Understanding Immunotherapy Part 3: CTLA-4

By Amrita Bhatt, MRA Intern

Now that you’ve read our background on immunotherapy and learned about PD-1, it’s time to focus on another protein that plays a key role in cancer development, CTLA-4.

What is CTLA-4?

In addition to displaying PD-1 on the cell surface, T cells also display CTLA-4. This protein will bind to its partner, B7, causing the T cell to be turned off. Consequently, the immune response is impaired. As with the PD-1/PD-L1 interaction, this is a normal negative control of the immune response. Unfortunately, melanoma cells can take advantage of this, allowing the cancer cells to flourish.

What anti-CTLA-4 drugs are available now?

Currently, two anti-CTLA-4 drugs have been approved by the FDA – Ipilimumab (Yervoy®) and a combination therapy, Nivolumab + Ipilimumab (Opdivo® + Yervoy®). Yervoy is a checkpoint inhibitor that boosts your immune system in order to attack cancer cells. Specifically, it promotes the function and growth of T-cells, which are part of the immune response. When used in combination, Nivolumab and Ipilimumab help build your immunological “memory,” meaning that your immune system may continue attacking melanoma cells even after treatment. A phase II clinical trial in 2015 indicated that using the two in combination showed a higher response rate than just using ipilimumab alone.

Watch Dr. Evan J. Lipson of Johns Hopkins Medicine discuss more on the benefits of combination therapy.

What type of CTLA-4 research has MRA funded?

Anti-CTLA-4 therapy is a promising agent for the treatment of cancer patients and research funded by MRA plays a crucial role in advancing the field. MRA is currently funding the melanoma supplement of the SU2C-CRI Immunology Dream Team co-led by Drs. James Allison and Antoni Ribas. Their studies aim to identify biomarkers of response in patients treated with ipilimumab, nivolumab, and a combination of the two.

In 2008, MRA funding helped Dr. Jedd Wolchok of Memorial Sloan Kettering Cancer Center and Dr. Padmanee Sharma of MD Anderson Cancer Center work on research projects focused on biomarkers for ipilimumab. Biomarkers are biological substances that can be indicative of a certain disease – in this case, melanoma. Additionally, Dr. Frank Hodi of the Dana-Farber Cancer Institute worked on two funded projects that investigated combination therapy involving ipilimumab.

What’s Next?

Immunotherapy provides hope to not only melanoma patients, but patients of all cancer types. Recent clinical trials have shown that ipilimumab allows for greater survival compared to a vaccine. Additionally, ipilimumab can be used as adjuvant therapy in cases of high-risk melanoma. In these situations, ipilimumab is given in addition to the primary treatment, which is usually surgery. High-risk patients undergoing adjuvant therapy are able to experience a longer relapse-free survival. As we continue to learn more about immunotherapy, and CTLA-4 in particular, MRA is committed to accelerating research in order to benefit even more patients.

We hope you enjoyed and learned more through mini-series on immunotherapy!

Learn more about the promise of immunotherapy:

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