By Jennifer Robin Raj

BANGALORE, June 22 (Reuters) - Shares of Medarex Inc (MEDX.O) rose as much as 22 percent Monday on a Mayo Clinic report that two prostate cancer patients became cancer-free after being treated with the company's experimental drug, ipilimumab, in combination with other therapies and surgery.

On Friday, the Mayo Clinic said both patients experienced reduction in levels of a protein called PSA, or prostate specific antigen, and tumor shrinkage after receiving one dose of ipilimumab, which allowed them to be treated with surgery.

The two patients had tumors that were considered inoperable at diagnosis, the Mayo Clinic said.

Patients in the mid-stage study were being treated with ipilimumab in combination with hormone treatment and radiation therapy.

"It is really the headline itself of these dramatic responses irrespective of the patient number that is driving the stock at this point," Merriman Curhan Ford analyst Joseph Pantginis said.

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