BACKGROUND: Despite the excellent prognostic of chronic myeloid leukemia (CML) patients since the introduction of tyrosine kinase inhibitors (TKIs), approximately 50% of patients that are treated with TKIs will discontinue first line treatment due to lack of efficacy or intolerance. Once patients need a second line treatment, a considerable proportion of patients will need third or even fourth line therapy during further evolution. At this moment, there is a lack of data about real benefit of this group of patients. We have recently published our experience of 30 CML patients treated with bosutinib in 4th line. We present an update of the study where we have increased the number of patients, and the follow-up. The aim of this study is to present safety and efficacy data CML chronic phase patients treated with bosutinib in 4th line. METHODS: We have collected data from 59 CML patients treated with bosutinib in 4th line after resistance or intolerance to IM, NI and DA. 51 patients have been treated under the Spanish compassionate use program (36 centers) and 10 patients were treated in a single institution from United Kingdom. Median age of patients at diagnosis was 53 years. The percentage of low, intermediate and high risk Sokal groups were 47%, 37% and 16%. Median time TKIs exposure before bosutinib was 9 years. The most common indication (30/59) was intolerant to DA and NI. Patients' dispositions and main line characteristics are shown in table 1. RESULTS: Median follow-up was 14.3 months. All patients started bosutinib at 500mg/d, median dose of was 450mg/d. Overall probabilities to either achieve or maintain previous response were 96% (57/59), 62% (37/59), 40% (24/59) and 17% (10/59) for complete hematological response (CHR), complete cytogenetic response (CCyR), major molecular response (MMR) and MR4.5 respectively. However, probabilities to obtain responses (in patients without response evaluated at baseline) were 27% (7/26), 26% (12/45) and 12% (7/55) for CCyR, MMR and MR4.5. As expected, probabilities to obtain CCyR were lower for patients resistant to DA and NI patients than for patients intolerant to DA and NI (8% VS 44%). Event free survival (EFS) and progression free survival (PFS) probabilities were 50% and 83% by 27 month. Treatment was discontinued in 20/58 (34%), most frequent reasons being adverse events 9/59(15%), lack of efficacy 5/59 (8.5%), disease progression 2/59 (3.4%) and death 1/59 (1.7%). Two patients discontinued due to stem cell transplantation. The adverse events that led to treatment discontinuation were pleural effusion (3), diarrhea (2), rash, renal impairment, auricular fibrillation and liver enzyme elevation one patient each. Overall, bosutinib was well tolerated. Grade 3-4 hematological toxicities were 3%, 6% and 6% for anemia, thromboctytopenia and neutropenia. Most common non hematological side effects were diarrhea (39%, nauseas 13% and liver alterations 14% and pleural effusion 14%. CONCLUSIONS: Little is known about the therapeutic role of Bosutinib in 4th line. The series presented here is, to our knowledge, the largest being presented. Bosutinib seems to be an appropriate treatment option for patients resistant or intolerant to three prior TKIs. Table 1. IM+NI-I+DA-R (N=4) IM+NI-R+DA-R (N=18) IM+NI-I+DA-I (N=30) IM+NI-R+DA-I (N=7) Total (N=59) Sex, N (%) Male 2 (50) 11 (61.1) 16 (53.3) 2 (28.6) 31 (52.5) Median age of diagnosis, yr (range) 57.32 (50-64) 49.19 (23-73) 54.95 (21-89) 48.87 (26-68) 53.15 (21-89) Median age of Bosutinib initiation, yr (range) 69.13 (61-70) 62.27 (39-79) 64.85 (25-90) 64.79(35-74) 63.7 (25-9) Median follow up, months (range) 