This study will involve participants with a condition called Follicular Non Hodgkin Lymphoma (Follicular Lymphoma).~The main purpose of this study is to see if it is safe to give an induction schedule of the drug BMS-986369, in combination with Rituximab +/- Nivolumab, and to see how effective this combination is in patients who have had no previous drug treatment for their lymphoma. In particular, we will be monitoring for any specific side effects which may be increased by adding BMS-986369 to Rituximab treatment +/- Nivolumab for 8 cycles (28 days per cycle), with up to 2 years of maintenance treatment of rituximab in eligible patients following induction.~Participants will be reviewed at baseline and prior to each cycle of treatment for toxicity, scans will be performed at baseline, after 2 and 5 cycles of induction treatment, and every 8 weeks during maintenance phase. Following completion of treatment, participants will be followed up for a total of 3 years (every 6 months). In participants with relapsed disease, these will be followed for survival every 3 months.
First line treatment with combination rituximab and BMS-986369 with, or without nivolumab, in patients in previously untreated Follicular Lymphoma