Molecular Response to Tyrosine Kinase Inhibitors (TKIs) for Chronic Myeloid Leukemia (CML), the Experience At Tawam Hospital, Abudhabi, UAE

Abstract 4458

Chronic Myeloid Leukemia (CML) is a clonal myeloproliferative disorder characterized by the presence of a balanced reciprocal translocation involving the long arms of chromosomes 9 and 22. The fusion gene that is created by this translocation (BCR-ABL1) encodes for a constitutively active protein tyrosine kinase that is primarily responsible for the leukemic phenotype.

Targeted therapy with Tyrosine Kinase Inhibitors (TKIs) has become the recommended first-line treatment for patients with CML. Monitoring of the CML is done with quantification of the BCR-ABL transcripts by RQ-PCR–based molecular technique.

Twenty nine patients were diagnosed with CML in chronic phase between January 2009 till June 2012. The median age was 32 years (range 22–68 years). Male to female ratio was4.14:1. Three patients were lost from follow up after diagnosis and are excluded. Molecular response is available for 16 patients. Nine patients were treated with Imatinib 400 mg daily, four with Dasatinib 100 mg daily and three with Nilotinib 400 mg BID daily as upfront therapy. Twelve patients have achieved MMR/CMR (75 %) within 18months of starting therapy. Four patients have failed to achieve MMR by 24 months. All non responders were on Imatinib. Interestingly six (37.5%) patients achieved MMR/CMR within 9 months of starting TKIs. Of these only 1 was on Imatinib while the rest were on 2^nd generation TKIs (Nilotinib 3 and Dasatinib 2).

MMR report from Enestnd trial is 67–71% in favor of Nilotinib as compared to Imatinib 44%, while the Dasision trial reported a MMR of 44 % in favor of Dasatinib with faster rate to response. Our results mirror the results of these phase 3 randomized trial with MMR/CMR of 75 %. Until today there has been no case of progressive disease.

Our data is limited but shows that the median age is much lower compared to Western countries, just reflecting differences in the age distribution of the population in the UAE with 80% being below the age of 65 years. Expatriates accounts for approximately 80% of the population in the UAE and many are temporary employed, having limited health care coverage, limited financial means as well as limited possibilities to attend regular follow-ups. This leads to compliance problems, loss from follow-up and suboptimal management and monitoring of their disease.