Intralesional Rituximab in the Treatment of Primary Cutaneous B‐cell Lymphomas: a Single‐center Experience

Introduction: Primary cutaneous B-cell lymphomas (PCBCL) are rare lymphoproliferative disorders characterized by an indolent course and a life-long tendency to relapse. The management has always been based on radiotherapy and/or intravenous rituximab (IVR). To minimize toxicity, intralesional rituximab (ILR) has been applied with encouraging results. Methods: We retrospectively collected data on patients diagnosed with primary cutaneous marginal zone lymphoma (PCMZL) and follicular center lymphoma (PCFCL) who received at least one cycle of ILR from 2010 to 2022 at our Center. A cycle consisted of three doses in a week of intralesional rituximab (10 mg each). In some patients, subsequent cycles were administrated to reach a deeper response. Statistical analysis was conducted to identify variables associated with response and recurrence. Cox regression models were used to estimate hazard ratios and their 95% confidence intervals. Results: With a median follow-up of 86 months (range 1–153), ILR was administered to 26 patients, 73% with PCMZL histology. The median age at diagnosis was 51 years, with a predominance of males (62%). Fourteen (54%) were classified as T2 according to TNM staging and 11 (42%) patients presented with 3 or more lesions (Table 1). All patients experienced at least a partial response (PR), with 58% of complete responses (CR), the majority (80%) reached with only one ILR cycle. Patients with head localization presented a lower CR rate (17%, p-value = 0.007), without other significant factors associated to CR. Twenty-one (81%) patients relapsed, in a median time of 7 months (range 2–118) and the median time to next treatment was 10.8 months (range 4–119). Sixteen patients (62%) were retreated with ILR, achieving an overall response of 93% (CR 81%). PCFCL histology showed a significant association with recurrence (HR = 4.07, 95% CI, 1.29–12.87). Neither infusion reactions nor infectious complications were seen. The median progression-free survival was 7 months (2–134 months), and 6 patients are still in CR. Conclusion: Our study confirms the efficacy and safety of ILR in the management of PCBCL. With a very well-tolerated profile, all patients achieved at least PR, without losing efficacy at retreatment. Factors such as the localization of lesions and the subtype of lymphoma emerged associated with response and relapse, respectively. Keywords: Cutaneous non-Hodgkin lymphoma, Immunotherapy No conflicts of interests pertinent to the abstract.