Redundancy in Growth Factor Receptor Signaling in Adult Astrocytoma Resistance to Small-Molecule Tyrosine Kinase Inhibitors

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript entitled “Redundancy in Growth Factor Receptor Signaling in Adult Astrocytomas: Resistance to Small-Molecule Tyrosine Kinase Inhibitors” by Radu et al. provides a comprehensive overview of growth factor receptors (GFRs) and their associated signaling pathways in adult astrocytomas, with particular emphasis on mechanisms of resistance that may limit the therapeutic efficacy of tyrosine kinase inhibitors. The authors have made a reasonable effort to organize the manuscript using clear headings and subheadings and to provide background information for each GFR and its downstream signaling components. However, the manuscript would benefit from substantial improvement in writing quality, as numerous grammatical and contextual errors detract from clarity and, at times, make the narrative difficult to follow. In addition, the review lacks a sufficiently critical and forward-looking analysis of the current state of the field and does not clearly articulate emerging challenges or future directions necessary to advance therapeutic strategies. Additionally, the manuscript will benefit from addressing the following major points -

Major:

While the manuscript primarily focuses on GFR signaling, genetic alterations beyond GFR control can also drive aberrant pathway activation. For example, PTEN and NF1 loss result in constitutive activation of the PI3K–AKT and RAS–MAPK pathways, respectively, and often form the primary rationale for testing targeted therapies. Adding a dedicated section on such mutations prior to the discussion of GFR signaling would strengthen the manuscript by highlighting parallel and redundant mechanisms of pathway activation.

GFR signaling in cancer is not only driven by tumor cells but is also critically shaped by non-malignant cellular constituents of the tumor microenvironment. A growing body of literature has begun to elucidate the signaling pathways that govern crosstalk between cancer cells and surrounding stromal and immune cells, ultimately influencing therapeutic response. Incorporating discussion of these interactions is an important consideration and highlights future directions for the rational design of targeted combination therapies.

The blood–brain barrier (BBB) represents a major obstacle to the clinical translation of small-molecule kinase inhibitors for central nervous system (CNS) malignancies. Several tyrosine kinase inhibitors have failed in clinical trials for CNS tumors primarily due to inadequate BBB penetration and insufficient intracranial drug exposure. Therefore, it is important to emphasize the critical need for selecting or developing BBB-permeable therapeutic agents. This point could be strengthened by summarizing clinically evaluated kinase inhibitors in a table that details their therapeutic responses alongside evidence of BBB penetration. Such an approach would enhance clarity and rigor, and would help avoid vague descriptions used throughout the manuscript (e.g., statements such as “results were rather unsatisfactory” or “results were rather limited”) by providing concrete, comparative data.

Figures as presented do not substantially elaborate to express the complexity of GFR signaling pathways. Please revise the figure to incorporate nuances in key signaling pathways, making separate subfigure for distinct pathways and incorporating some aspects of tumor microenvironment.

Author Response

Dear Sir/Madam,

We kindly thank you for the opportunity to revise our manuscript.

We welcomed the referee’s comments and clear and revised the manuscript accordingly.

 

Comments and Suggestions for Authors

1.The manuscript entitled “Redundancy in Growth Factor Receptor Signaling in Adult Astrocytomas: Resistance to Small-Molecule Tyrosine Kinase Inhibitors” by Radu et al. provides a comprehensive overview of growth factor receptors (GFRs) and their associated signaling pathways in adult astrocytomas, with particular emphasis on mechanisms of resistance that may limit the therapeutic efficacy of tyrosine kinase inhibitors. The authors have made a reasonable effort to organize the manuscript using clear headings and subheadings and to provide background information for each GFR and its downstream signaling components. However, the manuscript would benefit from substantial improvement in writing quality, as numerous grammatical and contextual errors detract from clarity and, at times, make the narrative difficult to follow. In addition, the review lacks a sufficiently critical and forward-looking analysis of the current state of the field and does not clearly articulate emerging challenges or future directions necessary to advance therapeutic strategies. Additionally, the manuscript will benefit from addressing the following major points –

R: As Reviewer 1 suggested, we improved the manuscript in writing quality, we corrected the grammatical and contextual errors.

