US-based antibody drug conjugate (ADC) developer Mersana Therapeutics has filed for a $75m initial public offering that will give exits to pharmaceutical firms Takeda and Pfizer.
Mersana is working on ADC therapies for cancer and the IPO proceeds will fund a phase 1 clinical trial for its lead drug candidate, a breast cancer treatment called XMT-1522. The capital will also support preclinical and phase 1 trials for a second candidate, XMT-1536.
The company has raised approximately $130m in equity financing, according to press releases and regulatory filings.
Pfizer invested $4.1m as part of a $27m series A-1 round in 2012 that was led by New Enterprise Associates and backed by F-Prime Capital Partners, Rho Ventures, ProQuest Investments and Harris & Harris Group.
Pfizer subsequently provided $5.6m of a $35m round in early 2015 that was also led by NEA with participation from F-Prime, Rho Ventures, Rock Springs Capital Master Fund and company president and CEO Anna Protopapas.
Takeda subsidiary Millennium Pharmaceuticals invested $10m in Mersana as part of a $33m round in June 2016 that included NEA, Rock Springs and investment vehicle Hadley Harbor Master Investors, according to the IPO filing.
NEA is Mersana’s largest shareholder, with a 41% stake, while Pfizer owns 11.6% and Millennium Pharmaceuticals 5.6%. Other notable investors include F-Prime (9.9%), Rho Ventures and Rock Springs (7.6% each), Wellington Management (5.6%) and ProQuest (5.5%).
JP Morgan Securities, Cowen and Company, Leerink Partners and Wedbush Securities have been appointed underwriters for the offering.