NEW YORK, Aug 14 (Reuters) - Private equity firm THL

Partners has agreed to buy a majority stake in Headlands

Research, a U.S.-based network of clinical trial sites, from KKR

in a deal valued at about $600 million, according to

people familiar with the matter.

The transaction could be announced as soon as Thursday, the

sources said.

Clinical trial sites are experiencing steady business growth

as pharmaceutical companies ramp up research spending, driven by

new types of therapies and the growing healthcare needs of an

aging population.

Private equity firms have stepped up their involvement in

clinical trials, drawn by the potential to leverage technology

to scale operations and consolidate a fragmented network of

stand-alone sites into more integrated and valuable platforms.

THL has been active in pharma services for more than two

decades, with past investments including Syneos Health, PCI

Pharma Services, Adare Pharma Solutions, and Red Nucleus.

The transaction marks an exit for private equity firm KKR,

which acquired Headlands in 2018 and is said to have at least

doubled its investment, according to a person familiar with the

matter.

KKR's exit in Headlands followed its successful $12 billion

divestment of PRA Health Sciences, a clinical research

organization where it delivered a sixfold return for investors.

Recent deals by private equity firms in clinical trials

include BayPine's $1.5 billion acquisition of CenExel, and

Genstar Capital's majority investment in Flourish Research, for

an undisclosed amount.

AI is accelerating drug discovery and development, and

private equity firms are betting that faster approvals of new

therapies will boost demand for clinical trials.

Headlands operates more than 20 sites and has conducted over

5,000 trials in therapeutic areas including central nervous

system disorders, mental health, vaccines, and metabolic

diseases.