Bosutinib in the Real-Life Treatment of Chronic Phase Chronic Myeloid Leukemia (CML) Patients Aged > 65 Years Resistant/Intolerant to Frontline Tyrosine-Kynase Inhibitors

Abstract

Background Bosutinib is a 2nd generation tyrosine-kinase inhibitor (TKI) active in Chronic Myeloid Leukemia (CML) patients resistant or intolerant to frontline imatinib, dasatinib or nilotinib; the favourable toxicity profile makes bosutinib potentially useful in elderly patients, but at present there are no data in unselected cohorts of these subjects. Aim To highlight this issue, a real-life cohort of 91 patients followed in 21 Italian Centers and treated with bosutinib when aged > 65 years was retrospectively evaluated. Patients The main clinical features of the whole cohort at diagnosis and at baseline of bosutinib treatment are reported in the Table; all patients were in CP when bosutinib was started. Median interval from diagnosis to bosutinib treatment was 49.7 months [interquartile range (IQR) 14.2 - 117.5]. Results Starting dose of bosutinib was 500 mg/day in 20 patients (22.0%), 400 mg/day in 7 patients (7.7%), 300 mg/day in 28 patients (30.8%), 200 mg/day in 34 patients (37.3%) and 100 mg/day in 2 patients (2.2%), respectively. After a median period of treatment of 18.1 months (IQR 9.4 - 27.7) all patients were evaluable for toxicity; on the whole, all grade hematological and extra-hematological toxicities were reported in 12/91 (13.1%) and 45/91 (49.4%) patients, respectively. A grade 3 - 4 hematological toxicity occurred in 5/91 patients (5.4%); a grade 3 - 4 extra-hematological toxicity occurred in 16/91 patients (17.5%). Overall, 46 patients (50.5%) never discontinued bosutinib: a temporary discontinuation < 6 weeks was needed in 19 patients (20.9%) and a temporary discontinuation > 6 weeks in 2 patients (2.2%). A permanent bosutinib discontinuation was needed in the remaining 24 patients (26.4%): in particular, 11 patients (12.1%) permanently discontinued bosutinib due to toxicity (skin rash in 3 cases, gastro-intestinal toxicity in 3 cases, pleural effusion in 2 cases, transaminitis, QTc prolongation and myalgia in 1 case each), 6 patients (6.6%) due to resistance and 7 patients (7.7%) due to other reasons (unrelated death in 6 cases and patient decision in 1 case). As to response, 5 patients (5.5%) were considered too early for assessment (< 3 months of treatment); among the 86 patients evaluable for response, 11 patients (12.7%) did not have any response (including 6 patients who discontinued bosutinib for early toxicity), 4 (4.6%) achieved hematological response only, and 71 (82.5%) achieved Cytogenetic Response (CyR) (Major CyR in 4, Complete CyR in 67). Among the 67 patients in Complete CyR, 58 (67.4% of all 86 evaluable patients) also achieved Molecular Response (MR) [Major MR (MR 3.0) in 19 (22.1%), Deep MR (MR 4.0/4.5) in 39 (45.3%)]. The 3-year Overall Survival and Event-Free Survival of the whole cohort of patients from bosutinib start were 83.0% (CI95% 71.6 - 94.4) (Figure 1) and 59.5% (CI95% 39.9 - 72.1), respectively. Conclusions Our real-life data show that bosutinib is effective, even if initial doses in many cases were lower than recommended, with a favourable safety profile also in elderly patients with important comorbidities resistant/intolerant to previous TKI treatments,: as a consequence, it could play a significant role in the current clinical practise for these frail patients. Disclosures Latagliata: Celgene: Honoraria; Janssen: Honoraria; Novartis: Honoraria; Pfizer: Honoraria. Trawinska:Novartis: Consultancy, Honoraria. Annunziata:Pfizer: Consultancy; Incyte: Consultancy; Novartis: Consultancy. Elena:Novartis: Consultancy; Pfizer: Consultancy. Crugnola:Incyte: Honoraria; Novartis: Honoraria. Bonifacio:Novartis: Honoraria; Amgen: Honoraria; Pfizer: Honoraria; Incyte: Honoraria; BMS: Honoraria. Sgherza:Incyte: Honoraria; Pfizer: Honoraria; BMS: Honoraria; Novartis: Honoraria. Iurlo:Pfizer: Other: Speaker Honoraria; Incyte: Other: Speaker Honoraria; Novartis: Other: Speaker Honoraria. Breccia:Celgene: Honoraria; Incyte: Honoraria; Novartis: Honoraria; BMS: Honoraria; Pfizer: Honoraria.

Real-World Analysis of the Therapeutic Management and Disease Burden in Chronic Myeloid Leukemia Patients with Later Lines in Italy

“…The analysis of the patients' characteristics showed that the comorbidity profile was in line with the age trend and that bosutinib tends to be prescribed to older patients in both 2nd L and ≥3rd L cohorts. In this direction, RCTs are currently ongoing [13] on the use of bosutinib in older population, and real-life studies evaluated the efficacy of this drug on elderly patients with intolerance/resistance to other TKIs [14], suggesting an increased use of bosutinib in this sub-population. This tendency could also explain the switch to bosutinib as 3rd L observed in the analysis of line sequence.…”

The Role of Bosutinib in Chronic Myeloid Leukemia: An Indian Perspective

“…In a retrospective real-world study of bosutinib use in 91 elderly (>65 years) patients with CP-CML, all grade hematological and extrahematological toxicities were reported in 13.1 and 49.4% patients, respectively, after 18.1 months median period of treatment. 46 Among the 86 elderly patients evaluable for response, approximately 4.6% achieved hematological response and 82.5% achieved CCyR (MCyR: 4.7%, CCyR: 77.9%). 46 Furthermore, bosutinib may be better tolerated at lower doses (300 mg QD) in elderly patients.…”

Adverse events and dose modifications of tyrosine kinase inhibitors in chronic myelogenous leukemia

“…Sixty seven percent of patients achieved MMR or deeper with a discontinuation rate of 26.4%. Therefore, lower dose of bosutinib can be considered in frail patients with severe comorbidities who failed multiple TKI therapies ( 77 ).…”