Is DNA Vaccine Effective for Castration-Resistant Prostate Cancer?

After skin cancer, prostate cancer is the second most common cancer in American men. The American Cancer Society has estimated that about 288,300 new cases of prostate cancer will be diagnosed in 2023 with approximately 34,700 deaths from prostate cancer.

A clinical trial has investigated the use of a DNA vaccine MVI-816 along with a drug known as pembrolizumab in the treatment of castration-resistant prostate cancer (mCRPC).

Prostate cancer is one of the most commonly diagnosed cancers in men, with an estimated 1 in 8 men being diagnosed with it at some point in their lifetime. Metastatic, castration-resistant prostate cancer is a particularly aggressive form of prostate cancer that has spread to other parts of the body and has stopped responding to hormone therapy. Over the last 15 years, several therapies have been approved by Food and Drug Administration based on their ability to prolong overall survival in patients with mCRPC. One of these is a DNA vaccine called MVI-816. However, strong clinical data on its efficacy has been lacking.

Clinical Trial

The trial has investigated the safety and effectiveness of combination therapy for mCRPC. The therapy involved using two drugs, MVI-816, and pembrolizumab, to activate the patient's T-cells and boost their immune system to fight off cancer.

Pembrolizumab is a type of immunotherapy. It stimulates the body's immune system to fight cancer cells. Pembrolizumab targets and blocks a protein called PD-1 on the surface of certain immune cells called T-cells. Blocking PD-1 triggers the T-cells to find and kill cancer cells.

The trial involved 40 patients with mCRPC who had already received previous treatments for cancer. 20 patients were treated with MVI-816 and pembrolizumab every 3 weeks and the remaining 20 patients received MVI-816 every 2 weeks and pembrolizumab every 4 weeks. The 6-month progression-free survival was monitored.

Results

The results showed that the overall progression-free survival rate was 47.2% at 6 months. 4/40 patients (10%) had a prostate-specific antigen decline >50%. The average survival was 22.9 months. These results indicate that the combination of MVI-816 and pembrolizumab is an effective treatment option for treating castration-resistant prostate cancer.

Additionally, the combination therapy was well-tolerated by the patients, with no major side effects reported. 42% of the patients had minor immune-related adverse events and only one patient reported hyperglycemia.

These results are particularly exciting because mCRPC is a very difficult cancer to treat, and there are limited treatment options available once cancer becomes resistant to hormone therapy. The combination therapy of MVI-816 and pembrolizumab represents a new approach to treating mCRPC by harnessing the patient's own immune system to fight off cancer.

Conclusion

This clinical trial has shown promising results for the treatment of mCRPC using a combination therapy of MVI-816 and pembrolizumab. The findings here demonstrate that combining programmed cell death 1 blockade with MVI-816 is safe, and can result in a favorable 6-month disease control rate. This is significant as it represents an exciting new approach to treating this difficult and aggressive form of prostate cancer.
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