Review Reports

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

In this review, the authors provide an overview of using ADCs to treat gynecologic cancers, particularly in cases where the cancer has spread or recurred, and treatment options are limited. Overall, ADCs have demonstrated to be more effective than traditional chemotherapy regimens with less toxicity, especially in platinum-resistant patients. But it is important to be cautious of the reality that ADCs can still cause specific side effects such as ocular toxicity and neuropathy. Therefore, it is crucial to take preventive measures, closely monitor patients, and promptly address any issues that arise during treatment. In general, this review paper is very interesting, but there are still two major issues to be addressed before its acceptance.

Major comments:

1.    The authors should further discuss the potential treatment strategies for recurrent/ refractory patients after ADC treatment

2.  What do the authors think of the next-generation ADCs for patients with gynecologic cancers? (for example: bispecific ADCs, payloads with distinct MOA or etc?)

Author Response

Comments 1: 

The authors should further discuss the potential treatment strategies for recurrent/ refractory patients after ADC treatment

Response 1: Heading 4 Line 565-571

At the moment there is no clear consensus how to treat recurrent/refractory gynaecological cancers. Chemotherapy at this stage is usually not effective and can lead to unnecessary toxicities. Depending upon the molecular profile certain targeted agents can be used. For example, Larotrectinib or Entrectinib can be used in NTRK fusion positive tumors Selpercatinib is also an option for RET gene fusion positive tumors 

Comment 2: What do the authors think of the next-generation ADCs for patients with gynecologic cancers? (for example: bispecific ADCs, payloads with distinct MOA or etc?)

Response 2: Heading 3.6 Line 546-562

Next Generation ADCs

Recently newer techniques have been incorporated and next generation ADCs have been created. Keeping with tumor heterogeneity in consideration bispecific antibodies have come up as way to enable simultaneous binding to two distinct target molecules and or cells¹⁰⁸. Few examples of biparatropic ADCs which target different epitopes of Her2 are under investigation, few notable examples are MEDI4276 containing 4 antigen binding sites and targets 2 epitopes^109,110. Another anti Her2 targeting biparatropic ADC is Zanidatamab Zovodotin¹¹¹. ADCs often targets known receptors which are not only expressed in tumor cells but also normal tissues. To overcome this cross reactivity probody- drug conjugates (PDC) are under development. Praluzatamab Ravtansine (CX-2009) is a conditionally activated PDC, a CD166-targetingADC is recently being explored in epithelial ovarian epithelial cancer¹¹². Few more examples are of immune stimulating ADCs which carry immune stimulators as payloads are under development. Degrader-Antibody Conjugates (DACs) are composed of an antibody that targets a specific protein on the surface of cancer cells, and a small molecule degrader that binds to the targeted protein and induces its degradation are also been around and hold promise. Another example is for ADCs which can deliver dual chemotherapeutic agents.

Reviewer 2 Report

Comments and Suggestions for Authors

This manuscript presents a comprehensive review of the emerging therapeutic strategy of antibody-drug conjugates (ADCs) in gynecological cancers and is overall well-constructed. However, several critical areas require further elaboration and improvement to enhance the manuscript's clarity and comprehensiveness.

Firstly, Figure 2 lacks a discussion on the "Bystander effect," which is a crucial aspect of ADCs' mechanism of action. Including a detailed explanation of this effect will provide readers with a better understanding of how ADCs function, particularly in targeting tumor cells while minimizing damage to surrounding healthy tissues.

In Section 2.1.2, the manuscript should address Tecan-based compounds, which are now considered the gold standard in ADC development. Discussing these compounds and their role in ADCs will ensure that the manuscript reflects the current state of the field and acknowledges the importance of these compounds in the design of effective ADCs.

Additionally, the manuscript would benefit from a discussion on the future directions of ADCs. For instance, advancements in antibody technology, such as masked antibodies and biparatopic antibodies, should be discussed with appropriate references. This would provide readers with insights into the potential next steps in ADC development.

Similarly, the manuscript should explore recent advancements in conjugation techniques, such as the AJICAP-M method, which allows for the site-specific conjugation of ADCs in a more efficient and cost-effective manner. These advancements are significant as they offer the potential to broaden the therapeutic index of ADCs, and including a discussion on these methods, along with relevant references, would add substantial value to the manuscript.

Finally, the manuscript should delve deeper into the advancements in payload technology. The emergence of novel format conjugates, which are becoming increasingly prominent, should be discussed with proper references. Including this information will ensure the manuscript provides a comprehensive overview of the current and future landscape of ADC development.

 

Addressing these points will significantly improve the manuscript's depth and ensure it serves as a valuable resource for readers interested in the evolving field of ADCs in gynecological cancers.

Author Response

Comments 1: Firstly, Figure 2 lacks a discussion on the "Bystander effect," which is a crucial aspect of ADCs' mechanism of action. Including a detailed explanation of this effect will provide readers with a better understanding of how ADCs function, particularly in targeting tumor cells while minimizing damage to surrounding healthy tissues

Response 1: Line 104-113

Other factor is that depending on their hydrophobicity can determine the efficacy and toxicity of an ADC. Hydrophobic payloads can diffuse from target expressing cells to adjacent normal cells, a phenomenon called as “bystander effect”. This occurrence is very important specially in regards of heterogeneity of tumors as the therapeutic effects is enhanced due to bystander effect^23,24. At the same time the level of hydrophobicity can affect penetration of the payload into liver causing liver toxicity if being less hydrophobic or can be taken up by tissues causing hematological and ocular toxicities^25–27.Fine tuning of payload in necessary to maintain the bystander effect yet maintaining the efficacy by controlling the drug antibody ratio (DAR)

Comment 2: In Section 2.1.2, the manuscript should address Tecan-based compounds, which are now considered the gold standard in ADC development. Discussing these compounds and their role in ADCs will ensure that the manuscript reflects the current state of the field and acknowledges the importance of these compounds in the design of effective ADCs. 

