Data from Multimodal Molecular Imaging Detects Early Responses to Immune Checkpoint Blockade
This article has been Reviewed by the following groups
Listed in
- Evaluated articles (eLife)
Abstract
<div>Abstract<p>Immune checkpoint blockade (ICB) has become a standard therapy for several cancers, however, the response to ICB is inconsistent and a method for noninvasive assessment has not been established to date. To investigate the capability of multimodal imaging to evaluate treatment response to ICB therapy, hyperpolarized <sup>13</sup>C MRI using [1–<sup>13</sup>C] pyruvate and [1,4–<sup>13</sup>C2] fumarate and dynamic contrast enhanced (DCE) MRI was evaluated to detect early changes in tumor glycolysis, necrosis, and intratumor perfusion/permeability, respectively. Mouse tumor models served as platforms for high (MC38 colon adenocarcinoma) and low (B16-F10 melanoma) sensitivity to dual ICB of PD-L1 and CTLA4. Glycolytic flux significantly decreased following treatment only in the less sensitive B16-F10 tumors. Imaging [1,4–<sup>13</sup>C2] fumarate conversion to [1,4–<sup>13</sup>C2] malate showed a significant increase in necrotic cell death following treatment in the ICB-sensitive MC38 tumors, with essentially no change in B16-F10 tumors. DCE-MRI showed significantly increased perfusion/permeability in MC38-treated tumors, whereas a similar, but statistically nonsignificant, trend was observed in B16-F10 tumors. When tumor volume was also taken into consideration, each imaging biomarker was linearly correlated with future survival in both models. These results suggest that hyperpolarized <sup>13</sup>C MRI and DCE MRI may serve as useful noninvasive imaging markers to detect early response to ICB therapy.</p>Significance:<p>Hyperpolarized <sup>13</sup>C MRI and dynamic contrast enhanced MRI in murine tumor models provide useful insight into evaluating early response to immune checkpoint blockade therapy.</p><p><i>See related commentary by Cullen and Keshari, p. 3444</i></p></div>
Article activity feed
-
-
-
-
-
###Reviewer #3:
This manuscript by Yu et al. explores the potential predictive value of Hyperpolarized 13C MRI and DCE-MRI in detecting early response of ICB. 2 mouse tumor models with different sensitivities to ICB were used in the study. Early changes in tumor glycolysis and necrosis were evaluated via [1-13C] pyruvate and [1,4-13C2] fumarate MRI, and perfusion/permeability state could be reflected by DCE-MRI. While the paper describes several intriguing pieces of data concerns below limit enthusiasm:
Figure 1A-C. Tumor growth curves in the anti-PD-L1 and anti-PD-L1 plus anti-CTLA4 groups appear to be steadily increasing, albeit at a slightly delayed pace than the control treated tumors. Most reports showed that PD-1/PD-L1 blockade results in tumor clearance in MC38 model, particularly when the treatment was started at small tumor …
###Reviewer #3:
This manuscript by Yu et al. explores the potential predictive value of Hyperpolarized 13C MRI and DCE-MRI in detecting early response of ICB. 2 mouse tumor models with different sensitivities to ICB were used in the study. Early changes in tumor glycolysis and necrosis were evaluated via [1-13C] pyruvate and [1,4-13C2] fumarate MRI, and perfusion/permeability state could be reflected by DCE-MRI. While the paper describes several intriguing pieces of data concerns below limit enthusiasm:
Figure 1A-C. Tumor growth curves in the anti-PD-L1 and anti-PD-L1 plus anti-CTLA4 groups appear to be steadily increasing, albeit at a slightly delayed pace than the control treated tumors. Most reports showed that PD-1/PD-L1 blockade results in tumor clearance in MC38 model, particularly when the treatment was started at small tumor sizes as presented in Figure 1A. The combination of anti-PD-L1 and anti-CTLA4 antibodies displayed more effective clearance of MC38 tumors. That is not the case here, where tumors are growing progressively throughout.
Figure 2A. I am surprised that CD4 T cells were barely detected in MC38 and B16 tumors. An example gating strategy must be shown, including an isotype or FMO control for each of the antibodies used.
Figure 3A. Given the therapeutic effect relies on the blockad of the binding between PD-1 and PD-L1, a careful assessment of the contribution of PD-1 binding to the metabolic change of tumor cells should be performed to provide clarity.
The microenvironment and structure of transplanted tumors are quite different from spontaneous tumor models, which are similar to human tumors. To demonstrate the clinical relevance of these findings, the authors will need to show more results in spontaneous tumor models or human tumors.
