Sidewinder Therapeutics Raises $137 Million Series B to Advance Precision Bispecific ADC Pipeline
Sidewinder Therapeutics, a San Diego-based biopharmaceutical company developing next-generation bispecific antibody-drug conjugates (ADCs) for cancer, has closed an oversubscribed $137 million Series B financing round. The new capital will support the advancement of the company’s lead precision bispecific ADC programs into clinical development, expand its research pipeline, and strengthen its position in the rapidly growing oncology therapeutics market.
The Series B financing was co-led by Frazier Life Sciences and Novartis Venture Fund. The round also included significant participation from existing investor OrbiMed, alongside new investors Life Sciences at Goldman Sachs Alternatives, DCVC Bio, Samsara BioCapital, Longwood Fund, Astellas Venture Management, and Alexandria Venture Investments. The financing increases Sidewinder’s total capital raised to approximately $162 million since its founding in 2023.
Founded in partnership with OrbiMed, Sidewinder Therapeutics is focused on developing precision bispecific ADCs designed to overcome limitations associated with existing antibody-drug conjugates. The company’s technology aims to improve tumor specificity by targeting receptor co-complexes that are highly expressed on cancer cells while minimizing activity in healthy tissues. By enhancing selective drug delivery and cellular internalization, Sidewinder seeks to expand the therapeutic window of ADC therapies and improve treatment outcomes for patients with difficult-to-treat solid tumors.
The proceeds from the Series B financing will primarily fund the advancement of Sidewinder’s lead oncology programs toward clinical trials. The company expects its first internally developed precision bispecific ADC candidate to enter clinical development in 2027 while continuing to expand its broader pipeline of targeted cancer therapies. Sidewinder is concentrating on cancers with significant unmet medical needs, including squamous cell carcinomas of the lung and head and neck, as well as gastrointestinal malignancies such as colorectal cancer.
Chief Executive Officer and co-founder Eric Murphy said the financing positions the company to advance a new generation of ADC therapies capable of addressing important limitations associated with current treatments. According to Murphy, recent advances in antibody engineering and targeted drug delivery have created an opportunity to develop therapies that deliver potent anti-cancer agents more precisely while reducing unwanted toxicity.
The financing also brings additional scientific and investment expertise to Sidewinder’s board of directors. Following the transaction, Daniel Estes, Ph.D., of Frazier Life Sciences, Michal Silverberg of Novartis Venture Fund, Josh Richardson, M.D., of Life Sciences at Goldman Sachs Alternatives, and John Hamer, Ph.D., of DCVC Bio joined the company’s board, further strengthening its leadership as it prepares for clinical development.
Investor interest reflects the rapid expansion of the global ADC market, which has become one of the most active areas of oncology drug development. While first-generation ADCs have demonstrated significant clinical success across multiple cancer types, researchers continue working to improve their safety, efficacy, and applicability through new targeting strategies. Sidewinder’s bispecific platform seeks to address these challenges by requiring simultaneous recognition of multiple tumor-associated targets before delivering its therapeutic payload, potentially increasing selectivity while limiting off-target effects.
Earlier this year, Sidewinder also entered into a multi-target licensing agreement with Synaffix, part of Lonza, providing access to site-specific linker-payload technology that supports the development of several pipeline candidates. The agreement complements the company’s proprietary targeting platform and is expected to accelerate development of multiple bispecific ADC programs.
The latest financing underscores continued investor enthusiasm for next-generation oncology platforms capable of improving the precision of cancer treatment. Venture capital investment in ADC developers has accelerated in recent years as pharmaceutical companies increasingly pursue targeted therapies that combine the specificity of biologics with the potency of cytotoxic drugs. Sidewinder’s differentiated approach has attracted backing from a syndicate of leading life sciences investors with deep experience supporting innovative oncology companies through clinical development.
With $137 million in new funding, Sidewinder Therapeutics is positioned to advance its precision bispecific ADC platform toward human clinical trials while expanding its pipeline of targeted therapies for patients with cancers that currently have limited treatment options. Supported by a consortium of prominent healthcare investors and strengthened by new scientific leadership, the company aims to contribute to the next generation of antibody-drug conjugates designed to improve efficacy, enhance safety, and broaden treatment possibilities across multiple solid tumor indications.
