AusperBio Raises $120M Series C to Take Hep B Drug to Phase 3

AusperBio Therapeutics has raised $120 million in a series C financing round to carry its oligonucleotide therapy for chronic hepatitis B through phase 3 clinical testing and, if successful, toward commercialization.

AusperBio Therapeutics has closed a $120 million series C financing, money the company says will carry its oligonucleotide therapy for chronic hepatitis B through phase 3 clinical testing and, if the data hold up, toward commercialization. The round was reported by Fierce Biotech.

The figure matters more than its size alone suggests. A series C of that scale is a late-stage private raise: the sort of check written not to test whether a molecule works, but to fund the confirmatory trials, manufacturing scale-up and regulatory work that sit between a promising mid-stage result and a product a physician can prescribe. Companies that get there in hepatitis B are rare, because the field has swallowed a great deal of capital without producing a cure.

Why a phase 3 hepatitis B program is a landmark, not a formality

Chronic hepatitis B is one of the largest untreated viral disease burdens in the world, and the standard of care has barely changed in structure for years. Nucleoside and nucleotide analogues suppress viral replication effectively and are cheap as generics, but patients generally stay on them indefinitely. Stopping usually means the virus rebounds. The prize the entire field is chasing is what researchers call a functional cure: sustained loss of hepatitis B surface antigen, and undetectable viral DNA, that persists after treatment is withdrawn.

That bar is why hepatitis B has been so unforgiving. A candidate does not merely have to beat placebo on a lab marker; it has to beat an existing, well-tolerated, low-cost pill regimen on a durability endpoint measured after dosing ends. Several large pharmaceutical companies have written down or deprioritized hepatitis B assets after mid-stage results showed surface antigen declines that did not hold once therapy stopped.

Committing $120 million to a phase 3 push, then, is a statement about the strength of the earlier data package rather than a routine step up the clinical ladder. Phase 3 in this indication typically means long follow-up, multiple geographies and endpoints that cannot be rushed — an expensive combination.

What an oligonucleotide therapy actually does

Oligonucleotides are short, synthetic strands of genetic material designed to bind a specific RNA sequence inside cells. Rather than blocking a protein after it has been made, as a conventional small molecule or antibody does, they intervene a step earlier and stop the protein from being produced at all. In hepatitis B, that logic is attractive: the virus floods the bloodstream with surface antigen, and the prevailing theory is that this antigen load exhausts the immune system's ability to clear the infection. Silence the RNA that codes for it, and the immune system may get a chance to finish the job.

The class has already been validated commercially in other diseases — liver-targeted oligonucleotide drugs have reached the market in rare metabolic and cardiovascular indications — which reduces some of the platform risk. Delivery to hepatocytes, the liver cells where hepatitis B replicates, is the one part of the puzzle the industry has largely solved. What remains unsolved is whether antigen suppression alone is enough to produce a lasting cure, or whether it has to be paired with an immune-modulating agent.

The competitive field the money is buying into

AusperBio is not walking into an empty room. Multiple functional-cure programs are in the clinic globally, spanning small interfering RNA candidates, antisense oligonucleotides, capsid assembly modulators and therapeutic vaccines, and several groups are testing combinations of these mechanisms on the theory that no single approach will get patients off therapy for good. Some of those programs sit inside large pharmaceutical companies with the commercial infrastructure to launch in dozens of countries at once.

That is the strategic tension in a raise like this one. Reaching phase 3 as a private, venture-backed company means AusperBio has options — a licensing deal, an outright sale, a public listing — that a company still in phase 1 does not. It also means the clock is running. Late-stage trials burn capital quickly, and the company will need either a partner or a further financing event before a launch. The phrasing around this round, which explicitly reaches beyond phase 3 to commercialization, suggests management is at least entertaining the harder path of going it alone.