2. While the manuscript primarily focuses on GFR signaling, genetic alterations beyond GFR control can also drive aberrant pathway activation. For example, PTEN and NF1 loss result in constitutive activation of the PI3K–AKT and RAS–MAPK pathways, respectively, and often form the primary rationale for testing targeted therapies. Adding a dedicated section on such mutations prior to the discussion of GFR signaling would strengthen the manuscript by highlighting parallel and redundant mechanisms of pathway activation.

R: As Reviewer 1 suggested, genetic alterations allowing cancer cells to bypass blocked RTKs by activating alternative pathways,  increasing GFRs expression or ligand production  have benn described in the introduction (pg.3), but also in subchapters 4.1(pg.12 and 13) and 4.2(pg.14 and 15). This information has been integrated into the relevant sections, without dedicating a new section to this topic, which in our opinion would not fit very well with the topic of the article.

3. GFR signaling in cancer is not only driven by tumor cells but is also critically shaped by non-malignant cellular constituents of the tumor microenvironment. A growing body of literature has begun to elucidate the signaling pathways that govern crosstalk between cancer cells and surrounding stromal and immune cells, ultimately influencing therapeutic response. Incorporating discussion of these interactions is an important consideration and highlights future directions for the rational design of targeted combination therapies.

R: As Reviewer 1 suggested, we incorporated the information in pg.3

4. The blood–brain barrier (BBB) represents a major obstacle to the clinical translation of small-molecule kinase inhibitors for central nervous system (CNS) malignancies. Several tyrosine kinase inhibitors have failed in clinical trials for CNS tumors primarily due to inadequate BBB penetration and insufficient intracranial drug exposure. Therefore, it is important to emphasize the critical need for selecting or developing BBB-permeable therapeutic agents. This point could be strengthened by summarizing clinically evaluated kinase inhibitors in a table that details their therapeutic responses alongside evidence of BBB penetration. Such an approach would enhance clarity and rigor, and would help avoid vague descriptions used throughout the manuscript (e.g., statements such as “results were rather unsatisfactory” or “results were rather limited”) by providing concrete, comparative data.

R: As Reviewer 1 suggested, we added information about BBB (pg.3,5,7,8,10,11,12,13,14). We also added Table 1,  in accordance with Reviewer’s 1 request.

5. Figures as presented do not substantially elaborate to express the complexity of GFR signaling pathways. Please revise the figure to incorporate nuances in key signaling pathways, making separate subfigure for distinct pathways and incorporating some aspects of tumor microenvironment.

R: As Reviewer 1 requested we revised the Figures and added another Figure (Figure 2), which incorporated some aspects of tumor microenvironement.

Reviewer 2 Report

Comments and Suggestions for Authors

Review:

In this review article, Radu et al. have provided a comprehensive overview of growth factor receptor signaling in adult astrocytomas, their role in drug resistance and currently available therapeutic strategies.

Major comments: The reviewer suggests that the article could be enhanced by citing recent information on novel drugs designed to exhibit improved BBB permeability.   

1. For example, ERAS-801 is a highly CNS-penetrant EGFR inhibitor and a fourth-generation TKI BDTX-1535, designed to target specific EGFR mutations with good BBB permeability.
2. Can the authors specify which alternate pathways IGF activates to induce drug resistance?
3. Is there any combination therapy tested to target these alternative pathways to combat drug resistance?
4. The review article may benefit by adding information on how the crosstalk between signalling pathways results in cell state transition. E.g. EMT transition.
5. The reviewer feels that the section with the heading “Molecular mechanisms of resistance of adult astrocytomas to small protein tyrosine kinases inhibitors” can be integrated into the previous relevant sections for better flow.
6. Particularly, how do different molecular pathways maintain glioma stem plasticity?
7. The figures can be improved by adding a biological outcome for each mechanism.