-
###Reviewer #2:
Saida et al. performed multi-modal imaging to detect the early response to immune checkpoint blockade (ICB) therapy in murine models. This non-invasive method is attractive to monitor ICB response, thus it is valuable to discover relevant biomarkers in preclinical animal models before potential application in clinics. In ICB sensitive MC38 model, the authors identified increased cell death and intratumor perfusion/permeability, by 13C fumarate MRI and DCE MRI, respectively. While these descriptive results are interesting, this referee has a concern for the limited conceptual advance brought by this manuscript.
Major comment:
In recent years, new MRI technology has been shown to be promising to study pathophysiological changes, particularly in the metabolic field. To identify the efficacy of ICB, particularly at the early …
###Reviewer #2:
Saida et al. performed multi-modal imaging to detect the early response to immune checkpoint blockade (ICB) therapy in murine models. This non-invasive method is attractive to monitor ICB response, thus it is valuable to discover relevant biomarkers in preclinical animal models before potential application in clinics. In ICB sensitive MC38 model, the authors identified increased cell death and intratumor perfusion/permeability, by 13C fumarate MRI and DCE MRI, respectively. While these descriptive results are interesting, this referee has a concern for the limited conceptual advance brought by this manuscript.
Major comment:
In recent years, new MRI technology has been shown to be promising to study pathophysiological changes, particularly in the metabolic field. To identify the efficacy of ICB, particularly at the early stage of treatment, is an important issue in immunotherapy. Thus the authors have chosen two murine models with a purpose to discover potential biomarkers with MRI. For metabolism, the author focused on glycolysis. In ICB sensitive MC38 model, no glycolytic changes were observed. Can the authors further clarify the role of glycolytic changes in ICB sensitive models? For instance, by using another ICB sensitive model; checking ECAR by using ex vivo digested tumor cells.
-
###Reviewer #1:
The identification and validation of non-invasive imaging biomarkers for early response to cancer immunotherapy is a research hotspot. Dr. Krishna and colleagues proposed a potential combination of [1-13C] pyruvate-based detection of glycolysis, [1,4-13C2] fumarate-based analysis of necrosis, and Gd-DTPA-based quantification of perfusion/permeability with MRI technologies. To make the conclusions more convincing, some major issues should be carefully addressed.
It is a bit unfair to compare two different tumor models (MC38 colon cancer versus B16 melanoma). Reasonable solutions can be: 1) to compare good responders versus bad responders in the same type of cancer; 2) to compare ICB resilient tumor cell clones versus ICB sensitive clones, which originate from the same parental cell lines. To test whether these potential …
###Reviewer #1:
The identification and validation of non-invasive imaging biomarkers for early response to cancer immunotherapy is a research hotspot. Dr. Krishna and colleagues proposed a potential combination of [1-13C] pyruvate-based detection of glycolysis, [1,4-13C2] fumarate-based analysis of necrosis, and Gd-DTPA-based quantification of perfusion/permeability with MRI technologies. To make the conclusions more convincing, some major issues should be carefully addressed.
It is a bit unfair to compare two different tumor models (MC38 colon cancer versus B16 melanoma). Reasonable solutions can be: 1) to compare good responders versus bad responders in the same type of cancer; 2) to compare ICB resilient tumor cell clones versus ICB sensitive clones, which originate from the same parental cell lines. To test whether these potential biomarkers can be generalized to multiple cancer types. Several tumor models should be tested.
It seems that the authors didn't test these parameters at different time points. As delayed response can be frequently observed in ICB, it is recommended to monitor tumor-bearing mice at different time points. These recorded parameters can be correlated to the therapeutic outcomes, once the whole tumor growth kinetics is finalized.
It is not accurate to consider the area of necrosis as the equivalent of immunogenic cell death.
Were any of these findings validated in a small cohort of cancer patients?
With radioactive probe-based analysis of glycolysis, it is difficult to judge whether metabolic changes were from tumor cells or from tumor-infiltrating immune cells. Ex vivo seahorse-based analyses of ECAR and OCR do not resemble in situ metabolic status of tumor cell.
Once glycolysis is reduced, OXPHOS and fatty acid oxidation may be switched on. A systemic analysis of the metabolic programs may be necessary. Mechanistic explorations on why these parameters correlate with late therapeutic outcomes is weak.
-
##Preprint Review
This preprint was reviewed using eLife’s Preprint Review service, which provides public peer reviews of manuscripts posted on bioRxiv for the benefit of the authors, readers, potential readers, and others interested in our assessment of the work. This review applies only to version 1 of the manuscript.
###Summary:
A major concern is that the two transplantable murine tumor models used in this study may not be appropriate: it is odd to compare the therapeutic efficacy of ICB in colon cancer versus that in melanoma; the responsiveness of MC38 tumors seem to be much less than a series of reports; the composition of immune cells in the tumor microenvironment seems to be a bit abnormal; and the reviewers also have concerns on whether these transplantable tumor models can mimic human cancer patients.
-
