Response and Adverse Effects of Nilotinib in Imatinib-resistant Chronic Myeloid Leukemia Patients: Data From a Developing Country

Battling chronic myeloid leukemia in a resource-constrained country: A case of public-private partnerships

Pakistan, where chronic myeloid leukemia constitutes around 80% of all myeloproliferative disorders, has been exploring multiple avenues in order to ensure the accessibility and affordability of imatinib and nilotinib. While most provinces of the country have joined hands with a pharmaceutical company to dispense free anti-CML medicines as part of a public-private partnership, the patients are still facing numerous challenges in the form of geographical disparity in the availability of these medicines, other out-of-pocket expenditures and most importantly, the uncertainty associated with the long-term continuation of this public-private endeavor due to procedural delays. In light of these predicaments, channeling resources towards research and development, fostering partnerships between government and NGOs and tapping into the domain of compulsory licensing appear to be the most sustainable solutions.

Is dose modification or discontinuation of nilotinib necessary in nilotinib-induced hyperbilirubinemia?

Nilotinib is a specific breakpoint cluster region-Abelson leukemia virus-tyrosine kinase inhibitor that is used as an effective first- or second-line treatment in imatinib-resistant chronic myelogenous leukemia (CML) patients. Hepatotoxicity due to nilotinib is a commonly reported side effect; however, abnormal liver function test (LFT) results have been reported in asymptomatic cases. When alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels are more than five-fold the upper limit of the normal (ULN) or when the serum total bilirubin level is more than three-fold the ULN, dose modification or discontinuation of nilotinib is recommended, resulting in decreased levels of hematological indicators in certain patients with CML. Nilotinib-induced hyperbilirubinemia typically manifests as indirect bilirubinemia without elevated ALT or AST levels. Such abnormal liver functioning is thus not attributed to the presence of a true histologic lesion of the liver. The underlying mechanism may be related to the inhibition of uridine diphosphate glucuronosyltransferase activity. Therefore, nilotinib dose adjustment is not recommended for this type of hyperbilirubinemia, and in the absence of elevated liver enzyme levels or presence of abnormal LFT findings, physicians should consider maintaining nilotinib dose intensity without modifications.

Experience with the Use of Nilotinib in Indian Patients

Important genetic and ethnic factors could affect the toxicity and efficacy of tyrosine kinase inhibitors. Though nilotinib has been available in India since 2010, there is no report on its safety and toxicity from Indian patients with chronic myeloid leukemia. This is an analysis of efficacy and toxicity of nilotinib when used as a second line drug after failure or intolerance to imatinib. Thirty-seven patients started nilotinib [median age 46 years, median duration from diagnosis 5 years, 73% in chronic phase at time of switch] between 2010 to 2016. Reason for switch: failure of imatinib in 33 (89%) and intolerance in 4 (11%). Starting dose 600 mg/day. Dose modifications: 15 (40%) patients required initial dose modifications, but subsequently 25 (67%) patients could tolerate 600 mg/day. Nine (24%) patients were able to tolerate 800 mg/day. The commonest grade 3/4 toxicities were thrombocytopenia (n = 9, 24%), hyperbilirubinemia (n = 7, 18%) and leukopenia (n = 3, 8%). Six patients (16%) discontinued nilotinib due to toxicity while 8 (21%) stopped due to lack of efficacy. After a median duration of 14 months among those continuing nilotinib, 54% of patients responded which included 14 patients who achieved CHR and seven who achieved major molecular response. In the first report on use of nilotinib in Indian patients, we observed a higher incidence of liver toxicity compared to previous reports. This should be seen the context that all these patients received nilotinib as second line therapy.