Understanding Immunotherapy in Cancer Treatment

What is Immunotherapy?

Immunotherapy, also known as biological therapy, represents a cancer treatment strategy that leverages the immune system to enhance its natural defenses against cancer.

Adoptive Cell Transfer (ACT)

One method of immunotherapy is adoptive cell transfer (ACT). In this approach, cells are sourced from either a patient or a donor, genetically modified to transform them into a specific type of white blood cell. After enhancing their immune capabilities and multiplying these cells, they are reintroduced into the patient’s body. While ACT has shown effectiveness in treating melanoma, its impact has been less pronounced in cases of ovarian, esophageal, stomach, and breast cancers.

Modified ACT Approach

A new variant of ACT focuses on the mutations present in cancer cells rather than the cancer type itself. This updated method is particularly beneficial for cancers exhibiting a higher mutation burden, contrasting with traditional ACT, which is less effective for low-mutation cancers.

Recent Developments from the National Cancer Institute

Research and Clinical Trials

Researchers at the National Cancer Institute (NCI) in the United States have pioneered this modified ACT approach. Their findings, published in Nature Medicine, stem from an ongoing phase-2 clinical trial assessing its effectiveness.

Utilizing Tumor-Infiltrating Lymphocytes

This innovative method employs tumor-infiltrating lymphocytes, a type of immune cell indicative of the immune system’s attack on cancer cells. The study aimed to ascertain whether these lymphocytes could effectively target tumor mutations and reduce tumor size, akin to other ACT strategies. To achieve this, lymphocytes were cultured in significant quantities in the laboratory before being infused back into the patient to stimulate a robust immune response against the tumor.

Case Study: Metastatic Breast Cancer

Individualized Treatment Approach

In this phase-2 clinical trial, a patient with metastatic breast cancer—who had not responded to prior treatments—was selected for the study. Her tumor had continued to grow despite chemotherapy. To tailor the treatment to her specific needs, researchers sequenced the DNA and RNA from her tumor and compared it with healthy tissue, identifying 62 unique mutations present in her cancer cells.

Infusion of Targeted Lymphocytes

Following this analysis, the researchers tested various tumor-infiltrating lymphocytes from the patient to determine which could recognize her tumor’s mutated proteins. Lymphocytes that identified four of these mutant proteins were cultivated in large numbers and subsequently infused back into the patient. Additionally, the patient received medication to prevent her tumor from neutralizing the infused cells.

Results and Implications

Complete Regression of Cancer

The results indicated that this novel immunotherapy method led to the complete regression of the patient’s breast cancer. Despite initial metastatic lesions in her breast and liver, MRI scans conducted 14 months post-treatment revealed that these lesions had vanished and remained absent 22 months later.

Broader Efficacy Observed

Similar outcomes were noted in patients with liver and colorectal cancers, marking a significant advancement since ACT traditionally struggled with these cancer types. This underscores the potential of immunotherapy not only for breast cancer but also for a wider array of cancers.

Future Directions and Insights

Potential for Various Cancer Types

The findings suggest that all cancers possess mutations, making them susceptible to this immunotherapy approach. Dr. Rosenberg, one of the researchers, highlighted the irony that “the very mutations that cause cancer may prove to be the best targets to treat the cancer.”

Need for Expanded Research

While these results are promising, the authors emphasize the necessity for larger studies encompassing a broader range of cancers to fully realize the potential of this innovative treatment method.

Reference

New approach to immunotherapy leads to complete response in breast cancer patient unresponsive to other treatments. National Institute of Health website https://www.nih.gov/news-events/news-releases/new-approach-immunotherapy-leads-complete-response-breast-cancer-patient-unresponsive-other-treatments. Accessed June 7, 2018.