Newly uncloaked Stipple Bio is connecting the dots toward multiple early-stage clinical studies for its lead precision oncology asset, buoyed by a $100 million series A financing round.
The “heavily oversubscribed” raise was co-led by RA Capital, a16z Bio+Health and Nextech Invest, according to an April 6 release. The round, which is expected to fund the company through 2029, also saw participation from existing partners Emerson Collective Investments (managed by Yosemite), Google Ventures, LoLa Capital Partners and GordonMD Global Investments, among others.
With the cash in hand, Stipple expects its lead asset to enter the clinic early next year. Dubbed STP-100, the program is an antibody-drug conjugate (ADC) leveraging tumor-specific binders designed to avoid on-target and off-tumor toxicity, according to the biotech.
Stipple's name evokes the process of marking a surface with small dots or specks, and the company's lead asset was aptly identified using the company's bespoke Pointillist platform. Named in honor of the eponymous painting technique, Pointillist is a modality-agnostic system that identifies tumor-specific cell surface epitopes—sections of antigens bound by an antibody’s paratope or a T-cell receptor—for development into potential cancer therapies.
Stipple CEO Jeff Landau explained to Fierce Biotech that the company has found a way to enhance the therapeutic index of drug candidates by identifying differences between the epitopes on tumor cells and healthy tissue. The contrast provides for a unique bonding opportunity.
“We are looking for specific binding epitopes and have a map of different options, but we are looking for the ones that have binding opportunities for cancer cells that don't bind to normal cells,” Landau said. “If you know how to do it the right way, there are a lot of them.”
Stipple is not revealing the indication for its lead target, but the biotech says the drug is focused on a clinically prosecuted target that has been limited by its ability to bind to the tumor cell.
“We are unlocking a target and making it amenable to a highly potent modality,” Landau says. “We think it could be a massive breakthrough for the patient population.”
The company has also identified additional unique binding opportunities, Landau said, and has been approached by other biopharma companies that want to collaborate via Stipple's platform. Landau said he could see a partnership in the future if the right deal comes along, but the value of the current financing is in the lead asset, and he plans on focusing on wholly-owned candidates.
While much of today's raise will support STP-100, Stipple also plans to use the cash to identify additional tumor-specific cell surface epitopes that could help the biotech build out a pipeline of oncology candidates.
Founded in 2022 by UCSF researchers, Stipple aims to target tumor-specific cell surface epitopes and discover previously untreatable targets, ultimately developing safer and more effective therapies.
Epitope-level R&D helped Georgiamune earn a spot in Fierce Biotech's Fierce 15 in 2025. The company’s cancer immunotherapy is designed to offer an opportunity for the 85% of patients who lack the active T cells needed to benefit from PD-1/L1 checkpoint inhibitors. The asset works by removing immune checkpoints that activate T cells.