Study to Evaluate the Response to Treatment With Mosunetuzumab in Relapsed/Refractory Follicular Lymphoma (FL) After at Least Two Lines of Therapy, Within the Compassionate Use Program (CUP).

This observational study is tracking the real-world outcomes of patients with follicular lymphoma (a slow-growing type of blood cancer) who are receiving a drug called mosunetuzumab through a compassionate use program after their cancer has come back or stopped responding to at least two prior treatment lines. **You may be eligible if...** - You are an adult (over 18) with follicular non-Hodgkin's lymphoma - You have already received at least two lines of therapy for your lymphoma - You are being treated with mosunetuzumab through the compassionate use program - You have signed consent for treatment **You may NOT be eligible if...** - You are under 18 - You have a different type of cancer or lymphoma - You do not qualify for the mosunetuzumab compassionate use program Talk to your doctor to see if this trial is right for you.