Phase II Study of Peg-Asparaginase, Etoposide, Gemcitabine (PEG) Followed by Involved- Field Radiation Therapy in Early-Stage Extranodal Natural Killer/T-Cell Lymphoma

Abstract Background The prognosis of extra-nodal NK-/T-cell lymphoma (ENKTL) is poor and the best therapy controversial. We studied safety and efficacy of a new combined modality therapy. Methods Phase-2 study of peg-asparaginase, etoposide and gemcitabine (PEG) and involved field radiation therapy (IFRT) in newly-diagnosed subjects with early-stage ENKTL. 2–6 course of PEG were given depending on response followed by IFRT. The primary endpoint were complete response(CR),partial response(PR),and objective response rate(ORR) after IFRT. Secondary endpoints included progression-free survival (PFS), survival and adverse events. Results 34 consecutive subjects who were Ann Arbor stage-I/-II were enrolled. 3 subjects progressed on PEG, the remaining 31 received IFRT. The ORR was 88.2%(30/34),included 28(82.4%)complete and 2 ༈5.8%༉ partial responses. At a median follow-up of 56.0 months (Interquartile Range [IQR], 36.0-66.9 months),the 5-year PFS and survival were 87.4% (95% Confidence Interval [CI],69.5%-94.8%) and 97.1% (95%CI,80.1%-99.6%). Most adverse events were haematological and easily managed. Conclusions PEG followed by IFRT is a safe and effective initial therapy for low-stage ENKTL, with similar toxicity and response rates, but higher progression-free survival(PFS) and overall survival(OS) rates compared to other regimens, providing an effective and tolerable new regimen for the newly diagnosed early-stage ENKTL.This conclusion needs validation in a randomized controlled trial.