GSK’s plan to bring blood cancer drug Blenrep (belantamab mafodotin) back to markets has hit a stumbling block, after the US Food and Drug Administration (FDA) identified eye safety concerns ahead of a meeting to discuss the therapy’s benefit-risk ratio.
FDA reviewers flagged high rates of ocular toxicity, including corneal disease, known as keratopathy, and visual acuity changes. Experts also identified poor tolerability of regimens and resulting uncertainty regarding proposed dose, as per a briefing document published on 15 July.
US Tariffs are shifting - will you react or anticipate?
Don’t let policy changes catch you off guard. Stay proactive with real-time data and expert analysis.
By GlobalDataShares in London-listed GSK closed 1.19% down to a price of £1,402.5 following the document release compared to the market open on 15 July. Prices had not recovered by the market open on 16 July. The British drugmaker has a market cap of £57bn.
The briefing document was published ahead of an Oncologic Drugs Advisory Committee (ODAC) on 17 July that will review data for Blenrep’s safety and effectiveness. The recommendation given by ODACs is usually followed by the FDA when deciding if a drug should be approved.
FDA reviewers wrote: “While ocular adverse events have been seen with other antibody-drug conjugates used for the treatment of cancer, this toxicity is unique among therapies for the treatment of multiple myeloma.”
The key trials supporting the drug’s approval are the DREAMM-7 (NCT04246047) and DREAMM-8 (NCT04484623) studies. FDA reviewers said the majority of patients in these trials experienced keratopathy and Visual Acuity (KVA) events. All grade KVAs occurred in 92% and 93% of patients in DREAMM-7 and DREAMM-8, respectively, while more serious grade 3-4 events were found in 77% and 78% of patients in the same two studies.
GSK is looking to get Blenrep FDA-approved in combination with Takeda’s Velcade and dexamethasone to treat adults with multiple myeloma who have already tried one prior line of therapy. The drugmaker is also seeking a positive decision for the antibody-drug conjugate (ADC) used in combo with Bristol Myers Squibb’s Pomalyst and dexamethasone in the same proposed patient group.
Blenrep originally won FDA approval in 2020 to treat multiple myeloma. Although initially getting ahead in the now lucrative ADC market, GSK pulled the drug in 2022 after confirmatory trial shortcomings.
Since then, GSK has been busy conducting trials to showcase Blenrep’s effectiveness in treating the rare type of blood cancer. In its own briefing document, the British big pharma company said that results from DREAMM-7 and DREAMM-8 “consistently demonstrated meaningful benefit across endpoints and supported the positive benefit-risk of Blenrep”.
Data from the studies were enough to convince the European equivalent of the ODAC – the European Medicines Agency’s (EMA) Committee for Medicinal Products for Human Use (CHMP) issued a positive recommendation for Blenrep in May 2025. However, the European Commission (EC) has not yet decided whether to approve the drug. The UK was the first country to authorise Blenrep in the revised treatment setting in April 2025.
Buoyed by momentum in the wider ADC market, GSK has forecast more than £3bn in peak annual sales for Blenrep. Estimates by GlobalData – which go as far as 2031 – predict peak sales of $1.9bn.
How ODAC votes will be a key factor in whether this sales figure is reached, however. While other ADCs are known for their side effects, a snag for GSK is that Blenrep seems to be the sole product in which eye safety has been a concern.
ADC content on Pharmaceutical Technology (Or Clinical Trials Arena) is supported by Syngene. Editorial content is independently produced and follows the highest standards of journalistic integrity. Topic sponsors are not involved in the creation of editorial content.
