The Role of Rarely Studied Chemokines in Tumor Progression in Multiple Myeloma (MM)

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This manuscript provides a comprehensive and timely review of chemokines that have been relatively underexplored in the context of MGUS and multiple myeloma (MM). By systematically covering a wide range of CC, CXC, XC, and CX3C chemokines and integrating bioinformatic survival analyses using the GSE4204 dataset, the authors successfully differentiate this work from existing reviews that primarily focus on well-established axes such as CXCL12–CXCR4 or CCL3–CCR1.

 

A particular strength of the manuscript is the molecular subgroup–specific interpretation of chemokine expression and prognosis, which provides potentially valuable insights for translational research and hypothesis generation. Overall, the review is scientifically sound, well referenced, and highly informative.

However, the manuscript would benefit from structural refinement, clearer conceptual framing, and a more explicit discussion of analytical limitations and translational relevance. Addressing the points below would substantially strengthen the clarity and impact of the review.

 

The central concept of “rarely studied chemokines” is intuitively appealing but not explicitly defined. It is currently unclear whether “rarely studied” refers to:
 • Lower publication frequency in MM literature
 • Lack of functional/mechanistic studies
 • Absence of clinical or therapeutic exploration

Please add a short paragraph in the Introduction clearly defining what criteria were used to classify these chemokines as “rarely studied.

The integration of KM-plotter/GSE4204 data is a strong feature of the manuscript; however, its limitations are not sufficiently emphasized.

Important constraints include:
 • The dataset is derived from CD138⁺ myeloma cells, excluding stromal and immune microenvironmental expression.
 • The cohort predates current therapeutic paradigms (anti-CD38 antibodies, CAR-T, bispecific antibodies).
 • Observed associations reflect cell-intrinsic expression only, whereas many chemokines primarily function in intercellular signaling.

A dedicated paragraph in the Discussion (or a recurring caveat at the end of relevant sections) should explicitly state these limitations to avoid overinterpretation of prognostic associations.

Although MGUS is highlighted in the title, the discussion predominantly focuses on established MM. The biological transition from MGUS to MM, particularly in terms of immune surveillance and microenvironmental remodeling, is not fully developed.

Author Response

Rev.1.

This manuscript provides a comprehensive and timely review of chemokines that have been relatively underexplored in the context of MGUS and multiple myeloma (MM). By systematically covering a wide range of CC, CXC, XC, and CX3C chemokines and integrating bioinformatic survival analyses using the GSE4204 dataset, the authors successfully differentiate this work from existing reviews that primarily focus on well-established axes such as CXCL12–CXCR4 or CCL3–CCR1.

 

A particular strength of the manuscript is the molecular subgroup–specific interpretation of chemokine expression and prognosis, which provides potentially valuable insights for translational research and hypothesis generation. Overall, the review is scientifically sound, well referenced, and highly informative.

However, the manuscript would benefit from structural refinement, clearer conceptual framing, and a more explicit discussion of analytical limitations and translational relevance. Addressing the points below would substantially strengthen the clarity and impact of the review.

 

The central concept of “rarely studied chemokines” is intuitively appealing but not explicitly defined. It is currently unclear whether “rarely studied” refers to:
 • Lower publication frequency in MM literature
 • Lack of functional/mechanistic studies
 • Absence of clinical or therapeutic exploration

Please add a short paragraph in the Introduction clearly defining what criteria were used to classify these chemokines as “rarely studied.

A precise definition of rarely studied chemokines in MM has been added

The integration of KM-plotter/GSE4204 data is a strong feature of the manuscript; however, its limitations are not sufficiently emphasized.

Important constraints include:
 • The dataset is derived from CD138⁺ myeloma cells, excluding stromal and immune microenvironmental expression.
 • The cohort predates current therapeutic paradigms (anti-CD38 antibodies, CAR-T, bispecific antibodies).
 • Observed associations reflect cell-intrinsic expression only, whereas many chemokines primarily function in intercellular signaling.

A dedicated paragraph in the Discussion (or a recurring caveat at the end of relevant sections) should explicitly state these limitations to avoid overinterpretation of prognostic associations.

 

The limitations of bioinformatics analysis are outlined in the introduction. An additional section on limitations is included at the end of the paper.

