GSK Completes $950 Million Acquisition of 35Pharma to Boost Pulmonary Hypertension Pipeline

GSK acquires 35Pharma for $950M, adding potential best-in-class pulmonary hypertension drug HS235 to its pipeline.

15 April 2026by Joshua Thompson5 min read15 views

This article covers information on GSK PLC.

GSK seals 35Pharma deal: a $950 million bet on pulmonary hypertension innovation

GSK has completed its acquisition of 35Pharma Inc., a private Canadian biotech focused on protein-based therapies, for $950 million. The headline asset is HS235, a potential best-in-class medicine targeting the activin receptor signalling pathway in pulmonary hypertension (PH) – a serious, progressive condition with limited treatment options and poor long-term survival.

Why this matters: PH therapies are forecast to be a $18 billion market by 2032, with activin signalling inhibitors expected to account for half of that. If HS235 can deliver on its early promise, this could be a strategically significant addition to GSK’s Respiratory, Immunology & Inflammation (RI&I) pipeline.

What GSK is buying: HS235 and a focused PH strategy

HS235 is designed to act on a clinically validated target in PH – the activin receptor signalling pathway. The molecule has been engineered with enhanced selectivity to reduce binding to BMP9 and BMP10, ligands associated with side effects like bleeding and telangiectasia (broken blood vessels). In practice, that could mean a cleaner safety profile, especially important because many PH patients are on anticoagulants or antiplatelet therapy.

Early clinical observations also hint at broader metabolic benefits: fat-selective weight loss, preservation of lean mass, and improved insulin sensitivity. If these translate in larger trials, it could provide clinical differentiation and extra commercial upside, particularly given the high prevalence of obesity and insulin resistance among PH patients.

Pulmonary hypertension: big unmet need, concentrated prescribers

PH is marked by high blood pressure in the lungs and comes in several forms, including pulmonary arterial hypertension (PAH) and PH due to heart failure with preserved ejection fraction (PH-HFpEF). The RNS puts the global PH population at approximately 82 million people across its various forms, with a five-year survival rate around 50%. That’s a heavy burden and a stark reminder that current options are limited.

Commercially, PH is managed by a concentrated group of pulmonologists and cardiologists, with patients often treated at specialist centres. For a company like GSK, that means a focused go-to-market model if HS235 progresses – fewer prescribers to reach, but high expectations for compelling clinical data.

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Why HS235 could stand out in a crowded pipeline

Safety-first design around bleeding risk

By lowering off-target binding to BMP9 and BMP10, HS235 aims to reduce bleeding risk, pericardial effusion (fluid around the heart), and dose-limiting increases in haemoglobin – all relevant drawbacks seen with some current PAH therapies. That’s not yet proven in larger studies, but the molecular design sets a clear differentiation thesis.

Metabolic gains as a bonus

Those early signs of fat-selective weight loss and insulin sensitivity improvements are noteworthy. PH patients frequently have overlapping metabolic issues, so a therapy that can address both pulmonary and metabolic dimensions could be meaningful in the clinic and commercially compelling. To be clear, this remains to be confirmed in future clinical trials.

Near-term catalysts: proof-of-concept trials

Proof-of-concept (PoC) trials – early-stage studies designed to show whether a drug has the intended effect in patients – are expected to start imminently in PAH and PH-HFpEF. Positive PoC readouts would validate HS235’s mechanism and safety profile, and could set up a fast-moving development path in indications with high unmet need.

Strategic fit: bolstering GSK’s RI&I engine

GSK’s RI&I unit focuses on the inflammatory and fibrotic drivers of chronic disease. HS235 fits neatly here and expands GSK’s work into mechanisms that straddle metabolic and vascular biology across lung, liver, and kidney disease. That cross-organ optionality can be valuable, offering multiple shots on goal from a single platform approach.

From an investor’s perspective, this is a pipeline-building deal in a high-value specialty area with clear clinical unmet need. It also plays into GSK’s broader strategy of finding assets that can unlock multi-disease potential, rather than one-and-done molecules.

Deal terms and what’s not disclosed

GSK has acquired 100% of the equity of 35Pharma for $950 million. The announcement does not disclose any earn-outs, milestones, royalty structures, or the cash/stock mix. Integration plans and timelines are also not disclosed.

Key numbers at a glance

Purchase price	$950 million
Target indication	Pulmonary hypertension (including PAH and PH-HFpEF)
Global PH market forecast	$18 billion by 2032
Expected share for activin signalling inhibitors	50% of PH therapies by 2032
Estimated PH patient population	Approximately 82 million
Five-year survival rate	Around 50%
Development next step	Proof-of-concept trials starting imminently in PAH and PH-HFpEF

Opportunities and risks for investors

Clear market pull: PH remains under-served with poor outcomes, and the addressable market is large and specialised.
Mechanistic edge: Enhanced selectivity that may reduce bleeding and other adverse events could be a real differentiator if borne out in data.
Metabolic upside: Early signs of weight and insulin sensitivity benefits broaden the value proposition, but require confirmation.
Execution risk: As with any clinical-stage asset, success hinges on trial outcomes. PoC data will be the first real test.
Disclosure gaps: Beyond the $950 million price and asset focus, financial structuring and integration details are not disclosed.

Jargon buster

Pulmonary hypertension (PH): High blood pressure in the lungs that strains the heart and reduces survival.
PAH: Pulmonary arterial hypertension – a specific, severe form of PH.
PH-HFpEF: PH due to heart failure with preserved ejection fraction – a heart condition where the heart pumps normally but is stiff.
Activin receptor signalling: A cellular pathway; inhibiting it is a clinically validated approach in PH.
BMP9/BMP10: Ligands linked to adverse events like bleeding; reduced binding may improve safety.
Proof-of-concept (PoC): Early clinical trials that test whether a drug works as intended in patients.
RI&I: GSK’s Respiratory, Immunology & Inflammation therapeutic area.

My take: a focused, high-upside swing with near-term readouts

This is a high-conviction move by GSK into a large, specialist market with clear unmet need. The design of HS235 aims straight at known safety pain points while dangling the carrot of metabolic benefits – exactly the sort of profile that could reshape treatment if proven.

The price tag reflects clinical-stage risk, but the opportunity – a potential best-in-class therapy in a $18 billion market with concentrated prescribers – is plain. For now, everything rides on data. With PoC trials set to start imminently, investors won’t have to wait years for the first signal. As always, GSK flags the usual forward-looking risks, and until we see human efficacy and safety at scale, this remains a promising thesis rather than a done deal.