Implication of programmed cell death ligand 1 expression in tumor recurrence and prognosis in rectal cancer with neoadjuvant chemoradiotherapy

PD-L1 Expression in Paired Samples of Rectal Cancer

Immune checkpoint inhibitors and immune-related biomarkers are increasingly investigated in rectal cancer (RC). We retrospectively analysed PD-L1 expression in diagnostic biopsy and resection samples from RC patients treated at our centre between 2000 and 2020. PD-L1 immunostaining (22C3 clone) was evaluated according to tumour proportion (TPS), immune cell (ICS), and the combined positive score (CPS). Eighty-three patients were included. At diagnosis, PD-L1 expression ≥1%/≥5% was observed in 15.4%/0%, 80.7%/37.4%, and 69.2%/25.6% of patients based on TPS, ICS, and CPS, respectively. At surgery, the respective figures were 4.6%/1.5%, 60.2%/32.5%, and 50.7%/26.2%. Using the 1% cut-off and regardless of the scoring system, PD-L1 was less expressed in surgery than biopsy samples (p ≤ 0.04). In paired specimens, PD-L1-ICS reduction was especially observed following neoadjuvant long-course (chemo)radiotherapy (p = 0.03). PD-L1-ICS of ≥5% in surgical samples (HR: 0.17; p = 0.02), and a biopsy-to-surgery increase in PD-L1-ICS (HR: 0.19; p = 0.04) was predictive for longer disease-free survival, while the PD-L1-ICS of either ≥1% (HR 0.28; p = 0.04) or ≥5% (HR 0.19; p = 0.03) in surgical samples and the biopsy-to-surgery increase in PD-L1-ICS (HR: 0.20; p = 0.04) were associated with better overall survival. Our study suggests that PD-L1 expression in RC is largely reflective of immune cell infiltration, and its presence/increase in surgical samples predicts better outcomes.

Immune Response and Immune Checkpoint Molecules in Patients with Rectal Cancer Undergoing Neoadjuvant Chemoradiotherapy: A Review

It is well-established that tumor antigens and molecules expressed and secreted by cancer cells trigger innate and adaptive immune responses. These two types of anti-tumor immunity lead to the infiltration of the tumor's microenvironment by immune cells with either regulatory or cytotoxic properties. Whether this response is associated with tumor eradication after radiotherapy and chemotherapy or regrowth has been a matter of extensive research through the years, mainly focusing on tumor-infiltrating lymphocytes and monocytes and their subtypes, and the expression of immune checkpoint and other immune-related molecules by both immune and cancer cells in the tumor microenvironment. A literature search has been conducted on studies dealing with the immune response in patients with rectal cancer treated with neoadjuvant radiotherapy or chemoradiotherapy, assessing its impact on locoregional control and survival and underlying the potential role of immunotherapy in the treatment of this cancer subtype. Here, we provide an overview of the interactions between local/systemic anti-tumor immunity, cancer-related immune checkpoint, and other immunological pathways and radiotherapy, and how these affect the prognosis of rectal cancer patients. Chemoradiotherapy induces critical immunological changes in the tumor microenvironment and cancer cells that can be exploited for therapeutic interventions in rectal cancer.

Total neoadjuvant treatment and PD-1/PD-L1 checkpoint inhibitor in locally advanced rectal cancer

For local advanced rectal cancer (LARC), total neoadjuvant treatment (TNT) has shown more complete response (CR), reduced risk of distant metastasis (DM) and increase of the sphincter preservation rate. Now it is the one and only recommendation for high-risk group of LARC according to National Comprehensive Cancer Network (NCCN) rectal cancer guideline, while it is also preferentially recommended for low-risk group of LARC. TNT is also beneficial for distant rectal cancer patients who have need for organ preservation. Even though the prognostic value of programmed cell death-ligand 1 (PD-L1) in the neoadjuvant chemoradiotherapy (NACRT) of LARC patients is undetermined yet, the combination of NACRT and programmed cell death-1 (PD-1)/PD-L1 antibodies seem bring new hope for mismatch repair proficient (pMMR)/microsatellite stable (MSS) LARC patients. Accumulating small sample sized studies have shown that combining NACRT with PD-1/PD-L1 antibody yield better short-term outcomes for pMMR/MSS LARC patients than historic data. However, ideal total dose and fractionation of radiotherapy remains one of unresolved issues in this combination setting. Thorough understanding the impact of radiotherapy on the tumor microenvironment and their interaction is needed for in-depth understanding and exquisite design of treatments combination model.

Role of IDO expression in patients with locally advanced rectal cancer treated with preoperative chemoradiotherapy

BACKGROUND

The role of the immune system in locally advanced rectal cancer (LARC) following preoperative chemoradiotherapy (CRT) has been widely investigated in recent years. This study examined the prognostic significance of indoleamine-pyrrole 2,3-dioxygenase (IDO) expression in patients with LARC who received preoperative CRT.

METHODS

Ninety patients with LARC who underwent preoperative CRT and curative resection were enrolled. IDO and programmed death-ligand 1 (PD-L1) expression was evaluated by immunohistochemistry.

RESULTS

Clinicopathological factors did not significantly differ between patients with positive or negative IDO expression, excluding the correlation of positive IDO expression with better tumor differentiation (p = 0.02). IDO expression was not associated with pathological response (p = 0.44), but it was associated with PD-L1 expression. The 5-year overall survival (OS) rate was significantly worse in the IDO-positive group than in the IDO-negative group (64.8% vs. 85.4%, p = 0.02). Univariate analysis identified IDO and PD-L1 expression (p = 0.02), surgical procedure (p = 0.01), final pathological stage (p = 0.003), lymph node metastasis (p < 0.001), and lymphatic invasion (p = 0.002) as significant prognostic factors for OS. Multivariate analysis revealed that IDO expression (HR: 7.10, p = 0.0006), surgical procedure (HR: 5.03, p = 0.01), lymph node metastasis (HR: 2.37, p = 0.04) and lymphatic invasion (HR: 4.97, p = 0.01) were independent prognostic indicators. Disease-free survival was not correlated with IDO or PD-L1 expression.

CONCLUSIONS

IDO expression in patients with LARC who received preoperative CRT could be a potential prognostic indicator. IDO expression could be a useful marker for specifying individual treatment strategies in LARC.

Evaluation of the ability of fatty acid metabolism signature to predict response to neoadjuvant chemoradiotherapy and prognosis of patients with locally advanced rectal cancer

Neoadjuvant chemoradiotherapy (nCRT) is widely used to treat patients with locally advanced rectal cancer (LARC), and treatment responses vary. Fatty acid metabolism (FAM) is closely associated with carcinogenesis and cancer progression. In this study, we investigated the vital role of FAM on the gut microbiome and metabolism in the context of cancer. We screened 34 disease-free survival (DFS)-related, FAM-related, and radiosensitivity-related genes based on the Gene Expression Omnibus database. Subsequently, we developed a five-gene FAM-related signature using the least absolute shrinkage and selection operator Cox regression model. The FAM-related signature was also validated in external validation from Fujian Cancer Hospital for predicting nCRT response, DFS, and overall survival (OS). Notably, patients with a low-risk score were associated with pathological complete response and better DFS and OS outcomes. A comprehensive evaluation of the tumor microenvironment based on the FAM-related signature revealed that patients with high-risk scores were closely associated with activating type I interferon response and inflammation-promoting functions. In conclusion, our findings indicate the potential ability of FAM to predict nCRT response and the prognosis of DFS and OS in patients with LARC.

