-Author name in bold denotes the presenting author
-Asterisk * with author name denotes a Non-ASH member
Clinically Relevant Abstract denotes an abstract that is clinically relevant.

PhD Trainee denotes that this is a recommended PHD Trainee Session.

Ticketed Session denotes that this is a ticketed session.

1592 Outcomes of Newly Diagnosed Chronic Phase Chronic Myeloid Leukemia (CML) Who Switch to Imatinib Following Optimal Response to Second Generation Tyrosine Kinase InhibitorsClinically Relevant Abstract

Chronic Myeloid Leukemia: Therapy
Program: Oral and Poster Abstracts
Session: 632. Chronic Myeloid Leukemia: Therapy: Poster I
Saturday, December 5, 2015, 5:30 PM-7:30 PM
Hall A, Level 2 (Orange County Convention Center)

Vamsi K Kota, MD1, Elliott F. Winton, MD1, Martha Arellano, MD1, Anand Jillella1*, Morgan L. McLemore, MD1, Fuad El Rassi, MD2 and H Jean Khoury1

1Winship Cancer Institute of Emory University, Atlanta, GA
2The Georgia Comprehensive Sickle Cell Center at Grady Health System, Atlanta, GA

The second-generation TKIs (2G-TKIs) Dasatinib (DAS) and Nilotinib (NIL) yield faster responses in newly diagnosed chronic phase (CP) CML as compared to Imatinib (IM) however, long-term safety of these agents is a growing concern.

We identified 10 patients with CP CML diagnosed between 08/2013 and 06/2015 who initiated 2G-TKIs and were then switched after optimal response at 3 months to IM. DAS was administered to 8 patients at 100 mg/d and NIL in two patients at 300 mg twice a day. Response to TKI was assessed by quantitative reverse transcriptase polymerase chain reaction (qPCR) for BCR-ABL1. Response to 2G-TKIs after 3 months was as follows: CHR (n=10), 1 log (<10%, n=10), 2 log (<1%, n=7), and 3 log (<0.1%, n=2) reduction of BCR-ABL1 transcripts.  Median qPCR at 3 months was 0.77% by IS (range 0-7%).

NIL was discontinued due to grades 2-3 non-hematological toxicities in both patients. DAS was discontinued due to patient or physicians' preference or drug availability. Median time to discontinuation of 2G-TKIs and initiation of IM was 103 days (range, 92 – 120) from diagnosis.  IM was started at 400 mg/d and was well tolerated except in 2 patients who required dose-reduction and discontinuation due to grade 2 skin rash (1) and grade 2 anxiety (1). Both patients switched back to DAS at 54 and 228 days after initiation of IM respectively. 9/10 patients that switched to IM were evaluable with a follow up of at least 3 months. These patients have shown a continuous response with 9/9(100%) achieving a 2 log reduction at 6 months. With a median follow-up from initiation of IM of 8 months (range 2-20 months), 5/9 (55.5%) evaluable patients achieved MMR at 6 months and 3/6 MR5 at 9 months from diagnosis.

 In conclusion, this retrospective analysis shows that IM can be safely and effectively administered following optimal response to 2G-TKIs. Longer follow-up is needed, but with up to 20 months follow-up, all patients showed continuous decrease in their transcripts (Figure 1) and no losses of major molecular response or progression to blast phase were observed.  A strategy of induction with 2G-TKIs followed by maintenance with IM is worth evaluating in a prospective trial. 

Figure 1: BCR-ABL1 qPCR (IS value) at diagnosis and follow-up after a switch to IM at 3 months from 2G-TKIs.

Disclosures: Kota: Leukemia Lymphoma Society: Research Funding ; Pfizer: Membership on an entity’s Board of Directors or advisory committees .

*signifies non-member of ASH