Therapeutics · Cancer drug resistance
Viosera Therapeutics
A Washington University spinout that built a three drug antibiotic for MRSA, then rebuilt itself around cancer drug resistance as resistanceBio. One peer reviewed paper, one Form D, and a website that went dark in 2025.
Eight days, one catheter, three old drugs
Rabbits were fitted with surgically implanted vascular catheters. Through each catheter went 1,000 organisms of a MRSA isolate called USA300-TCH1516, locked in for 24 hours. Then an eight day course of therapy began, infused over an hour, every four hours.
The therapy was not new. It was meropenem, piperacillin and tazobactam, three approved antibiotics, blended at a fixed ratio. On day two the blood drawn through the catheter came back clear, and it stayed clear through day 10. At the end of the study no organisms were recovered from liver, spleen, lung, heart or kidney. Untreated controls carried at least 10,000 colony forming units per gram in those same tissues.
The blend had a name, VIO-001, and a company behind it. The paper says so directly: “VIO-001 is a formulation developed by Viosera Therapeutics as a combination of MER, PIP, and TAZ at a ratio that covers clinical MRSA isolates with a variety of resistance profiles while suppressing the development of drug resistance due to its internal collateral sensitivity”.
That 2021 paper is, as of September 2026, the only peer reviewed publication in which this company’s own asset appears.
The idea underneath
Resistance is the through line. Bacteria evolve around antibiotics. Tumors evolve around targeted therapy. Both do it by the same logic, because a drug applies selective pressure to a mixed population of cells.
The founders’ wager was that resistance is not only a barrier but a map. If a cell has to change in order to survive a drug, the change itself creates a new vulnerability. Find it first, in the laboratory, and you can design a combination that closes the escape route before a patient is ever dosed.
For bacteria that produced VIO-001, sold in 2018 under the earlier label VT1. Viosera’s own investor calls it “an intravenously administered antibiotic therapy comprised of three FDA-approved off-patent antibiotics given at a specific ratio that converts MRSA’s antibiotic resistance mechanisms into weaknesses, restoring susceptibility”. A 2018 trade write up reported that “it is 100% effective in vitro and in mouse MRSA models, according to Viosera’s study”. That was a company figure.
Two PhDs from the same lab
Nicholas Goldner and Christopher Bulow met in Gautam Dantas’s laboratory at Washington University in St. Louis and joined it on the same day. Goldner worked mechanisms at the bench, Bulow worked population level dynamics computationally. They defended their theses back to back on the same day, then went to Y Combinator.
Goldner has said the motivation was not abstract. He was diagnosed with Crohn’s disease in high school, and has described a MRSA infection in his arm followed by a C. difficile infection. A genealogy database lists a third founder, Gautam Dantas, alongside the two of them; the company’s own investor page names only Bulow and Goldner.
From bacteria to tumors
Fierce Biotech reported in March 2021 that “Goldner and Bulow started a company called Viosera to focus on treatments for bloodstream infections in 2016”, and that “They started cancer-focused resistanceBio in early 2021 and are still involved with Viosera”. The plan then was “to pass the baton of the anti-infectives company to a new team soon”.
The oncology tool was ResCu, short for resistance culturing: a cell culture system meant to hold a large, mixed population of tumor cells under controlled drug exposure long enough for the resistant subpopulation to declare itself. A conference abstract describes a system that “predicts resistance mechanisms to novel and existing therapies often not seen until the clinic”, paired with a ranking algorithm called ResistanceRank. By 2023 the website claimed a drug class of its own, Resistance Suppressing Therapy.
Money in, then quiet
By March 2021 “the duo has raised $5.5 million and plans to raise a series A round this year”. No Form D covers that money. The first and only Form D arrived on January 31, 2024: $12,776,288 offered and the same amount sold, from 44 investors, first sale two days earlier. It was signed not by Goldner but by Kyle Lapham, as chief executive officer. A general partner at NFX, Omri Amirav-Drory, is listed as a director.
After that, very little. A biotech directory now records the entry in four words: “resistanceBio is defunct.” It dates the website going down to the window between July 2025 and January 2026. Y Combinator’s page, still filed under the slug viosera-therapeutics, lists the founders under the heading Former Founders.
