Top Line: Can radiation be omitted in patients with primary mediastinal B-cell lymphoma who have a complete response to chemoimmunotherapy?
PMBCL is a rarer subtype of B-cell lymphoma that can often affect younger women. The patient population and anatomic location make this an appealing target for a PET-adaptive strategy to limit consolidative radiation. We first saw results from the IELSG37 trial at ASCO 2023, and here we have the full publication. This randomized trial was designed to demonstrate that PFS with PET-adaptive therapy and omission of RT after CMR was non-inferior to standard therapy. CMR was initially defined as a Deauville score of 1-2, but this was amended during enrollment to include DS 3. The authors anticipated a 70% CMR rate and an 85% PFS rate at 30 months with the non-inferiority margin set at 10%. 545 patients were enrolled and received 6 cycles of induction chemoimmunotherapy. Of these, 49% had a CMR (much lower than the 70% expected), and they were randomized to receive no further therapy or 30 Gy consolidative radiation. At 30 months, rates of PFS were similar and far higher than anticipated (98.5% with RT, 96.2% without). Patients who had a DS 4 and required RT had similar PFS to those with a CMR (95.8%). However, patients with a DS 5 had inferior PFS (60.3%).
TBL: Roughly half of patients with PMBCL have a complete metabolic response to induction therapy and have excellent outcomes without consolidative RT. Incomplete responders with DS 4 do equally well with consolidative RT while those with DS 5 have inferior outcomes. | Martelli, J Clin Oncol 2024
PMBCL is a rarer subtype of B-cell lymphoma that can often affect younger women. The patient population and anatomic location make this an appealing target for a PET-adaptive strategy to limit consolidative radiation. We first saw results from the IELSG37 trial at ASCO 2023, and here we have the full publication. This randomized trial was designed to demonstrate that PFS with PET-adaptive therapy and omission of RT after CMR was non-inferior to standard therapy. CMR was initially defined as a Deauville score of 1-2, but this was amended during enrollment to include DS 3. The authors anticipated a 70% CMR rate and an 85% PFS rate at 30 months with the non-inferiority margin set at 10%. 545 patients were enrolled and received 6 cycles of induction chemoimmunotherapy. Of these, 49% had a CMR (much lower than the 70% expected), and they were randomized to receive no further therapy or 30 Gy consolidative radiation. At 30 months, rates of PFS were similar and far higher than anticipated (98.5% with RT, 96.2% without). Patients who had a DS 4 and required RT had similar PFS to those with a CMR (95.8%). However, patients with a DS 5 had inferior PFS (60.3%).
TBL: Roughly half of patients with PMBCL have a complete metabolic response to induction therapy and have excellent outcomes without consolidative RT. Incomplete responders with DS 4 do equally well with consolidative RT while those with DS 5 have inferior outcomes. | Martelli, J Clin Oncol 2024