Although MGUS is highlighted in the title, the discussion predominantly focuses on established MM. The biological transition from MGUS to MM, particularly in terms of immune surveillance and microenvironmental remodeling, is not fully developed.

 

We agree with the reviewer that we should have better described the importance of chemokines in MGUS. This is especially true given that we stated in the title that the article would address MGUS in addition to MM. However, the role of rarely studied chemokines in neoplastic processes in MGUS has been very little studied. Therefore, we are unable to add additional information to our paragraph. Because the title of our review is misleading, we have deleted the information that it also addresses MGUS.

 

 

 

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Cytokines are a group of important non-cellular components in the bone marrow microenvironment. They exert multifaceted functions in the initiation, progression, and drug resistance of multiple myeloma (MM). This review focuses on the significance of less well-known chemokines in MM tumorigenic processes, summarizes the functions of these cytokines, performs prognostic bioinformatic analyses using the KM-plotter portal, and outlines potential therapeutic targets in MM. However, several aspects of the manuscript could be improved to enhance its quality and impact:

1. The manuscript states, “Multiple myeloma (MM) is a plasma cell malignancy that resides in the bone marrow.” This description is not concise and overlooks extramedullary disease, which occurs frequently in MM patients.
2. What is the concentration of common cytokines (e.g., CXCL1–12) and their receptors (CXCR1–4) compared to that of less common cytokines? If the concentration of these less common cytokines is extremely low, their functional relevance is likely limited. Additionally, the biological roles of some of these less common cytokines have not been experimentally validated, which diminishes the significance of this review.
3. The authors only describe the mechanisms of cytokine action by citing relevant literature. It is recommended that these mechanisms be summarized in figures to improve readability and facilitate the audience’s understanding.
4. The functions of these less common cytokines in the precursor states of MM, namely monoclonal gammopathy of undetermined significance (MGUS) and smoldering multiple myeloma (SMM), are rarely addressed in the manuscript.
5. The authors only utilized the GSE4204 dataset, which is relatively outdated. It is suggested that more recent datasets (e.g., CoMMpass) be incorporated to strengthen the robustness of the bioinformatic analyses. Furthermore, the KM survival analyses only evaluated cytokine levels in MM cells to predict prognosis, which is insufficiently accurate. Cytokines also regulate the function of other cell types in the bone marrow microenvironment, such as immune cells, and these regulatory effects can also influence patient prognosis—particularly in those receiving immunotherapies such as CAR-T cell therapy and bispecific antibodies.

Author Response

Rev.2.

Cytokines are a group of important non-cellular components in the bone marrow microenvironment. They exert multifaceted functions in the initiation, progression, and drug resistance of multiple myeloma (MM). This review focuses on the significance of less well-known chemokines in MM tumorigenic processes, summarizes the functions of these cytokines, performs prognostic bioinformatic analyses using the KM-plotter portal, and outlines potential therapeutic targets in MM. However, several aspects of the manuscript could be improved to enhance its quality and impact:

1. The manuscript states, “Multiple myeloma (MM) is a plasma cell malignancy that resides in the bone marrow.” This description is not concise and overlooks extramedullary disease, which occurs frequently in MM patients.

The MM definition has been improved as recommended by the reviewer.

1. What is the concentration of common cytokines (e.g., CXCL1–12) and their receptors (CXCR1–4) compared to that of less common cytokines? If the concentration of these less common cytokines is extremely low, their functional relevance is likely limited. Additionally, the biological roles of some of these less common cytokines have not been experimentally validated, which diminishes the significance of this review.

In our paper, we discussed 30 different chemokines. We cited 81 experimental studies examining these chemokines in in vitro and in vivo models, as well as articles examining material from MM patients. Of course, some of these chemokines do not play any role in the mechanisms of tumorigenesis in MM. However, demonstrating the lack of significance of a given chemokine is also an important scientific finding. In our paper, we aimed to discuss all rarely studied chemokines in the mechanisms of tumorigenesis in MM, which we achieved.

Different articles report different concentrations of a given chemokine. This may be due to the study methodology, sample collection, and so on. In our paper, we cited experimental studies demonstrating statistically significant differences between concentrations in MM patients and healthy individuals. Extremely low concentrations of a given chemokine do not rule out its involvement in the neoplastic mechanisms of MM. It may act locally. Therefore, we compared all chemokines with a bioinformatic analysis. This analysis demonstrates the correlation between the concentration of a given chemokine in MM cells and the prognosis for MM patients, which significantly indicates some correlation between the analyzed chemokine and MM.

