Summary Background Post-transplantation lymphoproliferative disorder (PTLD) develops in 1–10% of transplant recipients and can be Epstein–Barr virus (EBV) associated. To improve long-term efficacy ...after rituximab monotherapy and to avoid the toxic effects of CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisolone) chemotherapy seen in first-line treatment, we initiated a phase 2 trial to test whether the subsequent use of rituximab and CHOP would improve the outcome of patients with PTLD. Methods In this international multicentre open-label phase 2 trial, treatment-naive adult solid-organ transplant recipients diagnosed with CD20-positive PTLD who had failed to respond to upfront immunosuppression reduction received four courses of rituximab (375 mg/m2 intravenously) once a week followed by 4 weeks without treatment and four cycles of CHOP every 3 weeks. In case of disease progression during rituximab monotherapy, CHOP was started immediately. Supportive therapy with granulocyte-colony stimulating factor after chemotherapy was mandatory and antibiotic prophylaxis was recommended. The primary endpoint was treatment efficacy measured as response rates in all patients who completed treatment with rituximab and CHOP, per protocol, and response duration, in all patients who completed all planned therapy and responded. Secondary endpoints were frequency of infections, treatment-related mortality, and overall survival. This study is registered at ClinicalTrials.gov , number NCT01458548. Findings 74 patients were enrolled between Dec 12, 2002 and May 5, 2008, of whom 70 patients were eligible to receive treatment. PTLD was of late type in 53 (76%) of 70 patients, monomorphic in 67 (96%) of 70, and histologically EBV associated in 29 (44%) of 66 cases. Four of 70 patients did not receive CHOP. 53 of 59 patients had a complete or partial response (90%, 95% CI 79–96), of which 40 (68%, 55–78) were complete responses. At data cutoff (June 1, 2011) median response duration in the 53 patients who had responded to treatment had not yet been reached (>79·1 months). The main adverse events were grade 3–4 leucopenia in 42 of 62 patients (68%, 55–78) and infections of grade 3–4 in 26 of 64 patients (41%, 29–53). Seven of 66 patients (11%, 5–21) had CHOP-associated treatment-related mortality. Median overall survival was 6·6 years (95% CI 2·8–10·4; n=70). Interpretation Our results support the use of sequential immunochemotherapy with rituximab and CHOP in PTLD. Funding F Hoffmann-La Roche, Amgen Germany, Chugaï France.
