Clarithromycin Enhances tyrosine Kinase Inhibitor – Induced Cell Death by Inhibition of Late Stage Autophagy in Patients with Chronic Myeloid Leukemia At Diagnosis or with Resistant Stage of Disease
Authors: Carella A. M. , Beltrami G. , Pica G. , Ghiggi C. , Lovera D. , Cirmena G. , Garuti A. 
Published: October 2019

Abstract
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 <20×109/L WBC after TKI alone. Since TKIs can inhibit CYP3A3, all patients were evaluated weekly for GOT/GPT/gGT, bilirubin, lipase, amylase; moreover imatinibemia or nilotinibemia were evaluated every 7–10 days. In case of the increase of TKIs value >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.