiological mutant isoforms with example.
Response 2: We thank the reviewer for this excellent suggestion, which significantly enhances the clinical and physiological relevance of the figure. In accordance with your advice, we have updated Figure 3. We explicitly incorporated representative examples of physiological mutant isoforms directly into the diagram to provide a clearer connection between the molecular classification and actual clinical observations. Specifically, we added major hotspot mutations (e.g., R273, R248) under the "Contact Mutation" branch, and (e.g., R175, R282) under the "Structural Mutation" branch. We have also updated the corresponding figure legend to reflect these specific examples.
Comments 3: In the tables authors should include physiological effect of the drug like apoptosis, cell cycle arrest etc.
Response 3: We agree with the reviewer that detailing the physiological and cellular outcomes is crucial for providing a comprehensive overview of these targeted agents. In response to this valuable suggestion, we have added a new column/row titled "Pharmacological and Physiological Effects" to our targeted therapy summary tables (Table 1 and Table 2). Specifically, in Table 1 (Small-Molecule Inhibitors Targeting MDM2) and Table 2 (Compounds Targeting Mutant p53), we have systematically detailed both its specific molecular mechanism of action and the resulting cellular phenotypes (such as apoptosis and cell cycle arrest, as suggested). We believe this comprehensive addition significantly enhances the pharmacological depth and practical clarity of our summary tables.
Author Response File: 
Author Response.docx
Reviewer 2 Report
Comments and Suggestions for AuthorsThe manuscript deals with one of the important aspects of osteoarcoma molecular biology, namely with Mdm2-p53 axis. Authors comprehensively describe its role in this type of malignancy along with current state of our available pharmacological interventions.
There are no major criticism concerning the bulk of the presented information, the reason why it is believed that the manuscript should be revised is the last part of it (section 5), namely summary and conclusion. These parts keep repeating and rehashing the same information and thus are felt to be overredundant. They need to be revised and shorthened.
Minor issue - 4.1.2. heading says small molecule MDM2 inhibitors but many stated ones in the text are said to inhibit p53 itself and not MDMD2
Author Response
Comments 1: There are no major criticism concerning the bulk of the presented information, the reason why it is believed that the manuscript should be revised is the last part of it (section 5), namely summary and conclusion. These parts keep repeating and rehashing the same information and thus are felt to be overredundant. They need to be revised and shorthened.
Response 1: Thank you for this constructive feedback. We agree that the Summary and Conclusion sections were overly repetitive. We have thoroughly revised and consolidated these sections to eliminate redundancy, focusing on delivering a concise yet comprehensive synthesis of the key points. The revised Conclusion is now more streamlined and forward-looking as belows:
“The MDM2-p53 axis serves as the pivotal driver of osteosarcoma initiation, progression, and chemoresistance. In this malignancy, frequent amplification of the MDM2 gene and subsequent ubiquitin-mediated degradation of p53 represent the predominant mechanisms for inactivating wild-type p53. Consequently, restoring p53 tumor-suppressive function has emerged as a highly promising strategy in precision oncology. Significant progress has been made, from the discovery of classic inhibitors like Nutlins to the clinical evaluation of next-generation agents such as Milademetan and APG-115. However, severe hematological toxicities observed in early clinical feedback and acquired resistance driven by feedback upregulation of MDM2 proteins remain major obstacles to clinical translation.
Looking forward, the therapeutic landscape is shifting from single-agent antagonism toward a multi-dimensional integration of technologies. Future strategies will likely encompass: (1) employing PROTAC technology to directly degrade MDM2 proteins, thereby circumventing non-canonical oncogenic effects associated with protein accumulation; (2) utilizing bone-targeted nanodelivery systems and intermittent dosing regimens to mitigate systemic toxicity; and (3) leveraging single-cell sequencing and AI algorithms to decipher osteosarcoma heterogeneity and optimize combination strategies. This convergence of multi-dimensional approaches holds the potential to unlock the therapeutic promise of the MDM2-p53 pathway, offering a viable and scientifically grounded path toward personalized recovery for patients with osteosarcoma.”
Comments 2: Minor issue - 4.1.2. heading says small molecule MDM2 inhibitors but many stated ones in the text are said to inhibit p53 itself and not MDMD2.
