Colorectal Cancer

Medically reviewed by Prof. Shimon Slavin, MD. Updated: August 2026

Immunotherapy for colon cancer is designed to help the immune system recognize and attack cancer cells.

At Biotherapy International, individualized immunotherapy programs are considered primarily for patients with advanced colon and rectal cancer, recurrent disease, metastases, or progression after previous treatment.

The methods used and their sequence are selected according to the characteristics of the tumor, previous treatments, and the patient’s overall condition.

Colon Cancer Treatment and the Role of Immunotherapy

The main treatments for colon and rectal cancer include surgery, chemotherapy, and targeted therapy.

Patients with advanced colorectal cancer usually require systemic treatment. Targeted drugs may be selected according to the molecular characteristics of the tumor, including RAS, BRAF, HER2, and other biomarkers.

If the disease continues to progress or the tumor becomes resistant to previous treatment, additional therapeutic approaches may be needed.

Immunotherapy works differently from conventional anti-cancer treatments. Its purpose is to help the immune system detect cancer cells and develop a stronger anti-tumor immune response.

When Is Immunotherapy Used for Colon Cancer?

The effectiveness of immunotherapy for colon and colorectal cancer depends on the biological characteristics of the tumor.

One important factor is how effectively cancer cells are able to repair errors that occur in their DNA. This is evaluated using MMR and MSI status.

MSI-H / dMMR Colorectal Cancer

When the DNA repair system does not function properly, the tumor may have deficient mismatch repair (dMMR) and/or high microsatellite instability (MSI-H).

These tumors accumulate a greater number of genetic abnormalities. As a result, they may become more recognizable to the immune system and often respond better to treatment with immune checkpoint inhibitors.

For this reason, MSI/MMR testing is an important part of evaluating immunotherapy options for patients with colon and rectal cancer.

MSS / pMMR Colorectal Cancer

Most colon and rectal cancers are classified as MSS/pMMR.

In these tumors, the DNA repair system remains functional. They generally respond much less effectively to checkpoint inhibitors when these drugs are used alone.

MSS tumors may remain poorly recognized by the immune system and may also create a tumor environment that suppresses an effective immune response.

In such cases, combination approaches may be considered. The goal may be to first make the tumor more visible to the immune system and then strengthen the anti-tumor immune response that has been initiated.

Immunotherapy for Stage 4 Colon Cancer and Metastatic Disease

Immunotherapy may be considered for patients with:

• stage 4 colon cancer;
• metastatic colon or rectal cancer;
• recurrent or progressive disease after previous treatment;
• tumors that have developed resistance to chemotherapy, targeted therapy, or other treatments.

For patients with metastatic colon cancer, the choice of treatment depends on the location and number of metastatic lesions, the molecular characteristics of the tumor, previous therapies, and how the disease responded to those treatments.

Immunotherapy Approaches for Colon Cancer

At Biotherapy International, different immunotherapy methods may be used sequentially, with each treatment stage designed to complement the previous one.

Oncolytic Virus Therapy

Oncolytic viruses can preferentially enter cancer cells and destroy them.

When tumor cells are destroyed, tumor-associated antigens are released. This may make malignant cells more visible to the immune system and help immune cells recognize the tumor.

At the same time, oncolytic viruses can stimulate a local inflammatory and immune response within the tumor environment and promote the recruitment of immune cells to the tumor.

For this reason, oncolytic virus therapy for colon cancer may be used not only for direct anti-tumor activity but also as a way to prepare the immune system for subsequent stages of immunotherapy.

The objective is to transform a tumor that is poorly recognized by the immune system into a more immunologically active target.

Immune Checkpoint Inhibitors and CMI

Cancer cells can suppress T-cell activity through immune checkpoint pathways, including PD-1/PD-L1 and CTLA-4.

Immune checkpoint inhibitors block these mechanisms and help maintain an active anti-tumor immune response.

In Biotherapy International treatment programs, checkpoint inhibitors are often considered after oncolytic virus therapy. The purpose of the preceding oncolytic treatment is to help make the tumor more recognizable to the immune system and initiate an anti-tumor immune response.

Checkpoint inhibition may then help prevent cancer cells from suppressing the activated T cells and allow the immune response to continue.

As an alternative to checkpoint inhibitors, Cytokine-Mediated Immunotherapy (CMI) may be used.

CMI is designed to stimulate and support the anti-tumor immune response through cytokines that regulate immune-cell activation and activity.

