Gazyvaro and Low Dose Radiotherapy in Early Stage Follicular Lymphoma

Extended field or total nodal irradiation had been the gold standard for early stage follicular lymphoma for a long time in Germany. An involved field (IF) irradiation has been favored due to the toxicity of large field irradiation in other countries (e.g. USA). However, smaller irradiation fields have been accompanied with an increased risk of recurrence. A combination of involved field irradiation with the anti-CD20 antibody Rituximab (MIR trial) has led to similar efficacy results compared to the large field irradiation but with markedly reduced side effects. Haas et al. showed in a prospective trial, that a low dose radiation therapy (LDRT) can lead to a complete remission in up to 60% in follicular lymphoma. This is presumed to result from immune modulatory effects induced by LDRT. The effectiveness of LDRT could also be demonstrated in another prospective, randomized British trial (FORT trial: 2 x2 Gy vs. 12 x 2 Gy) with a CR rate of 40% after 2 x 2 Gy (60% after 12 x 2 Gy). Currently, it is unknown, which patients need a higher radiation dose and which not. A metabolic complete remission (CR) is an important prognostic marker for progression-free survival. According to the results of the PRIMA trial, CR is a very strong predictive parameter if the CR is established using FDG-PET. In the present GAZAI trial, patients with early stage nodular follicular lymphoma will be treated in a combined approach of immunotherapy with an anti-CD20 antibody and small field (involved site) irradiation as in the MIR trial. In GAZAI, the fully humanized anti-CD20 antibody Obinutuzumab (GAZYVARO) will be used, which showed a high efficacy in combination with bendamustin in patients with follicular lymphoma refractory to Rituximab (GADOLIN trial). In addition, the radiation dose will be limited to 2 x2 Gy in responding patients. A dose build-up to a total of 40 Gy (dose in the MIR trial) will be performed in case of failure to achieve a complete CR based on a FDG-PET in week 18. Primary endpoint of the trial is the rate of CR (based on FDG-PET/CT) after Obinutuzumab and 2x2 Gy IS radiotherapy in week 18. Secondary endpoints are the morphological CR rate in week 7, week 18 and month 6, the PFS, the toxicity, the recurrence rate, the recurrence pattern, overall survival and quality of life.