TO THE EDITOR

We read the interesting study by Zhi

[1]on the immune status of BRAF

-mutated colorectal cancer(CRC),titled “BRAF

mutant colorectal cancer cells mediate local immunosuppressive microenvironment through exosomal long noncoding RNAs”,in which they utilized patient tissue samples,CRC cell lines as well as in silico analysis to study correlations between the BRAF

mutation and changes in the local immune microenvironment of CRC.The authors reported an immunosuppressive microenvironment induced by exosomal long noncoding RNAs in BRAF

mutant CRC as well as higher angiogenic and lymphangiogenic activity compared to wild-type CRC.

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We would like to point out the complementary findings to this study from previous work that has alluded to other parts of the immune landscape of the tumor microenvironment of BRAF

CRC.From this study,Zhi

[1]reported a higher level of M2 macrophages in BRAF

-mutated patients compared to the wild-type,with no difference in M1 macrophages levels.Yet,the sample number from which these results were obtained was relatively small(BRAF

mutation: 10;BRAF wild-type: 20),and this translated to high standard deviations in the M2 counts in both samples.In a recent study by Cen

[2],which used a larger sample(mutated patients: 110,wild-type patients: 798)from the Cancer Genomic Atlas and the Gene Expression Omnibus databases,the authors reported a higher immune cell infiltration and lower tumor purity.Specifically,a higher proportion of CD8

T cells,M1 macrophages as well as neutrophils were found in BRAF

-mutated CRC patients,whereas no difference was found in M2 macrophage levels.Furthermore,according to the consensus molecular subtypes’ classification,which provides the most comprehensive description of CRC heterogeneity at the gene expression level,BRAF

mutation is associated with consensus molecular subtype 1,which correlates with high immune infiltration and immune-response pathway activity[3].

Interestingly,subtypes of BRAF

based on expression patterns in CRC have been further identified.There are two subtypes regardless of microsatellite instability,PI3K mutation status,sex and sidedness: BM1 and BM2[4].Differences between those subtypes exist,including the prognosis(BM1 was found to have a poorer prognosis than BM2)and the immune status.BM1 has an overall stronger immune profile,emphasized by the activation of pathways like IL2/STAT5,tumor necrosis factor-α signaling

nuclear factor kappa B,IL6/JAK/STAT3 and allograft rejection[4].Taking these subtypes into consideration will reveal a deeper understanding of the tumor immune microenvironment in BRAF-mutated CRC patients.

The immune status of the tumor microenvironment is a multilayered complex subject that leads to crucial implications regarding tumor cell immune evasion,therapeutic response or distant invasion tendency.Therefore,we feel that limiting the immune landscape to the levels of tumor-associated macrophages(M1/2)and cancer-associated fibroblasts,as in the study by Zhi

[1],would not reflect the whole story.This is particularly due to the fact that other key immune components,such as CD8

and CD4+ T cells,neutrophils,myeloid-derived suppressor cells and regulatory T cells,were not investigated.Of note,higher levels of cytotoxic CD8

T cells could possibly be neutralized in the tumor microenvironment by immune checkpoints,such as programmed death protein and its ligand or cytotoxic T lymphocyte-associated protein 4[5].In addition,microsatellite status is of paramount importance in this context,since a higher abundance of CD8

T cells,activated natural killer cells and M1 macrophages,and upregulated immune checkpoints were identified in microsatellite instability compared to microsatellite-stable CRC[6].Hence,future investigations including a wider array of immune components,taking into consideration significant genomic features(microsatellite instability and tumor mutational burden),will likely shed light on more reflective findings into the tumor immune status.

Abushukair HM and Zaitoun SM drafted the manuscript and contributed to conceptualization;Saeed A contributed to conceptualization of core concepts and critically revised the draft.

Folklore heros, and occasionally heroines, are often given quests and/or tasks to achieve a reward. Here the heroine must search for her husband to prove her worthiness104 and dedication105 after her indiscretion. The most famous quest in folklore is perhaps that of King Arthur s knights106 and their search for the Holy Grail.Return to place in story.

The Ogre s wife, who believed she could conceal26 them from her husband till morning, let them come in, and brought them to warm themselves at a very good fire; for there was a whole sheep upon the spit, roasting for the Ogre s supper.

FOOTNOTES

In conclusion,the authors presented compelling findings that provide a new perspective on BRAF

-mutated CRC immune microenvironment by discussing a proposed mechanism for inducing an immunosuppressed state through the release of exosomal long noncoding RNAs.Future studies targeting this topic should take into consideration the entire spectrum of the dynamic immune activity in the tumor microenvironment,covering relevant immune cells,immune checkpoints and molecular aberrations.Such comprehensive studies will provide insight for promising therapeutic opportunities for this subset of CRC patients.

Hassan Mohammed Abushukair 0000-0002-0068-5201;Sara Mu'amar Zaitoun 0000-0002-0317-612X;Anwaar Saeed 0000-0001-8024-9401.

United States

The mermaid kissed his high, smooth forehead, and stroked back his wet hair; he seemed to her like the marble statue in her little garden, and she kissed him again, and wished20 that he might live

This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers.It is distributed in accordance with the Creative Commons Attribution NonCommercial(CC BYNC 4.0)license,which permits others to distribute,remix,adapt,build upon this work non-commercially,and license their derivative works on different terms,provided the original work is properly cited and the use is noncommercial.See: https://creativecommons.org/Licenses/by-nc/4.0/

Saeed A reports research grants from AstraZeneca,Bristol Myers Squibb,Merck,Exelixis,KAHR Medical,and Incyte,and advisory board fees from AstraZeneca,Bristol Myers Squibb,Merck,Exelixis,and Pfizer.The other authors report no conflicts of interest.

American Society of Clinical Oncology.

Fan JR

A

Fan JR

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