Metro Manila (CNN Philippines) – Sen. Miriam Defensor-Santiago passed away Thursday morning. She was 71.

Senator Grace Poe announced the news at the hearing on the Freedom of Information (FOI) bill, asking for a moment of silence to pray for Santiago’s soul.

Santiago "peacefully" died at 8:52 a.m., according to the Senator's official Twitter account.

The three-term Senator, who finished last in the May 9 presidential race, was diagnosed with lung cancer in 2014. She showed physical weakness during the campaign, taking long breaks from the hustings and making the fewest public appearances among the candidates.

Also read: Despite absence, Santiago makes presence felt through social media

Prior to the elections, Santiago told CNN Philippines she was “perfectly normal” because of an anti-cancer pill she is taking.

But she admitted she occasionally had to take short pauses to catch her breath and her sense of balance was “very precarious” – she would sometimes stumble and fall in the bathroom.

Santiago wrote Senate President Franklin Drilon on May 24 to inform fellow senators that she will be on medical leave until her term ends on June 30. She said she had developed anorexia, or the inability to eat, as a side effect of one of her anti-cancer medications, which weakened her body.

The feisty senator was rushed by ambulance to the Makati Medical Center on May 31 after she contracted pneumonia. She was moved to the intensive care unit (ICU) the following day, and transferred to a regular private room two days later after her condition stabilized.

Santiago leaves behind husband Narciso Santiago, Jr. and one son.

She is the first Filipino to be elected in the International Criminal Court in 2011, but she never assumed her post due to chronic fatigue syndrome.

Battle with cancer

In 2014, Santiago announced, she was battling cancer. The following year, she said she's "cured" of the illness.

Announcing she was cancer-free, Santiago declared she was running in the 2016 presidential for the third time.

Santiago: Bongbong Marcos will be my running mate

She insisted she could perform all functions of the highest official of the land.

"I can. Otherwise, I wouldn't run," she quipped.

Who is Miriam?

The young Santiago was class valedictorian from elementary to high school in her hometown in Iloilo.

Also read: Santiago tells youth: 'You have a duty to challenge the status quo'

She graduated magna cum laude with a degree in political science, and a cum laude for bachelor of laws from the University of the Philippines.

She was the first female editor-in-chief of UP's decades-old campus newspaper, the Philippine Collegian.

After passing the bar in 1969, Santiago pursued further studies here and abroad.

She spent practically her entire career in public service. First, as a regional trial court judge in Quezon City, then moving on to become immigration commissioner and agrarian reform secretary during President Corazon Aquino's administration.

With her rising popularity, Santiago first ran for the presidency in 1992 under the People's Reform Party.

She lost to Fidel Ramos amid allegations of widespread cheating.

The defeat, however, did not dampen her spirit -- she tried but failed again in her 1998 presidential bid.

Santiago was elected senator in 1995. There, she fully utilized her legal expertise in pushing for measures on international humanitarian law, the Magna Carta for women, and anti-bullying law.

She has been called the "Iron Lady of Asia" for his strong campaign against corruption in the government. She called on the electorate to watch out for those who showed moral weakness and displayed greed for power.

This is a developing story. Please refresh page for updates.

CNN Philippines Digital Producer Eimor P. Santos contributed to this report.