The aim of the trial is to improve efficacy of nivolumab in patients with relapsed or refractory HL who recently progressed on anti-PD1 therapy. Nivolumab is highly effective and well tolerated in rrHL, nevertheless CR-rates are low and a considerable proportion of patients suffers from progressive disease. Localized RT induces an immunogenic effect which might work synergistically and facilitate augmented systemic (i.e. abscopal) responses in combination with nivolumab.

Inclusion Criteria:

• Progression of refractory or relapsed cHL during treatment with an anti-PD1 agent
• At least two distinct FDG-avid HL-lesions with at least 5 cm distance between them, and one of them considered eligible for irradiation with 20Gy based on localization and prior RT exposure
• Age at registration ≥ 18 years

Exclusion Criteria:

• Nodular-lymphocyte predominant HL (NLPHL) or composite/greyzone lymphoma
• Lymphoma involving the central nervous system
• Naïve to treatment with anti-PD1 targeting antibodies