Response 2: Line 101-104

More recently Topoisomerase I (TOP1) inhibitors constitute as an emerging payload class to engineer antibody drug conjugates labelled as next-generation ADCs. These Exatecan based linker- payload complex is more potent and stable and can carry more concentration of drug to antibody ratio (DAR). 

Comment 3: 

Additionally, the manuscript would benefit from a discussion on the future directions of ADCs. For instance, advancements in antibody technology, such as masked antibodies and biparatopic antibodies, should be discussed with appropriate references. This would provide readers with insights into the potential next steps in ADC development.

Response 3: Heading 3.6 Line 546-562

3.6. Next Generation ADCs

Recently newer techniques have been incorporated and next generation ADCs have been created. Keeping with tumor heterogeneity in consideration bispecific antibodies have come up as way to enable simultaneous binding to two distinct target molecules and or cells¹⁰⁸. Few examples of biparatropic ADCs which target different epitopes of Her2 are under investigation, few notable examples are MEDI4276 containing 4 antigen binding sites and targets 2 epitopes^109,110. Another anti Her2 targeting biparatropic ADC is Zanidatamab Zovodotin¹¹¹. ADCs often targets known receptors which are not only expressed in tumor cells but also normal tissues. To overcome this cross reactivity probody- drug conjugates (PDC) are under development. Praluzatamab Ravtansine (CX-2009) is a conditionally activated PDC, a CD166-targetingADC is recently being explored in epithelial ovarian epithelial cancer¹¹². Few more examples are of immune stimulating ADCs which carry immune stimulators as payloads are under development. Degrader-Antibody Conjugates (DACs) are composed of an antibody that targets a specific protein on the surface of cancer cells, and a small molecule degrader that binds to the targeted protein and induces its degradation are also been around and hold promise. Another example is for ADCs which can deliver dual chemotherapeutic agents.

Response 3: Also Line 79-82

IgG1 antibodies are now more commonly used because of their overall stability in the systemic circulation with a long half-life of 2 to 3 weeks and strong influence on innate immune cells, such as natural killer (NK) cells and macrophages, through interactions with Fcγ receptors¹⁹ "

Comment 4: Similarly, the manuscript should explore recent advancements in conjugation techniques, such as the AJICAP-M method, which allows for the site-specific conjugation of ADCs in a more efficient and cost-effective manner. These advancements are significant as they offer the potential to broaden the therapeutic index of ADCs, and including a discussion on these methods, along with relevant references, would add substantial value to the manuscript.

Response 4: Heading 2.1.4 Line 133-144

2.1.4 Conjugation

Other than the structural details, conjugation is a crucial component for making the ADC more therapeutically effective. Most ADCs have traditionally been constructed using cysteine–maleimide alkylation or, less commonly, lysine–amide coupling. To lessen the chances of heterogeneity, different conjugation techniques are being used to improve the payload delivery. Prime objective is to make homogenous conjugation which produces ADCs which are predictive in terms of DAR. Few of the novel techniques of conjugation used are full alkylation of interchain disulfides used in T-DXd and sacituzumab govitecan, THIOMAB³⁴, incorporation of non-naturally occurring reactive amino acids^35,36, cysteine re-bridging^37,38, Fc-affinity tags³⁹, and site-specific conjugation using various enzymes (such as engineered glycosidases^40,41, transglutaminases^42,43,formyl glycine-generating enzymes^44,45 and sortases^46,47.

Comment 5: Finally, the manuscript should delve deeper into the advancements in payload technology. The emergence of novel format conjugates, which are becoming increasingly prominent, should be discussed with proper references. Including this information will ensure the manuscript provides a comprehensive overview of the current and future landscape of ADC development. 

Response 5: Line 104-115

Other factor is that depending on their hydrophobicity can determine the efficacy and toxicity of an ADC. Hydrophobic payloads can diffuse from target expressing cells to adjacent normal cells, a phenomenon called as “bystander effect”. This occurrence is very important specially in regards of heterogeneity of tumors as the therapeutic effects is enhanced due to bystander effect^23,24. At the same time the level of hydrophobicity can affect penetration of the payload into liver causing liver toxicity if being less hydrophobic or can be taken up by tissues causing hematological and ocular toxicities^25–27.Fine tuning of payload in necessary to maintain the bystander effect yet maintaining the efficacy by controlling the drug antibody ratio (DAR)²⁸. Other than the conventional payloads immunomodulators²⁹ and protein-degrader-recruiting molecules³⁰ have recently emerged as novel payloads.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Following the authors' responses, the manuscript has been sufficiently improved to warrant publication in Current Oncology

Author Response

Comments 1: Following the authors' responses, the manuscript has been sufficiently improved to warrant publication in Current Oncology

Response 1: No response needed 

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have adequately addressed nearly all of the reviewer’s comments. However, regarding Fc-affinity-mediated conjugation, the reviewer recommends including recent advancements in addition to ref 39. The following citation should be added:

Org. Lett. 2024, 26, 27, 5597–5601.

Author Response

Comments 1: 

The authors have adequately addressed nearly all of the reviewer’s comments. However, regarding Fc-affinity-mediated conjugation, the reviewer recommends including recent advancements in addition to ref 39. The following citation should be added:   Org. Lett. 2024, 26, 27, 5597–5601.

Response 1: Line 173

I have added Fc-affinity peptides (AJICAP-M) reference is 40