Loss of SATB2 expression correlates with cytokeratin 7 and PD-L1 tumor cell positivity and aggressiveness in colorectal cancer

Colorectal carcinoma (CRC) is a disease that causes significant morbidity and mortality worldwide. To improve treatment, new biomarkers are needed to allow better patient risk stratification in terms of prognosis. This study aimed to clarify the prognostic significance of colonic-specific transcription factor special AT-rich sequence-binding protein 2 (SATB2), cytoskeletal protein cytokeratin 7 (CK7), and immune checkpoint molecule programmed death-ligand 1 (PD-L1). We analyzed a cohort of 285 patients with surgically treated CRC for quantitative associations among the three markers and five traditional prognostic indicators (i.e., tumor stage, histological grade, variant morphology, laterality, and mismatch-repair/MMR status). The results showed that loss of SATB2 expression had significant negative prognostic implications relative to overall survival (OS) and cancer-specific survival (CSS), significantly shortened 5 years OS and CSS and 10 years CSS in patients with CRC expressing CK7, and borderline insignificantly shortened OS in patients with PD-L1 + CRC. PD-L1 showed a significant negative impact in cases with strong expression (membranous staining in 50-100% of tumor cells). Loss of SATB2 was associated with CK7 expression, advanced tumor stage, mucinous or signet ring cell morphology, high grade, right-sided localization but was borderline insignificant relative to PD-L1 expression. CK7 expression was associated with high grade and SATB2 loss. Additionally, a separate analysis of 248 neoadjuvant therapy-naïve cases was performed with mostly similar results. The loss of SATB2 and CK7 expression were significant negative predictors in the multivariate analysis adjusted for associated parameters and patient age. In summary, loss of SATB2 expression and gain of CK7 and strong PD-L1 expression characterize an aggressive phenotype of CRC.

The implications from the interplay of neoadjuvant chemoradiotherapy and the immune microenvironment in rectal cancer

Neoadjuvant chemoradiotherapy (nCRT) is recommended for the treatment of locally advanced rectal cancer. Even though the combination of nCRT and immune checkpoint inhibitors (ICIs) has received much attention, the specific combination modes and dose fractions in radiotherapy (RT) are still indistinct. This review focuses on the immunological mechanism involved in nCRT, the clinical efficacy, the immunological effect of different combined strategies, concurrent or sequential nCRT plus ICIs, long-course RT and short-course RT. This review discusses the impact of nCRT on tumor immunity and summarizes the availability of different dose fractions in RT and distinct combined strategies, aiming at providing clues for optimal neoadjuvant therapy options that maximize efficacy and minimize side effects.

Current insight into the regulation of PD-L1 in cancer

The molecular mechanisms underlying cancer immune escape are a core topic in cancer immunology research. Cancer cells can escape T cell-mediated cellular cytotoxicity by exploiting the inhibitory programmed cell-death protein 1 (PD-1)/programmed cell death ligand 1 (PD-L1, CD274) immune checkpoint. Studying the PD-L1 regulatory pattern of tumor cells will help elucidate the molecular mechanisms of tumor immune evasion and improve cancer treatment. Recent studies have found that tumor cells regulate PD-L1 at the transcriptional, post-transcriptional, and post-translational levels and influence the anti-tumor immune response by regulating PD-L1. In this review, we focus on the regulation of PD-L1 in cancer cells and summarize the underlying mechanisms.

Predicting response to neoadjuvant chemoradiotherapy in rectal cancer: from biomarkers to tumor models

Colorectal cancer (CRC) is a major contributor to cancer-associated morbidity worldwide and over one-third of CRC is located in the rectum. Neoadjuvant chemoradiotherapy (nCRT) followed by surgical resection is commonly applied to treat locally advanced rectal cancer (LARC). In this review, we summarize current and novel concepts of neoadjuvant therapy for LARC such as total neoadjuvant therapy and describe how these developments impact treatment response. Moreover, as response to nCRT is highly divergent in rectal cancers, we discuss the role of potential predictive biomarkers. We review recent advances in biomarker discovery, from a clinical as well as a histopathological and molecular perspective. Furthermore, the role of emerging predictive biomarkers derived from the tumor environment such as immune cell composition and gut microbiome is presented. Finally, we describe how different tumor models such as patient-derived cancer organoids are used to identify novel predictive biomarkers for chemoradiotherapy (CRT) in rectal cancer.

Beyond Microsatellite Instability: Evolving Strategies Integrating Immunotherapy for Microsatellite Stable Colorectal Cancer

OPINION STATEMENT

Advanced colorectal cancer (CRC) is a heterogeneous disease, characterized by several subtypes with distinctive genetic and epigenetic patterns. During the last years, immune checkpoint inhibitors (ICIs) have revamped the standard of care of several tumors such as non-small cell lung cancer and melanoma, highlighting the role of immune cells in tumor microenvironment (TME) and their impact on cancer progression and treatment efficacy. An "immunoscore," based on the percentage of two lymphocyte populations both at tumor core and invasive margin, has been shown to improve prediction of treatment outcome when added to UICC-TNM classification. To date, pembrolizumab, an anti-programmed death protein 1 (PD1) inhibitor, has gained approval as first-line therapy for mismatch-repair-deficient (dMMR) and microsatellite instability-high (MSI-H) advanced CRC. On the other hand, no reports of efficacy have been presented in mismatch-repair-proficient (pMMR) and microsatellite instability-low (MSI-L) or microsatellite stable (MSS) CRC. This group includes roughly 95% of all advanced CRC, and standard chemotherapy, in addition to anti-EGFR or anti-angiogenesis drugs, still represents first treatment choice. Hopefully, deeper understanding of CRC immune landscape and of the impact of specific genetic and epigenetic alterations on tumor immunogenicity might lead to the development of new drug combination strategies to overcome ICIs resistance in pMMR CRC, thus paving the way for immunotherapy even in this subgroup.

Immune Checkpoint Inhibition as a Strategy in the Neoadjuvant Treatment of Locally Advanced Rectal Cancer

The treatment of locally advanced rectal cancer (LARC) has seen major advances over the past 3 decades, with multimodality treatment now standard of care. Combining surgical resection with radiotherapy and/or chemotherapy can reduce local recurrence from around 20% to approximately 5%. Despite improvements in local control, distant recurrence and subsequent survival rates have not changed. Immune checkpoint inhibitors have improved patient outcomes in several solid tumor types in the neoadjuvant, adjuvant, and advanced disease setting; however, in colorectal cancer, most clinical trials have been performed in the metastatic setting and the benefits confined to microsatellite instability-high tumors. In this article, we review the current preclinical and clinical evidence for using immune checkpoint inhibition in the treatment of LARC and discuss the rationale for specifically exploring the use of this therapy in the neoadjuvant setting. We summarize and discuss relevant clinical trials that are currently in setup and recruiting to test this treatment strategy and reflect on unanswered questions that still need to be addressed within future research efforts.

