The biotech IPO window looks like it’s reopening. This past week closed with three biotech companies joining the public markets, a flurry of activity that helped make April the biggest month for biotech IPOs since March 2021, according to Renaissance Capital.
Hemab Therapeutics and Seaport Therapeutics began trading Friday. Those companies followed respiratory disorder biotech Avalyn Pharma, which began trading Thursday after its own upsized IPO. The four companies raised $1.5 billion combined. There was strong investor interest in these clinical-stage biotechs. Each one was able to upsize its deal and each saw its stock price surge during its first day of trading.
Here’s a look at the two newest biotech companies that joined the Nasdaq on Friday.
Hemab’s IPO Hauls In $301M for Pivotal Test of Rare Platelet Disorder Drug
Hemab develops drugs for rare bleeding disorders. The company’s lead disease target is Glanzmann thomboasthenia, a genetic disorder that results in improperly functioning platelets. No drugs are available for this disease. While a blood platelet transfusion offers a treatment option, it requires patients to make regular visits to a transfusion center for life. These treatments can lose efficacy if the body develops antibodies against the infused platelets.
Lead Hemab drug candidate sutacimig (formerly HMB-001) is a bispecific antibody designed to bind to Factor VII circulating in the blood and TREML1, a receptor expressed exclusively on activated platelets. Binding to both targets is intended to facilitate clotting. In Phase 1/2 testing, Hemab reported a significant reduction in the annualized treated bleed rate, according to the IPO filing. Sutacimig’s Phase 3 study is expected to begin in the second half of this year. A Phase 2 test of sutacimig is ongoing in a different disorder, Factor VII deficiency. Hemab expects to report clinical data from this study late this year or early next year.
Hemab’s next drug candidate, HMB-002, is in development as a prophylactic treatment for von Willebrand disease, a disorder in which patients have low levels of von Willebrand factor (VWF). This clotting protein mediates platelet adhesion to damaged blood vessel walls and serves as the carrier for another protein called Factor VIII, protecting it from being prematurely degraded and cleared away. The Hemab antibody drug targets VWF it in its inactive conformation, stabilizing the protein and extending its half-life. Consequently, circulating levels of VWF should increase.
In preliminary results from Phase 1/2 testing, Hemab has reported a 1.5-fold increase in VWF and Factor VIII. Additional data are expected late this year or early next year. The company’s pipeline has additional assets in preclinical development. Hemab plans to bring the first of these assets into the clinic in the second half of this year. Data from this drug candidate are expected in mid-2027.
Since its formation in 2020, Hemab had raised $346 million as a private company. The most recent financing was a $157 million Series C round last October led by Sofinnova Partners. Hemab’s largest stockholder is RA Capital Management with an 11.4% post-IPO stake followed by the 9.85% stake of Novo Holdings.
As of the end of 2025, Hemab reported its cash and marketable securities totaled $185.5 million. With that capital and the IPO proceeds, Hemab plans to spend $120 million to $130 million for clinical testing of sutacimig in Glanzmann thrombasthenia and Factor VII deficiency; $60 million to $70 million on clinical testing of HMB-002 for Von Willebrand disease; and $25 million to $35 million for other programs. Hemab expects its capital will last into 2029.
In its preliminary IPO terms, Hemab planned to offer 15 million shares in the range of $16 to $18 each. Hemab ended up pricing 16.75 million shares at the top of the targeted price range. Those shares trade on the Nasdaq under the stock symbol “COAG.”
Seaport Therapeutics Sails Into the Public Markets
Seaport Therapeutics raised $254.9 million to support its pipeline of neuropsychiatric drugs intended to overcome limitations of currently available therapies. Its lead indication is major depressive disorder (MDD). The market for depression drugs is crowded, but the available therapies still leave room for improvement in efficacy and tolerability.
One of the limitations of orally administered drugs is high first-pass metabolism, which means much of a drug is metabolized by the liver or intestines before it even enters the body’s circulation. Seaport’s drugs come from its proprietary Glpyh platform to leverages the lymphatic system for delivery, which the company calls “Glyphing.” Its therapies are prodrugs, compounds that convert to an active drug inside the body. This approach is intended to overcome high first-pass metabolism.
Seaport’s lead drug candidate is GlyphAllo (formerly SPT-300), is an oral prodrug of allopregnanolone. This molecule, found naturally in the body, reduces stress. Analogs of allopregnanolone developed by Sage Therapeutics became the post-partum depression (PPD) drugs Zulresso and Zurzuvae. Despite clinical and regulatory success in PPD, Sage failed to secure FDA approval of these drugs in MDD.
Seaport is trying to succeed where Sage fell short. In the IPO filing, the company says its drug is designed to overcome the bioavailability limitations of allopregnanolone to deliver rapid and durable efficacy. In Phase 1 testing, Seaport reported GlyphAllo reached therapeutically relevant exposure in the body with oral dosing. In Phase 2a testing, the study drug demonstrated initial proof-of-concept and a favorable tolerability profile in healthy volunteers. A Phase 2b study is underway in MDD patients; preliminary data are expected in the first half of 2027.
The next Seaport drug candidate, GlpyhAgo (formerly SPT-320), is a Glyphed oral prodrug of agomelantine, a molecule that has clinical validation for applications in anxiety and depression. GlyphAgo is in development for generalized anxiety disorder. In Phase 1 testing, Seaport reported its drug achieved greater bioavailability and exposure in the body compared to unmodified agomelantine. The study drug was also well tolerated with no liver-related adverse events. Seaport plans to start a Phase 2a test GlyphAgo to evaluate potential sleep benefit of the drug in patients with anxiety and sleep disturbance; preliminary data are expected in early 2028. In parallel, Seaport plans a Phase 2b study evaluating this drug in generalized anxiety disorder; preliminary data are expected by the end of 2028.
Seaport was formed in 2024 by PureTech Health, a company that builds startups around platform technologies. According to the IPO filing, Seaport had raised $325 million in its history prior to the IPO. Its last financing was a $225 million Series B round in 2024 led by Arch Venture Partners and Sofinnova Investments. PureTech is Seaport’s largest shareholder with a 32.9% post-IPO stake followed by Arch’s 10.3% stake, the filing shows.
As of the end of 2025, Seaport reported its cash position was $233.6 million. Together with the IPO proceeds, Seaport plans to spend about $121 million to advance GlyphAllo through Phase 2b testing and into Phase 3. Another $97 million is budgeted to take GlyphAgo through Phase 2a testing and the preliminary readout of Phase 2b data. The company said it expects its capital will last into 2029.
Seaport initially planned to offer 11.8 million shares in the range of $16 to $18 each. The company ended up pricing 14.16 million shares at the top of the targeted price range. Those shares trade on the Nasdaq under the stock symbol “SPTX.”
Photo: Stephanie Keith/Bloomberg, via Getty Images
