The actor died last week after a battle with colon cancer, his family confirmed in a statement on Friday.
Now, new details have emerged regarding the star's harrowing battle in a report from The Hollywood Reporter.
The outlet said no one at the Disney-owned Marvel Studios was aware of Boseman's cancer diagnosis. In fact, studio head Kevin Feige was sent an email with limited information within an hour of the star's death but by the time Feige read the memo, Boseman had passed.
A source close to the actor told THR that Boseman was convinced he had beaten cancer and would be able to bounce back in time to star in "Black Panther II," which he planned to begin preparing for this month.
It wasn't until a week or so before his death that the Boseman reportedly understood the dire position he was in.
Only a handful of people outside of Boseman's family had knowledge of his diagnosis, including his producing partner Logan Coles, his agent, his trainer and Brian Helgeland, the director of the star's breakout film "42."
Boseman elected to keep his cancer battle private from the Marvel team.
The star even was able to evade semi-traditional physical examinations by doctors before filming, as large studios often forgo the process, a film finance attorney told the outlet.
Disney, who has made no announcement regarding plans for "Black Panther II" and any planned appearances for Boseman's King T'Challa, is said to be focusing on paying tribute to the late star rather than developing plans.
Disney did not immediately respond to Fox News' request for comment.
Posthumously, he will appear in "Ma Rainey's Black Bottom" alongside Viola Davis.