New ITC Analyses Support Overall Survival Benefit of Mogamulizumab in CTCL

On June 30, 2026, Kyowa Kirin announced findings from two independent indirect treatment comparison (ITC) analyses evaluating the long-term survival impact of mogamulizumab (POTELIGEO®) in patients with relapsed or refractory mycosis fungoides (MF) or Sézary syndrome (SS), two subtypes of cutaneous T-cell lymphoma (CTCL). Presented at the World Congress of Cutaneous Lymphoma 2026, these independent analyses combined clinical trial and real-world data to address an important evidence gap by estimating comparative overall survival (OS), a clinically meaningful endpoint that has historically been difficult to evaluate directly in this rare disease.

Understanding MF and SS

MF and SS are rare, progressive forms of CTCL that can be difficult to treat, particularly in advanced stages where patients often require multiple lines of systemic therapy. The pivotal Phase 3 MAVORIC trial (NCT01728805) demonstrated that mogamulizumab significantly improved progression-free survival (PFS) compared with vorinostat in this patient population. However, extensive treatment crossover from the vorinostat arm to mogamulizumab limited the trial’s ability to directly assess overall survival. The two new ITC analyses were specifically designed to address this limitation by estimating comparative survival using clinical trial and real-world evidence.

Study Design

Both studies compared patient-level data from the mogamulizumab arm of MAVORIC (NCT01728805; n=186) against real-world registry data from two separate countries, using ITC statistical methods to adjust for baseline differences between patient populations. This approach enabled researchers to estimate comparative overall survival despite the crossover limitations of the MAVORIC trial while generating evidence that may better reflect routine clinical practice. According to Kyowa Kirin, these analyses also aim to address evidence gaps that may influence treatment access in some countries and support more informed treatment decision-making.

Australia ITC Results (Campbell BA, et al.)

This ITC drew on real-world data from the Australian Peter MacCallum Cancer Centre Cutaneous Lymphoma database, covering 67 patients treated with vorinostat between January 2005 and November 2024. Vorinostat is part of the standard of care in Australia and therefore served as the comparator in this analysis. After adjusting for baseline differences between groups, the results demonstrated a statistically significant overall survival advantage for mogamulizumab:

• Median OS: Not reached with mogamulizumab versus 31.0 months with vorinostat.
• Risk of death: 52% lower with mogamulizumab (HR: 0.48; 95% CI: 0.30-0.76; p=0.002).
• Time to next treatment (TTNT): Numerically longer with mogamulizumab (9.13 months vs. 5.82 months; HR: 0.76; 95% CI: 0.52-1.11; p=0.20), although the difference did not reach statistical significance.

Findings were presented by Campbell BA, et al. at the 6th World Congress on Cutaneous Lymphomas (WCCL 2026).

Denmark ITC Results (Morgante N, et al.)

Unlike Australia, vorinostat is unavailable in Denmark, making standard of care the appropriate comparator for this analysis. The Denmark ITC used Danish national registry data from 209 patients receiving standard of care between January 1996 and April 2024. After statistical weighting, the findings were consistent with the Australian analysis and further supported an overall survival benefit with mogamulizumab:

• Median OS: Not reached with mogamulizumab versus 17.0 months with standard of care.
• Risk of death: 62% lower with mogamulizumab (HR: 0.38; 95% CI: 0.25-0.59; p<0.001).

Results were presented by Morgante N, et al. at the 6th World Congress on Cutaneous Lymphomas (WCCL 2026).

Clinical Implications

Professor H. Miles Prince of Peter MacCallum Cancer Centre said indirect treatment comparisons help address critical evidence gaps in MF and SS by providing clinicians with clearer insights into long-term real-world outcomes, supporting more informed treatment decisions.

Dr. Angela Williams, PhD, Global Head of Health Economics and Outcomes Research at Kyowa Kirin, said integrating clinical trial and real-world data helps evaluate long-term outcomes such as overall survival in rare diseases where conventional clinical trials often cannot fully assess these endpoints.

Study Limitations

Both analyses were retrospective in nature and carry inherent limitations, including potential differences in advances and standards of care over time between the clinical trial and real-world cohorts. Variations in healthcare practices and patient management across countries and treatment periods should also be considered when interpreting the estimated overall survival benefits.

U.S. Regulatory Status

In the United States, POTELIGEO® (mogamulizumab-kpkc) is approved for the treatment of adult patients with relapsed or refractory mycosis fungoides or Sézary syndrome after at least one prior systemic therapy.

What This Means for Patients

For people living with relapsed or refractory mycosis fungoides or Sézary syndrome, treatment options often become limited after earlier therapies stop working. These new analyses suggest that patients treated with mogamulizumab may live longer than those receiving standard treatments. While the findings come from indirect comparisons rather than head-to-head clinical trials, they provide valuable real-world evidence that could help doctors make more informed treatment decisions and support broader access to the therapy.

Reference

New Analyses Advance Understanding of Long-Term Survival Outcomes with Mogamulizumab in Mycosis Fungoides and Sézary Syndrome | Kyowa Kirin North America

Campbell BA, et al. Presented at the 6th World Congress on Cutaneous Lymphomas (WCCL 2026)
Morgante N, et al. Presented at the 6th World Congress on Cutaneous Lymphomas (WCCL 2026)