Cegal Protocol : Evaluation of the Feasibility of a Chemogenomic Approach to Identify Personalized Therapy for Relapse or Refractory AML Patients

Introduction :

Significant improvements of leukemia free survival have been obtained over the last 30 years in AML. This progress has resulted from optimization of the same chemotherapy-based "one-size-fits-all" approach. However, even though the majority of patients eligible for intensive chemotherapy achieve complete remission (60% to 80%), the majority still relapse and ultimately die (5-year overall survival being around 20%). Recent genomic studies have revealed the heterogeneity of AML at the molecular level, stressing the need for personalized therapeutic approaches. The fundamental idea in genomic medicine is that somatic genetic alterations can be identified and matched with drugs targeting those abnormalities for a patient's benefit. However, there are not that many potent, tolerated targeted agents in the clinic that can induce significant clinical responses. Interestingly, the majority of the most effective drugs do not function by exploiting genetic mutations in individual tumors. Thus, additional functional approaches are needed to identify new drugs and assign existing drugs to larger numbers of patients with AML.From this perspective, the"chemogenomic" approach realizes an integratedanalysis of the molecular clonal abnormalities for the leukemic patients, and compares it to a functional drug sensitivity testing (DST) which can test simultaneously dozens of drugsex vivo. This approach aims to identify correlations between genomic changes and sensibilities increased in certain categories of drugs. The CEGAL project is a prospectivemonocentric study aiming to evaluate the feasibility of this personalized approach for relapse or refractory AML patientsby determining the proportion of patients whosechemogenomic results are available in less than 21 days.

Methods :

Patients with relapsed and/or refractory AML were eligible if no alternative therapy was available. Written consent was obtained from all patients (Study CeGAL-IPC 2014-012, EUDRACT 2014-A01209-38). Ex vivo sensitivity profiling was performed on freshly isolated AML blasts derived from patient bone marrow aspirates and peripheral blood with a panel of 78 drugs representative of the main therapeutic classeskwown to be active in AML. After 48h of incubation, cellular viability was measured with the CellTiter-Glo© Luminescent cell viability assay (Promega) kit to obtain one EC50. Next generation sequencing (NGS) was performed on a 200 genes panel with Mi-Seq (Illumina) and genomic profils by cGH-array (Agilent4x180K) were established. Personalized treatment plans were then reviewed by an institutional personalized committee, which issued final treatment recommendations.

Results: A total of 48 AML patients were included (refractory=8,relapse=40) with a median age of 64 years old (range 24-81) and a median number of prior therapies of 2. More than half of the patients presented an adverse prognostic according to the 2017 ELN risk stratification (n=29). The most frequent genomic alterations were TET2 in 32.5% of the patients, ASXL1 (27.5%), DNMT3A (25%), TP53 (22.5%), SRSF2 (20%) and RUNX1 (17.5%). The median number of mutations per patient was 5,6. The main objective was completed with chemogenomic results in less than 21 days for 62.5% of the patients (n=25) with a median time of 22.4 days. Twenty four patients (67,5%, n=27) had targetable mutations and for 36 patients (90%), there was at least one drug predicted efficient. In light of the chemogenomic analysis, we found a correlation between genomic alteration and drug sensitivy for 28 patients. Thirteen patients (32.5%) received a treatment guided by the analysis whatsoever chemotherapies or targeted therapies. The 27 others didn't receive a personalized treatment either because the molecule wasn't commercially available or because the physician decided so.

Conclusion : In our experience, the chemogenomic is an innovative and promising approach, allowing to assign patient-specific treatment options according to their mutational profile and to in vitro drugs' response in a median time of 3 weeks.