A Phase II, Single-Arm Study of De-Escalation and Treatment-Free Remission in Patients with Chronic Myeloid Leukemia Treated with Nilotinib in First-Line Therapy Followed By a Second Attempt after Nilotinib and Asciminib Combination: Dante Study

Introduction: Treatment-free remission (TFR) is considered one of the main goals of therapy in patients with chronic myeloid leukemia (CML). Several studies have shown that treatment discontinuation can be successfully achieved in roughly 50% of patients with a sustained deep molecular response (sDMR). However, the remaining 50% require reintroduction of tyrosine kinase inhibitor (TKI) therapy. Although about 90% of patients who experience molecular relapse regain a major molecular response (MMR) after restarting TKI therapy, due to poorly understood mechanism(s), the probability for those patients of failing a second attempt to discontinue TKI (TFR2) is higher compared to the first attempt. The above-mentioned data implies that, to aim to a second TFR, a different therapeutic strategy might be needed.

Asciminib (ASC), unlike all approved TKIs that bind to the ATP site of the BCR-ABL1 oncoprotein, is an allosteric, first-in-class STAMP (Specifically Targeting the ABL Myristoyl Pocket) inhibitor with a new mechanism of action that has shown efficacy in heavily pre-treated patients after two or more TKIs (Rea et al. 2021). An ongoing phase I dose-finding study (NCT02081378) has shown that ASC combined with TKI is both effective and well tolerated in heavily pretreated CML patients, suggesting that combination treatment between an allosteric and an ATP-competitive TKI may deepen clinical responses without serious safety concerns (Mauro et al. 2019).

The changes introduced in the DANTE study (NCT03874858) by the amendment 4 aim to assess whether ASC in combination with nilotinib (NIL) can lead to higher and more durable TFR2 rates than those reported in other studies.

Methods: After providing written informed consent, the TFR2 phase will enroll - from 29 Italian centers, approximately 60-70 adult CML patients in chronic phase, who have been (i) treated for at least 3 calendar years with NIL, (ii) failed a first TFR attempt, (iii) restarted NIL for at least 1 year and (iv) fulfill all inclusion/exclusion criteria.

The study consists of 4 phases: screening, re-induction (week 0-96), TFR2 (week 96-144) and follow up phase. In the re-induction phase, patients will be treated with ASC 40 mg BID and NIL 300 mg BID for 96 weeks and will have scheduled biweekly/monthly visits until week 12, and then every 12 weeks. NIL dose may be less than 300 mg BID if appropriate by clinical judgement but must be at least 300 mg daily.

During re-induction, sDMR is defined as no loss of MR4.0 (BCR-ABL level ≤ 0.01% IS) in any BCR-ABL RQ-PCR assessment. Patients with sDMR at the end of re-induction will enter in TFR2 and ASC plus NIL will be discontinued. If two or more consecutive quarterly BCR-ABL RQ-PCR assessments are not performed during re-induction or results are not available, the patient will not be eligible for TFR2 and will be treated with NIL 300 mg BID until the end of the TFR2 stage (week 144). Patients not eligible for TFR2 but with a response more than an MMR will continue treatment with ASC and NIL until the end of re-induction (week 96) and then continue NIL monotherapy at 300 mg BID until the end of the TFR2 stage (week 144). Patients with loss of MMR at any time during re-induction or during NIL monotherapy will be discontinued from the study. If MMR loss occurs during TFR2, NIL 300 mg BID will be restarted and administered until end of study (Fig1).

Endpoints: The primary endpoint is the percentage of patients in TFR 48 weeks after stopping NIL and ASC combination. Key secondary endpoints are: (i) percentage of patients eligible for TFR2, (ii) the number of patients with loss of MMR in TFR2 and regain MMR/DMR by the end of the TFR2 stage (iii) BCR-ABL kinetics in the different study phases (iv), OS, TFS and PFS and (v) the safety of the combination. The TFR2 stage is descriptive and no formal statistical testing is necessary or applicable.

Conclusions: The expected results from this phase II interventional study, will potentially represent a milestone in treatment strategy for those patients who aim to discontinue NIL for the second time by providing them with several benefits including an improved quality of life.

References: Rea et al., Blood . 2021 Nov 25;138(21):2031-2041; Mauro et al., 2019. 24th European Hematology Association Congress

Rosti:Novartis, Incyte, BMS, Pfizer: Honoraria, Speakers Bureau. Saglio:Novartis: Speakers Bureau. Stagno:Celgene, Incyte, Novartis, Pfizer: Honoraria, Speakers Bureau. Valsecchi:Novartis: Current Employment. Nardozza:Novartis: Current Employment. Coco:Novartis: Current Employment. Breccia:Novartis, Incyte, Pfizer, BMS, Abbvie: Honoraria. Iurlo:Novartis, BMS, Celgene, Incyte, Pfizer: Honoraria.

Nilotinib (TASIGNA) in combination with asciminib for TFR purpose.