An update on the use of immunotherapy in patients with colorectal cancer

Introduction: Colorectal cancer (CRC) is the third most common malignancy worldwide, with recent trends demonstrating increasing incidence amongst younger patients. Despite multiple treatment options, metastatic disease remains incurable. A new therapeutic strategy to harness the host immune system, specifically with immune checkpoint inhibitors, now has reported results from a number of clinical trials. Areas covered: This review will discuss in detail microsatellite instability (MSI) and other biomarkers for response to immunotherapy, summarize the pivotal clinical trials of immune checkpoint inhibitors in early-stage and metastatic MSI colorectal cancer, explore strategies to induce treatment responses in MSS CRC and highlight the emerging treatments and novel immune-based therapies under investigation. Expert opinion: Immunotherapy is now a standard of care for the proportion of CRC patients with MSI. While overall survival data are still awaited, the promise of profound and durable responses is highly anticipated. The lack of efficacy in MSS CRC is disappointing and strategies to convert these 'cold' tumors are needed. Further elucidation of optimal use of treatment sequences, combinations and novel agents will improve outcomes.

Clinicopathological and prognostic significance of PD-L1 expression in colorectal cancer: a meta-analysis

PURPOSE

To systematically evaluate the correlation between PD-L1 expression and clinicopathological features and prognosis of colorectal cancer (CRC).

METHODS

Seven databases (PubMed, Cochrane Library, EMBASE, Web of Science, CBM, Wanfang, and CNKI) were searched through May 2020. Risk of bias and quality of evidence were assessed by using the Newcastle-Ottawa scale (NOS), and meta-analysis was carried out by using the Review Manager 5.3 software on the studies with the quality evaluation scores ≥ 6. Meta-regression analysis was used to determine the independent role of PD-L1 expression on CRC prognosis after adjusting clinicopathological features and treatment methods.

RESULTS

A total of 8823 CRC patients in 32 eligible studies. PD-L1 expression was correlated with lymphatic metastasis (yes/no; OR = 1.24, 95% CI (1.11, 1.38)), diameter of tumor (≥ 5 cm/< 5 cm; OR = 1.34, 95% CI (1.06, 1.70)), differentiation (high-middle/low; OR = 0.68, 95% CI (0.53, 0.87)), and vascular invasion (yes/no; OR = 0.80, 95% CI (0.69, 0.92)). PD-L1 expression shortened the overall survival (hazard ratio (HR) = 1.93, 95% CI (1.66, 2.25)), disease-free survival (HR = 1.76, 95% CI (1.50, 2.07)), and progression-free survival (HR = 1.93, 95% CI (1.55, 2.41)). Meta-regression showed that PD-L1 expression played a significant role on poor CRC OS (HR = 1.95, 95% CI (1.92, 3.98)) and disease-free survival (HR = 2.14, 95% CI (0.73, 4.52)).

CONCLUSION

PD-L1 expression independently predicted a poor prognosis of CRC.

A meta-analysis of CD274 (PD-L1) assessment and prognosis in colorectal cancer and its role in predicting response to anti-PD-1 therapy

BACKGROUND

PD-1 checkpoint inhibitors are novel therapeutic agents in colorectal cancer (CRC). Immunohistochemical staining for CD274 assessment is standardised in upper GI cancer, but not in CRC.

METHODS

Methodologies of relevant studies were scrutinized and meta-analysis of survival and CD274/PDCD1 performed. Furthermore, anti-PD-1 therapy clinical trial results in CRC were assessed with particular emphasis on CD274 assessment.

RESULTS

24 studies were included. CD274 on immune cells was associated with good prognosis. CD274 on tumour cells has heterogenous outcomes and does not meet requirements of a prognostic marker. As a marker of response to anti-PD-1 therapy, CD274 assessment is not standardised in CRC.

CONCLUSION

CD274 does not appear useful as a prognostic marker. As a marker of response to anti-PD-1 therapy, assessment methodology requires standardisation. As the Combined Positive Score (CPS) is used in upper GI cancer, this seems a logical method to adopt. Thresholds for CRC remain to be determined.

Impact of PD-L1 Scores and Changes on Clinical Outcome in Rectal Cancer Patients Undergoing Neoadjuvant Chemoradiotherapy

Reports on the prognostic role of programmed death-ligand 1 (PD-L1) expression in rectal cancer are controversial. We investigated expression patterns and changes of PD-L1 in rectal cancer patients undergoing neoadjuvant chemoradiotherapy (CRT). Seventy-two patients diagnosed with rectal cancer and/or treated with fluorouracil-based neoadjuvant CRT at the Department of Internal Medicine III of the Paracelsus Medical University Salzburg (Austria) between January 2003 and October 2012 were included. PD-L1 scoring was performed according to the tumor proportion score (TPS), combined positive score (CPS), and immune cell score (IC). PD-L1 TPS prior to neoadjuvant CRT had a statistically significant impact on survival (median: ≤1%: 95.4 months (95% CI: 51.8-not reached) vs. >1%: not reached, p = 0.03, log-rank). Patients with a PD-L1 TPS ≤1% prior to and after CRT showed an inferior survival compared to all other patients (median: 56.7 months (95% CI: 51.4-not reached) vs. not reached, p = 0.005, log-rank). In multivariate analysis, PD-L1 TPS prior to neoadjuvant CRT (>1% vs. ≤1%, hazard ratio: 0.29 (95% CI: 0.11-0.76), p = 0.01) remained independently associated with survival. In conclusion, low PD-L1 TPS was associated with inferior survival in rectal cancer patients undergoing neoadjuvant CRT. A prospective validation of the prognostic value of PD-L1 expression in rectal cancer patients within a clinical trial is necessitated.

The Determination of Immunomodulation and Its Impact on Survival of Rectal Cancer Patients Depends on the Area Comprising a Tissue Microarray

BACKGROUND

T cell density in colorectal cancer (CRC) has proven to be of high prognostic importance. Here, we evaluated the influence of a hyperfractionated preoperative short-term radiation protocol (25 Gy) on immune cell density in tumor samples of rectal cancer (RC) patients and on patient survival. In addition, we assessed spatial tumor heterogeneity by comparison of analogue T cell quantification on full tissue sections with digital T cell quantification on a virtually established tissue microarray (TMA).

METHODS

A total of 75 RC patients (60 irradiated, 15 treatment-naïve) were defined for retrospective analysis. RC samples were processed for immunohistochemistry (CD3, CD8, PD-1, PD-L1). Analogue (score 0-3) as well as digital quantification (TMA: 2 cores vs. 6 cores, mean T cell count) of marker expression in 2 areas (central tumor, CT; invasive margin, IM) was performed. Survival was estimated on the basis of analogue as well as digital marker densities calculated from 2 cores (Immunoscore: CD3/CD8 ratio) and 6 cores per tumor area.

