Chemoimmunotherapy response may allow omission of radiotherapy in lymphoma

Radiation therapy may be omitted in patients with primary mediastinal large B-cell lymphoma who respond to chemoimmunotherapy, according to the results of a recent phase III trial.

Despite these findings, the researchers noted that the event rates in the trial were at expected levels and longer follow-up is needed to adequately assess long-term toxicity. .

Data from the IELSG37 study presented at the 2023 international conference EHA Conference With a median follow-up of 58.8 months, the 30-month progression-free survival rate (the period during and after treatment in which cancer patients can live without their disease worsening) was 96.2% in the observation group and 98.5% in the radiotherapy group. proved that it was

Furthermore, the 30-month overall survival rate (percentage of patients alive over a period of time after treatment) was 99.2% with observation versus 99.3% with radiotherapy.

“IELSG37 is the largest randomized trial ever conducted in (primary mediastinal large B-cell lymphoma). We can assume that mediastinal radiotherapy can be safely omitted in patients who achieve a response),” said study lead author Maurizio Martelli, Ph.D., Department of Hematology, Translational Precision Medicine. At a data presentation at Sapienza University in Rome, Italy.

Primary mediastinal large B-cell lymphoma accounts for 6% of all diffuse large B-cell lymphomas and is more common in young patients between the ages of 14 and 30, Martelli said.

Primary mediastinal large B-cell lymphoma is a aggressive disease with a favorable prognosis if rapid remission is achieved with dose-intensive chemoimmunotherapy. Mediastinal radiotherapy may enhance response but is associated with increased risk of coronary or valvular heart disease and secondary malignancies. Therefore, according to Martelli, radiation therapy for primary mediastinal large B-cell lymphoma represents a “therapeutic dilemma” in the field.

In his presentation, Martelli said a Deauville score of 1 to 3 better identifies patients at low or high risk of failure after induction therapy. Regardless of this score, 102 of his 115 patients received intensive radiation therapy at the end of first-line therapy.

In the IELSG37 trial, investigators investigated mediastinal large B-cell lymphoma in patients with primary mediastinal large B-cell lymphoma who achieved a complete metabolic response (negative findings on PET scans during or after treatment) after conventional Rituxan (rituximab). We began evaluating whether radiation therapy could be omitted. – Regimens that include chemotherapy.

To be eligible for enrollment, patients must have CD20-positive, untreated primary mediastinal large B-cell lymphoma with no evidence of extranodal disease (affecting areas or organs outside the lymph nodes). had to be They had to be eligible for curative radiation and chemotherapy.

After a baseline PET scan confirmed the diagnosis of primary mediastinal large B-cell lymphoma, the patient received standard chemoimmunotherapy.

All patients who tested negative for PET (defined as having a Deauville score of 1 to 3) were randomly assigned to mediastinal radiation therapy or observation.

The primary focus of the study was progression-free survival 30 months after assigned treatment in patients who were PET-negative at the end of overall survival at the end of induction chemoimmunotherapy. The researchers also focused on overall survival and long-term toxicity 5 years after enrollment.

Patients who were PET-negative (defined as Deauville score 1-3) were randomly assigned to observation (n = 132) or radiotherapy (n = 136).

Most patients in the observation and radiotherapy groups had a PET Deauville score of 2 (51% vs. 52%) at the end of treatment, followed by a score of 3 (45% vs. 45%) and a score of 1 (5% vs. 5%). was. 3%).

Regarding safety, one patient in the radiotherapy arm had severe heart failure and another patient in that arm had both life-threatening heart failure and severe hypertension. All these toxicities have been resolved.

Life-threatening metastatic melanoma was observed 22 months after randomization in patients in the radiotherapy group. This patient died from complications of sepsis. In a patient in the radiotherapy group, he developed severe glioblastoma more than 55 months after randomization, leading to death. Finally, life-threatening acute myeloid leukemia occurred 15 months after he was randomized to receive radiotherapy, but this patient had a complete response after allogeneic transplantation.

“Longer follow-up is needed to adequately assess long-term toxicity,” Martelli concluded.

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