What is proven, and what is still claimed
| Evidence | What the record shows | Source type |
|---|---|---|
| VIO-001 animal data | Antimicrobial Agents and Chemotherapy, Aug 30, 2021, PMID 34460301. Rabbits with implanted vascular catheters infected with MRSA USA300-TCH1516. Blood cultures cleared on day 2 and stayed negative through day 10; no organisms recovered from liver, spleen, lung, heart or kidney; effect comparable to vancomycin. | Public record |
| VIO-001 stage | A commercial drug database lists VIO-001 as a combination for staphylococcal infections, originator Viosera Therapeutics, highest phase reached: preclinical. Record updated May 8, 2025. | Public record |
| Registered trials | ClinicalTrials.gov returns zero studies for Viosera and zero for resistanceBio, searched Sep 23, 2026. | Not found |
| Federal funding | NIH RePORTER returns no awards under either name. No NSF award or FDA record appears in the records pull. | Not found |
| Oncology results in print | In 2021 Fierce Biotech reported that “The company hasn’t yet published the results of those efforts but is working with its scientific advisory board to do so.” PubMed still returns nothing on the cancer work. | Not found |
| Oncology assets | Two potential assets, in non-small cell lung cancer and colorectal cancer, described in 2021. A 2024 company description adds that “resistanceBio’s platform was used to preclinically identify drug resistance mechanisms to a KRAS inhibitor in colorectal cancer.” No compound or partner named. | Company-stated |
| Capital | Form D filed Jan 31, 2024: $12,776,288 offered, the same sold, nothing remaining, 44 investors, equity and debt, Rule 506(b). Delaware corporation, year of incorporation 2021. | Public record |
| Founding year | Company profiles give 2016, matching the St. Louis origin of Viosera. The Form D gives 2021, matching the separate founding of resistanceBio. Both are true, of different entities. | Records differ |
| Operating status | One commercial database still lists the company as alive. A biotech directory lists it as defunct, website down July 2025 to January 2026, and Y Combinator lists the founders as former. | Records differ |
Read plainly: this is a preclinical story from end to end. The antibiotic has real animal data in a real journal and never reached a registered trial. The cancer platform, which drew the larger money, has no published results at all. Everything known about the oncology work comes from the company, its investors, or reporters relaying what the company said.
What to watch
- Whether the ResCu results ever reach print. The promise to publish dates to 2021 and has not been met.
- Where VIO-001 ends up. The stated plan in 2021 was to hand the anti-infectives company to a new team.
- Any new SEC filing. There has been exactly one, in January 2024, and no amendment since.
- Whether resistance.bio comes back online, and under whose control.
In their words
“We’re focusing on getting the cancer to reveal resistance mechanisms inherent in each cell of the tumor.”
Nick Goldner, CEO and co-founder, Fierce Biotech, 2021 · Independent
“It turned out there were not good longitudinal data sets in oncology of how resistance evolves to a single therapy or course of therapy over time, so we created our own system that lets you look at a tumor in a large population of cells with controlled drug exposure.”
Chris Bulow, COO and co-founder, Fierce Biotech, 2021 · Independent
“My mentor, the person who gave me the first opportunity to be a scientist, passed away from treatment resistant breast cancer.”
Nick Goldner, BIOS Community founder interview, 2021 · Interview
“Our initial company, Viosera, was focused on antibiotics but I’ve always been interested in how treatment resistance can be applied to disease such as cancer.”
Nick Goldner, BIOS Community founder interview, 2021 · Interview
“We created a cell culture system in less than 18 months that can recapitulate human disease.”
Nick Goldner, BIOS Community founder interview, 2021 · Interview
“What we realized was there are just so many cancer types out there and there are so many targets, it was a selfish decision to only use this platform internally.”
Nick Goldner, NFX podcast summary, December 2022 · Interview
“Cancer developing resistance to our arsenal of drugs is responsible for up to 90% of cancer deaths each year.”
Fifty Years, seed investor, April 2021 · Investor
Related companies
Sources
- Public recordForm D, resistanceBio, Inc., CIK 0002010024
- Public recordPharmacokinetics, Tissue Distribution, and Efficacy of VIO-001 in Immunocompetent Rabbits
- Public recordClinicalTrials.gov study search, zero results
- Public recordNIH RePORTER project search, zero awards
- Public recordVIO-001 drug record, highest phase preclinical
- Public recordViosera Therapeutics vendor profile, St. Louis, established 2016
- IndependentCould a single pill treat a tumor today and head off its drug resistance mechanisms tomorrow?
- InterviewFounder Spotlight #19: Nicholas Goldner @ resistanceBio
- IndependentSt Louis-based startup is fighting the war against antibiotic resistance
- IndependentresistanceBio company profile and NFX podcast summary
- IndependentresistanceBio directory listing, recorded as defunct
- IndependentresistanceBio files notice of exempt offering of $12,776,288
- IndependentViosera Therapeutics record, Y Combinator batch W19
- InvestorresistanceBio seed round post
- InvestorViosera Therapeutics portfolio entry
- CompanyresistanceBio home page, Resistance Suppressing Therapy
- CompanyNick Goldner speaker profile, ResCu and ResistanceRank
- CompanyResistanceBio company page, founders listed as former
Profile researched and written by Healthcare Discovery. Last updated September 29, 2026.