RESULTS

Irradiated RC samples showed a significant decrease in CD3 and CD8 positive T cells, independent of quantification mode. T cell densities of 6 virtual cores approximated to T cell densities of full tissue sections, independent of individual core density or location. Survival analysis based on full tissue section quantification demonstrated that CD3 and CD8 positive T cells as well as PD-1 positive tumor infiltrating leucocytes (TILs) in the CT and the IM had a significant impact on disease-free survival (DFS) as well as overall survival (OS). In addition, CD3 and CD8 positive T cells as well as PD-1 positive TILs in the IM proved as independent prognostic factors for DFS and OS; in the CT, PD-1 positive TILs predicted DFS and CD3 and CD8 positive T cells as well as PD-1 positive TILs predicted OS. Survival analysis based on virtual TMA showed no impact on DFS or OS.

CONCLUSION

Spatial tumor heterogeneity might result in inadequate quantification of immune marker expression; however, if using a TMA, 6 cores per tumor area and patient sample represent comparable amounts of T cell densities to those quantified on full tissue sections. Consistently, the tissue area used for immune marker quantification represents a crucial factor for the evaluation of prognostic and predictive biomarker potential.

Expression of PD-1/PD-L1 in head and neck squamous cell carcinoma and its clinical significance

OBJECTIVE

To investigate the role of programmed death-1 (PD-1), programmed death-ligand 1 (PD-L1), and P16 in patients with head and neck squamous cell carcinoma (HNSCC).

METHODS

A total of 95 paraffin-embedded samples of tumorous tissue of HNSCC were collected. Expression levels of PD-1, PD-L1, and P16 were determined by immunohistochemistry.

RESULTS

A significantly higher proportion of PD-1 among patients infected with the human papillomavirus was found. PD-L1 expression is closely associated with the primary site of the tumor, postoperative recurrence, survival, PD-1 expression and P16 expression. Univariable analysis indicated that T stage, N stage, tumor node metastasis stage, tumor differentiation, and PD-L1 expression were all shown to be prognostic variables for overall survival in patients with HNSCC. In the multivariate analysis, only N stage (P = 0.010) and PD-L1 expression (P = 0.001) were found to be independent prognostic variables for overall survival. In addition, for disease recurrence, multivariate analysis showed that only PD-L1 expression was the associated independent risk factor. For the patients with negative PD-L1 expression, Kaplan-Meier analysis revealed that they had significantly worse outcomes in terms of overall survival (P = 0.001). Similarly, compared with the patients with positive PD-L1 expression, those with negative PD-L1 expression had a higher probability of recurrence (P = 0.026).

CONCLUSIONS

The expression of PD-L1, PD-1, and P16 in HNSCC is significantly correlated. Human papillomavirus infection (P16 positive) is negatively related to postoperative recurrence. HNSCC patients with positive PD-L1/PD-1 expression tend to have better overall survival outcomes and lower probability of recurrence, providing more evidence for the PD-l-targeted immunotherapy of HNSCC.

Programmed death-ligand 1 and survival in colorectal cancers: A meta-analysis

BACKGROUND

Programmed death-ligand 1 (PD-L1) is a programmed death 1 (PD-1) ligand that plays a pivotal role in the inhibition of the T-cell-mediated immune response. The expression of PD-L1 is associated with the prognosis and clinical outcomes of multiple tumors. However, the prognostic value of PD-L1 overexpression in colorectal cancer is still controversial. In this study, we sought to clarify this by presenting a meta-analysis of relevant studies.

METHODS

Databases including PubMed, Web of Science, and EMBASE were systematically searched for studies concerning the expression of PD-L1 and survival in colorectal cancer. The reported hazard ratios (HR) with 95% confidence intervals (CI) of overall survival, disease-free survival, and recurrence-free survival in the included studies were analyzed by fixed effects/random effects models.

RESULTS

Fifteen studies involving 3078 patients with colorectal cancer were included in our meta-analysis. Overexpression of PD-L1 was found to be associated with poor overall survival (HR 1.83; 95% CI 1.21, 2.79; P = 0.005) and poor recurrence-free survival (HR 2.78; 95% CI 1.43, 5.42; P = 0.003). However, no correlation was found between PD-L1 overexpression and poor disease-free survival (HR 1.23; 95% CI 0.83, 1.82; P = 0.305). Overexpression of PD-L1 indicating poor survival held true across different geographical areas, sample sizes, analysis types, sources of HRs, and cell types.

CONCLUSION

Overexpression of PD-L1 is associated with worse prognosis in patients with colorectal cancer and can guide physicians in the application of PD-1/PD-L1 immune checkpoint-targeted therapy.

Tumor Infiltrating Lymphocytes and Macrophages Improve Survival in Microsatellite Unstable Colorectal Cancer

Due to the loss of DNA repair mechanisms in colorectal cancer (CRC) with microsatellite instability (MSI), somatic mutations accumulate within DNA; making them more prone to attack by tumor infiltrating lymphocytes (TIL) and macrophages. We hypothesize that MSI-High (MSI-H) patients have favorable survival due to increased tumor immunogenicity. The Cancer Genome Atlas (TCGA) was used to evaluate gene expression from 283 patients with CRC, comparing MSI-H and microsatellite stable (MSS) patients. CIBERSORT algorithm estimated the fraction of immune cell types. We found that low expression of DNA repair genes (MLH1, MLH3, PMS1, PMS2, ATR, PRKDC, ATM, BRCA2) associated with MSI-H. MSI-H was directly associated with Helper T-cells (p = 0.034) and M1 macrophages (p < 0.0001). MSI-H tumors associated with diminished intra-tumoral heterogeneity as well as higher expression of checkpoint molecules PD-1, PD-L1, CTLA4, LAG3 and TIM3 (p < 0.0001). Improved OS was seen in patients with low ATM, PMS2 and MLH3. In the TCGA CRC cohort, decreased expression of DNA repair genes associated with MSI-H. MSI-H patients had improved survival, likely due to higher TIL and M1 macrophage infiltration as well as lower intra-tumoral heterogeneity. MSI-H also associates with expression of immune checkpoint molecules with potential for development of therapeutic targets.

