The former Penrith talent was back in the headlines this week after wife Shanelle's strong public endorsement of anti-vaccination on social media went viral.

The couple have one child and another on the way, with the 20-year-old claiming she would home-school them rather than vaccinate if laws were made to prevent unvaccinated children from attending certain schools.

Her Q&A on Instagram prompted a warning from the Australian Medical Association about "unnecessary dangers to public health" and put Cartwright under the spotlight as he attempts to bounce back from an ordinary 2018 campaign.

But, apart from bringing extra heat on the ball-playing backrower, Brennan insisted there were no concerns at the Titans.

"He didn't need that publicity, but you'll find there's people in other clubs with the same beliefs," he told AAP.

"And at the end of the day what people do in their personal life and how they raise their children is no concern of mine, as long as it's not illegal.

"He's not speaking on behalf of the Titans, it's their own views, it's not new and the other partners have been fully aware of their views."

Cartwright's move north went pear-shaped last season when he was demoted to reserve grade after a series of sub-standard defensive efforts.

But Brennan, who had worked with the 24-year-old in Penrith, said he had given himself every chance to respond in the trial games from next weekend.

"He got questioned a lot last year about 'did he really want to be a footballer' and I had to ask him the question myself," the coach said.

"But the way he's trained since, he wouldn't put himself through that pain if he didn't really want it.

"The test now is going to come when he goes on the football field, because that's where he's got to put his head where he could put his foot."

Cartwright has enlisted the help of hooker Nathan Peats, regarded as the Titans' fittest man, to get him into shape and Brennan hopes it brings out the best in his unpredictable recruit.

"We become a whole new Titans outfit if Bryce Cartwright fires," Brennan said.

"He can do stuff with the ball in hand that no other player can do."

Australian Associated Press