Amgen and Merck announced Friday the expansion of their research collaboration to develop a new drug intended to treat head and neck cancer.

Head and neck cancers are common in both men and women, especially those over 50 years old. People who often smoke tobacco and drink alcohol are the most vulnerable in developing the diseases; about 75 percent of the cases are linked to these activities. The treatment varies depending on the location of the tumor, the cancer stage and the patient's age and health. Doctors may recommend surgery, radiation therapy, chemotherapy, targeted therapy, or a combination of treatments.

The two drug makers set out on a clinical trial to assess the effectiveness of the combination of Amgen's experimental talimogene laherparepvec (T-VEC) with Merck's Keytruda on patients with carcinoma of the head and neck.

Keytruda is currently used to treat melanoma, while T-VEC is a virus designed to destroy cancer cells.

"We hope these trials will provide us with insights on the combination of these therapies for patients with this form of cancer for whom treatment options are currently limited. We will discuss the design of the Phase 3 melanoma trial with global regulators and look forward to collaborating with Merck on this study," Sean E. Harper, executive vice president of Research and Development at Amgen, said in a press release.

Amgen and Merck also said that they plan to test the drug combination on melanoma patients as well. Both decided to share resources instead of competing with each other on the immunotherapy market. The Wall Street Journal analysts predicted that the market could generate up to $30 billion in annual sales in the next decades.