This month, Mark Walker is celebrating his company's one year anniversary of going public — only the ninth Black-founded business to accomplish this feat on a U.S. stock exchange. Photo courtesy

After working in both sides of the advertising world, Mark Walker thought he could reimagine a platform that would be more efficient and equitable.

Walker co-founded his company, Direct Digital Holdings, an adtech platform, after serving in several roles — from an early hire at Houston digital media startup Questia to business development director at NRG Energy and COO of EBONY Media. He shares on the Houston Innovators Platform how he took this experience in tech, advertising, and media to create his company's platform.

"NRG Energy gave me a top-down view of the value chain, and Ebony gave me a bottoms-up view of the value chain of how media is purchased," Walker says on the show. "At Direct Digital Holdings, we help companies buy and sell media — and we leverage technology to do it. It's really the culmination of both of those experiences."

With over 30,000 publishers on its platform, Direct Digital makes it easier for its core customers — middle market companies looking to buy into the digital media ecosystem — to tap into these opportunities without the tech know-how they might otherwise need. Walker explains that at EBONY, he saw how small to midsize publications — especially the multicultural ones — were being left out on the ad selling side of the equation. The Direct Digital platform bridges the gap on each end.

Founded in 2018 in partnership with Keith Smith, who went through similar professional experiences, Direct Digital went public exactly one year ago after growing the company through strategic M&A activity. Walker says the decision to IPO made the most sense for his company — though it wasn't an easy process. Direct Digital is only the ninth company founded by a Black entrepreneur to go public on a US stock exchange.

"If you think the process is hard — it actually is," Walker says on the journey to IPO. "We were a privately held company, and we knew we had a good growth trajectory and we looked a couple different options. We decided to go public in a very traditional way."

Walker explains there were some risks involved, but the co-founders ultimately decided to shy away from adding in investors who might not have the same ideas for the company's future.

Direct Digital has been a Houston company from the star — despite the city not being home to a booming adtech ecosystem. Instead, Houston — with its collection of Fortune 500 companies and rich diversity — has allowed the business to stand out.

"If you look at and reflect on how our company has been built — from our board of directors to our leadership and management team — we're a majority minority organization all the way across the board," Walker says. "Diversity is very important to us. It's the lifeblood of our business — especially because we're serving publishers in those communities in big way. And moreso, we think you get the best product, thoughts, and ideas from a diverse workforce, and Houston fits right into that mold for us."

Walker shares more about his company's future, advice on IPO, and what all he's watching in adtech — from AI to streaming — on the podcast. Listen to the interview below — or wherever you stream your podcasts — and subscribe for weekly episodes.


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New 'living pharmacy' biotech company launches out of Rice venture studio

fighting cancer

Rice University’s biotech venture studio RBL LLC has launched a new “living pharmacy” company, Duracyte, designed to make cancer treatment easier on patients.

Backed by an up to $45 million Advanced Research Projects Agency for Health (ARPA-H) award, Duracyte aims to commercialize implantable biohybrid pharmacy devices that are designed to produce therapeutic proteins inside the human body around the clock, replacing the need for regular injections and infusions for some cancer patients.

The company’s main platform is its Hybrid Advanced Molecular Manufacturing Regulator (HAMMR), a rechargeable, implantable device that can sense biological signals, monitor tumor environments and adjust therapeutic output in real time. HAMMR has wireless communication capabilities, which allow patients and clinicians to remotely monitor results through an app every five minutes and make changes to treatment plans without a hosptial visit. Additionally, the device can generate its own oxygen supply, which is key for the therapeutic cells’ survival.

“Biologic medicines such as monoclonal antibodies, cytokines and metabolic regulators already account for a significant share of modern therapeutics, but the way we deliver them today often requires frequent injections or infusions that can be demanding for patients and lead to inconsistent drug levels,” Daniel Anderson, MIT professor and co-founder of Duracyte, said in a news release. “Our vision is to enable a continuous, stable therapy by producing these medicines directly inside the body, which could improve treatment consistency, reduce side effects and ultimately transform how biologic therapies are delivered across many diseases.”

Duracyte’s first clinical trial is slated to begin by the end of 2026 and will focus on recurrent ovarian cancer. The Phase I study will build upon existing work on encapsulated cytokine pharmacy technology, and the company hopes that within a few years this treatment can reach clinical application.

The development of Duracyte is supported by ARPA-H's Targeted Hybrid Oncotherapeutic Regulation (THOR) project, which supports a multidisciplinary research consortium co-led by Omid Veiseh, a professor of bioengineering at Rice. The consortium also includes others at Rice, The University of Texas MD Anderson Cancer Center, Stanford University, Carnegie Mellon University, Northwestern University and the University of Houston, plus industry collaborators like Chicago-based CellTrans.

“What we are building is the culmination of years of progress in cell engineering, biomaterials and implantable device technology,” Veiseh added in the release. “By combining these advances with real-time sensing and adaptive drug delivery, we are working with the support of RBL to create a true ‘living pharmacy’ that can deliver continuous, precisely controlled biologic therapies and fundamentally change how these treatments reach patients.”

