Sidewinder Therapeutics’ bispecific antibody-drug conjugates target pairs of receptors found on cancer cells, which the company claims improves their specificity and minimizes off-target effects.
Sidewinder Therapeutics has closed a series B round, giving its coffers a $137 million boost to advance bispecific antibody-drug conjugates for solid tumors with limited treatment options.
The money will help bankroll the development of Sidewinder’s lead program, which the biotech hopes to bring to the clinic next year, according to a news release on Wednesday. The company did not reveal much about the asset in its press announcement, but a company presentation seen by Fierce Biotech dubbed the candidate SWT012, which has undergone animal testing for bladder cancer.
An investigational new drug (IND) submission for SWT012 is planned by year-end, the publication reported on Wednesday.
Aside from SWT012, Sidewinder is also working on other bispecific antibodies, including SWT019 and SWT020, which have been tested in preclinical studies for lung cancer and colorectal cancer, respectively. Sidewinder is planning to file an IND for SWT019 in the first half of 2027, while also settling on a final formula for SWT020, Fierce reported, citing the company deck.
Sidewinder’s platform generates bispecific ADCs that target specific protein co-complexes—pairs of receptors that are found on certain cancers. One part of this doublet brings signals from inside the cell while the other, when activated, drives the tumor’s growth.
By designing their ADCs to seek out two targets instead of one, Sidewinder’s approach ensures the better delivery of therapeutic payloads to malignant cells while minimizing off-target effects on healthy cells, according to the Wednesday release. The biotech is going after indications “that have limited treatment options and affect substantial patient populations,” such as squamous lung and head and neck cancers.
The fundraising push on Wednesday was led by Novartis Venture Fund and Frazier Life Sciences. OrbiMed, Sidewinder’s only series A supporter in 2023, participated in this recent effort, alongside Astellas Venture Management, Samsara BioCapital and Life Sciences at Goldman Sachs Alternatives. All told, Sidewinder’s has raised a total of $162 million since its founding.
With its Wednesday haul, Sidewinder joins a growing list of biotechs that, despite the industry’s tough times, have successfully attracted money from investors. Last week, Ambrosia Biosciences closed a $100 million series B round for small-molecule GLP-1 pills, looking to set itself apart from the largely peptide-based approach the space. A few days earlier, Sanofi and Pfizer put their financial firepower behind Earendil Labs, which brought in $787 million in a private placement for its AI engine for antibodies and biologics.
