Cancer Vaccine Setback. Failed product is one of therapeutic cancer vaccines. Unlike typical vaccines given to healthy people to prevent disease, therapeutic cancer vaccines are given to patients already diagnosed with cancer

September 5, 2013, 6:34 p.m. ET

Cancer Vaccine Setback

Failed Glaxo Trial Is Unlikely to Dampen Drug Firms’ Interest in Hot R&D Area

JEANNE WHALEN and RON WINSLOW

LONDON—An experimental cancer vaccine failed to help skin-cancer patients in aGlaxoSmithKline GSK.LN -0.81% PLC clinical trial, a setback for a hot area of medicine that seeks to harness the body’s immune system to fight tumors. When compared to a placebo, the vaccine, called MAGE-A3, didn’t increase the amount of time melanoma patients lived without their disease returning, Glaxo said Thursday. The 1,345 patients in the late-stage trial were given either the vaccine or a placebo after their tumors were surgically removed.The trial will continue until Glaxo can assess whether the treatment benefits a subset of patients with a particular genetic profile, the company said. Glaxo also continues to test MAGE-A3 in a separate study in patients with lung cancer.

The product is one of several so-called therapeutic cancer vaccines—also known as immunotherapies—under development by pharmaceutical companies. Unlike typical vaccines, which are given to healthy people to prevent disease, therapeutic cancer vaccines are given to patients already diagnosed with cancer. But as with typical vaccines, these cancer treatments seek to deploy the immune system to fight disease.

Glaxo’s product delivers into the body a dose of MAGE-A3, a protein found in certain types of tumors, including in 65% of advanced melanoma cases, but not in normal, healthy cells. The hope is that the body will recognize this abnormal protein as foreign, and attack it anywhere it exists in the body, including in cancerous cells.

Despite Glaxo’s disappointing results, the news isn’t likely to dampen enthusiasm for immunotherapy, especially for a class of medicines known as immune checkpoint inhibitors that work by a different mechanism and are churning interest for their sometimes dramatic effect against melanoma and other cancers.

Bristol-Myers Squibb Co.’s BMY -0.64% Yervoy is already on the market for melanoma, and that company, along with Merck MRK -0.36% & Co. and Roche Holding AG, RHHBY -1.68% have candidates advancing in clinical trials. The checkpoint inhibitors target molecular mechanisms that enable tumors to evade detection by the immune system. The effect when they work, researchers say, is to release the brakes on the immune system to allow it to attack the tumor.

Another cancer vaccine, the prostate-cancer treatment Provenge from Seattle-basedDendreon Corp., DNDN -2.73% is also on the market. It works in a still different way—a patient’s own cells are taken from his blood, processed outside the body and infused back into the patient to activate the immune system against prostate tumors. Sales have been disappointing, reflecting such factors as competing medicines that are much easier to administer and skepticism among some doctors about the product’s efficacy.

Analysts have long considered the MAGE-A3 vaccine a risky project, and on Thursday, Citigroup pharmaceutical analyst Andrew Baum said the disappointing trial results underscored his view that the treatment isn’t potent enough to elicit a strong enough immune response.

But some experts said it was too soon to write the product off.

Elizabeth Mittendorf, a surgeon and cancer vaccine researcher at the University of Texas MD Anderson Cancer Center, said she was eager to see whether the MAGE A3 vaccine could help patients with a specific genetic profile. “That will be very important data we’ll all be interested in,” she said. “Let’s say this vaccine doesn’t work in all MAGE-A3 [patients], but what if it works in 50%? That would still be good.”

Meantime, small studies of other experimental immune system treatments recently have reported encouraging results. In May, researchers said a combination of Yervoy and an experimental Bristol-Myers agent called nivolmab resulted in “rapid and deep tumor regressions” in nearly one-third of 52 skin-cancer patients treated with the combination. The combination was more effective than each drug given alone, researchers said.

Also in May, Roche said the company’s experimental cancer vaccine, called MPDL3280A, shrank tumors in 21% of 140 patients participating in a trial. The patients had a variety of different cancers. Roche is now testing the drug in a larger trial in lung-cancer patients.

Merck is developing a checkpoint inhibitor called MK-3475 that recently was granted a so-called breakthrough drug designation by the U.S. Food and Drug Administration, intended to speed to the market certain medicines demonstrating significant promise in early trials.