Short summary

It is currently unknown which cells of the immune system are responsible for tumor shrinkage during treatment and whether the intra-tumoral coordination between the immune cells differs according to treatment modality. 

We speculate that a characterization and quantification through multiplex immunofluorescence analysis of infiltrating immune cells and expression of PD-1/PD-L1 in tumor tissue surgically resected in patients diagnosed with colorectal cancer stage II, potentially can discriminate between patients with recurrence of the disease and patients who remain with no recurrence.

Rationale

Colorectal cancer (CRC) is one of the most common types of cancer in the world and the third most common in Denmark with approximately 4,800 new cases each year. The CRC diagnosis is generally related to considerable morbidity and the overall 5-year survival is only around 65%. The number of new cases has increased since the initiation of screening in Denmark in 2014. The overall best prognostic marker for CRC is still the pTNM staging, which is also used for treatment stratification. Around 80% of the patients are resectable at the time of diagnosis. Patients with stage I-III disease are operated upfront with curative intent.

Cancer cells are defined by their ability to grow and divide uncontrolled, spread invasively to surrounding tissues, and disseminate and give rise to metastases by different mechanisms often referred to as hallmarks of cancer. Multiple studies indicate that the immune system also plays a major role in the development of cancer, and our understanding of the critical interactions between the immune system and disease is constantly growing, but several questions are still unanswered, also in patients with CRC. 

The PD-1/PD-L1 axis is a negative regulator of immune activation. PD-L1 can be expressed by immune cells as well as tumor cells and has recently become the target of novel, immune-modulating therapies that antagonize PD-1 signaling to improve tumor specific immune responses. 

Studies indicate that high expression of PD-L1 in solid tumors is related to a poor prognosis while the clinical impact in CRC is largely unknown. Likewise, the predictive value of soluble PD-L1 levels in CRC is unknown whereas in several other types of cancer high levels have been related to a poor prognosis. 

The prevalence of cytotoxic T-cells has been demonstrated to have great value in multiple tumor types. Especially CD8 positive T-cells seem to be superior to traditional pTMN staging in patients with colon cancer. Studies have demonstrated that high counts of CD8 positive T-cells is associated with better survival in e.g. patients with breast cancer.

This study is a retrospective study based on an approved research biobank. We plan to characterize and quantify infiltrating immune cells in tumor tissue resected in patients diagnosed with colorectal cancer through multiplex immunofluorescence analysis. Furthermore, we will search if the multiplex immunofluorescence analysis is valid in a clinical setting. We will also analyze for PD-L1/PD-1 expressing cells in the surgically resected primary tumor specimen in order to search for any correlation between patient outcome and PD-L1/PD-1 expression.

In conclusion, the results of this retrospective study may add to the current knowledge of a new approach to analyzing for several antibodies in the tumor tissue.

Description of the cohort

Tissue and data from the research database "Syddansk Colorectal Cancer Database" registering data on all patients with colorectal cancer treated at Vejle Hospital since August 2016. In this study we include tissue and clinical data from 40 adult patients both men and women operated for colorectal cancer stadium II disease. Twenty patients with recurrent disease and 20 patients without recurrence.

Data and biological material

Clinical data based on the patient's medical record.

Biological material based on formalin-fixed paraffin-embedded tissue from the operation for colorectal cancer.

Collaborating researchers and departments

Department of Oncology, Vejle Hospital

• Associate professor Torben Frøstrup Hansen, MD, PhD

Department of Clinical Pathology, Vejle Hospital

• Associate professor Jan Lindebjerg, MD, PhD

Bioneer A/S, Kogle Allé 2, 2970 Hørsholm

• Business and Research Manager, Molecular Histology, Boye Schnack Nielsen, PhD