Theseus Pharmaceuticals, Inc.

General Information

We are a biopharmaceutical company focused on improving the lives of cancer patients through the discovery, development and commercialization of transformative targeted therapies. Our development programs are designed to address drug resistance mutations in key driver oncogenes, which are mutated genes that cause cancer. Resistance mutations limit the efficacy of existing targeted therapies by rendering tumor cells unresponsive to drugs, and therefore present a critical challenge in cancer treatment today. Our initial focus is on developing the next generation of tyrosine kinase inhibitors, or TKIs, and is rooted in the critical role that tyrosine kinases play in the development of cancer. Despite the commercial success of approved TKIs, the development of drug resistance is a persistent limitation, narrowing the number of effective treatment options available to patients as they progress through subsequent lines of therapy.

Our goal is to develop “pan-variant” kinase inhibitors—inhibitors that target all major cancer causing and drug resistance mutations in clinically significant protein kinases. 

Our lead product candidate, THE-630, is a pan-variant inhibitor of all major classes of activating and resistance mutations of the KIT kinase, or a pan-KIT inhibitor, for the treatment of gastrointestinal stromal tumors, or GIST, a type of cancer characterized by oncogenic activation of KIT. THE-630 is derived from intellectual property exclusively licensed to us by ARIAD Pharmaceuticals, Inc., or ARIAD. We have recently submitted an Investigational New Drug, or IND, application to the U.S. Food and Drug Administration, or FDA, for the evaluation of THE-630 in patients with advanced GIST whose disease has developed resistance to prior KIT-targeting therapies, and, if cleared by the FDA, we plan to initiate a phase 1/2 dose escalation and expansion clinical trial between late fourth quarter 2021 and mid-first quarter 2022.

Our second program is focused on next-generation inhibitors of epidermal growth factor receptor, or EGFR, that are active against C797S, the most common EGFR mutation that causes resistance to first- or later-line osimertinib treatment in patients with non-small cell lung cancer, or NSCLC. 

(Note: Theseus Pharmaceuticals upsized its IPO at pricing on Oct. 6, 2021, to 10 million shares, up from 8.3 million in the prospectus, and priced the stock at $16 – the high end of its $14-to-$16 price range – to raise $160 million.)


Employees: 14
Founded: 2017
Contact Information
Address 245 Main Street Cambridge, Massachusetts 02142
Phone Number (857) 400-9491
Web Address
View Prospectus: Theseus Pharmaceuticals, Inc.
Financial Information
Market Cap $537.9mil
Revenues $0 mil (last 12 months)
Net Income $-15.6 mil (last 12 months)
IPO Profile
Symbol THRX
Exchange NASDAQ
Shares (millions): 10.0
Price range $16.00 - $16.00
Est. $ Volume $160.0 mil
Manager / Joint Managers Jefferies/ SVB Leerink/ Cantor Fitzgerald/ Wedbush Securities
CO-Managers -
Expected To Trade: 10/7/2021
Status: Priced
Quiet Period Expiration Date:
Lock-Up Period Expiration Date:
SCOOP Rating
Rating Change