Westlake Village BioPartners

Westlake Village BioPartners

Westlake Village BioPartners formed in 2018 when Beth Seidenberg and Sean Harper, two veterans of Amgen, pooled their operating and venture capital experience to build a dedicated life sciences firm rooted in Southern California. Seidenberg had spent the prior 15 years as a general partner at Kleiner Perkins, where she backed biotech and digital health companies including Flexus Biosciences (acquired by Bristol Myers Squibb for $1.25 billion). Harper's scientific career included roles as executive vice president of R&D at Amgen and head of global drug development at Merck. The fund's locale is deliberate: Amgen, one of the world's largest biotech companies, is headquartered in Thousand Oaks, a few miles from Westlake Village. The talent density created by Amgen alumni in the region provides a proprietary sourcing pipeline that generic coastal VCs cannot replicate. The firm leads or co-leads seed and Series A rounds across biotechnology, diagnostics, and tools, with a mandate to stay engaged through the clinical inflection points that often cause early investors to dilute or exit. Fund I closed at $320 million in 2018 (per the firm's official communications). Fund II, announced in 2022, secured $450 million, bringing total committed capital to $770 million (per Endpoints News, 2022). The firm has published named portfolio companies including Acelyrin, a late-stage inflammation biotech that priced a $540 million IPO in 2023; and Terray Therapeutics, an AI-driven small molecule discovery platform that raised a $120 million Series B in 2024. The geographic spread of portfolio companies extends from San Diego to Seattle, reflecting a West Coast life sciences corridor thesis rather than a single-metro bet. Seidenberg and Harper remain the only named managing directors. The firm does not publish a headcount or organizational chart, though its deployment pace — 20-plus portfolio companies across two funds — implies a lean investment team supported by scientific advisors and venture partners. In October 2024, Westlake Village BioPartners participated in the $200 million Series C financing of Terray Therapeutics (per Terray Therapeutics, October 2024). The firm has not announced affiliated philanthropic vehicles, incubators, or club structures, functioning instead as a pure-play venture capital firm organized around two decision-makers. Westlake Village BioPartners' structural distinction is its single-geography thesis applied to an industry where venture capital remains hyper-concentrated in Cambridge and South San Francisco. The firm's proximity to Amgen's headquarters and the talent pool that cycles through one of biotech's largest employers gives it access to company formation opportunities before they reach coastal syndicates. For institutional allocators, the question is succession: the firm has not publicly addressed whether the next generation of investors is being developed internally or whether the franchise remains tightly held by its co-founders.