GSK's Blenrep Demonstrates Superior Efficacy Compared to Daratumumab in Phase 3 Trial in Japan, Receives PMDA Approval
1. Blenrep's Return: Targeting the Japanese Market
GSK (GlaxoSmithKline, ticker: GSK)'s B-cell maturation antigen (BCMA)-targeting antibody-drug conjugate (ADC), Blenrep (belantamab mafodotin), has made a remarkable comeback in the Japanese market. Japan's Ministry of Health, Labour and Welfare (MHLW) granted final approval for Blenrep on May 19, 2025, for use in combination therapy for patients with relapsed or refractory multiple myeloma (RRMM). This is a significant regulatory milestone for GSK, which experienced a setback with the voluntary withdrawal of the drug from the U.S. market in 2022. In Japan, where the population is rapidly aging, the introduction of innovative therapies for hematological malignancies offers new hope to patients.
2. Overwhelming Efficacy Demonstrated Through Phase 3 Clinical Data
The key basis for this approval is the Japan Expansion Cohort (clinical trial number: NCT06868667) Phase 3 trial, which surprised the industry. In this trial, which involved 24 patients, the median progression-free survival (mPFS) for the Blenrep combination arm (BVd) was not yet reached, while the standard treatment arm, Daratumumab (Darzalex) combination (DVd), was 11.1 months. The results, which reduced the risk of disease progression and death by 60% (HR: 0.40), are consistent with the global DREAMM-7 trial. The overall response rate (ORR) was also significantly higher in the Blenrep arm, at 90.0%, compared to 71.4% in the control arm.
3. Value of Managing Side Effects and Mechanistic Differentiation
The maximum weakness of Blenrep, ocular toxicity, including dry eye and keratopathy, has been evaluated as manageable through dose adjustments and treatment delays. Japanese physicians and patients can now maximize the benefits of treatment by adhering to the side effect management protocol. In particular, it provides a completely different mechanism as a BCMA-targeting ADC for patients who have become resistant to CD38-targeting agents such as Janssen (ticker: JNJ)'s Daratumumab, which has significant clinical value. The medical community's judgment that the benefits of treatment outweigh the concerns about ocular toxicity was crucial in this approval.
4. Anticipating Changes in the Multiple Myeloma Market Landscape
The global multiple myeloma treatment market is currently worth approximately $20 billion annually, and Japan, with its large elderly population, accounts for a significant portion of this market. The approval of Blenrep is a strong signal that will disrupt the market dominance of existing standard treatments, such as CD38 monoclonal antibody Daratumumab. In particular, it is likely to establish itself as a viable alternative as a next-generation standard treatment for patients who relapse after first-line therapy. GSK is expected to diversify its oncology pipeline and expand its market share through Blenrep.
5. Securing Mid- to Long-Term Growth and Prospects
This Japanese approval is expected to have a positive impact on the re-approval review by the U.S. Food and Drug Administration (FDA) and the European Medicines Agency (EMA). The industry expects Blenrep to grow into a blockbuster drug and become a strong cash cow that will drive GSK's hematological oncology revenue growth. The off-the-shelf product, which has higher ease of administration and immediate availability compared to CAR-T cell therapy, is a key factor in increasing market penetration. In the future, Blenrep's performance is expected in a fierce competitive landscape with competing drugs such as Pfizer (ticker: PFE)'s Elrexfio.
This approval by the Japanese MHLW for Blenrep in combination therapy represents a crucial turning point in reassessing the value of GSK's BCMA pipeline, which had been stalled since the 2022 FDA withdrawal of the single-agent indication. The robust data from the Phase 3 trial (NCT06868667), demonstrating a median progression-free survival not yet reached and a 60% reduction in the risk of disease progression (HR 0.40), solidifies its position as a superior second-line treatment option compared to Janssen's Daratumumab, a competing CD38 monoclonal antibody. This is expected to accelerate short-term revenue growth in the global multiple myeloma treatment market, which is approximately $20 billion annually, based on its unique mechanism of action. In the medium to long term, it will maximize the possibility of passing the re-approval review by the FDA and EMA, enabling it to gain an advantageous position in the market competition with other BCMA-targeting bispecific antibodies such as Pfizer's Elrexfio. In particular, its higher ease of administration and immediate availability compared to CAR-T cell therapy will be a key competitive advantage in increasing market penetration in Japan and the global hematological oncology market, where the elderly population is increasing.
Source: ClinicalTrials.gov (api_ct)