Abstract 1804: Efficacy and clinical outcome of Philadelphia (Ph) positive acute lymphoblastic leukemia (ALL) patients treated with second generation tyrosine kinase inhibitors (TKIs): The Bologna experience
Authors: Papayannidis Cristina , Iacobucci Ilaria , Soverini Simona , Colarossi Sabrina , Gnani Alessandra , Lonetti Annalisa , Ferrari Anna , Testoni Nicoletta , Amabile Marilina , Ottaviani Emanuela , Abbenante Maria Chiara , Curti Antonio , Paolini Stefania , Lama Barbara , Clissa Cristina , Parisi Sarah , Guadagnuolo Viviana , Baccarani Michele , Martinelli Giovanni 
Published: February 2011

Background. Approximately 30% of adult ALL patients are characterized by the presence of the Philadelphia (Ph) chromosome, which derives from a reciprocal translocation t(9;22)(q34;q11) and results in a chimeric BCR-ABL oncogene. The prognosis of this subset of patients treated with standard therapies, including multi-agent chemotherapy, Imatinib, and allogeneic stem cell transplantation, is still dismal, due to a high risk of relapse. Dasatinib and Nilotinb are second generation TKIs developed to overcome the problem of resistance to Imatinib in relapsed Ph+ leukemias.

Design and Methods. We retrospectively evaluated the single center experience on therapy efficacy of Dasatinib, Nilotinib, and experimental third generation TKIs, administered as second or subsequent line of therapy on 25 relapsed Ph+ adult ALL patients. All patients were previously treated with Imatinib. The median age at time of diagnosis was 50 years (range 18-74), 17 patients were male and 8 female. Ten patients presented a BCR-ABL P190 fusion protein and corresponding fusion transcript, the remaining a BCR-ABL P210. Nineteen patients received Dasatinib, 2 patients Nilotinib and the remaining 4 patients were treated with third generation TKIs. Fourteen patients (56%) were in first relapse, and 7 (28%), 3 (12%) and 1 (4%) were in second, third and fourth relapse, respectively.

A mutational analysis was performed in all the patients before TKIs (9 wild type, 16 mutated, including T315I) and at the time of subsequent relapse; gene expression profiling, SNPArray (6.0 Affymetrix chip), and Ikaros deletions were also analyzed.

Results. 13 out of 25 patients (52%) obtained a haematological response (HR) (11 patients treated with Dasatinib, 1 patient with Nilotinib and 1 patient with a third generation experimental TKI). 10 patients obtained also a cytogenetic response (CyR) and 6 patients a molecular response (MolR). With a median follow up of 10.8 months (range 2-29 months), median duration of HR, CyR and MolR were 117 days (range 14-385 days); progression free survival were 162 days with Dasatinib and 91 days with Nilotinib. Overall survival was 25.8 months. Interestingly, in 6 out of 9 wild-type patients, treated with Dasatinib, the mutational analysis showed the emergence of T315I or F317I mutation at the time of relapse.

Conclusion. Second and third generation TKIs represent a valid approach in relapsed Ph+ adult ALL patients; the subsequent relapse is often associated to the emergence of mutation, conferring resistance to TKIs.

Acknowledgments. Work supported by European LeukemiaNet, FIRB 2006, AIRC, AIL, COFIN, University of Bologna and BolognAIL; Fondazione del Monte di Bologna e Ravenna, Programma Ricerca Regione-Università 2007 – 2009.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1804.