Nelarabine is safe and effective in adult relapsed or refractory T cellacute lymphoblastic leukemia (T-ALL) and lymphoblastic lymphoma (T-LBL): The Bologna experience

Background. Nelarabine (N) is approved for the treatment of T-ALL and T-LBL that have not responded to or has relapsed after treatment with at least 2 chemotherapy regimens. Aim. To evaluate safety profile and efficacy of N as savage therapy in 16 adult relapsed or refractory T-ALL or T-LBL. Methods. After obtaining an informed consent, 16 patients (median age 33 years, range 19-45, M/F = 13/3) affected by T-ALL (n=10) and T-LBL (n=6) received savage therapy with N (median cycle=1, range 1-3), administered at standard adult dosage (1500 mg/sqm on days 1, 3 and 5, every 21). Four patients were primary resistant to induction treatment, 7 patients were relapsed after two previous chemotherapy regimens (including allogeneic BMT in 4 cases and autologous SCT in 1 case); the remaining 6 patients had a molecular relapsed disease (MRD positive). Molecular characterization was performed, including NOTCH and WT-1 genes mutational status. GEP analysis, according to Ferrando A. stratification (Cancer Cell 2002), is still ongoing. Results. Currently, 12 out of 16 patients are evaluable, due to a too short follow up in the other 4 cases. Seven out of 12 patients obtained a complete remission (CR) (5 T-ALL 2 T-LBL);a partial remission (PR) was documented in 2 cases, with an overall response rate (ORR) of 75%. Median duration of CR was 10 weeks (range 2.8-54+). Among these, 2 out of 4 patients in molecular relapse reached a molecular CR and underwent an allogenic BMT (currently in CR after a median follow up of 12 months). Extra- hematological toxicity, not clearly related to the drug, occurred in 3 cases, determining, a complete and irreversible paraplegia, a condition of mental confusion, and a peripheral neuropathy, respectively. Conclusions. N showed a strong efficacy also in cases with low levels of residual disease, in addition to a good safety profile. Neurological toxicity needs to be strictly monitored. Acknowledgments. European LeukemiaNet, AIL, AIRC, Fondazione Del Monte di Bologna e Ravenna, FIRB 2006, PRIN 2008, Ateneo RFO grants, Project of integrated program (PIO), Programma di Ricerca Regione – Università 2007 – 2009.