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 (t