Evaluating the outcomes after second-line therapy for relapsed or refractory PMBCL

This study investigated the outcomes of pretreated patients with relapsed (cancer recurrence) or refractory (does not respond to treatment) primary mediastinal large B-cell lymphoma (PMBCL) after second-line therapy and stem cell transplant (SCT). The study concluded that this treatment strategy was effective in most patients.

PMBCL is one type of diffuse large B-cell lymphoma. First-line treatment typically involves high-dose chemotherapy with or without radiation therapy. However, treatment options for patients with relapsed or refractory disease are limited.

One treatment option involves second-line chemotherapy followed by SCT. Before the transplant, high-dose chemotherapy is needed to get rid of any remaining cancer cells. Then, the patient’s cancer cells are replaced with healthy stem cells collected from the patient’s blood. The outcomes of patients with refractory PMBCL after these treatments remain under investigation.

This study involved 60 pretreated patients with relapsed (42%) or refractory (58%) PMBCL. 40% of patients had advanced (stage 3 – 4) disease. All patients received chemotherapy as a second-line treatment. 85% of patients then received high-dose chemotherapy followed by SCT. Patients were followed-up for an average of 4.8 years.

Overall, 65% of patients responded to second-line treatment. 40% of patients had a disappearance of all signs of cancer (complete response; CR). 25% of patients had tumor shrinkage (partial response). Significantly more patients with relapsed disease responded to treatment (80% vs 54%) or had a complete response (56% vs 29%) compared to those with refractory disease. 

The 3-year overall survival (OS; patients still alive 3 years later) rate was 61%. For patients who had a SCT, this rate was 65%. The 3-year progression-free survival (patients still alive without a return of disease) for these patients was 60%.

Certain factors were associated with a higher risk of lower OS. Having advanced or refractory disease was associated with a 2.68 times lower OS and having both (advanced and refractory disease) was associated with a 6.86 times lower OS. Mortality risk was 9.4 times higher for patients who did not respond to treatment before SCT than in those who responded to treatment.

This study concluded that second-line chemotherapy followed by stem cell transplant can be effective in many of the patients with relapsed or refractory PMBCL.

The patient population in this study was quite small. Larger studies are needed to confirm these results.