A growth marketing founder who builds systems, not campaigns - and puts them to work moving cancer patients toward the treatment they deserve.
Jack Gierlich spends his days on a problem most marketers never touch: getting people with cancer to the right treatment faster. As the marketing and growth lead at Leal Health, the AI-powered platform formerly known as TrialJectory, he works where oncology, technology, and human urgency collide. The platform helps patients find FDA-approved treatments and clinical trials, and Gierlich's job is to make sure the people who need it can actually find it.
His approach is unusually deliberate. Where many growth marketers chase the next viral tactic, Gierlich talks about infrastructure. He describes his work as building marketing systems that compound over time rather than campaigns that end the moment a budget runs dry. It is a philosophy shaped by 15-plus years spanning healthcare, SaaS, and AI, and by a portfolio that runs into the hundreds of startups.
"I build marketing systems, not campaigns, that compound over time."
The numbers he cites are the kind founders notice: more than 400 startups supported, north of $300 million in revenue generated, over 140 founders mentored, and a dozen growth tools shipped along the way. But he is careful about how he spends his attention. As a fractional CMO he works closely with only two or three founders at a time, trading breadth for depth so the systems he builds actually take root.
That restraint sits alongside a quieter kind of reach. Gierlich moderates several of the largest marketing and business communities on Reddit - among them r/Marketing, r/salestechniques, and r/BusinessIdeas - shaping conversations that reach tens of millions of readers a year. Most of those readers will never learn his name, which seems to suit him fine.
His path was not a straight line to healthtech. He studied economics at Baruch College, part of the City University of New York, then moved through media strategy and growth roles before settling into the fractional-CMO model. Along the way he picked up the labels he now wears comfortably: former founder, serial tinkerer, mentor, AI strategist. His GitHub handle, Gr0wthHacker, hints at the engineer who sits behind the marketer - someone as likely to ship a tool as write a brief.
In healthcare, the marketing job carries a weight most industries do not. Privacy rules tighten, ad platforms change what health brands can and cannot say, and every message has to clear a compliance bar. Gierlich treats that constraint as a design problem rather than a wall.
"Compliance doesn't have to be a drain - smart, ethical marketing that builds trust and grows your bookings."
In 2025, Leal Health was acquired by Nexus Precision Health, a milestone for the company whose growth engine Gierlich helped run. He continues to offer fractional marketing leadership to healthcare, SaaS, and AI companies from his base in Brooklyn, still working with a small handful of founders at a time, still building for the long compound rather than the quick spike.
Go-to-market planning, funnel design, and marketing automation built to compound - not one-off campaigns tied to a single budget cycle.
Marketing for oncology and digital-health platforms, navigating privacy rules and ad-platform restrictions without losing momentum.
Part-time senior marketing leadership for two or three founders at a time, embedding deep rather than spreading thin.
Moderating major marketing, sales, and business communities that inform millions of practitioners every month.
Product-led growth and AI-driven systems that stay compliant while boosting acquisition and engagement.
Shipping small, purpose-built tools - the engineer behind the marketer, true to the Gr0wthHacker handle.
Studies Economics at Baruch College, City University of New York.
Director of Media Strategy, then Head of Marketing & Growth at TrialJectory.
TrialJectory rebrands as Leal Health; Gierlich leads marketing and growth.
Board Advisor at Glimpse, Founding Advisor at Actually Health, and moderator of major subreddits.
Leal Health acquired by Nexus Precision Health.
"I build marketing systems, not campaigns, that compound over time."
"Compliance doesn't have to be a drain - smart, ethical marketing that builds trust and grows your bookings."
He is a Brooklyn-based growth marketing founder and fractional CMO with more than 15 years scaling healthcare, SaaS, and AI companies, currently leading marketing and growth at Leal Health.
Leal Health, formerly TrialJectory, is an AI-powered platform that helps cancer patients find and access advanced treatment options and clinical trials. It was acquired by Nexus Precision Health in 2025.
He provides part-time senior marketing leadership - growth strategy, go-to-market planning, marketing automation, and product-led growth - typically working closely with just two or three founders at a time.
He studied Economics at Baruch College, part of the City University of New York (CUNY).
He moderates major marketing and business subreddits including r/Marketing, r/salestechniques, and r/BusinessIdeas, reaching millions of members each month.