PROSPECTUS SUMMARY
This summary highlights certain information about us, the Asset Acquisition (as defined below) and selected information contained elsewhere in or
incorporated by reference into this prospectus. This summary is not complete and does not contain all of the information that you should consider before making an investment decision. For a more complete understanding of our company, you should read
and consider carefully the more detailed information included or incorporated by reference in this prospectus and any applicable prospectus supplement, including the factors described under the heading “Risk Factors” on page 4 of this
prospectus, as well as the information incorporated herein by reference, before making an investment decision.
Company Overview
We are a clinical-stage biotechnology company advancing a diversified portfolio of cell therapy and small molecule product candidates. In February 2026, we
expanded our pipeline through a strategic transaction under which we acquired rights to a portfolio of dual-targeting chimeric antigen receptor T-cells
(“CAR-T”) product candidates with the potential to treat certain blood cancers, solid tumors and immunology indications, including TPST-2003, an autologous
CD19/B-cell maturation antigen CAR-T therapy currently in clinical development for relapsed or refractory multiple myeloma (“rrMM”). Our portfolio also
includes two clinical-stage small molecule product candidates with the potential to treat certain cancer indications. One of our small-molecule product candidates, amezalpat (previously known as TPST-1120), has completed a Phase 2 study in
first-line hepatocellular carcinoma (“HCC”). Amezalpat remains Phase 3-ready in HCC and we plan to pursue business development discussions to advance pivotal development. Our second small-molecule
product candidate is TPST-1495, which we plan to initiate a Phase 2 study for in familial adenomatous polyposis. The study is expected to be funded by the National Cancer Institute and conducted through the Cancer Prevention Clinical Trials Network,
enabling advancement with limited internal capital deployment.
Additional information about our company, including recent developments, is contained in
the documents incorporated by reference into this prospectus supplement and the accompanying prospectus, including our Annual Report on Form 10-K that we filed with the SEC on March 30, 2026.
Asset Purchase Agreement
On November 19, 2025, we
executed the Asset Purchase Agreement with Erigen LLC, a Delaware limited liability company (“Erigen”), and Factor Bioscience Inc., a Delaware corporation (together with Erigen, “Sellers”), pursuant to which Sellers agreed to
sell and transfer to the Company all right, title and interest of Sellers in and to all of the assets primarily related to (a) the autologous BCMA/CD19 dual-targeting CAR T-cell therapy known as TPST-2003
currently being evaluated in a Phase 1/2a clinical study in patients with rrMM, (b) the autologous CD70/CD70 dual-targeting CAR T-cell therapy known as TPST-2206, (c) the allogeneic BCMA/CD19
dual-targeting CAR T-cell therapy with a gene edit in the TRAC locus that inactivates the T cell receptor known as TPST-3003, and (d) the allogeneic CD70/CD70 dual-targeting CAR T-cell therapy with a gene edit in the TRAC locus that inactivates the T cell receptor known as TPST-3206 (collectively referred to herein as the “Assets”), in exchange for an aggregate purchase price of
8,268,495 shares of our common stock issued to Erigen on behalf of both Sellers.
On February 3, 2026, we completed the acquisition of the Assets
(the “Closing”) under the Asset Purchase Agreement (the “Asset Acquisition”) and issued to Erigen 8,268,495 shares of our common stock (the “Share Issuance”).
Pursuant to the Asset Purchase Agreement, at Closing we obtained an exclusive license to specified patents and
know-how in all fields worldwide, but excluding Greater China, India, Turkey, and Russia, to exploit the TPST-2003 and TPST -2206 programs and allogeneic CAR-T therapies
based on the TPST-2003 and TPST-2206