ZURICH, Sept 28 (Reuters) - Relief Therapeutics said on Monday it is getting more money from its largest stockholder to lift its cash to 48 million Swiss francs ($52 million) to fund trials of a decades-old medicine it hopes to repurpose against COVID-19.

Relief said the transaction is the final tranche of a share subscription facility with New York-based GEM Global Yield, with the amount raised reaching almost 18 million francs.

GEM Global Yield, run by founder Christopher Brown, owns nearly 31% of Relief, according to Refinitiv data, with more than 2.58 billion shares outstanding after the transaction's completion.

In 2019, Relief had sold nearly all of its assets after its management resigned. During the pandemic, however, it has partnered with private U.S. company NeuroRx to resurrect a 50-year-old drug called aviptadil, which it calls RLF-100 in the current formulation, and is conducting U.S. trials for COVID-19 acute respiratory distress syndrome and lung injury.

Relief's share price has surged this year, following a drop of 81% last year, boosting its market capitalisation to about 1.45 billion francs.

"The available cash on the balance sheet of the company, after receipt of the funds, will be approximately 48 million francs and will be used primarily to fund" COVID-19 trials, Relief said. "With the conclusion of this raise, its capital resources will be sufficient to support its planned operations through 2022, without taking into account potential revenues generated from sales of RLF-100." ($1 = 0.9287 Swiss francs) ($1 = 0.9286 Swiss francs) (Reporting by John Miller)