The choice between checkpoint inhibitors and CMI depends on the characteristics of the tumor, previous treatments, the patient’s clinical condition, and the overall treatment strategy.

Personalized Cancer Vaccines

A personalized cancer vaccine may be prepared from the patient’s own tumor material preserved after surgery.

Tumor tissue is used to produce a tumor lysate containing antigens from that individual patient’s cancer.

The tumor lysate is combined with an oncolytic virus in order to enhance the immune reaction and help the immune system recognize tumor-associated antigens more effectively.

The purpose of vaccination is to stimulate a more targeted immune response against remaining cancer cells.

A personalized colon cancer vaccine may therefore be incorporated into a broader sequential immunotherapy program rather than being used as an isolated treatment.

ATACK Cellular Immunotherapy

ATACK (Allogeneic Targeted Activated Cancer Killer Cells) is a form of cellular immunotherapy that uses activated immune cells obtained from a healthy donor.

T cells, NK cells, and NKT cells are activated and expanded outside the body before being administered to the patient to attack malignant cells.

ATACK may be particularly relevant during later stages of treatment, when the overall tumor burden has already been significantly reduced.

This situation is known as minimal residual disease (MRD).

At this stage, visible tumor masses may have been removed or substantially reduced, while small numbers of resistant cancer cells may still remain in the body.

Cellular immunotherapy may then be used to target these remaining malignant cells and strengthen an already established anti-tumor immune response.

For this reason, ATACK can be considered as a later stage of a sequential immunotherapy program rather than necessarily as the first treatment used.

Individualized Colorectal Cancer Immunotherapy Protocol

There is no single immunotherapy protocol that is appropriate for every patient with colon or rectal cancer.

The treatment program is developed individually, and the methods used may differ considerably between patients.

When an individualized colorectal cancer immunotherapy protocol is developed, the medical team considers:

• tumor type and histology;
• stage of the disease;
• location of metastases;
• overall tumor burden;
• previous surgery and systemic treatments;
• effectiveness of previous therapies;
• MSI/MMR status;
• KRAS, NRAS, BRAF, HER2, and other available molecular findings;
• the patient’s overall condition.

Depending on the clinical situation, the program may include oncolytic virus therapy, a personalized cancer vaccine, checkpoint inhibitors or CMI, cellular immunotherapy, and other treatment methods.

The objective is not simply to select individual therapies, but also to determine the most appropriate sequence in which they should be used.

Different stages of treatment may have different purposes: reducing tumor burden, improving immune recognition of the tumor, activating an anti-tumor immune response, maintaining that response, or targeting remaining resistant cancer cells.

How We Evaluate Each Case

Before an immunotherapy program is developed, the medical team reviews the patient’s medical history and available medical records.

The initial evaluation usually requires:

• pathology and histology reports;
• recent CT, MRI, or PET-CT scans;
• molecular tumor testing results;
• information about previous treatments and their effectiveness;
• recent blood test results.

The molecular profile is particularly important when evaluating colorectal cancer immunotherapy because it may influence both the expected response to specific treatments and the selection of an individualized treatment strategy.

If important information is missing, additional examinations or molecular tests may be recommended before the treatment protocol is finalized.

Colon Cancer Immunotherapy in Germany

Biotherapy International immunotherapy programs are performed at our partner clinic in Germany.

Before treatment begins, the medical team reviews the patient’s medical records and develops an individualized protocol based on the characteristics of the disease and previous treatment history.

The necessary procedures are then performed by physicians at the partner clinic according to this protocol.

The treatment program may include several stages, and subsequent therapy can be adjusted according to the patient’s condition and the response observed during treatment.

How Treatment Is Performed

If a patient is considered suitable for the program after the initial medical evaluation:

1. An individualized treatment protocol is developed.
2. The appropriate treatment methods and their sequence are determined.
3. Treatment is performed at our partner clinic in Germany.
4. The results are evaluated after the main stages of therapy.
5. Further treatment may be adjusted when necessary.

Because colorectal cancer can behave very differently from one patient to another, the sequence of treatment is determined individually rather than following one fixed immunotherapy regimen.

Could Immunotherapy Be Considered in Your Case?

Even with stage 4 colon cancer, metastatic disease, or progression after previous treatment, additional immunotherapy options may still be considered.

Send us your recent medical records. We can review your case and determine which treatment options may be appropriate.

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