Thử nghiệm Ianalumab liều ngắn kết hợp với Eltrombopag: Một bước chuyển hướng có tiềm năng đối với sự thuyên giảm kéo dài trong Thrombocytopenia Miễn dịch

Highlights

• Combination therapy with ianalumab (a BAFF-R monoclonal antibody) and eltrombopag significantly prolonged the time to treatment failure in adults with primary immune thrombocytopenia (ITP).
• The estimated probability of freedom from treatment failure at 12 months was 54% in the 9-mg ianalumab group versus 30% in the placebo group.
• Stable response rates at six months were markedly higher with the 9-mg dose of ianalumab (62%) compared to placebo (39%).
• Ianalumab was administered as a short 4-month course, potentially offering a path toward treatment-free remission in a disease often requiring chronic medication.

Introduction: The Challenge of Chronic ITP Management

Immune thrombocytopenia (ITP) remains a complex autoimmune disorder characterized by low platelet counts and an increased risk of bleeding. While first-line therapies, primarily glucocorticoids, provide initial responses, the majority of patients eventually experience relapse. Second-line treatments, including thrombopoietin-receptor agonists (TPO-RAs) like eltrombopag, have revolutionized care by stimulating platelet production. However, a significant limitation of TPO-RAs is the requirement for long-term, often indefinite, administration to maintain safe platelet levels. For many clinicians and patients, the ultimate therapeutic goal is ‘treatment-free remission’—a state where the patient maintains a safe platelet count without the need for ongoing pharmaceutical intervention.

Ianalumab (VAY736) represents a novel approach to achieving this goal. As a monoclonal antibody that targets the B-cell activating factor receptor (BAFF-R), ianalumab induces potent B-cell depletion through two distinct mechanisms: antibody-dependent cellular cytotoxicity and the inhibition of BAFF-mediated survival signals. By targeting B cells, which are central to the production of anti-platelet autoantibodies, ianalumab aims to reset the immune system. The VAYHIT2 trial was designed to evaluate whether a short course of ianalumab, when combined with standard eltrombopag therapy, could facilitate sustained remission and freedom from treatment failure.

Study Design and Methodology

The VAYHIT2 trial (NCT05653219) was a phase 3, randomized, double-blind, placebo-controlled study. The trial enrolled 152 adults with primary ITP who had either failed to respond to or relapsed after first-line glucocorticoid therapy. Participants were randomized in a 1:1:1 ratio to receive one of the following regimens:

• Ianalumab 9 mg/kg once monthly for 4 months plus eltrombopag.
• Ianalumab 3 mg/kg once monthly for 4 months plus eltrombopag.
• Placebo once monthly for 4 months plus eltrombopag.

Eltrombopag was initiated in all groups according to local prescribing guidelines. A critical component of the study design was the mandatory tapering and attempted discontinuation of eltrombopag by the end of week 24 for patients who achieved adequate platelet counts. This design specifically tested the ability of ianalumab to maintain remission after the withdrawal of the TPO-RA.

The primary end point was freedom from treatment failure (FFTF), analyzed as a time-to-event variable. Treatment failure was rigorously defined as a platelet count below 30×10^9 per liter after week 8, the need for rescue therapy or new ITP medications, the inability to discontinue eltrombopag due to low platelet counts, or death.

Key Findings: Efficacy of the Ianalumab Combination

The results of the VAYHIT2 trial suggest a significant clinical benefit for the addition of ianalumab to eltrombopag. The study met its primary objective, showing a statistically significant extension in the time to treatment failure for patients receiving ianalumab.

Freedom from Treatment Failure

At the 12-month mark, the estimated probability of being free from treatment failure was 54% (95% CI, 39 to 67) in the 9-mg ianalumab group and 51% (95% CI, 36 to 64) in the 3-mg group. In stark contrast, only 30% (95% CI, 18 to 43) of patients in the placebo group remained free from treatment failure. The hazard ratio for treatment failure was 0.55 (P = 0.04) for the 9-mg dose and 0.58 (P = 0.045) for the 3-mg dose compared to placebo, indicating a nearly 45% reduction in the risk of failure with the higher ianalumab dose.

Stable Response Rates

The secondary end point of stable response at 6 months—defined as maintaining a platelet count of at least 50×10^9 per liter in at least 75% of measurements between weeks 19 and 25 without rescue therapy—was also significantly improved. In the 9-mg group, 62% of patients achieved a stable response, compared to 39% in the placebo group (P = 0.045).

Safety and Adverse Event Profile

Safety is a paramount concern when introducing potent B-cell depleting agents. In VAYHIT2, the overall frequency of adverse events was generally comparable across the three study arms during the treatment period. However, there was a higher incidence of serious adverse events in the 9-mg ianalumab group (16%) compared to the 3-mg group (6%) and the placebo group (4%). Clinicians must balance the potential for sustained remission against the risk of serious complications, although the specific nature of these events in the trial suggested a manageable safety profile in the context of advanced ITP management.

Expert Commentary: A Shift in the Treatment Algorithm?

The results of VAYHIT2 are scientifically significant because they challenge the current paradigm of chronic TPO-RA use. Traditionally, B-cell depletion in ITP has relied on rituximab, which targets CD20. However, rituximab responses are often transient and unpredictable. Ianalumab’s targeting of BAFF-R may provide a more profound or different quality of B-cell modulation, particularly by affecting B-cell survival and maturation pathways that CD20-directed therapies might miss.

The concept of combining a drug that stimulates platelet production (eltrombopag) with a drug that addresses the underlying immune dysregulation (ianalumab) is pharmacologically sound. By rapidly raising platelet counts with eltrombopag while simultaneously ‘resetting’ the immune system with ianalumab, clinicians may be able to bridge patients toward long-term, medication-free health. The ability to discontinue eltrombopag in over half of the ianalumab-treated patients at one year is a compelling outcome for a patient population that often faces a lifetime of pill burdens and monitoring.

Limitations of the study include the 12-month follow-up period; longer-term data will be essential to determine if these remissions persist beyond the first year. Additionally, the higher rate of serious adverse events in the 9-mg group warrants careful patient selection and monitoring in clinical practice.

Conclusion

The VAYHIT2 trial demonstrates that a short, 4-month course of ianalumab in combination with eltrombopag significantly improves the likelihood of sustained, treatment-free remission in patients with ITP. By reducing the risk of treatment failure by nearly half compared to eltrombopag alone, ianalumab offers a promising new strategy for managing relapsed or refractory disease. This study marks a significant step toward moving the therapeutic objective in ITP from mere symptom management to durable immune restoration.

Funding and Trial Information

The VAYHIT2 trial was funded by Novartis. ClinicalTrials.gov number: NCT05653219.

References

Cuker A, Stauch T, Cooper N, et al. Ianalumab plus Eltrombopag in Immune Thrombocytopenia. N Engl J Med. 2025 Dec 9. doi: 10.1056/NEJMoa2515168. Epub ahead of print. PMID: 41363800.