Prognostic and clinicopathological value of PD-L1 in colorectal cancer: a systematic review and meta-analysis

Purpose: The prognostic role of programmed death-ligand 1 (PD-L1) in colorectal cancer remains unclear. We employed a meta-analysis to explore the prognostic value of PD-L1 and to ascertain the relationship between PD-L1 expression and clinicopathological characteristics in CRC patients. Methods: We systematically searched PubMed, Embase and the Cochrane Library until October 2018. Eligible studies about colorectal cancer that pay attention to PD-L1 expression and studies reporting survival information were included. In order to evaluate the prognostic role of PD-L1 for overall survival (OS) and recurrence-free survival (RFS)/disease-free survival (DFS), Hazard ratio (HR) with 95% confidence interval (CI) was used. Odds ratio (OR) with 95% CI was selected to appraise the correlation between PD-L1 with clinicopathological characteristics of colorectal cancer patients. Begg's funnel plot was used to assess publication bias. Results: Twelve studies involving 4344 patients published from 2013 to 2018 were included in this meta-analysis. Pooled results revealed that PD-L1 overexpression was relevant to shorter OS (HR 1.47, 95% CI =1.01-2.15, p=0.04) and shorter RFS/DFS (HR 1.47, 95% CI =1.01-2.15, p=0.04). Moreover, Patients with high expression of PD-L1 associated with inferior tumor stage (OR=0.57, 95% CI: 0.45, 0.74, p<0.0001) and Vascular invasion-negativity (OR=0.75, 95% CI: 0.6, 0.94, p=0.01). But the expression of PD-L1 is not related to age, sex, tumor location, tumor differentiation, pT stage, pN stage, MSI/MMR status. Conclusion: This meta-analysis revealed that PD-L1 can serve as a significant biomarker for negative prognosis and the adverse clinicopathological features of colorectal cancer and could facilitate the better management of individual patients.

Prognostic relevance of programmed cell death-ligand 1 expression and CD8+ TILs in rectal cancer patients before and after neoadjuvant chemoradiotherapy

PURPOSE/BACKGROUND

Radiotherapy has been recently reported to boost the therapeutic response of immune checkpoint blockade (ICB); however, few studies have focused on programmed cell death-ligand 1 (PD-L1) expression in locally advanced rectal cancer (LARC) patients who receive preoperative neoadjuvant chemoradiotherapy (neoCRT). The aim of the present study was to investigate the PD-L1 expression status and CD8+ intra-tumoral infiltrating lymphocytes (TILs) before and after neoCRT and its association with clinicopathological characteristics in rectal cancer.

MATERIALS AND METHODS

Immunostainings of PD-L1 and CD8+ TILs were performed in 112 pair-matched LARC patients treated by neoCRT. Tumor PD-L1 expression and CD8+ TILs within the tumor microenvironment before and after neoCRT were evaluated via immunohistochemistry.

RESULTS

High tumor PD-L1 expression was significantly increased from 50 to 63%, and high CD8+ TILs counts were also slightly increased from 32 to 35% after neoCRT treatment. High tumor PD-L1 before and after neoCRT was associated with improved disease-free survival (DFS, pre-neoCRT: p = 0.003 and post-neoCRT: p = 0.003) and overall survival (OS, pre-neoCRT: p = 0.045 and post-neoCRT: p = 0.0001). High CD8+ TILs before neoCRT was associated with improved DFS (p = 0.057), and it was significantly associated with improved DFS after neoCRT (p = 0.039). Patients with high tumor PD-L1 and CD8+ TILs before and after neoCRT were significantly associated with improved DFS (pre-neoCRT: p = 0.004 and post-neoCRT: p = 0.006).

CONCLUSION

The present results provide evidence that tumor PD-L1 expression and recruitment of CD8+ TILs within the tumor microenvironment were increased by neoCRT treatment. Tumor PD-L1 and CD8+ TILs are prognostic biomarkers for the survival of LARC patients treated with neoCRT.

Immunohistochemical Study of PD-1/PD-L1 Axis Expression in Oral Tongue Squamous Cell Carcinomas: Effect of Neoadjuvant Chemotherapy on Local Recurrence

While neoadjuvant chemotherapy (NAC) for patients with oral tongue squamous cell carcinoma (OTSCC) may improve tumor microenvironment, it may lead to local immune suppression caused by residual cancer cells. The efficacy of NAC is therefore controversial. In our study, we investigated tumor microenvironments after NAC using immune checkpoint molecules, and evaluated the association between tumor microenvironments, clinicopathological factors and outcomes. We reviewed the records of 121 patients who underwent radical surgery for OTSCC between April 2001 and March 2015. Patients with a positive surgical margin and a follow up period of less than 6 months were excluded. For these patients, programmed death 1 (PD-1) and programmed death ligand 1 (PD-L1) expressions were immunohistochemically examined. The expression of PD-1 and PD-L1 were significantly associated with local recurrence in patients with OTSCC (P < 0.01 and P < 0.01, respectively). We found a significant decrease in 5-year disease specific survival rate for patients with combined PD-1+/PD-L1+ expressions (P < 0.05). In the subgroup analysis of local recurrence between the NAC treated group and those who received surgery alone, high levels of PD-1 and PD-L1 expressions were significantly found in the former, but not in the latter group. Local recurrence in the NAC-treated group may contribute to local immune suppression in OTSCC. NAC lead to local immune suppression and immune checkpoint molecules play an important role in local recurrence in patients with OTSCC who received NAC. NAC modality can't be recommended for patients with OTSCC at present.

Upregulation of tumor PD-L1 by neoadjuvant chemoradiotherapy (neoCRT) confers improved survival in patients with lymph node metastasis of locally advanced rectal cancers

The expression of programmed cell death 1 ligand 1 (PD-L1) and interferon-γ (IFN-γ) is of great interest for the development of chemoradiotherapy and immune checkpoint inhibitor treatments. Patients with nodal metastasis (pN+) tend to have a poor prognosis, even after neoadjuvant chemoradiotherapy (neoCRT) and surgical treatment. In this study, we examined the roles of tumor PD-L1 and IFN-γ before and after neoCRT in locally advanced rectal cancer (LARC) patients. Our results demonstrate that patients with high PD-L1 expression in post-neoCRT tissues exhibit improved 5-year disease-free survival (DFS) and overall survival (OS) compared with those with low PD-L1 expression (p < 0.001). Furthermore, in the pN+ population, patients with high PD-L1 expression in post-neoCRT tissues exhibit improved 5-year DFS and OS. PD-L1 and IFN-γ upregulation increased in tumor tissues after neoCRT, and patients with high PD-L1 and high IFN-γ exhibit improved 5-year DFS and OS (p = 0.04 and p = 0.001, respectively). To the best of our knowledge, this study is the first to demonstrate that PD-L1 upregulation in a pN+ cohort correlates with improved prognosis, which is similar to that in patients without nodal metastasis. Moreover, this study verified that PD-L1 and IFN-γ were upregulated by neoCRT treatment in LARC patients and demonstrated that neoCRT may be useful not only for immune checkpoint inhibitor treatment but also for reinvigorating preexisting anti-cancer immunity.

Clinicopathological and prognostic significance of PD-L1 expression in colorectal cancer: a systematic review and meta-analysis

OBJECTIVE

To analyze the prognostic value of programmed death factor ligand 1 (PD-L1) in colorectal cancer.

METHODS

Electronic databases, such as PubMed, Web of Science, Embase, and Cochrane library, were searched to identify studies evaluating the PD-L1 expression and overall survival (OS) in these patients. Afterwards, the relevant data were extracted to perform the meta-analysis.

