By Mrinalika Roy and Michael Erman (Reuters) – Pfizer Inc on Monday agreed to pay $5.4 billion in cash for sickle cell disease drugmaker Global Blood Therapeutics, as it looks to capitalize on a surge in revenue from its COVID-19 vaccine and treatment. Pfizer will pay $68.50 per GBT share, which represents a 7.3% premium to its Friday closing price. The deal is at a more than 40% premium where GBT was trading before the Wall Street Journal reported that Pfizer was in advanced talks to buy it on Thursday. Pfizer’s 2021 revenue of $81.3 billion was nearly double the mark from the previous year, …