Response 2: Thank you for catching this discrepancy. The reviewer is correct. Due to a formatting error, the heading for Section 4.1.2 was incorrectly duplicated from the previous section. To accurately reflect the content, which focuses on drugs that reactivate mutant p53, we have corrected the heading to: "Functional Reactivation of p53". (Page 12, Line 351).
Author Response File: Author Response.docx
Reviewer 3 Report
Comments and Suggestions for AuthorsDeng et al. nicely summarize a wide range of findings on the p53 tumor suppressor gene and the MDM2-p53 axis, which have significant therapeutic implications in osteosarcoma. This review article not only includes basic knowledge of p53 and MDM2 families at non-expert levels but also extends to an expert-level discussion of the development and improvement of mono-therapeutic strategies, combination therapies, newly developed therapies, translational challenges and future directions. This reviewer has a few comments and suggestions as below.
- Although the authors begin by mentioning TP53 gene mutations (through page 6 and Figure 3), the primary therapeutic target addressed in this article is the MDM2-p53 interaction in the context of wild-type TP53 (Figures 4 and 5). This reviewer feels that the current structure may blur the focus of the article. Descriptions of TP53 mutations may be minimized.
- Sulanemadlin (ALRN-6924), a MDM2/MDMX stapled peptide inhibitor in clinical trials, should be cited somewhere in the manuscript.
- Currently, sections 4.1.1 and 4.1.2 have identical subheadings.
- A schematic illustration of PROTACs may be helpful for readers.
Author Response
Comments 1: Although the authors begin by mentioning TP53 gene mutations (through page 6 and Figure 3), the primary therapeutic target addressed in this article is the MDM2-p53 interaction in the context of wild-type TP53 (Figures 4 and 5). This reviewer feels that the current structure may blur the focus of the article. Descriptions of TP53 mutations may be minimized.
Response 1: We sincerely appreciate the reviewer's insightful observation regarding the structural focus of our manuscript. Our initial intention was to provide a comprehensive overview of the entire "MDM2-p53 axis," which intrinsically encompasses both the hyperactivation of MDM2 (in the context of wild-type p53) and the loss of function due to TP53 mutations.
However, we completely agree with your assessment. Given that the current therapeutic landscape and the predominant drug development efforts are indeed heavily focused on targeting the MDM2-p53 interaction in wild-type tumors, an over-elaboration on TP53 mutations could distract readers from the core message of the article.
To prevent blurring the main focus, we have taken your valuable advice and significantly streamlined the descriptions of TP53 mutations in the revised manuscript. We have condensed the background information and minimized the redundant mechanistic details regarding mutant p53. We are confident that this adjustment sharpens the article's focus, ensuring the spotlight remains on therapies targeting the MDM2-p53 interaction.
Comments 2: Sulanemadlin (ALRN-6924), a MDM2/MDMX stapled peptide inhibitor in clinical trials, should be cited somewhere in the manuscript.
Response 2: We are very grateful to the reviewer for pointing out this important omission. Sulanemadlin (ALRN-6924) is indeed a crucial clinical-stage dual inhibitor of MDM2 and MDMX, and its inclusion significantly updates and strengthens our comprehensive review of targeted therapies. Following your excellent recommendation, we have incorporated a detailed introduction of Sulanemadlin (ALRN-6924) into Section 4.1.1. In the revised manuscript, we now discuss its unique mechanism as a stapled peptide, its dual-targeting capability, and its current status in clinical trials. These updates have been integrated both into the descriptive text in Section 4.1.1 (Page 12, Line 337-350) and as a newly added entry in our summary Table 1 (Page 11), with all relevant literature properly cited and added to the reference list.
Comments 3: Currently, sections 4.1.1 and 4.1.2 have identical subheadings.
Response 3: Thank you for pointing out this duplication error. The heading for Section 4.1.2 was incorrectly copied from the previous section during formatting. We have corrected it to "Functional Reactivation of p53"​ to accurately reflect the section's focus on therapies that rescue mutant p53.
Comments 4: A schematic illustration of PROTACs may be helpful for readers.
Response 4: Thank you for this constructive suggestion. We agree that a schematic would enhance clarity. In response, we have designed and incorporated a new figure (Figure 6) into the manuscript. This illustration clearly depicts the mechanism of PROTAC action, including ternary complex formation, ubiquitination, and proteasomal degradation, thereby improving the educational value of the section.
Author Response File: Author Response.docx