RESULTS

A total of 3481 patients were included in 10 studies. The combined hazard ratio (HR) was 1.22 (95%CI = 1.01-1.48, P = 0.04), indicating that high expression of PD-L1 was significantly correlated with poor prognosis of colorectal cancer. Apropos of clinicopathological features, the merged odds ratio (OR) exhibited that highly expressed PD-L1 was firmly related to lymphatic invasion (OR = 3.49, 95%CI = 1.54-7.90, P = 0.003) and advanced stage (OR = 1.77, 95%CI = 1.41-2.23, P < 0.00001), but not correlative with patients' gender, microsatellite instability, or tumor location.

CONCLUSION

The expression of PD-L1 can be utilized as an independent factor in judging the prognosis of colorectal cancer, and patients with advanced cancer or lymphatic invasion are more likely to express PD-L1. This conclusion may lay a theoretical foundation for the application of PD-1/PD-L1 immunoassay point inhibitors but still needs verifying by sizeable well-designed cohort studies.

Non-operative management of rectal cancer: understanding tumor biology

The management of locally-advanced rectal cancer involves a combination of chemotherapy, chemoradiation, and surgical resection to provide excellent local tumor control and overall survival. However, aspects of this multimodality approach are associated with significant morbidity and long-term sequelae. In addition, there is growing evidence that patients with a clinical complete response to chemotherapy and chemoradiation treatments may be safely offered initial non-operative management in a rigorous surveillance program. Weighed against the morbidity and significant sequelae of rectal resection, recognizing how to best optimize non-operative strategies without compromising oncologic outcomes is critical to our understanding and treatment of this disease.

Correlation between tumor microenvironment-associated factors and the efficacy and prognosis of neoadjuvant therapy for rectal cancer

The tumor microenvironment contributes to the survival and development of tumor cells and is therefore a key target for cancer therapy. The tumor microenvironment has unique physical and chemical properties and is associated with inflammation and immunity. To examine the correlation between tumor microenvironment-associated factors and the efficacy and prognosis of neoadjuvant therapy for rectal cancer, and to compare the differences between two treatments [neoadjuvant chemotherapy (NAC) vs. neoadjuvant chemoradiotherapy (NACR)], an immunohistochemical method was used to measure the expression levels of CD4⁺ tumor-infiltrating lymphocytes (TILs), cluster of differentiation (CD)8⁺TILs, forkhead box P3 (FOXP3)⁺TILs, cytotoxic T lymphocyte-associated antigen-4⁺TILs and programmed death ligand-1 (PD-L1)⁺TILs in 109 patients with rectal cancer, pre- and post-neoadjuvant therapy. The significance of these protein expression patterns was also analyzed using tissue microarrays, and the prognostic significance of these findings evaluated. The results indicated that high levels of CD4⁺TILs, CD8⁺TILs and PD-L1⁺TILs may be associated with favorable responses to neoadjuvant therapy, whereas high levels of FOXP3⁺TILs were associated with poor therapeutic responses. Expression levels of CD8⁺TILs and FOXP3⁺TILs following neoadjuvant therapy were independent prognostic factors and affected the total survival of patients subjected to neoadjuvant therapy for the treatment of rectal cancer. Moreover, the effects of NAC and NACR on the tumor microenvironment may be different.

Clinical significance of programmed death 1 ligand-1 (CD274/PD-L1) and intra-tumoral CD8+ T-cell infiltration in stage II-III colorectal cancer

Programmed cell death-1 (PDCD1/PD-1) and its ligand programmed cell death 1 ligand 1 (CD274/PD-L1) have been reported to suppress anti-tumor T cell-mediated immune responses. However, the clinical significance of CD274 in colorectal cancer were still elusive. We aim to clarify the relationships between CD8+ intratumor-infiltrating lymphocytes (TILs) and CD274 as well as their prognostic values in stage II-III colon carcinoma. Tumor differentiation, perineural invasion (PNI), pN stage and DNA mismatch repair (MMR)-deficient were clearly correlated with CD8+ TILs counts within the tumor microenvironment (p < 0.0001). Furthermore, tumor differentiation and PNI were suggestively correlated with tumor CD274 expression (p = 0.02 and p = 0.0195). Tumor CD274 level was significantly correlated with higher CD8+ TILs (p < 0.0001) but was not associated with MMR-deficient status (p = 0.14). High tumor CD274 expression [hazard ratio (HR) = 2.16, 95% CI = 1.63-2.86, p < 0.0001] and CD8+ TILs [HR = 1.51, 95% CI = 1.19-1.91, p = 0.0007] were associated with improved disease-free survival and overall survival. Additionally, the subgroup of patients who had a high CD8+ TILs/tumor CD274 have better survival outcomes compared with other subgroups (71% vs 53%; p < 0.0001). Therefore, the CD8+ TILs counts and tumor CD274 may be prognostic factors to predict survival and therapeutic responses in stage II-III colon carcinoma patients.

The Clinical and Biomarker Association of Programmed Death Ligand 1 and its Spatial Heterogeneous Expression in Colorectal Cancer

Background: Programmed death ligand 1 (PD-L1) expression has been shown to predict benefit from anti-PD-1 treatment in several cancers. However, its predictive value in colorectal cancer seems limited. This study was aimed to explore the clinical and biomarker association of programmed death ligand 1 and its spatial heterogeneous expression in colorectal cancer.

Methods: Tissue microarrays of 422 primary colorectal cancers from our hospital were used for the interpretation of PD-L1 and programmed death 1 (PD-1) expression, cluster of differentiation 4 (CD4) and CD8 density and microsatellite instability (MSI) status by immunohistochemistry. To assess the spatial heterogeneity of PD-L1 expression, Tissue microarrays of 383 paired intra-primary-tumor tissues, and 105 paired lymph node metastatic tumors and 64 paired distant metastatic tumors were also used.

Results: PD-L1 was positive in 188 (44.5%) primary colorectal cancers. PD-L1 expression was associated with less advanced N category (P<0.001), less advanced TNM stage (P<0.001) and less nervous invasion (P=0.04). Higher PD-L1 expression was associated with higher PD-1 expression (P<0.001), higher CD4 (P<0.001) and CD8 (P<0.001) density and DNA mismatch repair deficiency (P=0.01). PD-L1 expression was associated with better disease-free survival and overall survival, but it was only an independent prognostic factor for disease-free survival (hazard ratio and 95% confidence interval: 0.42 [0.25-0.72], P<0.001). The probability of inconsistent PD-L1 expression was respectively 17.8%, 31.4% and 39.1% within primary tumors, between primary tumors and lymph node metastatic tumors, and between primary tumors and distant metastatic tumors. All the three differences were statistically significant (P<0.001, P<0.001 and P=0.05, respectively).

Conclusions: PD-L1 expression was a marker of pre-existing immune responses in colorectal cancer, however, it was heterogeneously expressed in colorectal cancer, especially between primary and metastatic tumors. This might partially explain the low-efficiency of its predictive value for benefit from anti-PD-1 treatment.

