The results were clear: Naptumomab estafenatox failed to prolong overall survival for renal cell carcinoma patients in a large trial, definitively enough that Active Biotech effectively shelved it in 2013.

But three years later NeoTX, a scavenger startup that had been digging through drugs that failed in hopes of finding a subpopulation with a biomarker that the original developer had missed, stumbled upon the data and saw the unexpected gem they were looking for.

Asher Nathan
“Their Phase I data was stellar, great Phase I, and then they had this Phase II that failed primarily because they added the wrong drug,” Asher Nathan, CEO and co-founder of NeoTX, told Endpoints News as he unveils $45 million in new financing.

Interferon alpha was “absolutely the wrong drug” to combine with naptumomab estafenatox as it negated certain qualities of the experimental fusion protein, Nathan said. More importantly, Active Biotech didn’t really know just the kind of potential they had in a platform tech that binds to the tumor and coat it with a bacterial “superantigen” that attracts an immune attack.

“This is a natural immune response as opposed to if you look at other technologies like bispecifics, where they gauge CD3 molecules, that’s something you’ll never find in nature,” Nathan said.

So the Israeli biotech licensed the drug from Active for $250,000 upfront, and has been collaborating to start a Phase I that tests a combo of nap and AstraZeneca’s checkpoint drug, Imfinzi (durvalumab).

Roger Kornberg
Roger Kornberg, a Nobel laureate, Stanford cancer researcher and longtime friend of Nathan’s, helped guide the company’s pivot to focus on this approach, which they call selective T cell redirection or STR. And longtime Bristol-Myers Squibb exec Marcel Rozencweig is onboard as CMO, leading a small office in Princeton, New Jersey in preparation for a trial expansion to the US.

They are enrolling patients with a wide range of solid tumors to the Phase Ib dose escalation trial — from pancreatic adenocarcinoma and ovarian cancer to prostate cancer and triple negative breast cancer — as naptumomab targets the oncofetal antigen 5T4.

Other drugmakers have mounted efforts to hone in on 5T4, ranging from Sanofi and Oxford Biomedica’s Phase III cancer vaccine to Pfizer’s early-stage antibody-drug conjugate to Genmab’s preclinical CD3/5T4 bispecific.

Marcel Rozencweig
NeoTX is also working on a second candidate hitting a different target specifically tailored to glioblastoma. They’ve brought David Reardon of Dana Farber on for that program, which also utilizes the bacterial component.

The team of around 20 has some powerful — if unconventional — backers. For the Series C, they enticed “one of the top 10 richest people in the world,” former Blackstone vice chairman Tomilson Hill, American businessman Paul Marinelli as well as Korean investor Andrew Kim.

Credit: Amber Tong