ALBERT

Description: Abstract 4458 Acquired resistance to Imatinib in advanced phase of CML has been associated with mutations in the kinase domain (KD) of BCR-ABL. We have recently reviewed the status of the mutations in 52 patients with early CP-CML on the samples collected at diagnosis. Mutations were identified by direct sequency (DS) with BidDye Terminator V1.1. cycle sequencing kit and analyzed with a 3130 AB capillary electrophoresis system. Twenty-eight patients had low risk, 10 intermediate risk and 14 high risk, according to Sokal/Euro. Ten out of 14 high Sokal risk patients showed the following mutations: Y253C, S265R, E255K, F359Y, N374S, E255V, E255V, E255V, R332L, E334G. Three of these patients progressed during Imatinib and second-line TKIs and died of blastic phase CML at 23, 33 and 69 months. Curiously, S265R and N374S mutations disappeared during Imatinib treatment but were substituted during follow-up by other two mutations: E255L and H396R. The patient carrying E255L mutation died in blastic phase at 33 months and the one with mutation H396R was well controlled by Nilotinib and he is now alive in CMR 26 months after. Only one out of the 10 intermediate Sokal risk carried KD mutations at diagnosis (D363G). This patient is alive in MMR at 26 months after diagnosis under Imatinib. None of the 28 low Sokal risk patients carried KD mutations at diagnosis and no patients developed cytogenetic evolution while on treatment. In conclusion, the fact that KD mutations were more present in patients with high Sokal risk supports the hypothesis that the probability developing a mutation is related to the basic biology of the disease rather than being merely a random event. Disclosures: No relevant conflicts of interest to declare.

Description: Abstract 3777 Recent laboratory studies have demonstrated that clarithromycin (CAM) is effective at increasing the sensitivity of chronic myeloid leukemia (CML) cells to tyrosine kinase inhibitors (TKIs). The mechanism of induction of cell death by CAM combined with TKI appears to be via inhibition of late stage autophagy inhibitor chloroquine. This is clearly demonstrated by an increase in LC3-II protein levels and a concomitant increase in cellular vacuole formation (L. Shafranek, T.P. Hughes, Leukemia & Lymphoma 2012, early online 1–4). On our protocol, approved by our Ethical Committee, we treated 8 CML patients. Four consecutive patients, with advanced CML, who were in all cases resistant to TKI alone, achieved remarkable responses to the combination of TKI and CAM (Table 1). According to this positive experience, we thought that the combination CAM + TKI could be employed upfront at diagnosis, in the attempt to increase a faster complete molecular remission. Until now we have treated four patients at diagnosis. The median age was 45 years (range, 40 – 52). Two patients had intermediate and 2 patients high Sokal/Euro risk (Table 2). Two patients received imatinib 400 mg/die and 2 patients nilotinib 600 mg/die. CAM was given at a dose of 500 mg b.i.d. when the patients reached 1.000 ng/mL, we reduced the dose of CAM to 500 mg/die or we discontinued the drug if the value was 〉2.000 ng/mL. In six patients this combination did not result in liver, renal or cardiac toxicity. In two patients (one resistant and one at diagnosis) the TKI plasma levels reached values over 2.000 ng/mL and an increase of indirect bilirubinemia combined with amylase/lipase increase was achieved. We stop CAM and reduced TKIs with prompt renormalization of all values. With this adjustment the value of TKIs were maintained under 1.000 ng/mL. Three out four patients treated at diagnosis achieved CCyR and MMR at 3, 3, 6 months and 5, 10 and 12 months, respectively. No patient has gone off study for toxicity and in no case we observed grade 3–4 myelosuppression. The remarkable responses obtained in these patients support the hypothesis that inhibition of autophagy may make CML cells sensitive to killing by TKIs. Table 1. Clinical characteristics and responses to clarithromycin + TKI in resistant patients Age, sex Sokal/Euro Date of Diagnosis Previous therapy Best response Status at CAM start Best response after CAM + TKI 43, F High Risk 02/2000 INF-a/ARA-C Imatinib Nilotinib Dasatinib CHR PCyR Ph+ 100% bcr-abl/abl 6,1% CHR CCyR bcr-abl/abl 0,09% (d +81) 53, M Ly/BC-CML 08/2010 Chemio + Imatinib Allografting Dasatinib CHR CCyR bcr-abl/abl 143% under Dasatinib bcr-abl/abl 1,5% 68, M Intermediate Risk 10/1999 mini-ICE Autografting INF-a Imatinib Dasatinib CCyR Ph+ 100% bcr-abl/abl 42,5% bcr-abl/abl 0,0022% (d +37) 70, F High Risk 10/1998 INF-a/ARA-C Imatinib Nilotinib Dasatinib Omoharringot. +/− ARAC CHR CCyR Ph+ 100% bcr-abl/abl 140% E255V mutation bcr-abl/abl 0,09% (d +53) Ly/BCR-CML: Lymphoid blast crisis/CML d'emblee; CHR: Complete Hematologic Remission, CCyR: Complete Cytogenetic Remission; PCyR: Partial Cytogenetic Remission; MMR: Major Molecular Remission Table 2. Clinical characteristics and responses to clarithromycin + TKI at diagnosis in untreated patients Age, sex Sokal/Euro Therapy at diagnosis bcr-abl/abl at diagnosis bcr-abl/abl - best response after CAM + TKI 52, M Intermediate Risk Nilotinib 110,60% (nov-11) 0,07% (apr-12) (5 mo.) 40, M Intermediate Risk Nilotinib 69% (oct-11) 0,02% (jul-12) (10 mo.) 42, M High Risk Imatinib 178% (aug-11) 0,05% (aug-12) (12 mo.) 49, M High Risk Imatinib 90% (nov-11) 0,8% (jul-12) (9 mo.) Disclosures: No relevant conflicts of interest to declare.