NK Cell Therapy with Chemotherapy: Supporting Your Immune System

Hello, I am Dr. Hidenori Shimada of Grand Green Osaka Umekita Clinic in Osaka, Japan.

Receiving a cancer diagnosis and undergoing chemotherapy can be a challenging journey. While chemotherapy is a powerful and essential tool in modern oncology, it can also place significant stress on the body, particularly the immune system. Many patients and their families seek ways to support their well-being during this period. This article explores the relationship between chemotherapy and the immune system, and how NK cell therapy may serve as a complementary approach to support your body’s natural defenses when they are most vulnerable.

The Challenge: How Chemotherapy Affects Your Immune System

Chemotherapy drugs are designed to target and eliminate rapidly dividing cells, a hallmark of cancer. However, this mechanism is not entirely selective. Other healthy, rapidly dividing cells in the body can also be affected. This includes cells in the bone marrow, which are responsible for producing the components of your blood, including the white blood cells that form your immune system.

Consequently, a common side effect of many chemotherapy regimens is myelosuppression, or a decrease in the production of blood cells. This can lead to a state of weakened immunity (immunosuppression), making a person more susceptible to infections. Key immune cells, such as Natural Killer (NK) cells, can see their numbers and functional activity decline, potentially compromising the body’s innate ability to fight off not only infections but also residual or resistant cancer cells.

What Are NK Cells and Why Do They Matter in Cancer Treatment?

Natural Killer (NK) cells are a crucial part of the innate immune system—your body’s first line of defense. Unlike other immune cells that need to be ‘trained’ to recognize a specific threat, NK cells are born ready to act. They constantly patrol the body, identifying and destroying abnormal cells, such as cancer cells or virus-infected cells, on sight. This process is known as immune surveillance.

NK cells play a vital role for several reasons:

• Direct Attack: They can directly kill target cells without prior sensitization.
• Early Detection: They are skilled at recognizing cells that are trying to hide from the immune system by altering their surface markers.
• System Coordination: They release signaling proteins called cytokines, which can help activate and rally other parts of the immune system.

When NK cell activity is diminished—due to factors like age, stress, or the effects of cancer treatment—this surveillance network may be weakened. Supporting the function of these cells is therefore an area of significant interest in oncology.

A Complementary Approach: NK Cell Therapy as Adjunctive Support

NK cell therapy is a form of immunotherapy that aims to bolster this specific part of the immune system. It is important to understand that this is considered an adjunctive or complementary therapy, meaning it is used alongside—not as a replacement for—standard treatments like chemotherapy, radiation, or surgery.

The process typically involves:

• Collection: A sample of your own blood is drawn.
• Activation and Expansion: In a specialized cell processing facility, the NK cells are isolated from the blood sample. They are then cultured in a controlled environment that encourages them to multiply and enhances their cell-killing activity.
• Infusion: These activated, more numerous NK cells are returned to your body through a simple intravenous (IV) drip.

The goal of this approach is to reinforce your immune system by increasing the number of active NK cells available to perform their surveillance duties. By using your own (autologous) cells, the therapy is generally associated with a low risk of rejection-related side effects. The potential synergy between chemotherapy, which reduces the tumor burden, and a supported immune system, which may help manage remaining cells, is an active area of clinical research.

Important Considerations for Combining Treatments

If you are considering NK cell therapy alongside chemotherapy, a thorough discussion with a qualified physician is essential. This is not a one-size-fits-all treatment, and its suitability depends entirely on your individual medical condition, cancer type, and overall treatment plan.

It is crucial to note that NK cell therapy is a form of regenerative medicine provided as a private medical service (not covered by public health insurance). In Japan, such treatments are regulated under the Act on the Safety of Regenerative Medicine, which requires clinics to submit treatment plans to the government to ensure safety standards are met. The decision to proceed must be based on a comprehensive medical evaluation. A doctor will assess your eligibility and explain the expected benefits, as well as the potential risks and side effects, which may include temporary fever or fatigue.

