Preclinical radiopharma biotech closes $175M Series B backed by suite of top-tier investors

Despite advances in developing radiopharmaceuticals, manufacturing such drugs remains a challenge. One startup’s plan to tackle the issue is beginning to round into form and, simultaneously, it’s receiving a hearty, cash-rich endorsement.

Mariana Oncology, a biotech incubated by three prominent life sciences VC firms, closed a $175 million Series B round Thursday morning, as its first pipeline program prepares to begin human testing sometime next year. The startup, founded as Curie Therapeutics by Atlas Venture, RA Capital Management and Access Biotechnology, will focus that drug candidate in small cell lung cancer patients.

Mariana’s goal is not just to develop radiopharmaceutical drugs, but to completely own the manufacturing process behind them, CEO Simon Read tells Endpoints News. Alongside getting the program, known as MC-339, ready for Phase I studies, Mariana has also built its own manufacturing facility designed to supply Phase I and II studies.

Read credited the company’s chief technology officer, Bernard Lambert, and his team with that latter project.

“With those key pieces, I’ve been really pleased to — if you’d like — risk-manage the manufacturing challenges,” Read said. “But what has been particularly pleasurable is that you also see intellectual property being generated in terms of how you scale processes, and how you innovate things around things like dose presentation and delivery of doses to patients.”

Eventually, the biotech plans to build another facility for Phase III studies, when MC-339 and other pipeline programs need to be vastly scaled up. But construction on that hasn’t begun yet, and Read isn’t ready to commit to a timeline for the groundbreaking.

There are also few details regarding Mariana’s plans to deploy its new $175 million round, with Read playing coy about whether the money will specifically go toward that Phase III facility, or potentially other projects. Read also declined to comment on how much runway the Series B will provide.

The promise of the kind of company Read wants to build, however, has brought several other blue-chip investors to the table. Forbion co-led Thursday’s round with Deep Track Capital, and Eli Lilly chipped in as well. The three founding incubators — Atlas, RA and Access Biotechnology — all returned after launching the company out of stealth in December 2021.

Geert-Jan Mulder, managing partner at Forbion, told Endpoints that similar manufacturing approaches have seen success in the gene therapy and oncolytic virus spaces, naming a few of his firm’s investments like uniQure and Replimune. But Mariana is building out its manufacturing to supply trials in a much earlier part of the process than most are considering.

“To actually do it so early in the development is truly — I don’t want to call it visionary, but quite unique in our space,” Mulder said.

Geert-Jan Mulder

Mulder also stressed that Mariana has other programs currently in IND-enabling studies and isn’t solely focused on the lead candidate, MC-339. The program, a small molecule peptide-based drug, was developed fully in-house and features the rare Actinium-225 isotope as the payload, which has picked up interest after a key paper was published in 2020.

Challenges continue to plague the broader radiopharma space, particularly for the field’s biggest name: Novartis. The Big Pharma company scored a critical FDA approval last year when US regulators greenlit Pluvicto for late-line prostate cancer, but patients have faced significant waiting times. The supply crunch was so sharp that Novartis halted new patient starts in February.

In April, the FDA cleared a new Novartis manufacturing site to start making more of the drug, and execs said during the company’s second-quarter earnings call last month that it had begun adding new patients again. And as Novartis prepares to seek approvals for earlier treatment lines, future shortages will likely start affecting more potential patients.

Read wants to take the positives out of these circumstances, however, saying that companies following Novartis — as well as other radiopharma leaders like Bayer — have more data from which to learn. With radiopharma companies like Mariana, RayzeBio and Convergent Therapeutics learning how to better produce the drugs, they’ll be “ready for prime time” a lot sooner.

“I don’t think we should focus on the manufacturing challenges, because I think they’re well understood now,” Read said. “The perfect example is [Pluvicto]. Look at the robust sales that they have over the last three quarters since launch. And it looks like it’s on track to be a $2 billion drug. We believe that’s just the tip of the iceberg.”

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