UPDATE 1-BioNTech's OncoC4 partnership off to good start with mid-stage trial results

(Adds trial details, background on BioNTech, drug class)

By Ludwig Burger

FRANKFURT, June 2 (Reuters) - BioNTech said on Friday that a new cancer immunotherapy candidate that it is working on with U.S. partner OncoC4 Inc was shown to shrink tumours in close to 30% of participants in a mid-stage lung cancer trial.

The experimental drug, known as gotistobart, was tested on patients with metastatic non-small cell lung cancer which could no longer be helped by a group of so-called checkpoint inhibitor drugs such as Merck & Co's Keytruda.

A follow-on trial in the third and last phase of testing typically required for approval would start in the third quarter of this year, BioNTech added in its statement.

In the trial with 27 patients, 29.6% saw the disease improve, and 70.4% saw the disease improve or remain stable.

BioNTech, with

billions of euros

in cash from its COVID-19 vaccine alliance with Pfizer , is eager to brush up its credentials in new

oncology

drugs, which is its traditional focus.

BioNTech and OncoC4's drug is a so-called anti-CTLA-4 antibody, the same immunotherapy drug class as AstraZeneca's

Imjudo

, or tremelimumab, which won its first approval last October after years of disappointing trial results.

(Reporting by Ludwig Burger, Editing by Friederike Heine)