 

Minor comments:

1. The review article requires substantial writing improvement.
2. Some sentences require references e.g. “However, the World Health 35 Organization (WHO) established the most accurate classification.”
3. The following sentence needs to rewrite “In spite all these progresses, the median free-progression survival increased only slowly, mainly in GBM and the quality of life of these patients remain poor [4]”
4. The sentence in lines 59-61 requires more references.
5. In line 146, why STAT/5 has /?
6. What is “vis” in line 174?
7. Correction in line 177, cell not cel.
8. Line 315, is confusing “Next, Raf promotes MEK which further on activated ERK1/2”
9. Lines 348-350 have an incomplete sentence.
10. Line 379, Correct the name of the drug to Wortmannin
11. Ine 383, Correct the name of the drug to Enzastaurin
12. Lines 421-427, it is PKC not PCK.
13. Lines 594-610, is in a different format.
14. Lines 629-631, the statement requires more references.
15. There are spelling mistakes, incomplete sentences and incorrect drug names throughout the article.
16. Some references need correction.

 

Comments on the Quality of English Language

The writing needs to be improved for clarity.

Author Response

Dear Sir/Madam,

We kindly thank you for the opportunity to revise our manuscript.

We welcomed the referee’s comments and clear and revised the manuscript accordingly.

 

Reviewer 2

Comments and Suggestions for Authors

 

1.Major comments: The reviewer suggests that the article could be enhanced by citing recent information on novel drugs designed to exhibit improved BBB permeability. For example, ERAS-801 is a highly CNS-penetrant EGFR inhibitor and a fourth-generation TKI BDTX-1535, designed to target specific EGFR mutations with good BBB permeability.

R: As Reviewer 2 suggested, we added the information in the text(pg.8), and, as well in Table1.

2. Can the authors specify which alternate pathways IGF activates to induce drug resistance?

R: As Reviewer 2 suggested, we added the information ( pg.9)

3.Is there any combination therapy tested to target these alternative pathways to combat drug resistance?

R: As Reviewer 2 suggested, we added the information.

4. The review article may benefit by adding information on how the crosstalk between signalling pathways results in cell state transition. E.g. EMT transition.

R: As Reviewer 2 requested, we added the information (pg.12,13,15)

5. The reviewer feels that the section with the heading “Molecular mechanisms of resistance of adult astrocytomas to small protein tyrosine kinases inhibitors” can be integrated into the previous relevant sections for better flow.

R: As Reviewer 2 suggested, we made the necessary changes.

6. Particularly, how do different molecular pathways maintain glioma stem plasticity?

R: As Reviewer 2 suggested, we added the information at pg. 3

7. The figures can be improved by adding a biological outcome for each mechanism.

R: As Reviewer 2 suggested, we improved the Figures.

8. The review article requires substantial writing improvement.

R: As Reviewer 2 suggested, we improved the writing of the manuscript.

9. Some sentences require references e.g. “However, the World Health 35 Organization (WHO) established the most accurate classification.”

R: As Reviewer 2 suggested, we added more references.

10. The following sentence needs to rewrite “In spite all these progresses, the median free-progression survival increased only slowly, mainly in GBM and the quality of life of these patients remain poor [4]”

R: As Reviewer 2 suggested, we rewrited the sentence.

11. The sentence in lines 59-61 requires more references.

R:As Reviewer 2 suggested, we added more reference.

12. In line 146, why STAT/5 has /?

R:As Reviewer 2 suggested, we corrected the information.

13. What is “vis” in line 174?

R:As Reviewer 2 suggested, we corrected the information.

14. Correction in line 177, cell not cel.

R:As Reviewer 2 suggested, we corrected the information.

15. Line 315, is confusing “Next, Raf promotes MEK which further on activated ERK1/2”

R:As Reviewer 2 suggested, we rewrite the information.

16. Lines 348-350 have an incomplete sentence.

R:As Reviewer 2 suggested, we corrected the information.

17. Line 379, Correct the name of the drug to Wortmannin.

R:As Reviewer 2 suggested, we corrected the information.

18. Ine 383, Correct the name of the drug to Enzastaurin.

R:As Reviewer 2 suggested, we corrected the information.

19. Lines 421-427, it is PKC not PCK.

R:As Reviewer 2 suggested, we corrected the information.

20. Lines 594-610, is in a different format.

R:As Reviewer 2 suggested, we corrected the information.

21. Lines 629-631, the statement requires more references.

R:As Reviewer 2 suggested, we added more references.

22. There are spelling mistakes, incomplete sentences and incorrect drug names throughout the article.

R:As Reviewer 2 suggested, we made the corrections.

