(Mycosis Fungoides) Efficacy of Keytruda?

On September 18, 2019, Michael S. Khodadoust published in the medical journal Journal of Clinical Oncology the efficacy and safety results of pembrolizumab (Keytruda) monotherapy in patients with relapsed or refractory mycosis fungoides (MF)/Sézary syndrome (SS) with multiple prior therapies, from the CITN-10 Phase II clinical trial.

The CITN-10 trial was a multicenter, single-arm Phase II trial. Patients with relapsed or refractory mycosis fungoides/Sézary syndrome with multiple prior therapies (N=24) received Keytruda 2 mg/kg monotherapy on a 3-week cycle, with a maximum treatment duration of 24 months. The primary endpoint was objective response rate (ORR).

The rationale for this trial was that Sézary syndrome — the most common form of cutaneous T-cell lymphoma — is predominantly mycosis fungoides, and most patients have a poor prognosis. The ORR for systemic therapies has generally been below 50%, highlighting a need for new treatment approaches. Given demonstrated activity of Keytruda in other tumor types, and confirmed PD-L1 expression in cutaneous T-cell lymphoma (CTCL), this trial was initiated to assess its utility.

Patient Characteristics:

Disease Stage:

• Stage Ib: 4%; IIb: 8%; IIIa: 8%; IIIb: 12%; IVa: 67%

PD-L1 Expression:

• ≤30%: 54%; 31–60%: 29%; ≥61%: 17%

Results:

The primary endpoint ORR was 38%, comprising 2 complete responses (CR) and 7 partial responses (PR). Among the 9 responders, 6 had approximately 90% improvement in skin lesions. Median duration of response was not reached.

In terms of safety, no Grade 4 or 5 immune-related adverse events (irAEs) were observed. However, 11 irAEs were reported in 9 patients: Grade 1–2 skin events (6), arthritis (2), pneumonitis (1), AST elevation (1); Grade 3 skin events (4), arthritis (1), pneumonitis (1), colitis (1), AST elevation (1), and corneal ulcer (1).

Based on the CITN-10 results, Michael S. Khodadoust concluded: In patients with relapsed or refractory mycosis fungoides/Sézary syndrome with multiple prior therapies, Keytruda monotherapy demonstrated not only high objective response rates but also durable, sustained responses.

Source: Pembrolizumab in Relapsed and Refractory Mycosis Fungoides and Sézary Syndrome: A Multicenter Phase II Study. (J Clin Oncol. 2019 Sep 18. JCO1901056. doi: 10.1200/JCO.19.01056.)

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