Prognostic impact of programmed cell death ligand 1 expression on long-term oncologic outcomes in colorectal cancer

The present study evaluated the association between programmed cell death ligand-1 (PD-L1) expression and long-term oncologic outcomes in colorectal cancer (CRC). PD-L1 expression was evaluated using immunohistochemistry in 175 patients who underwent surgical resection for CRC between September 1999 and August 2004. Patients were grouped according to PD-L1 expression, with 82 (46.9%) and 93 (53.1%) in the low and high PD-L1 expression groups, respectively. The overall survival (OS) and disease-free survival (DFS) rates were significantly better in the high expression group compared with in the low expression group (OS: 48.2 vs. 32.9%, P=0.047; DFS: 43.3 vs. 32.9%, P=0.021). According to the Tumor-Node-Metastasis stage subgroups, the OS rates in the low and high expression groups, respectively, were 66.7 and 60.0% in stage I (P=0.715), 51.8 and 46.7% in stage II (P=0.789), 19.6 and 51.1% in stage III (P=0.011) and 9.1 and 0% in stage IV (P=0.005). The DFS rates in the low and high expression groups, respectively, were 66.7 and 60.0% in stage I (P=0.715), 51.8 and 46.7% in stage II (P=0.857), 19.6 and 38.3% in stage III (P=0.006) and 9.1 and 0% in stage IV (P=0.700). The systemic recurrence rate was significantly higher in the low expression group compared with in the high expression group (42.7 vs. 12.9%, respectively, P=0.030). Low PD-L1 expression was significantly associated with tumor relapse and poor prognosis in stage III CRC.

Cytolytic Activity Score to Assess Anticancer Immunity in Colorectal Cancer

BACKGROUND

Elevated tumor-infiltrating lymphocytes (TILs) within the tumor microenvironment is a known positive prognostic factor in colorectal cancer (CRC). We hypothesized that since cytotoxic T cells release cytolytic proteins such as perforin (PRF1) and pro-apoptotic granzymes (GZMA) to attack cancer cells, a cytolytic activity score (CYT) would be a useful tool to assess anticancer immunity.

METHODS

Genomic expression data were obtained from 456 patients from The Cancer Genome Atlas (TCGA). CYT was defined by GZMA and PRF1 expression, and CIBERSORT was used to evaluate intratumoral immune cell composition.

RESULTS

High CYT was associated with high microsatellite instability (MSI-H), as well as high levels of activated memory CD4+T cells, gamma-delta T cells, and M1 macrophages. CYT-high CRC patients had improved overall survival (p = 0.019) and disease-free survival (p = 0.016) compared with CYT-low CRC patients, especially in TIL-positive tumors. Multivariate analysis demonstrated that CYT- high associates with improved survival independently after controlling for age, lymphovascular invasion, colonic location, microsatellite instability, and TIL positivity. The levels of immune checkpoint molecules (ICMs)-programmed death-1 (PD-1), programmed death-ligand 1 (PD-L1), cytotoxic T-lymphocyte-associated protein 4 (CTLA4), lymphocyte-activation gene 3 (LAG3), T cell immunoglobulin and mucin domain 3 (TIM3), and indoleamine 2,3-dioxygenase 1 (IDO1)-correlated significantly with CYT (p < 0.0001); with improved survival in CYT-high and ICM-low patients, and poorer survival in ICM-high patients.

CONCLUSIONS

High CYT within CRC is associated with improved survival, likely due to increased immunity and cytolytic activity of T cells and M1 macrophages. High CYT is also associated with high expression of ICMs; thus, further studies to elucidate the role of CYT as a predictive biomarker of the efficacy of immune checkpoint blockade are warranted.

[Inflammatory and immune biomarkers of radiation response]

In radiotherapy, the treatment is adapted to each individual to protect healthy tissues but delivers most of time a standard dose according to the tumor histology and site. The only biomarkers studied to individualize the treatment are the HPV status with radiation dose de-escalation strategies, and tumor hypoxia with dose escalation to hypoxic subvolumes using FMISO- or FAZA-PET imaging. In the last decades, evidence has grown about the contribution of the immune system to radiation tumor response. Many preclinical studies have identified some of the mechanisms involved. In this context, we have realised a systematic review to highlight potential inflammatory and immune biomarkers of radiotherapy response. Some are inside the tumor microenvironment, as lymphocyte infiltration or PD-L1 expression, others are circulating biomarkers, including different types of hematological cells, cytokines and chemokines.

Programmed death-ligand 1 expression correlates with diminished CD8+ T cell infiltration and predicts poor prognosis in anal squamous cell carcinoma patients

Objective

Increased expression of programmed death-ligand 1 (PD-L1) on tumor cells can be found in various malignancies; however, very limited information is known about its role in anal squamous cell carcinoma (ASCC). This study explored PD-L1 expression in ASCC patients and its association with patients' clinicopathological features, CD8+ T cell infiltration, and prognosis.

Methods

Formalin-fixed paraffin-embedded tumor samples from 26 patients with ASCC were retrieved. The levels of PD-L1 expression on the membrane of both tumor cells and tumor-infiltrating mononuclear cells (TIMCs) were evaluated by immunohistochemistry. CD8+ T cell densities, both within tumors and at the tumor-stromal interface, were also analyzed. Baseline clinicopathological characteristics, human papilloma virus (HPV) status, and outcome data correlated with PD-L1-positive staining.

Results

PD-L1 expression on tumor cells and TIMCs was observed in 46% and 50% of patients, respectively. Nineteen patients (73%) were HPV positive, with 7 showing PD-L1-positive staining on tumor cells and 9 showing PD-L1-positive staining on TIMCs. Increasing CD8+ density within tumors, but not immune stroma, was significantly associated with decreased PD-L1 expression by both tumor cells and TIMCs (P=0.0043 and P=0.0007). Patients with negative PD-L1 expression had significantly better progression-free survival (P=0.038 and P=0.0443) and a non-statistically significant trend toward longer overall survival (P=0.0882 and P=0.1222) compared with patients with positive PD-L1 expression.

Conclusion

PD-L1 is widely expressed on the membrane of tumor cells and TIMCs in ASCCs. Its negative impact on prognosis may be due to the diminished CD8+ T cell infiltration within tumors.

Chemoradiation-Induced Alteration of Programmed Death-Ligand 1 and CD8+ Tumor-Infiltrating Lymphocytes Identified Patients With Poor Prognosis in Rectal Cancer: A Matched Comparison Analysis

PURPOSE

To evaluate chemoradiotherapy (CRT)-induced changes in the expression levels of programmed death-ligand 1 (PD-L1) and CD8⁺ tumor-infiltrating lymphocytes (TILs) and prognostic associations in rectal cancer.

METHODS AND MATERIALS

We performed a paired analysis using pre-CRT biopsies and the corresponding post-CRT resected tissues of 123 rectal cancer patients undergoing preoperative CRT followed by surgery between 2005 and 2012. Immunohistochemistry of PD-L1 and CD8 was analyzed for the specimens.

