The Good, the Bad and the Unknown of CD38 in the Metabolic Microenvironment and Immune Cell Functionality of Solid Tumors
Round 1
Reviewer 1 Report
The paper by Konen et al. reviewed that the role of CD38 in the metabolic microenvironment and immune cell functionality of solid tumors. Based on this, they conclude that targeting of the CD38 molecule would be an effective intervention to reinvigorate of immune responses to eliminate the tumor. However, the study addressing the role of CD38 in the immune function is limited. Inclusion of a more extensive discussion is highly recommended.
Major revise:
Line 112, “In T cells, CD38 ligation......effects similar to those observed through TCR/CD3” The effect of CD38 ligation actually has some overlap with induced by CD3, but not similar. Additionally, cytokines release induced by CD38 ligation is hardly the result of T cell, duo to the very low expression or negative of CD38 on the naïve T cells in peripheral blood.
Line 114, Does CD38 ligation induced the expression of multiple cytokines including IL-1b, IL-6, IL-10, and IFN-γ in T cells?
Line 117, “in certain cell types like T cells and NK cells CD38 cooperates with TCR signaling cascades as a part of a supramolecular complex often found most effective within lipid rafts.” Does CD38 cooperate with TCR signaling (or CD16? published in Blood journal) in NK cells?
Line 536, daratumumab does not only suppress CD38+ Tregs and MDSCs, but also depletes NK cells (published in Clinical Cancer Research; JCI Insight). Thus, targeting CD38 may increase the risk of infection and tumor relapse. Extensive discussion is necessary for these concerns.
It should be understood and clearly discussed that how Tregs and/or NK cells are depleted or activated by the CD38 ligation. Because it will provide the important message for the right choices of targeting methods.
Together, the distinct role of CD38 in different immune cells should be sorted out in one paragraph.
Without a figure legend, Figure 2 would be ambiguous and unreadable.
Minor revise:
Line 17: “immunotherapy” to “immunotherapies”
Line 23: “activity” to “activities”
Line 59: “progression” to “the progression”
Line 403: “blockade” to “the blockade”
Line 408: “initiation” to “the initiation”
Line 415: “blockade” to “the blockade”
Line 470: “study” to “studies”
Line 475 “most” to “the most”
Line 483: “there is” to “there are”
Line 527: “suggests” to “suggest”
Author Response
1. Line 112, “In T cells, CD38 ligation......effects similar to those observed through TCR/CD3” The effect of CD38 ligation actually has some overlap with induced by CD3, but not similar. Additionally, cytokines release induced by CD38 ligation is hardly the result of T cell, duo to the very low expression or negative of CD38 on the naïve T cells in peripheral blood.
We appreciate the reviewer’s clarification and have modified the text to more accurately reflect that the signaling regulated by CD38 has only a partial overlap with TCR/CD3 signaling, but is not entirely similar (Line 118).
2. Line 114, Does CD38 ligation induced the expression of multiple cytokines including IL-1b, IL-6, IL-10, and IFN-γ in T cells?
CD38 ligation has been shown to induce the expression of these cytokines in T cells (Ref: Ausiello C.M., Urbani F., la Sala A., Funaro A., Malavasi F. CD38 ligation induces discrete cytokine mRNA expression in human cultured lymphocytes. European journal of immunology. 1995;25(5):1477-80), but also in other cells including monocytes. We have added these details to the text (Line 121).
3. Line 117, “in certain cell types like T cells and NK cells CD38 cooperates with TCR signaling cascades as a part of a supramolecular complex often found most effective within lipid rafts.” Does CD38 cooperate with TCR signaling (or CD16? published in Blood journal) in NK cells?
The reviewer is correct and we have now updated the text to correct this error. We also added additional details for the cooperation between CD16 and CD38 in NK cells, as well as the function of CD38 in other immune cell types (Lines 124-138).
4. Line 536, daratumumab does not only suppress CD38+ Tregs and MDSCs, but also depletes NK cells (published in Clinical Cancer Research; JCI Insight). Thus, targeting CD38 may increase the risk of infection and tumor relapse. Extensive discussion is necessary for these concerns.
As discussed in section 8.1 of the review, there are pro- and antagonistic effects of anti-CD38 treatment strategies, and we agree that the effects of CD38 targeting can impact a variety of immune populations that may alter efficacy and tumor elimination. We have now added in our discussion the mechanism of action of the anti-CD38 antibody daratumumab, the dependency of this efficacy on NK cells mainly through antibody-dependent cell-mediated cytotoxicity, and the subsequent depletion of NK cells that results from daratumumab treatment that in turn impacts efficacy and increases the risk of infectious complications (lines 217-219; 232-236). However, additional work found no correlation between NK cell depletion and patient response to daratumumab or in the rate of infection (ref: Casneuf T., Xu X.S., Adams H.C., 3rd, Axel A.E., Chiu C., Khan I., Ahmadi T., Yan X., Lonial S., Plesner T., et al. Effects of daratumumab on natural killer cells and impact on clinical outcomes in relapsed or refractory multiple myeloma. Blood Adv. 2017;1(23):2105-14), so we have added this as an area requiring further study to determine if NK cell function is a necessary component for efficacy of CD38 targeted agents in solid tumors (Lines 494-496). Additionally, the mechanisms of action and biologic effects of CD38-targeted strategies depend on whether the reagents are antibodies, small molecule inhibitors, or other novel CD38-directed molecules. This important point is also included in the discussion.
