• Biotech Snap
  • Posts
  • Prolium launches with $50M to advance its T-cell engagers & Boehringer walks away from OSE parternship

Prolium launches with $50M to advance its T-cell engagers & Boehringer walks away from OSE parternship

AuthorAuthor

Joachim Eeckhout & Eduardo Longoria
March 04, 2026

Good morning! BioMarin’s Voxzogo has basically had the achondroplasia (the most common form of dwarfism) drug market to itself since 2021. Not anymore. The FDA handed accelerated approval to Ascendis Pharma’s Yuviwel, a once-weekly injection for kids 2+ with achondroplasia and open growth plates, firing a direct shot at BioMarin’s daily Voxzogo routine. Approval was based on improved annualized growth velocity (AGV), but Ascendis is still required to run confirmatory testing.

Why it matters: Treatment convenience could do serious damage to BioMarin’s monopoly. One analyst note says ~40% of current injection patients might switch to the weekly option even if Ascendis hasn’t announced pricing yet. Meanwhile, more competition is coming as BridgeBio just posted encouraging data for an oral pill and plans to talk with regulators later this year.

Bottom line: The achondroplasia market just went from one-horse race to full-on matchup, and 2026 is only the opening bell.

— Joachim E.

Don’t keep this newsletter a secret: Forward Biotech Snap to a friend!

Was this email forwarded to you? Sign up here.

SNAPSHOT

Prolium launches with $50M to advance T-cell engagers for severe autoimmune diseases

Prolium Bioscience launched with $50 million in Series A funding from RTW Investments and began dosing patients with PRO-203, a CD20xCD3 T-cell engager targeting severe autoimmune diseases, including systemic sclerosis and lupus.

Why it matters: Severe autoimmune diseases like systemic sclerosis (SSc) and lupus have limited treatment options. PRO-203 aims to deliver deep, durable B-cell depletion, similar to CAR-T therapy, without many of CAR-T’s logistical and safety challenges.

Backstory: Founded in 2025 by RTW Investments, Prolium in-licensed global non-oncology and ex-Asia oncology rights to PRO-203 from Chinese biotechs KeyMed Biosciences and InnoCare Pharma. The drug previously showed strong results in a Phase 1/2 trial in relapsed/refractory non-Hodgkin lymphoma (NHL) patients in China.

Big picture: T-cell engagers are emerging as a new frontier in autoimmune treatment, redirecting the immune system to selectively eliminate disease-driving B-cells. If successful, PRO-203 could reshape treatment paradigms in scleroderma and other B-cell–mediated conditions.

What’s next: A multinational Phase 1/2 trial in systemic sclerosis is planned for Q2 2026. Prolium plans to launch additional clinical studies in multiple severe autoimmune diseases this year and expects key data readouts across indications within two years.

SNIPPETS

What’s happening in biotech today?

✂️ Pipeline cut: Boehringer Ingelheim has discontinued development of OSE Immunotherapeutics’ SIRPα antagonist BI 770371 in metabolic dysfunction-associated steatohepatitis (MASH) after it failed to show efficacy in a phase 2 study, though the drug will continue to be developed in oncology. The decision marks another pipeline setback for OSE, following AbbVie’s recent exit from an inflammation partnership (OSE-230), prompting the French biotech to further streamline operations. OSE is pausing development of OSE-230 and ending research on its CLEC-1 oncology program to focus on two late-stage assets: lusvertikimab for inflammatory diseases and the cancer vaccine Tedopi, both with key clinical readouts expected soon.

💰 Merger money: Rallybio has agreed to merge with Candid Therapeutics in a deal that will see the combined company operate under the Candid name and trade on Nasdaq as “CDRX.” Candid secured more than $505 million in a concurrent private financing from major institutional investors, contributing to an expected cash balance of about $700 million at closing, which is projected to fund operations through 2030. The capital will advance Candid’s T-cell engager portfolio, including phase 2 studies of cizutamig in myasthenia gravis and interstitial lung disease. Upon closing, expected by mid-2026, Rallybio shareholders will own 3.65% of the combined entity, with Candid investors holding the remainder.

🛑 Trial terminated: Kyowa Kirin has discontinued all clinical trials of its anti-OX40 antibody rocatinlimab after two new cases of Kaposi sarcoma, in addition to a previously reported case, raised concerns about a potential link between OX40 pathway modulation and malignancy. The decision, made following a recent safety review, significantly undermines Kyowa’s prior plan to seek FDA approval in atopic dermatitis and comes shortly after Amgen exited its $400 million partnership on the drug. Rocatinlimab had been in eight phase 3 trials for atopic dermatitis and other late-stage studies. While overall malignancy rates remain below background levels, Kyowa said the likelihood of continuing development is extremely low.

 🍾 Safety success: The FDA has lifted the clinical hold on Intellia Therapeutics’ phase 3 Magnitude trial of its CRISPR gene therapy nexiguran ziclumeran (nex-z) for transthyretin amyloidosis with cardiomyopathy, following a previous patient death linked to liver toxicity. The hold, imposed last October alongside a pause of the related Magnitude-2 study, has now been fully resolved, though with added safety measures including excluding certain high-risk patients, closer liver enzyme monitoring and guidance on short-term steroid use. With both trials cleared, Intellia is focused on completing enrollment. Analysts described the adjustments as modest but noted the underlying cause of the liver toxicity remains unclear.

🫁 EGFR ambitions: Kairos Pharma has signed a binding agreement to acquire exclusive worldwide rights to CL-273 from Celyn Therapeutics, aiming to advance targeted treatments for EGFR-mutant non-small cell lung cancer (NSCLC). CL-273 is an AI-designed, reversible, wild-type-sparing pan-EGFR small molecule inhibitor intended to address resistance mutations that emerge during EGFR tyrosine kinase inhibitor therapy. The companies believe the candidate has the potential to be best-in-class in the growing lung cancer market.

TOUR OPERATOR

Upcoming events

What did you think of today's newsletter?

Your feedback helps us create the best newsletter possible.

Login or Subscribe to participate in polls.

Share the Snap!

Know someone who’d enjoy this? Hit forward and pass it along.