The Combination of Nilotinib + Pegylated IFN Alpha 2a Provides Somewhat Higher Cumulative Incidence Rates of MR4.5 at M36 Versus Nilotinib Alone in Newly Diagnosed CP CML Patients. Updated Results of the Petals Phase III National Study.

The combination of 2GTKI+pegylated IFN-α (Peg-IFN) is an attractive approach for first-line treatment of CP CML, inducing high rates of deep molecular responses in phase II trials. Thus, we evaluated nilotinib (NIL) alone versus NIL+Peg-IFN in newly diagnosed CP-CML patients (pts) in a randomised phase III trial (PETALs, EudraCT 2013-004974-82).

Newly diagnosed CP CML pts ≤65 y, without prior history of arterial occlusion were randomized 1:1 to get NIL 300 mg BID alone (M0 to M48, arm A) vs Peg-IFN alone for 30 days (M-1→M0) 30 μg/wk as priming, prior to NIL 300 mg BID + Peg-IFN 30 μg/wk 2 wks, upgraded to 45 μg/wk thereafter, for up to 2 y (M0 to M24, arm B) followed by NIL alone for 4 more years unless pts enter treatment-free remission (TFR). The primary endpoint is the rate of MR4.5 by 1 y. As a secondary endpoint, pts reaching MR4.5 ≥2 y are allowed to stop NIL and enter a TFR phase in both arms. The trigger for treatment resumption is loss of MMR. All molecular assessments are centralised, quantifications are expressed as BCR-ABL/ABL1 (IS) in % with ≥32,000 copies of ABL1 as control.

Two hundred pts were randomized (99 in A, 101 in B), 130 M and 35 F in each arm, median age of 46 (18-66) y. Median follow-up is 43.8 (34.3-55.9) Mo. Results are analysed in intention-to-treat. Sokal and EUTOS LTS scores were H in 25% and 2.5%, Int. in 33% and 16.5% and L in 42% and 81% pts respectively equally balanced. Median age is 46 (18-66) y, 18 pts (9%) had ACAs, all pts have a "Major" BCR transcript. CHR was obtained in 9.6% of pts at M0 (in B) and 88% of pts in A and 90.4% of pts in B at M1. CCyR rates at M3 were 63% vs 75% in A and B (p=ns), and BCR-ABL1 ≤1% at M6 were 87% in A vs 93% in B (p=ns). By M12, the rates of MMR were 68.1% vs 70.1% (p=0.44), MR4 were 34% vs 47.5% (p=0.041), MR4.5 were 15.9% vs 21.5% (p=0.049), MR5 11.7% vs 23.71% (p=0.023), in A vs B respectively. By M36 the rates of MMR were 83% vs 86.6% (p=0.31), MR4 were 70.2% vs 71.13% (p=0.50), MR4.5 were 37.2% vs 49.5% (p=0.05), MR5 33% vs 42.3% (p=0.12), in A vs B respectively The overall cumulative incidence of MR4.5 is superior in B (54.6 [43.7-65.5]%) vs A (44 [31.5-54]%) close to significance (unilateral Fisher test, p=0.05, see Figure).

Seven patients were mutated by Sanger in A (5 Y253, 1 E255K, 1 T315I) vs 2 in B (2 T315I). One pt (A) progressed toward AP and then myeloid BC with a Y253H mutation, is still alive in CMR on Ponatinib. Twenty nine (29%) pts were withdrawn from study in A (toxicity 9, cancer 3, resistance 14, investigator decision 2, lost for FU 1) vs 26 (26%) pts for B (toxicity 13, resistance 8, investigator decision 5), 1 pt died from cervix cancer (A). Median overall doses of NIL delivered by M36 were 600 mg/d in both arms (p=ns). The median overall dose of Peg-IFN delivered in B by M24 was 37.5 mg/wk. The overall rate of grade 3-4 hematologic toxicities was 22%; with 2% and 7% thrombocytopenia, 4% and 6% neutropenia, and 1% and 1% pancytopenia in A vs B respectively. Major grade 3-4 non-hematologic toxicities consisted in 9% of cardiac disorders in A (2 coronaropathies, 1 myocardial infarction, 2 thoracic pains, 2 atrial fibrillation, 1 bradycardia, 1 palpitations, 1 pericarditis) vs 8% in B (2 coronaropathies, 1 myocardial infarction, 3 atrial fibrillation, 1 palpitations, 1 pericarditis), 4% vascular disorders in A (1 thrombophlebitis + PE, 1 transient ischemic attack, 1 PAOD, 1 carotid stenosis) vs 3% in B (1 thrombophlebitis, 1 PAOD, 1 transient ischemic attack). Three % of gastro-intestinal disorders were observed in A (2 pancreatitis, 1 anal fissure) vs 6% in B (2 pancreatitis, 1 anal fissure, 1 abdominal pain, 2 cholecystectomies); 5% auto-immune disorders in B (1 recurrent pericarditis, 2 hemolytic anemia, 1 ITP, 1 thyroiditis); 5 and 8 pregnancies (2 pts + 3 partner Arm 1, 3 pts + 5 partner Arm B), despite recommended contraceptive methods. Secondary tumours were diagnosed in 4% (1 breast, 1 cervix, 1 thyroid, 1 neuroendocrine) in A vs 2% of pts (1 neuroendocrine and 1 testis) in B. Of note 8% psychiatric episodes were reported in B pts (2 unsuccessful suicide attempts), vs 2% in A. We observed 9% lipase elevations in A, 6% in B, 2% cholestatic episodes in A, 6% in B; 3% of transaminase elevations in A vs 2% in B. Infections were detected in 3% A vs 7% in B.

The combination of NIL + Peg-IFN seems to provide somewhat higher MR4.5 rates by M36 in newly diagnosed CP CML pts without inducing significant higher toxicities than NIL alone. Whether this will translate in higher TFR rates is under evaluation. Final updated results at M36 will be presented

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