RBL launched in 2024 and is based out of Houston’s Texas Medical Center Helix Park. Duracyte is the third company launched by RBL, including Sentinel BioTherapeutics, a clinical-stage immunotherapy company developing localized cytokine therapies for solid tumors, and SteerBio, a regenerative medicine company targeting lymphedema.

“Duracyte exemplifies the kind of breakthrough that Houston’s ecosystem is built to produce,” Paul Wotton, managing partner of RBL LLC and co-founder of Duracyte, added in the release. “With world-class clinical infrastructure, exceptional engineering talent and initiatives like the Texas Biotech Task Force driving alignment across industry, investment and talent, this region is uniquely positioned to move the most ambitious ideas in medicine from concept to patient, faster than anywhere else.”

Houston energy hub opens new fundraising cohort to fuel startups

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EnergyTech Cypher has opened applications for its second Liftoff fundraising program.

Applications close May 20 for the 10-week virtual fundraising sprint. The program is geared toward energy and climatech founders preparing to raise their first institutional round. It will cover fundraising requisites, like pitch materials, term sheet negotiation and round closing, according to a release from EnergyTech Cypher.

The program kicks off June 1 and runs every Monday from 1-3 p.m. CST. It will conclude with an in-person capstone simulation in Houston on August 3, where founders will work to close a mock round.

Jason Ethier, EnergyTech Cypher founder and CEO, will lead the program with Payal Patel, an EnergyTech fellow and entrepreneur in residence.

The program is available through Cephyron, EnergyTech Cypher's new investor relationship management platform, built specifically for energy and climatech founders. Users must have a Cephyron Boost membership to participate in the Liftoff program.

The Cephyron IRM app recently went live and is available to founders at any point in their fundraising process, according to the news release. The platform aggregates investor data, tracks market signals and delivers curated weekly recommendations.

EnergyTech Cypher launched Liftoff last year. The inaugural cohort included 19 startups, including Houston-based AtmoSpark Technologies, The Woodlands-based Resollant and others. Each participant closed at least one fundraising deal, according to EnergyTech Cypher.

EnergyTech Cypher rebranded from EnergyTech Nexus earlier this year. It also launched its CoPilot accelerator in 2025. The inaugural group presented its first showcase during CERAWeek last month.

EnergyTech Cypher's annual Pilotathon Pilot Pitch and Showcase applications also opened this month. Find more information here.

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This article originally appeared on EnergyCaptialHTX.com.

Cancer diagnostics startup wins top prize at annual Rice competition​

winner, winners

Rice University student-founded companies took home a total of $115,000 in equity-free funding at the annual Liu Idea Lab for Innovation and Entrepreneurship's H. Albert Napier Rice Launch Challenge last week.

2025 Rice Innovation Fellow Alexandria Carter won the top prize and $50,000 for her startup Bionostic. The startup offers personalized diagnostics for cancer patients by using 3D culturing through its Advanced Tumor Landscape Analysis System (ATLAS) platform.

Carter is working toward her PhD in bioengineering in Professor Michael King's laboratory. She recently completed the Rice Innovation Fellows program and plans to commercialize ATLAS, according to a news release from Rice.

Actile Technologies, founded by another former Rice Innovation Fellow, Barclay Jumet, won second place and $25,000. The company is developing and commercializing textile-integrated technologies. InnovationMap first covered Jumet's wearable technology back in 2023.

Kairos took home the third-place prize and $15,000, plus the $2,000 audience choice award and the $5,000 undergraduate business award. Founded last year by Sanjana Kavula and Adhira Tippur, Kairos is an AI-powered patient intake platform built specifically for independent dental practices.

The NRLC features top startups founded by undergraduate, graduate and MBA students at Rice each year. The top three finishers were named among a group of five finalists earlier this year, which also included HAAST Autonomous and Project Kestrel.

HAAST is developing an unmanned aircraft for organ transport, while Kestrel uses machine learning to organize bird photographers’ photo collections.

Teams presented multiple five-minute pitches throughout the application process over Zoom and in-person before the five finalists presented at the NRLC Championships April 21 at the Rice Memorial Center. Each finalist walked away with an equity-free investment.


Other awards went to:

UnitCode

  • $5,000 MBA Venture Award

HAAST Autonomous

  • $2,500 Chan-Kang Family Prize for Bold Ambition
  • $1,000 Healthcare Innovations Prize

Telstar Networks

  • $2,500 Outstanding Undergraduate Startup Award

Multiplay

  • $1,500 Frank Liu Jr. Prize for Creative Innovation in Music, Fashion, & the Arts

Butterfly Books

  • $1,500 Social Impact Award

SOOZ

  • $1,000 Interdisciplinary Innovation Prize sponsored by OURI

Dooly

  • $1,000 Consumer Goods Prize

Project Kestrel

  • $1,000 AI Prize

Veloci Running won the NRLC last year for its naturally shaped running shoe. Founder and CEO Tyler Strothman recently told InnovationMap that the company has gone on to sell roughly 10,000 pairs of its flagship Ascent shoe, designed to relieve lower leg tightness and absorb impact. Read more here.