Former banker and Aam Aadmi Party leader Meera Sanyal passed away in Mumbai, Maharashtra, on Friday at the age of 57. She was suffering from cancer.

Sanyal, the former chief executive officer and chairperson of the Royal Bank of Scotland in India, left banking in 2014 to contest that year’s general elections on the Aam Aadmi Party’s ticket. She had contested the 2009 General Elections from Mumbai South as an independent candidate.

In November, she released a book titled The Big Reverse, a trenchant critique of Narendra Modi’s demonetisation decision. In an article about her experiences writing the book, she noted that she had fallen ill shortly after being approached by her publisher in November 2016.

“My poor health and the lack of verifiable information walked hand in hand for several months,” she wrote. “There were days when I felt the book would never see the light of day. As I stumbled back on to my feet, I decided to tackle two chapters that needed no current numbers.”

Delhi Chief Minister Arvind Kejriwal and his deputy Manish Sisodia were among the first people to react to the news of her death on Twitter.

“Extremely sad to hear this,” said Kejriwal. “No words to express.” Sisodia said the country had lost a sharp economic brain and a gentle soul.

Sanyal was the daughter of Indian Navy officer Gulab Mohanlal Hiranandani, who had played an instrumental role in Operation Trident, the Naval attack on Karachi during the war with Pakistan in 1971.

Sanyal was a member of former US Secretary of State Hillary Clinton’s International Council on Women’s Business Leadership and a board member of Pradan, an organisation working to empower rural and Adivasi women in the country.