Mersana Therapeutics Closes in on IPO After Announcing Expected Price Range

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Mersana Therapeutics has registered an amended S-1 form with the U.S. Securities and Exchange Commission (SEC) for its initial public offering (IPO). The company expects to price its 5.0 million shares in the range of $14 to $16 per share, with an overallotment option for an additional 750,000 shares. At the maximum price, the entire offering is valued up to $92 million. The company intends to list its shares on the Nasdaq under the symbol MRSN.

The underwriters for the offering are JPMorgan, Cowen, Leerink Partners and Wedbush PacGrow.

This clinical stage biopharmaceutical company is focused on developing antibody drug conjugates (ADCs) that offer a clinically meaningful benefit for cancer patients with significant unmet need. Mersana has leveraged 20 years of industry learning in the ADC field to develop proprietary technologies that enable it to design ADCs to have improved efficacy, safety and tolerability relative to existing ADC therapies.

Its most advanced platform, Dolaflexin, has been used to generate a pipeline of proprietary ADC product candidates to address patient populations that are not currently amenable to treatment with traditional ADC-based therapies. The lead product candidate, XMT-1522, is a HER2-targeted ADC currently in a Phase 1 dose escalation study in primarily breast cancer patients, with interim safety results expected by the end of 2017. Upon the completion of dose escalation, Mersana plans to expand clinical development of XMT-1522 into additional breast cancer, non-small cell lung cancer (NSCLC) and gastric cancer patient populations, all of which are not addressed by existing HER2 therapies.

The second product candidate, XMT-1536, is an ADC targeting NaPi2b, an antigen broadly expressed in ovarian cancer and NSCLC. The firm expects XMT-1536 to enter clinical development in early 2018. Its current product candidates are all based on the Dolaflexin platform.

Mersana intends to use the net proceeds from this offering for:

  • Phase 1 clinical trial of XMT-1522
  • Preclinical activities and Phase 1 clinical trial of XMT-1536
  • New and ongoing research activities

The remainder of the net proceeds will be put toward working capital and other general corporate purposes.