Mechanism-of-Action-Based Development of New Cyclophosphamides
Round 1
Reviewer 1 Report
The paper entitled "Mechanism of action based development of new cyclophospha-2 mides" is a review focused on a group of anti-cancer drugs. The author has successfully searched for relevant published studies, and also successfully analyzed, presented and discussed the results of available studies.
In order to improve the paper, the text should be edited. On certain occasions the text is very informal or it seems to be a draft version of the text (eg. lines 136-137, 156-157, 279-280, 300-301...). The other point, although not as important as previously mentioned, is starting sentence with numeral which should be avoided.
All things considered this is an interesting paper, that is of sufficient quality to be published after text editing. At this moment the style of the text is strongly affecting the content, decreasing the overall quality of the article.
The text should be edited. On certain occasions the text is very informal or it seems to be a draft version of the article.
Author Response
Author's Reply to the Review Report (Reviewer 1)
Corrections are written in red. The manuscript was revised linguistically and the text (lines 136-137, 156-157, 279-280) and the sentence beginning with numbers changed according to the wishes of the reviewer.
Reviewer 2 Report
this paper provides a detailed review of the pharmacology of cyclophosphamide which as the author correctly highlights remains an important anticancer agent
the paper would benefit from editing line 137 and 156 elude to additional methods and studies - in a paper of this length text should be inclusive and complete
the text contains sections in red and green font which need to be integrated
the references need hyperlinking and editing eg Cancer Chemotherapy and Pharmacology journal is mistyped
occasional edits needed
Author Response
Author's Reply to the Review Report (Reviewer 2)
The text has been revised (corrections in red letters) and the references corrected. Lines 137 and 156 have been edited.
Reviewer 3 Report
The author in this review article describes the clinical significance of the alkylating cytostatic cyclophosphamide (CP) for cancer treatment. It further describes that the mechanism of action remained unknown until recently, resulting in failed attempts to improve its efficacy. The challenge was to apply in vitro methods for phosphoreamide mustard (PAM) production to in vivo circumstances without question. In vitro, PAM is formed by elimination of acrolein from aldophosphamide (ALD), whereas in vivo, ALD is enzymatically converted into 3-hydroxypropanal (HPA) by phosphodiesterases (PDE). The identification of HPA as a proapoptotic aldehyde that initiates p53-controlled DNA alkylation paved the path for a revised mechanism of action for CP and related oxazaphosphorine cytostatics. New CP-like chemicals with lower toxicity and much increased effectiveness add to this understanding. This review has been nicely written and includes all of the important information that is currently available. Here are my comments:
1. Please remove fig1 from line 43.
2. Under metabolism of CP please include other enzyme systems or metabolic routes that can activate CP more effectively than the cytochrome P450 enzymes. This would entail finding enzymes that directly make phosphoramide mustard (PAM) or the active metabolite ALD in greater quantities and with fewer adverse effects.
3. Are there inhibitors that specifically impede the enzymatic routes through which compounds like carboxyphosphamide (CARB) and ketocyclophosphamide, which are produced during detoxification, are formed? ALD and PAM would be more readily available for therapeutic purposes as a result.
4. Please mention techniques that are available to control the competition between PAM formation and CARB or other detoxified products formation. Manipulation of enzyme activity or substrate availability could be used to promote the desired therapeutic pathways.
5. Are there any information or published materials to create ways for introducing catalytic cofactors that stimulate the production of PAM or ALD in vivo, moving the equilibrium toward the targeted metabolites?
6. Examine genetic variants that impact CP metabolism and activation to PAM. This data can be utilized to tailor dosing regimens and improve treatment outcomes.
7. Line 89 please write the “3” in words instead.
8. The author can simply write “Fig. 3” instead of “see Fig. 3” to maintain the consistency in this manuscript.
9. The author has also emphasized on the immunological anti-metastatic therapy with SUM-IAP and have clearly described the preclinical studies. Please include the ongoing clinical trial studies if any associated with this.
10. Please comment on the following: Does SUM-IAP create immunological memory, giving long-term protection against metastatic recurrence? Does SUM-IAP might induce dormancy in metastatic cells, preventing them from reactivating. Does SUM-IAP may have the potential for immunomodulation-related adverse effects such as autoimmune responses or cytokine storms?
11. Please follow one style of citation format while writing the references.
12. Shorten the keywords to one word each and arrange these alphabetically.
Author Response
Author's Reply to the Review Report (Reviewer 3)
1 Please remove fig1 from line 43.
"fig. 1" line 43 has been removed
- Under metabolism of CP please include other enzyme systems or metabolic routes that can activate CP more effectively than the cytochrome P450 enzymes. This would entail finding enzymes that directly make phosphoramide mustard (PAM) or the active metabolite ALD in greater quantities and with fewer adverse effects.
I don't know of any other enzyme systems than Cyt P450 that can activate CP, it would be counterproductive to look for them because they would probably generate toxic CPOH, the formation of which should be avoided.
- Are there inhibitors that specifically impede the enzymatic routes through which compounds like carboxyphosphamide (CARB) and ketocyclophosphamide, which are produced during detoxification, are formed? ALD and PAM would be more readily available for therapeutic purposes as a result.
Yes, there are aldehyde dehydrogenase inhibitors such as disulfiram
- Please mention techniques that are available to control the competition between PAM formation and CARB or other detoxified products formation. Manipulation of enzyme activity or substrate availability could be used to promote the desired therapeutic pathways.
I have tried in vain (with CP-resistant P388 tumors) to shift the competition between detoxification to CARB and the formation of PAM in favor of the formation of PAM with aldehyde dehydrogenase inhibitors. It was these experiments, among others, that led me to consider the aldehyde hydrogenase theory of CP mechanism of action to be incorrect.
- Are there any information or published materials to create ways for introducing catalytic cofactors that stimulate the production of PAM or ALD in vivo, moving the equilibrium toward the targeted metabolites?
I am not aware of any such things
- 6.Examine genetic variants that impact CP metabolism and activation to PAM. This data can be utilized to tailor dosing regimens and improve treatment outcomes.
I've read about genetic cyt P450 variants and ethnic peculiarities of CP activation, but I can't remember the details
- Line 89 please write the “3” in words instead.
„3“ was replaced by the word "three".
- The author can simply write “Fig. 3” instead of “see Fig. 3” to maintain the consistency in this manuscript.
The word "see" has been deleted
- 9.The author has also emphasized on the immunological anti-metastatic therapy with SUM-IAP and have clearly described the preclinical studies. Please include the ongoing clinical trial studies if any associated with this.
I don't know anything about clinical studies with SUM-IAP
- Please comment on the following: Does SUM-IAP create immunological memory, giving long-term protection against metastatic recurrence? Does SUM-IAP might induce dormancy in metastatic cells, preventing them from reactivating. Does SUM-IAP may have the potential for immunomodulation-related adverse effects such as autoimmune responses or cytokine storms?
I cannot answer these three questions because there is no experimental data available. However, I assume that SUM-IAP creates an immunological memory because it allows tumor-directed cytotoxic T cells to proliferate by knocking out inhibitory Tregs.
- Please follow one style of citation format while writing the references.
The references have been revised and standardized
- Shorten the keywords to one word each and arrange these alphabetically.
The new keywords and their order: Aldophosphamide-perhydrothiazines; aldophosphamide-thiazolidines; antimetastatic-therapy; apoptose boosting; cyclophosphamide; immunological therapy; mechanism of action; SUM-IAP
Round 2
Reviewer 1 Report
The authors have modified the paper according to suggestions. I suggest for the paper to be accepted in present form.
