Long-term complete remission in a patient with high-risk primary mediastinal B-cell lymphoma and iatrogenic symptomatic bradycardia after only two courses of DA-EPOCH-R followed by chemo-free treatment

: Most patients with Primary Mediastinal B-Cell Lymphoma (PMBCL) are cured by rituximab and doxorubicin-based immunochemotherapy, with or without radiotherapy. In cases with relapsed and refractory (RR) disease the prognosis was historically poor. Recently, immune checkpoint-based strategies have been shown to be highly effective in patients with RR-PMBCL. We report the case of a 23-year-old woman who, due to recurring episodes of symptomatic chemotherapy-induced sinus bradycardia, was unable to receive the planned six courses of immunochemotherapy, mediastinal radiotherapy, and autologous transplantation, leading to the early initiation of a chemo-free strategy. The patient maintains a continuous complete remission at a four-year follow-up after only two cycles of immunochemotherapy followed by nivolumab plus brentuximab vedotin (BV) and pembrolizumab consolidation. Beyond describing an underreported complication of anticancer treatments, the favorable clinical outcome suggests that in PMBCL, a minimal load of chemotherapy, integrated by early PD-1 blockade, with or without BV, may be sufficient to achieve long-term disease control and cure at least in some patients.