18.5(7.8-34.1) 8.4(1.22-36.1) 16.3(0.5-34.7) 23.4(3.3-28.9) 14.3(0.7-36.1) SOKAL Index at diagnosis, N (%) High 2(50.0) 4 (23.5) 1 (4.3) 1 (20) 8 (16.3) Intermediate 1 (25.0) 5 (29.4) 10(43.5) 2 (40) 18 (36.7) Low 1 (25.0) 8 (47.1) 12 (52.2) 2 (40) 23 (46.9) Median Time from first TKI to BOS, (yr, range) 10.3 (4.8-11.9) 9.3 (2.0-11.4) 8.8 (0.7-13.6) 8.2 (5.1-12.3) 8.8 (0.7-13.6) Median duration of prior therapy, months (range) Imatinib 38.8 (11.8-69.8) 32.6 (6.3-96.8) 26.2 (1.6-102.6) 23.1 (8.3-66.8) 28.8 (1.6-102.6) Dasatinib 21.5 (12.6-75) 21.8 (7.7-69) 31.4 (0.4-87.1) 23.7 (10.3-53.6) 23.44 (0.4-87.1) Nilotinib 19.1 (2.1-46.2) 16.7 (5-65.6) 8.9 (0.2-58.5) 30.9 (6.9-49.3) 14.3 (0.2-65.6) BOS: bosutinib, IM, imatinib; DA, dasatinib; NI, nilotinib, I: Intolerance, R: Resistant, Yr: year Disclosures García-Gutiérrez: Ariad: Consultancy; Pfizer: Consultancy, Honoraria; BMS: Consultancy, Honoraria; Novartis: Consultancy, Honoraria. Milojkovic:Novartis: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Ariad: Consultancy, Honoraria; BMS: Consultancy, Honoraria. Boque:Novartis: Honoraria; BMS: Honoraria; Celgene: Honoraria. Casado:Novartis: Honoraria, Research Funding; BMS: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding; Roche: Honoraria, Research Funding. Jiménez:Pfizer: Consultancy, Honoraria. Giraldo:Pfizer: Consultancy. Steegmann:Novartis: Consultancy, Honoraria, Research Funding, Speakers Bureau; BMS: Consultancy, Honoraria, Research Funding, Speakers Bureau; Pfizer: Consultancy, Honoraria, Research Funding, Speakers Bureau; Ariad: Consultancy, Honoraria, Research Funding, Speakers Bureau.

PRIAPISMO SECUNDARIO A REACCIÓN LEUCEMOIDE PARANEOPLÁSICA EN PACIENTE CON CÁNCER DE VEJIGA El priapismo asociado a tumores sólidos suele producirse por metástasis peneanas o por infiltración tumoral directa de los cuerpos cavernosos. Las neoplasias son responsables del 3-8% de los casos de priapismo, y en el 80% de los casos el tumor primario es de origen génito-urinario. La reacción leucemoide es un trastorno hematológico caracterizado por una leucocitosis superior a 50000/µl, que se desarrolla de forma reactiva ante diversos procesos patológicos como inflamaciones severas, infecciones diseminadas, intoxicaciones y tumores. El mecanismo fisiopatológico que explica el priapismo secundario a reacción leucemoide es una obstrucción intravascular por hiperviscosidad sanguínea, que origina una estasis sanguínea en las venas cavernosas, impidiendo el drenaje de los cuerpos cavernosos. Presentamos un caso de priapismo en un paciente con un cáncer de vejiga localmente avanzado, que se desencadenó por la hiperviscosidad sanguínea producida por una reacción leucemoide paraneoplásica.

Priapism associated with solid tumours is usually produced by penile metastasis or direct tumour infiltration of the corpora cavernosa. Neoplasias are responsible for between 3-8% of all cases of priapism, and in 80% of cases the primary tumour has a genito-urinary origin. Leukemoid reaction is an haematological disorder characterised by a leukocytosis of over 50000/microl, which develops reactively with different pathological processes such as severe inflammation, disseminated infections, intoxications and tumours. The pathophysiologic mechanism that explains priapism following leukemoid reaction is an intravascular obstruction due to blood hyperviscosity, leading to a blood stasis in the cavernosa veins, and impeding the drainage of the corpora cavernosa. We present a case of priapism in a patient with locally advanced bladder cancer, which was probably the result of blood hyperviscosity produced by a paraneoplastic leukemoid reaction.