1. The authors only describe the mechanisms of cytokine action by citing relevant literature. It is recommended that these mechanisms be summarized in figures to improve readability and facilitate the audience’s understanding.

As recommended by the reviewer, figures were added to the article.

1. The functions of these less common cytokines in the precursor states of MM, namely monoclonal gammopathy of undetermined significance (MGUS) and smoldering multiple myeloma (SMM), are rarely addressed in the manuscript.

We agree with the reviewer that we should have better described the importance of chemokines in MGUS. This is especially true given that we stated in the title that the article would address MGUS in addition to MM. However, the role of rarely studied chemokines in neoplastic processes in MGUS has been very little studied. Therefore, we are unable to add additional information to our paragraph. Because the title of our review is misleading, we have deleted the information that it also addresses MGUS.

1. The authors only utilized the GSE4204 dataset, which is relatively outdated. It is suggested that more recent datasets (e.g., CoMMpass) be incorporated to strengthen the robustness of the bioinformatic analyses. Furthermore, the KM survival analyses only evaluated cytokine levels in MM cells to predict prognosis, which is insufficiently accurate. Cytokines also regulate the function of other cell types in the bone marrow microenvironment, such as immune cells, and these regulatory effects can also influence patient prognosis—particularly in those receiving immunotherapies such as CAR-T cell therapy and bispecific antibodies.

 

We are experiencing difficulties obtaining analyses from CoMMpass. Therefore, we have enriched our bioinformatics analysis with the GSE24080 dataset. Both datasets, GSE4204 and GSE24080, analyze gene expression in MM cells and correlate this analysis with patient survival. These results are not time-varying. We agree with the reviewer that such an analysis does not demonstrate the relationship between chemokine-mediated interactions between non-MM cells and MM cells. It only demonstrates the effects of chemokines on MM cells and the effects of chemokines produced by MM on the bone marrow microenvironment. For this reason, we have described the shortcomings of our bioinformatics analysis.

 

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The review effectively addresses less-studied chemokines and their receptors, emphasizing their roles in the biology, pathogenesis, prognosis, and treatment of multiple myeloma (MM) and monoclonal gammopathy of undetermined significance (MGUS). While the manuscript provides a comprehensive overview, including additional key findings would further enhance its impact.

1.     Recent evidence demonstrates that MM-derived CCL3 induces RANKL expression in both human and murine osteocytes. Inhibition of CCL3, through genetic or pharmacologic approaches, prevents RANKL upregulation in osteocytes and mitigates MM-cell-mediated bone loss. Mechanistic investigations indicate that MM-derived CCL3 stimulates osteocytes to secrete high mobility group box 1 (HMGB1), which is required for MM cell-induced RANKL upregulation in osteocytes (Anloague A. Haematologica 2025;110:doi: 10.3324/haematol.2024.286484).
2.     The interaction between CCL17and CCL22with the receptor CCR4 facilitates tumor immune evasion and is strongly associated with the initiation, progression, and prognosis of hematological malignancies. CCL17 concentrations are markedly increased in the plasma of MM patients. In a phase II, single-center, open-label trial involving MM patients treated with oral Panobinostat, lenalidomide, and dexamethasone, CCL22 levels decreased in individuals who achieved a sustained therapeutic response (Kobari L, Leukemia. 2022;36(2):540–8).
3.     Cox regression analysis has identified CCL18 and lactate dehydrogenase (LDH) as independent predictors of progression-free survival (PFS) in MM patients. Additionally, CCL18, creatinine, and LDH serve as independent predictors of overall survival (OS) (Qiao B. Carcinogenesis 2023;44:38-45).
4.     Elevated CCR1 expression in plasma cells from newly diagnosed MM patients correlates with poor prognosis. CCR1 may decrease the sensitivity of MM plasma cells to bortezomib, independent of CCL3 (Leuk Res 2024;139:107469). Both CCR1 and CCL3 contribute to reduced glucocorticoid sensitivity in MM cells; inhibition of CCR1 partially restores dexamethasone responsiveness, suggesting a potential strategy to resensitize MM cells to glucocorticoid therapy (Luyckx B. Pharmacol Res 2025;215:107709).
5.     Increased CXCL7levels significantly enhance MM cell proliferation and elevate the risk of pathological fractures in MM patients. In a mouse xenograft model, CXCL7 induces femoral fractures and reduces bone mineral density. Furthermore, CXCL7 activates the JAK/STAT3 pathway through CXCR2 and upregulates MMP13 and c-Myc expression, thereby promoting MM cell growth and stimulating osteoclast signaling (Wang Y. Cell Death Dis 2025;16:74).

