* New-style vaccines from German, U.S. teams cut relapses
* Aim to add 'neoantigen' vaccines to immunotherapy drugs
* Roche already in $310 mln deal with Germany's BioNTech
* BioNTech CEO says will look at IPO in two to four years
LONDON, July 5 (Reuters) - A novel class of personalised cancer vaccines, tailored to the tumours of individual patients, kept disease in check in two early-stage clinical trials, pointing to a new way to help the immune system fight back.
Although so-called immunotherapy drugs from the likes of Merck & Co, Bristol-Myers Squibb and Roche are starting to revolutionise cancer care, they still only work for a limited number of patients.
By adding a personalised cancer vaccine, scientists believe it should be possible to improve substantially the effectiveness of such immune-boosting medicines.
Twelve skin cancer patients, out of a total of 19 across both the trials, avoided relapses for two years after receiving different vaccines developed by German and U.S. teams, researchers reported in the journal Nature on Wednesday.
The small Phase I trials now need to be followed by larger studies, but the impressive early results suggest the new shots work far better than first-generation cancer vaccines that typically targeted a single cancer characteristic.
The new treatments contain between 10 and 20 different mutated proteins, or "neoantigens", that are specific to an individual's tumour. These proteins are not found on healthy cells and they look foreign to the immune system, prompting specialist T-cells to step up their attack on cancer cells.
One vaccine was developed at the U.S.-based Dana-Farber Institute and Broad Institute and the other by privately owned German biotech firm BioNTech, which uses so-called messenger RNA to carry the code for making its therapeutic proteins.
Roche, the world's largest cancer drugmaker, is already betting on BioNTech's technology after signing a $310 million deal last September allowing it to test the German vaccine with its immunotherapy drug Tecentriq.
BioNTech's co-founder and CEO Ugur Sahin told Reuters that combination trials using Roche's drug were due to start later this year against a number of different cancers.
Rival biotech firm Neon Therapeutics, which was formed to exploit the U.S. research, initiated tests of its personalised neoantigen vaccine in combination with Bristol-Myer's Opdivo drug last year.
New drugs like Opdivo and Tecentriq that enlist the body's immune system are improving the odds of survival, but their typical price tag of more than $150,000 a year is controversial and adding a personalised vaccine will jack costs up further.
Sahin acknowledged such vaccines would be expensive at first but said costs could be brought down by economies of scale and automation.
"In the mid to long term the cost will fall dramatically ... it is an individual treatment but it is a universal process," he said. "We are at a very early stage at the moment but in the long-run this approach could change everything."
Cornelius Melief of Leiden University Medical Center, who was not involved in either study, said the research confirmed the potential of neoantigen vaccines.
"Controlled, randomised Phase II clinical trials with more participants are now needed to establish the efficacy of these vaccines in patients with any type of cancer that has enough mutations to provide sufficient neoantigen targets for this type of approach," he said.
Mainz-based BioNTech is one of Europe's largest private biotech companies, with more than 500 employees and deals with Sanofi and Eli Lilly, as well as Roche. It is majority-owned by twin brothers Andreas and Thomas Struengmann, who sold generic drugmaker Hexal to Novartis in 2005.
Sahin said BioNTech would probably stay private for another two to four years before deciding on an initial public offering. (Editing by Mark Potter)