Positive data on BioNTech and U.S. partner Pfizer Inc's COVID-19 vaccine is an unlikely success for the married couple behind the German biotech firm, who have devoted their lives to harnessing the immune system against cancer.

Pfizer said Monday its experimental vaccine was more than 90% effective in preventing COVID-19, based on initial data from a large study.

Pfizer and BioNTech are the first drugmakers to show successful data from a large-scale clinical trial of a coronavirus vaccine. The companies said they have so far found no serious safety concerns and expect to seek U.S. emergency use authorization later this month.

From humble roots as the son of a Turkish immigrant working at a Ford factory in Cologne, BioNTech Chief Executive Uğur Şahin, 55, now figures among the 100 richest Germans, together with his wife and fellow board member Özlem Türeci, 53, according to weekly Welt am Sonntag.

The market value of Nasdaq-listed BioNTech, which the pair co-founded, had ballooned to $21 billion as of Friday's close from $4.6 billion a year ago, with the firm set to play a major role in mass immunization against the coronavirus.

"Despite his achievements, he never changed from being incredibly humble and personable," said Matthias Kromayer, board member of venture capital firm MIG AG, whose funds have backed BioNTech since its inception in 2008. He added Şahin would typically walk into business meetings wearing jeans and carrying his signature bicycle helmet and backpack with him.

Doggedly pursuing his childhood dream of studying medicine and becoming a physician, Şahin worked at teaching hospitals in Cologne and the southwestern city of Homburg, where he met Türeci during his early academic career.

Medical research and oncology became a shared passion.

Türeci, the daughter of a Turkish physician who had migrated to Germany, said in a media interview that even on the day of their wedding, both made time for lab work. Together they honed in on the immune system as a potential ally in the fight against cancer and tried to address the unique genetic makeup of each tumor.

Life as entrepreneurs started in 2001 when they set up Ganymed Pharmaceuticals to develop cancer-fighting antibodies, but Şahin – by then a professor at Mainz university – never gave up academic research and teaching.

They won funding from MIG AG as well as from Thomas and Andreas Struengmann, who sold their generic drugs business Hexal to Novartis in 2005. That venture was sold to Japan's Astellas in 2016 for up to $1.4 billion. By then, the team behind Ganymed was already busy building BioNTech, founded in 2008, to pursue a much broader range of cancer immunotherapy tools. That included mRNA, a versatile messenger substance to send genetic instructions into cells.

DREAM TEAM

For MIG's Kromayer, Türeci and Şahin are a "dream team" in that they reconciled their visions with the constraints of reality.

The BioNTech story took a twist when Şahin in January came across a scientific paper on a new coronavirus outbreak in the Chinese city of Wuhan and it struck him how small the step was from anti-cancer mRNA drugs to mRNA-based viral vaccines.

BioNTech quickly assigned about 500 staff to project "light speed" to work on several possible compounds, winning pharma giant Pfizer and Chinese drugmaker Fosun as partners in March.

Matthias Theobald, a fellow oncology professor at Mainz University who has worked with Şahin for 20 years, said his tendency towards understatement belies a relentless ambition to transform medicine, exemplified by the leap of faith to a COVID-19 vaccine.

"He is a very modest and humble person. Appearances mean little to him. But he wants to create the structures that allow him to realize his visions and that's where his aspirations are far from modest," Theobald said.

Şahin told Reuters on Monday the read-out amounted to an "extraordinary success rate" but that he did not know earlier in the year how difficult the task overall would be.

"It’s certainly not something that you would easily voice as a serious scientist, but it was within the realms of possibility from the beginning."