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Kassandra K. Castillo
Partner
Corporate
San Diego

D858-350-2271

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Kassandra K. Castillo practices corporate and securities law in the San Diego office of Wilson Sonsini Goodrich & Rosati, where she serves as outside general counsel and advises life sciences and technology companies at all stages of development. She works closely with entrepreneurs to counsel them through initial company formation issues, day-to-day corporate governance matters, venture capital financing transactions, and liquidity events. She also counsels venture capital funds on structuring and executing investment transactions and managing their existing portfolio companies.

Experience

Kassandra K. Castillo practices corporate and securities law in the San Diego office of Wilson Sonsini Goodrich & Rosati, where she serves as outside general counsel and advises life sciences and technology companies at all stages of development. She works closely with entrepreneurs to counsel them through initial company formation issues, day-to-day corporate governance matters, venture capital financing transactions, and liquidity events. She also counsels venture capital funds on structuring and executing investment transactions and managing their existing portfolio companies.

Focus Areas
Recent Insights
Client Highlights
Wilson Sonsini Represents Investors in Windward Bio’s $165 Million Crossover Financing
On May 4, 2026, Windward Bio, a private, clinical-stage biotechnology company committed to improving outcomes for people living with serious immunological diseases, announced an upsized $165 million crossover financing led by OrbiMed, with participation from existing Series A investors including Novo Holdings, Blue Owl Healthcare Opportunities, SR One, Omega Funds, RTW Investments, Qiming Venture Partners, Quan Capital, and Pivotal bioVenture Partners. The financing also included new investors RA Capital Management, Janus Henderson Investors, Sanofi Ventures, and Harbour BioMed. Wilson Sonsini Goodrich & Rosati represented OrbiMed, Novo Holdings, Blue Owl Healthcare Opportunities, and Omega Funds in the transaction.

Since its launch in January 2025, Windward Bio has in-licensed two clinical-stage assets, raised $365 million, and rapidly advanced both programs in the clinic. The proceeds from this latest financing will significantly extend the company’s cash runway and enable multiple clinical readouts in the next 12 months.

The Wilson Sonsini team that represented OrbiMed, Novo Holdings, Blue Owl Healthcare Opportunities, and Omega Funds in connection with the financing included:
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Client Highlights
Wilson Sonsini Advises Novo Holdings, Norwest, and Platanus on Ray Therapeutics’ $125 Million Series B
On April 21, 2026, Ray Therapeutics (RayTx), an industry-leading clinical-stage biopharmaceutical company pioneering differentiated vision restoration therapies for those living with severe retinal degenerations, announced the closing of an upsized and oversubscribed $125 million Series B financing. The round was led by Janus Henderson Investors, with participation from additional new investors Adage Capital Management, Franklin Templeton, Invus, and Marshall Wace. The financing includes strong follow-on support from existing investors 4BIO Capital, Deerfield Management, MRL Ventures Fund (the therapeutics-focused corporate venture arm of Merck & Co), Norwest, Novo Holdings A/S, and Platanus. Wilson Sonsini Goodrich & Rosati advised Novo Holdings A/S, Norwest, and Platanus on the transaction.
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Recent Events
WSGR Events
Wilson Sonsini’s 31st Annual Medical Device & Digital Health Conference
Wilson Sonsini Goodrich & Rosati’s 31st Annual Medical Device & Digital Health Conference will address topics of critical importance to medical device and digital health companies today, including key healthcare regulatory considerations, the relationship between intellectual property and valuation, a look back at 2023’s fundraising and deals, and how 2024 is shaping up along with partnering strategies in the current market.
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Affiliated Programs
Athena's Spring CXO Forum
Wilson Sonsini Goodrich & Rosati is pleased to support Athena's Spring CXO Forum. Athena's CXO Spring Forum creates a safe harbor exclusively for executive STEM women looking to optimize this circle of influence, renew coveted relationships, and share business resources directly from those running, leading, or launching STEM companies. In this intimate gathering, co-sponsored with JLL, we’ll delve into table discussions spanning the Corporate Transparency Act, trends in remote workplace dynamics, and other business challenges. Expect to exchange experiences and perspectives over a three-course dinner and take away new avenues to navigate the evolving market landscape.
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