RadioTimes.com understands the soap has been planning this heartbreaking storyline for a while and it will air later in the year. EastEnders bosses have been working closely with brain tumour charities on this sensitive storyline.
An EastEnders spokesperson declined to comment.
Harold's departure from the soap comes in a raft of cast changes announced previously.
Alongside Lola, fans can also expect to say goodbye to Stuart Highway (Ricky Champ), Peter Beale (Dayle Hudson), Dana Monroe (Barbara Smith), and Jada Lennox (Kelsey Calladine-Smith) over the coming months, though details of their exits are yet to be revealed.
The departures come as new executive producer Chris Clenshaw takes over the BBC soap.
A source had previously told Metro.co.uk: "He’s been working hard behind the scenes since January and is really planning to shake things up which means saying goodbye to some characters.
"It’s nothing personal to any of the cast going, it’s simply a creative decision – for big storylines to happen you have to say goodbye to people, that’s the nature of soap.
"Chris has some really big stories planned and viewers will see his stuff starting to air over the summer."
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