The financing backdrop for private biotech

Nine-figure private rounds for clinical-stage biotechs have become selective rather than routine. Investors have concentrated capital in fewer names with de-risked assets, and the exit environment has been uneven, which makes a crossover-style round for a phase 3-bound program a useful read on sentiment: money is available, but it is going to programs with data rather than to platforms with promise.

The public market context on the day of the report was cautious rather than exuberant. As of the last trade on Friday, 28 August 2026, the S&P 500 tracker (NYSEARCA: SPY) closed at $769.35, down 0.23% from the prior close of $771.10, having traded between $768.31 and $775.30. The Nasdaq 100 fund (NASDAQ: QQQ) ended at $716.43, off 0.65%, and the Dow tracker (NYSEARCA: DIA) finished at $535.06, a fractional 0.03% lower. A market grinding sideways is generally a harder one in which to price a biotech IPO, which is part of why large private rounds have become the preferred bridge.

What to watch next

Three things will determine whether this $120 million turns into a franchise. First, the design of the phase 3 program: which endpoint the company anchors on, how long patients are followed after stopping treatment, and whether the trial tests the candidate as monotherapy or in combination. Second, geography. Hepatitis B prevalence is heaviest in Asia and sub-Saharan Africa, so a commercially viable product has to work within pricing and reimbursement systems very different from those in the United States and Europe. Third, whether a larger partner steps in — a licensing deal signed during phase 3 would validate the asset while transferring launch risk, and it is the outcome the market has come to expect from single-asset hepatitis B companies.

For patients, the practical question is simpler and further out: whether a course of therapy could eventually replace lifelong daily pills. Nothing in a financing round answers that. But phase 3 is where the question finally gets asked properly.

Key facts

• Round size: $120 million series C
• Company: AusperBio Therapeutics (private, no listed ticker)
• Use of proceeds: Advance oligonucleotide therapy for chronic hepatitis B through phase 3 and toward commercialization
• Market backdrop: S&P 500 (SPY) last closed at $769.35, -0.23%, as of 28 Aug 2026 20:00 GMT

Frequently asked questions

How much did AusperBio raise and what for?

AusperBio Therapeutics raised $120 million in a series C round. The company said the proceeds will fund the advance of its oligonucleotide therapy for chronic hepatitis B through phase 3 clinical testing, and, if those trials succeed, support the move toward commercialization of the drug.

What is an oligonucleotide therapy?

An oligonucleotide is a short synthetic strand of genetic material designed to bind a specific RNA sequence inside a cell and prevent a target protein from being made. Unlike a conventional drug that blocks a protein after production, it acts one step earlier, at the instruction stage, silencing the gene's message.

Why is chronic hepatitis B so hard to cure?

Existing nucleoside and nucleotide analogues suppress viral replication well but usually must be taken indefinitely, because the virus rebounds when treatment stops. A functional cure requires sustained loss of hepatitis B surface antigen and undetectable viral DNA that persists after therapy is withdrawn — a far harder endpoint to hit.

Is AusperBio a publicly traded stock?

No. AusperBio is a private, venture-backed company, and a series C round is a private financing rather than a stock market listing. There is no exchange ticker to trade. A public offering or a sale to a larger pharmaceutical company would be possible future routes for its investors to realize a return.

What does reaching phase 3 signify?

Phase 3 is the final, largest and most expensive stage of clinical testing before a regulatory filing, designed to confirm efficacy and safety in a broad patient population. Funding a phase 3 program signals that earlier-stage results were strong enough to justify the substantial cost and long follow-up such trials require.

Who else is working on a hepatitis B functional cure?

Multiple programs are in clinical development worldwide, spanning small interfering RNA candidates, antisense oligonucleotides, capsid assembly modulators and therapeutic vaccines, with several groups testing combinations. Some sit inside large pharmaceutical companies, and a number of assets have been deprioritized after mid-stage data failed to show durable responses.

Sources

• AusperBio adds $120M series C to advance hep B oligo therapy through phase 3 and beyond — Fierce Biotech

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