5. It should be understood and clearly discussed that how Tregs and/or NK cells are depleted or activated by the CD38 ligation. Because it will provide the important message for the right choices of targeting methods.
The depletion of NK cells by CD38 blocking antibody treatment like daratumumab occurs via apoptosis of this CD38 high population. As mentioned in comment #4, we have now added an enhanced discussion about the role of NK cells in the efficacy of daratumumab treatment via ADCC as well as a comment about the depletion of NK cells via apoptosis (Lines 235-240).
6. Together, the distinct role of CD38 in different immune cells should be sorted out in one paragraph.
We agree that the nearly ubiquitous expression of CD38 in different immune cell populations is an important consideration when implementing anti-CD38 targeting strategies in solid tumors. Therefore, based on the reviewer’s feedback, we have now added additional information about CD38 functions in various immune cell populations, including NK cells, B cells, and myeloid cells (Lines 124-138), and the differences between different targeting strategies.
7. Minor revise:
Line 17: “immunotherapy” to “immunotherapies”
Line 23: “activity” to “activities”
Line 59: “progression” to “the progression”
Line 403: “blockade” to “the blockade”
Line 408: “initiation” to “the initiation”
Line 415: “blockade” to “the blockade”
Line 470: “study” to “studies”
Line 475 “most” to “the most”
Line 483: “there is” to “there are”
Line 527: “suggests” to “suggest”
We have made all the above grammatical changes to the text.
Reviewer 2 Report
The work is very well structured and includes the latest available information on the importance of CD38 in inflammatory diseases and tumours.
The importance of CD38 in solid tumours is now enhanced by the therapeutic strategy of immunotherapy.
High-quality review work.
Author Response
The work is very well structured and includes the latest available information on the importance of CD38 in inflammatory diseases and tumours. The importance of CD38 in solid tumours is now enhanced by the therapeutic strategy of immunotherapy. High-quality review work.
We appreciate the positive feedback regarding our review of CD38 to better understand this complicated ectoenzyme in the context of the solid tumor microenvironment.
Reviewer 3 Report
This is an exceptionally good review and balanced assessment about CD38.The article carefully summarises the important data sets and papers have been publised in the last decade. The manuscript is well organized and well written. Reviewer suggest to extend one area:
The functional changes in CD38 CRISPR CAS9 KO immune cells, especially T and NK cells. In future clinical trials it might have significance.Author Response
This is an exceptionally good review and balanced assessment about CD38.The article carefully summarises the important data sets and papers have been published in the last decade. The manuscript is well organized and well written. Reviewer suggest to extend one area:
The functional changes in CD38 CRISPR CAS9 KO immune cells, especially T and NK cells. In future clinical trials it might have significance.
We agree that the use of CD38 knockout models that specifically deplete CD38 expression in a single immune subpopulation would prove invaluable to better understand the functional relevance of this molecule, especially in the context of a heterogeneous and complex solid tumor microenvironment. In our literature searches, we were unable to find such a study utilizing the CRISPR/Cas9 system to selectively knockout CD38 in immune cells and subsequently perform functional analyses. However, we have included a brief discussion about the immune phenotype of the genetic CD38 knockout mouse, which demonstrate diminished humoral immunity, perhaps through aberrant dendritic cell and neutrophil migration and insufficient T cell priming (Lines 54-56).
Reviewer 4 Report
A well written manuscript, I suggest that the authors add a paragraph stating if tumor heterogenity plays a crucial role in the production and role of CD38 locally or systematically in the action of drugs
Author Response
A well written manuscript, I suggest that the authors add a paragraph stating if tumor heterogeneity plays a crucial role in the production and role of CD38 locally or systematically in the action of drugs.
Tumor heterogeneity of solid tumors undoubtedly impacts multiple aspects of tumor biology such as progression, treatment response and metastatic potential. Our understanding of CD38 biology in the tumor microenvironment is that its actions occur locally within the TME via alteration of the metabolic profile within the tumor. Since its expression is found throughout many populations of immune cells, as well as the tumor cells in some instances, the heterogeneity of expression would likely play an important role in treatment administration and response. Much more work is required in order to definitively answer these complex questions.