What to Discuss with Your Doctor Beforehand

To make an informed decision, it’s helpful to come to your consultation prepared with questions. At Grand Green Osaka Umekita Clinic, we encourage open dialogue to ensure you have a clear understanding of your options. Consider asking:

• How might NK cell therapy fit into my current chemotherapy schedule?
• Based on my health status, what are the potential benefits and risks I should be aware of?
• What does the treatment process involve, from the initial blood draw to the final infusion?
• What is the estimated timeline and number of sessions that might be suggested for my case?

Understanding the full scope of the therapy is key. For a detailed overview of the process and to prepare for your consultation, you can review the information on our NK Cell Therapy page. Our clinic in Osaka provides multilingual support for international patients seeking information on advanced treatment options available in Japan.

Summary: A Supportive Role in Your Cancer Journey

Chemotherapy remains a fundamental pillar of cancer care. However, its impact on the immune system is a significant consideration. Adjunctive therapies like NK cell therapy are being explored for their potential to support the body’s innate defenses during this vulnerable time. By aiming to restore the number and activity of critical immune cells, this approach seeks to work in concert with standard treatments.

No therapy can guarantee a specific outcome, and all medical treatments carry potential risks. The most important step is to have a detailed consultation with a physician to determine if this or any other complementary therapy is an appropriate and safe option for your unique situation. A personalized medical assessment is the only way to make a truly informed choice about your health.

1. 1Consultation with DoctorDiscuss suitability and your plan
2. 2Blood CollectionA sample of your own blood is taken
3. 3Cell Activation & ExpansionYour NK cells are multiplied in a lab
4. 4InfusionActivated cells returned via IV drip
5. 5Immune System SupportTo reinforce your body's defenses

This diagram provides a simplified overview of the process described in the article

References

• PubMed: Daratumumab, lenalidomide, and dexamethasone versus lenalidomide and dexamethasone alone in newly diagnosed multiple myeloma (MAIA): overall survival results from a randomised, open-label, phase 3 trial. (2021)
• PubMed: Bempegaldesleukin Plus Nivolumab Versus Sunitinib or Cabozantinib in Previously Untreated Advanced Clear Cell Renal Cell Carcinoma: A Phase III Randomized Study (PIVOT-09). (2024)
• PubMed: Research Status and Molecular Mechanism of the Traditional Chinese Medicine and Antitumor Therapy Combined Strategy Based on Tumor Microenvironment. (2020)
• PubMed: Induced pluripotent stem-cell-derived CD19-directed chimeric antigen receptor natural killer cells in B-cell lymphoma: a phase 1, first-in-human trial. (2025)
• PubMed: Single-cell RNA sequencing reveals enhanced antitumor immunity after combined application of PD-1 inhibitor and Shenmai injection in non-small cell lung cancer. (2023)
• PMC: Field Cancerization in NSCLC: A New Perspective on MicroRNAs in Macrophage Polarization. (2021)
• PMC: Inclusion of JNK-independent drugs within multiagent chemotherapy improves response in relapsed high-risk neuroblastoma. (2025)
• PMC: The interplay of immunotherapy and chemotherapy: harnessing potential synergies. (2015)
• MHLW (Japan): Regenerative Medicine — Ministry of Health, Labour and Welfare, Japan

Supervising Physician

Director, Medical Corporation Shimada Clinic
Head of Clinical Practice, Grand Green Osaka Umekita Clinic

Hidenori Shimada

Graduated from the University of Tokushima Faculty of Medicine in 2005. After his initial residency, he obtained U.S. medical certification (ECFMG) and trained as a sub-intern in general surgery at the University of Washington. After completing the doctoral program at Kyoto University Graduate School of Medicine and working as a researcher at the Center for iPS Cell Research and Application (CiRA), Kyoto University, he founded Shimada Clinic in 2013. At Grand Green Osaka Umekita Clinic (https://umekitaclinic.org), he is engaged in a wide range of care, from internal medicine and pediatrics to cell therapy and aesthetic medicine.

* The physician supervision of this article covers its academic content only and does not constitute a recommendation of any specific treatment or product.