RESULTS

The expression levels of PD-L1 and density of CD8⁺ TILs increased after CRT (P<.001 for both). With cutoffs using each median value, sustained higher expression of PD-L1 at pre- and post-CRT (high-to-high) was associated with less increase in the density of CD8⁺ TILs (P=.020). Patients representing sustained high-to-high PD-L1 expression had poorer overall survival and disease-free interval on univariate Kaplan-Meier analysis (P=.018 and .029, respectively), with inferior disease-free interval in low-to-low density CD8⁺ TILs (P=.010). On multivariate analysis, 2 subgroups with high baseline PD-L1 expression level, the high-to-low and high-to-high alterations, showed worse overall survival (hazard ratio 8.34, 95% confidence interval 1.85-37.53 and hazard ratio 11.03, 95% confidence interval 2.33-52.29, respectively), with the highest mortality risk observed in the high-to-high group.

CONCLUSIONS

This study verified the CRT-induced immunologic shift toward increases in PD-L1 expression and density of CD8⁺ TILs in rectal cancer patients. The alteration profiles of checkpoint-related molecules identified the patients with poor prognosis, suggesting potential candidates who can benefit from combining CRT and checkpoint inhibitors.

PD1-positive tumor-infiltrating lymphocytes are associated with poor clinical outcome after pulmonary metastasectomy for colorectal cancer

Pulmonary metastasectomy (PM) is routinely performed in colorectal cancer (CRC) patients with oligometastatic spreading to the lungs. Patients with an aggressive tumor phenotype should be excluded from PM, since its benefit is outweighed by early tumor recurrence and impaired prognosis. Expression of PD-1 and its ligands are prognostic factors in a variety of primary tumors. However, their impact on patients' outcome in the setting of PM for CRC has not been evaluated before. 53 CRC patients with pulmonary metastases receiving PM with curative intent were included in this study. Tissue samples of resected pulmonary metastases and available corresponding primary tumors were collected and assessed for PD-1, PD-L1 and PD-L2 expression by tumor-infiltrating lymphocytes (TILs) and tumor cells. Expression patterns were correlated with clinical outcome parameters. PD-1 and PD-L1 expression was commonly found in TILs and tumor cells. Expression levels significantly differed between metastases and primary tumors. High PD-1 expression by TILs was associated with impaired overall survival (low vs high expression (mean, 95% CI): 78 mo (60-96) vs 35 mo (25-44); p = 0.011). Additionally, the subgroup of patients, who experienced an upgrading in their TILs/PD1 status between primary and metastasis had a worse survival outcome compared with patients with the same grade or a downgrading (34 mo (26-42) vs 96 mo (72-120); p = 0.004). Thus, PD-1 expression by TILs is a strong prognostic marker in CRC patients with pulmonary spreading treated by PM. Moreover, this study provides a rationale for a therapeutic PD-1 pathway blockade in the treatment of CRC lung metastases. Future, large-scale studies are warranted to validate the findings of this single-center, retrospective analysis.

Tumor cell PD-L1 predicts poor local control for rectal cancer patients following neoadjuvant radiotherapy

The tumor cell (TC) PD-L1 expression has been reported by several studies in various types of cancer, and it reduces the cytotoxicity of T-cells toward cancer and evades the anticancer immune response. Herein, our study focuses on the impact of PD-L1 expression in prognosis and the correlation with clinical prognostic factors for local advanced rectal cancer with neoadjuvant radiotherapy (RT). A total of 68 rectal cancer patients treated with neoadjuvant RT were retrospectively enrolled in the present study. PD-L1 expression was investigated using immunohistochemistry. A regression model was used to identify prognostic factors associated with the disease-free survival, the local recurrence-free survival (LRFS), and the overall survival rates. The median follow-up was 32.5 months. Seven patients presented TC PD-L1 positive (TC PD-L1+), while the others were TC PD-L1 negative (TC PD-L1−). TC PD-L1+ patients showed frequent tumor recurrence than TC PD-L1− patients. Several patients with TC PD-L1− underwent long-course RT. TC PD-L1 expression was similar to interstitial cell (IC) PD-L1 expression, and the relationship between IC PD-L1 and pathological T stage was observed. TC PD-L1+ was related to poor LRFS. The multivariate analysis showed TC PD-L1+ as an independent negative prognostic factor for LRFS. In conclusion, TC PD-L1 expression putatively predicts the LRFS for patients with rectal cancer following neoadjuvant RT. The patients with TC PD-L1+ are susceptible to high local recurrent rate, thereby proposing a novel immunotherapeutic strategy for PD-L1 inhibition-mediated control.

Predictive and Prognostic Molecular Biomarkers for Response to Neoadjuvant Chemoradiation in Rectal Cancer

The standard of care in locally advanced rectal cancer is neoadjuvant chemoradiation (nCRT) followed by radical surgery. Response to nCRT varies among patients and pathological complete response is associated with better outcome. However, there is a lack of effective methods to select rectal cancer patients who would or would not have a benefit from nCRT. The utility of clinicopathological and radiological features are limited due to lack of adequate sensitivity and specificity. Molecular biomarkers have the potential to predict response to nCRT at an early time point, but none have currently reached the clinic. Integration of diverse types of biomarkers including clinicopathological and imaging features, identification of mechanistic link to tumor biology, and rigorous validation using samples which represent disease heterogeneity, will allow to develop a sensitive and cost-effective molecular biomarker panel for precision medicine in rectal cancer. Here, we aim to review the recent advance in tissue- and blood-based molecular biomarker research and illustrate their potential in predicting nCRT response in rectal cancer.

Prognostic role of PD-L1 in malignant solid tumors: a meta-analysis

PURPOSE

The aim of this study was to elucidate the rates and prognostic roles of programmed cell death ligand 1 (PD-L1) immunohistochemical (IHC) expression in various malignant tumors through a systematic review and meta-analysis.

METHOD

The current study included 16,176 patients from 97 eligible studies. We investigated PD-L1 expression and its correlation with survival rate in various malignant tumors.

RESULTS

The estimated rate of PD-L1 IHC expression was 0.449 (95% confidence interval [CI] 0.404-0.495). The highest and lowest PD-L1 expression levels were found in thyroid cancer (0.829, 95% CI 0.781-0.868) and small-cell neuroendocrine carcinoma (0.005, 95% CI 0.000-0.080), respectively. PD-L1 expression was significantly correlated with poorer overall survival and disease-free survival rates (hazard ratios 1.276, 95% CI 1.097-1.486 and 1.304, 95% CI 1.034-1.644, respectively). However, PD-L1 IHC expression was significantly correlated with worse overall survival rates in patients with esophageal cancer and renal cell carcinoma and with worse disease-free survival rates in patients with colorectal cancer, hepatocellular carcinoma, and renal cell carcinoma.

CONCLUSIONS

Our results show that PD-L1 expression rates and the correlations with survival varied between tumor types. Detailed evaluation criteria for PD-L1 will have to be standardized before application to specific tumor types.