 

Author Response

Rev.3.

The review effectively addresses less-studied chemokines and their receptors, emphasizing their roles in the biology, pathogenesis, prognosis, and treatment of multiple myeloma (MM) and monoclonal gammopathy of undetermined significance (MGUS). While the manuscript provides a comprehensive overview, including additional key findings would further enhance its impact.

1.     Recent evidence demonstrates that MM-derived CCL3 induces RANKL expression in both human and murine osteocytes. Inhibition of CCL3, through genetic or pharmacologic approaches, prevents RANKL upregulation in osteocytes and mitigates MM-cell-mediated bone loss. Mechanistic investigations indicate that MM-derived CCL3 stimulates osteocytes to secrete high mobility group box 1 (HMGB1), which is required for MM cell-induced RANKL upregulation in osteocytes (Anloague A. Haematologica 2025;110:doi: 10.3324/haematol.2024.286484).
2.     The interaction between CCL17and CCL22with the receptor CCR4 facilitates tumor immune evasion and is strongly associated with the initiation, progression, and prognosis of hematological malignancies. CCL17 concentrations are markedly increased in the plasma of MM patients. In a phase II, single-center, open-label trial involving MM patients treated with oral Panobinostat, lenalidomide, and dexamethasone, CCL22 levels decreased in individuals who achieved a sustained therapeutic response (Kobari L, Leukemia. 2022;36(2):540–8).

This paper has already been cited in our review, bibliographic item 115.

1.     Cox regression analysis has identified CCL18 and lactate dehydrogenase (LDH) as independent predictors of progression-free survival (PFS) in MM patients. Additionally, CCL18, creatinine, and LDH serve as independent predictors of overall survival (OS) (Qiao B. Carcinogenesis 2023;44:38-45).

This paper has already been cited in our review, bibliographic item 179.  

1.     Elevated CCR1 expression in plasma cells from newly diagnosed MM patients correlates with poor prognosis. CCR1 may decrease the sensitivity of MM plasma cells to bortezomib, independent of CCL3 (Leuk Res 2024;139:107469). Both CCR1 and CCL3 contribute to reduced glucocorticoid sensitivity in MM cells; inhibition of CCR1 partially restores dexamethasone responsiveness, suggesting a potential strategy to resensitize MM cells to glucocorticoid therapy (Luyckx B. Pharmacol Res 2025;215:107709).
2.     Increased CXCL7levels significantly enhance MM cell proliferation and elevate the risk of pathological fractures in MM patients. In a mouse xenograft model, CXCL7 induces femoral fractures and reduces bone mineral density. Furthermore, CXCL7 activates the JAK/STAT3 pathway through CXCR2 and upregulates MMP13 and c-Myc expression, thereby promoting MM cell growth and stimulating osteoclast signaling (Wang Y. Cell Death Dis 2025;16:74).

 

Following the reviewer's recommendation, we enriched our article with knowledge from the indicated articles.

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

The authors provided an interesting overview on rarely studied chemokine in MM. The paper is well organized and written. I'd like to ask the authors if they could hypotesize a possible combination therapy between modulators of these chemokines and current drug therapy. And the benefits and advantages of exploring these new therapeutic targets in the presence of a large number of available drugs. The same discussion should be described also concerning the prognostic role of these chemokines. 

Author Response

Rev.4.

The authors provided an interesting overview on rarely studied chemokine in MM. The paper is well organized and written. I'd like to ask the authors if they could hypotesize a possible combination therapy between modulators of these chemokines and current drug therapy. And the benefits and advantages of exploring these new therapeutic targets in the presence of a large number of available drugs. The same discussion should be described also concerning the prognostic role of these chemokines. 

 

In accordance with the reviewer's recommendations, the conclusions of the article have been expanded.

 

 

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

I have checked the authors' response, and all my concerns have been fully addressed. I have no additional questions.