23. Some references need correction.

R:As Reviewer 2 suggested, we made the correction.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The revised manuscript addresses my previous comments; however, numerous grammatical, stylistic, and contextual errors remain throughout the text and require careful attention. For example, the term “neutrophins” (line 57) appears to be a typographical error and should likely read “neurotrophins.” The sentence “In this way it is blocked the GF signal which activates the proliferation” (lines 78–79) is grammatically incorrect and lacks clarity. Similarly, the authors incorrectly refer to tyrosine kinase inhibitors (TKIs) as “an attractive therapeutic target” (line 83), which represents a conceptual error.

Additional contextual inaccuracies are evident, including the topic sentence “The PI3K/Akt/mTOR disruption is a hallmark for GBM patients, being related with the progression of the disease, and poor progression” (line 604), which is both grammatically flawed and conceptually incorrect. Overall, the manuscript would benefit substantially from thorough proofreading by a native English speaker with scientific expertise.

Line 114: The statement “Therapeutic resistance can be a consequence either of tumor resection which can enhance stem cell properties or by…” requires clarification. Specifically, the authors should explain the mechanistic basis by which tumor resection is proposed to enhance stem-like properties.

Lines 695–696: The sentence “PKCα together with Janus kinase 2 (JAK2) pathway are able to inhibit GBM cell proliferation and apoptosis [212]” is misleading and inconsistent with the preceding text, which describes PKCα as a protumorigenic signaling pathway. Moreover, the cited reference explicitly states that “cooperative blockade of PKCα and JAK2” induces apoptosis. This section should be corrected to eliminate these inaccuracies and ensure alignment with the cited literature.

Comments on the Quality of English Language

The manuscript would benefit substantially from thorough proofreading by a native English speaker with scientific expertise.

Author Response

We welcomed the Referees comments and revised the manuscript accordingly.

 

As reviewers suggested, following corrections were performed:

The revised manuscript addresses my previous comments; however, numerous grammatical, stylistic, and contextual errors remain throughout the text and require careful attention.

1. The term “neutrophins” (line 57) appears to be a typographical error and should likely read “neurotrophins.”

R: As Reviewer 1 suggested   we changed the term.

2. The sentence “In this way it is blocked the GF signal which activates the proliferation” (lines 78–79) is grammatically incorrect and lacks clarity.

R: As Reviewer 1 suggested we made the necessary change.

3. The authors incorrectly refer to tyrosine kinase inhibitors (TKIs) as “an attractive therapeutic target” (line 83), which represents a conceptual error.

R: As Reviewer 1 suggested we corrected the error.

4. The topic sentence “The PI3K/Akt/mTOR disruption is a hallmark for GBM patients, being related with the progression of the disease, and poor progression” (line 604), which is both grammatically flawed and conceptually incorrect.

R: As Reviewer 1 suggested we made the necessary changes.

5. The statement “Therapeutic resistance can be a consequence either of tumor resection which can enhance stem cell properties or by…” requires clarification. Specifically, the authors should explain the mechanistic basis by which tumor resection is proposed to enhance stem-like properties.

R: As Reviewer 1 suggested we added the needed information.

6. Lines 695–696: The sentence “PKCα together with Janus kinase 2 (JAK2) pathway are able to inhibit GBM cell proliferation and apoptosis [212]” is misleading and inconsistent with the preceding text, which describes PKCα as a protumorigenic signaling pathway. Moreover, the cited reference explicitly states that “cooperative blockade of PKCα and JAK2” induces apoptosis.

R: As Reviewer 1 suggested we corrected the information and eliminated the inaccuracies.

The manuscript would benefit substantially from thorough proofreading by a native English speaker with scientific expertise.

R: The manuscript has undergone English language editing by MDPI. The text has been checked for correct use of grammar and common technical terms, and edited to a level suitable for reporting research in a scholarly journal.

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript has been improved, and all the comments have been addressed. 

Comments on the Quality of English Language

The writing needs to be improved for clarity.

Author Response

We welcomed the Referees comments and revised the manuscript accordingly.

 The writing needs to be improved for clarity.

R: The manuscript has undergone English language editing by MDPI. The text has been checked for correct use of grammar and common technical terms, and edited to a level suitable for reporting research in a scholarly journal.