Macon, William

Abstract Primary cutaneous diffuse large B‐cell lymphoma, leg type (PCDLBCL, LT) is a rare, aggressive lymphoma characterized by skin involvement predominantly in the lower extremities. Immunochemotherapy with or without involved‐site radiation therapy (ISRT) is considered standard front‐line therapy. Over‐expression of PD‐L1/PD‐L2 is seen in a high proportion of PCDLBCL, LT cases, but efficacy of immune checkpoint inhibitors (ICI) in relapsed/refractory, PCDLBCL, LT has not been thoroughly studied. We conducted a retrospective cohort study of patients diagnosed with PCDLBCL, LT seen at Mayo Clinic from 1 January 2000 to 31 December 2020. Using the Kaplan–Meier method, we calculated progression‐free survival, duration of response, and overall survival in patients who received front‐line rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R‐CHOP) with and without ISRT, and salvage ICI therapy for relapsed/refractory disease. A total of 28 patients with PCDLBCL, LT were identified. The median PFS in patients treated with R‐CHOP plus ISRT was 58 months (95% CI: 18–112) compared to 14 months (95% CI: 5–not reached; p = 0.04) in those treated with R‐CHOP without ISRT. The median PFS from salvage ICI therapy was 10 months (95% CI: 4–not reached), and median DOR from salvage ICI therapy was 23 months [95% CI: 4–26]. R‐CHOP with ISRT had a significantly longer median PFS compared to R‐CHOP without ISRT as front‐line therapy for PCDLBCL, LT. ICIs may have a role in treating relapsed/refractory disease as reasonable activity in heavily pre‐treated patients was observed in this study.

Summary This study aimed to describe the patterns of care and outcomes of diffuse large B cell lymphoma ( DLBCL ) after failure of front line anthracycline‐based immunochemotherapy ( IC ). Patients with newly diagnosed lymphoma were prospectively enrolled in Molecular Epidemiology Resource ( MER ) of the University of Iowa/Mayo Clinic Lymphoma Specialized Program of Research Excellzence. All DLBCL and primary mediastinal B‐cell lymphoma ( PMBL ) patients treated with front‐line anthracycline‐based IC were followed for relapse. Patients with relapse on follow‐up and subsequently retreated were included in this analysis. 1039 patients received anthracycline‐based IC between 2002 and 2012, of which 244 relapsed and were subsequently retreated. Across all therapies, overall survival at 4 years ( OS 4) from relapse was 28% and 103 patients ultimately underwent autologous haematopoietic cell transplant (auto HCT ) with OS 4 from auto HCT of 51%. Patients relapsing after 12 months from initial diagnosis had OS 4 of 47% but those with a transient or no response to initial therapy had OS 4 of only 13%. Outcomes of relapsed or refractory DLBCL differ substantially when categorized by response to initial therapy, timing of relapse and opportunity to undergo auto HCT . The design and interpretation of uncontrolled trials should account for this heterogeneity in patients with relapsed DLBCL .

Key Points The mTOR pathway is constitutively activated in the TCL cells and is responsible for TCL proliferation. This is first trial to demonstrate that mTORC1 inhibitors (everolimus) have substantial antitumor activity (44% overall response rate) in patients with relapsed TCL.