GSK moves on 35Pharma: a bold $950 million bet on pulmonary hypertension
GSK has signed a deal to acquire 35Pharma Inc., a private Canadian biotech, for $950 million in cash at closing. The prize is HS235, a potential best-in-class drug aimed at pulmonary hypertension (PH) that has completed phase I in healthy volunteers, with patient studies in pulmonary arterial hypertension (PAH) and PH due to heart failure with preserved ejection fraction (PH-HFpEF) set to start imminently.
Why it matters: PH is a serious, progressive disease with limited treatments and a five-year survival rate of only around 50%. The market is forecast to reach $18 billion by 2032, and activin signalling inhibitors – the class HS235 belongs to – are expected to account for half of that. If HS235’s profile holds up in patients, GSK could be buying into the dominant mechanism in a large, growing space.
What exactly is HS235 and why is it interesting?
HS235 targets the activin receptor signalling pathway, a clinically validated target in PAH. In simple terms, it aims to rebalance signalling that contributes to vascular problems seen in PH.
Crucially, HS235 has been designed with enhanced selectivity to reduce binding to BMP9 and BMP10 – proteins linked with side effects such as bleeding and telangiectasia (visible, broken blood vessels). That design choice is not academic. Many PH patients are also on anticoagulants or antiplatelets, so a therapy that potentially lowers bleeding risk could be a real differentiator.
There is also a metabolic twist. Early clinical work suggests HS235 may drive fat-selective weight loss, preserve lean mass, and improve insulin sensitivity, alongside beneficial shifts in inflammation and adipokines (hormones from fat tissue). Given the high rates of obesity and insulin resistance in PH, that dual vascular-metabolic profile could add clinical and commercial punch.
Pulmonary hypertension: big unmet need, big market
PH is high blood pressure in the lungs that leads to breathlessness, fatigue and chest pain, and ultimately heart failure. It affects approximately 82 million people worldwide across multiple forms. In the US, the addressable population for PAH and PH-HFpEF is approximately 100,000 people.
Treatments are limited and outcomes are poor, with around 50% survival at five years. That backdrop explains the market growth outlook: by 2032, PH therapies are forecast to reach $18 billion, with activin signalling inhibitors expected to account for 50% of that. HS235 slots directly into this trend.
Strategic fit: strengthening GSK’s RI&I pipeline
GSK flags HS235 as a strong fit for its Respiratory, Immunology and Inflammation (RI&I) portfolio, highlighting potential protective effects on vascular function and fat-derived markers of metabolism and inflammation. The company also sees scope to extend this biology across chronic diseases that affect the lung, liver and kidney.
In other words, this is not just about one PH asset. It is about an emerging platform of products with protective metabolic and vascular benefits, which could be leveraged across multiple organ systems if clinical data cooperates.
Deal terms, approvals and what’s disclosed
The transaction is straightforward: GSK will acquire 100% of 35Pharma for $950 million in cash at closing. No earn-outs, milestones, or royalty structures are mentioned – not disclosed. The deal is subject to customary conditions, including regulatory clearance under the Hart-Scott-Rodino Act in the US, the Competition Act in Canada, and a filing under the Investment Canada Act.
Timelines to close are not disclosed. Specific development milestones, trial designs, and expected readouts are also not disclosed beyond the note that PAH and PH-HFpEF studies will start imminently.
Key numbers at a glance
| Purchase price | $950 million (cash at closing) |
| Lead asset | HS235 (activin signalling inhibitor) |
| Clinical stage | Completed phase I in healthy volunteers; PAH and PH-HFpEF studies to start imminently |
| Global PH prevalence | Approximately 82 million people |
| US addressable PAH + PH-HFpEF population | Approximately 100,000 people |
| 5-year survival in PH | Around 50% |
| PH market forecast (2032) | $18 billion; activin inhibitors expected to be ~50% |
| Regulatory conditions | HSR (US), Competition Act (Canada), Investment Canada Act filing |
Management’s take
GSK’s Chief Scientific Officer, Tony Wood, calls HS235 a potential best-in-class medicine with a differentiated profile to reduce bleeding risk and deliver metabolic benefits relevant to PH. He also points to broader opportunities across RI&I to address metabolic, inflammatory, vascular and fibrotic drivers of chronic disease.
35Pharma’s CEO, Ilia Tikhomirov, frames the deal within a shift in PH understanding, suggesting the disease could be reversed, and endorses GSK as a capable owner to advance HS235.
Investor view: what looks good and what to watch
Positives
- Strong strategic fit: HS235 complements GSK’s RI&I ambitions with a vascular-metabolic angle.
- Design advantage: enhanced selectivity aims to reduce bleeding risk – a practical, patient-relevant differentiator.
- Large, growing market: PH therapies forecast at $18 billion by 2032, with activin inhibitors expected to take 50% share.
- Pipeline breadth potential: GSK highlights scope across lung, liver and kidney diseases, not just PH.
Watch-outs
- Early stage: HS235 has completed phase I in healthy volunteers; efficacy and safety in PH patients remain to be proven.
- Regulatory path: deal closing is subject to US and Canadian approvals, and clinical timelines are not disclosed.
- Data depth: metabolic benefits are supported by early clinical signals; confirmatory patient data will be key.
- Financial detail: beyond the $950 million cash price, there is no disclosure on earnings impact or development costs.
Why this matters for GSK shareholders
This is a pipeline-building acquisition in a high-need, high-value category. If HS235’s bleeding risk profile and metabolic benefits are borne out in patients, it could underpin a meaningful position in PH where activin inhibitors are expected to dominate. The flip side is development risk: we are pre-proof-of-concept in the target populations.
In short, GSK is paying up for optionality in a biology it knows well within RI&I. The near term is about execution – starting studies promptly, generating clean safety and efficacy data, and charting a path to pivotal trials.
What to watch next
- Start of patient studies in PAH and PH-HFpEF – the company says these will begin imminently.
- Any initial safety and biomarker updates that speak to bleeding risk and metabolic effects – not disclosed yet.
- Regulatory clearances for closing under HSR, the Competition Act and the Investment Canada Act.
- Clarity on development plans within GSK’s broader RI&I strategy, including potential indications beyond PH – not disclosed.
Caution: GSK includes the usual forward-looking statement reminder. As ever with clinical-stage assets, actual outcomes may differ materially from projections.
