By Emily Hawkins Next 15 has cleared a final regulatory hurdle in the US as the London based media firm hopes to finalise a deal for advertising giant M&C Saatchi after months. Now, Next 15 has told shareholders it had received written notification from the committee on foreign investment in the United States (CFIUS), concluding its review into the deal. This paves the way for a takeover, with Next 15 confirming all regulatory clearances required have now been received. It follows a green light from the Competition and Markets Authority (CMA), with U.K. regulators not wishing to probe the offe…