Program: Oral and Poster Abstracts
Type: Oral
Session: 632. Chronic Myeloid Leukemia: Therapy: Treatment-Free Remission, Mutations, and Prognosis
Aims – We aimed to determine the frequency of BCR-ABL mutations as assessed by NGS vs conventional Sanger sequencing (SS) in CML pts with failure and warning to 1st- or 2nd-line TKI therapy as per the latest, 2013 ELN definitions.
Methods – Between May 2013 and June 2015, 298 consecutive CML pts on TKI therapy were referred to our laboratory for BCR-ABL mutation screening by SS. One hundred and fifty-eight cases had no clinical data available, or were not in CP, or were receiving ≥3rd-line TKI therapy, or had confirmed/ suspected nonadherence, or had experienced dose reductions for toxicity – leaving 140 pts who could be included in this study. Pts who were negative for mutations as determined by SS (n=105/140) were retrospectively reanalyzed by NGS on a Roche GS Junior, using a protocol already set up and optimized in the framework of the IRON II (Interlaboratory RObustness of NGS) international consortium. Sequencing depth allowed to achieve a lower mutation detection limit of 1% in all samples.
Results – Failures and warnings to 1st-line therapy (imatinib, n=57; nilotinib, n=22; dasatinib, n=13) were 63 and 29, respectively. BCR-ABL mutations were found in 15/63 (24%) failures and 3/29 (10%) warnings by SS (Table 1).
NGS reanalysis of the 74 pts with no evidence of mutations by SS revealed low burden (median, 6.6%; range, 1.5-11.7%) mutations in 6 failures and 1 warning, so that, overall, 21/63 (33%) failures and 4/29 (14%) warnings turned out to have mutations (Table 1). Mutations were E462K, E279K, K262R, F359I, E255K, F317L, K378R, A399T, L364I, V280A. No compound mutation was detected.
Failures and warnings to 2nd-line therapy (nilotinib, n=27; dasatinib, n=21) were 35 and 13, respectively. SS identified mutations in 13/35 (37%) failures and 2/13 (15%) warnings (Table 1).
NGS reanalysis of the 33 pts with no evidence of mutations by SS revealed low burden (median, 5.4%; range, 1.9-10.0%) mutations in 5 failures and 2 warnings, so that, overall, 18/35 (51%) failures and 4/13 (31%) warnings turned out to have mutations (Table 1). Mutations were T315I, E255V, F317I, E258D, P480L, Y393C, W261L, L370P, V371A, L324Q, again with no compound mutations.
|
All pts |
Pts positive for mutations by SS |
Additional pts positive for mutations by NGS |
Total pts positive for mutations |
1ST-LINE FAILURES |
|
|||
No CyR @ 3 mo |
9 |
1 |
0 |
1 |
BCR-ABL>10% @ 6 mo |
9 |
0 |
0 |
0 |
mCyR @ 6 mo |
1 |
1 |
0 |
1 |
BCR-ABL>1% @ 12 mo |
10 |
0 |
2 |
2 |
No CCyR @ 12 mo |
2 |
1 |
0 |
1 |
Loss of CCyR |
7 |
3 |
1 |
4 |
Loss of MMR |
20 |
6 |
3 |
9 |
Loss of CHR |
2 |
1 |
0 |
1 |
Progression to BP |
3 |
2 |
0 |
2 |
Total |
63 |
15 (24%) |
6 |
21 (33%) |
1ST-LINE WARNINGS |
|
|||
BCR-ABL>10% @ 3 mo |
7 |
1 |
0 |
1 |
BCR-ABL>1% @ 6 mo |
10 |
1 |
1 |
2 |
BCR-ABL>0.1% @ 12 mo |
12 |
1 |
0 |
1 |
Total |
29 |
3 (10%) |
1 |
4 (14%) |
2ND-LINE FAILURES |
|
|||
No CyR @ 3 mo |
3 |
1 |
1 |
2 |
BCR-ABL>10% @ 6 mo |
10 |
2 |
2 |
4 |
Loss of CCyR |
7 |
3 |
0 |
3 |
Loss of MMR |
6 |
1 |
2 |
3 |
Loss of CHR |
4 |
3 |
0 |
3 |
Progression to BP |
5 |
3 |
0 |
3 |
Total |
35 |
13 (37%) |
5 |
18 (51%) |
2ND-LINE WARNINGS |
|
|||
BCR-ABL>10% @ 3 mo |
6 |
2 |
0 |
2 |
BCR-ABL>0.1% @ 12 mo |
7 |
0 |
2 |
2 |
Total |
13 |
2 (15%) |
2 |
4 (31%) |
Conclusions
1) NGS allowed to identify BCR-ABL mutations in a greater proportion of cases as compared to SS. Low burden mutations included a T315I mutation in 2 pts on 2nd-line therapy classified as warnings: this would have turned them into failures.
2) Still, a substantial proportion of cases was found to not harbor any mutation, even when using a more sensitive NGS-based method. In particular, non-optimal achievement of the key molecular response milestones (10%, 1%, 0.1%) on 1st-line therapy was mostly not associated with BCR-ABL mutations, indicating that other mechanisms of molecular disease persistence have to be investigated in an attempt to optimize therapeutic outcomes.
A national, multicenter study ('NEXT-IN-CML') aimed at the prospective assessment of NGS for routine BCR-ABL mutation screening of CML patients has just started.
Supported by ELN, AIL, AIRC, FP7 NGS-PTL project, Progetto Regione-Università 2010-12 (L. Bolondi)
Disclosures: Soverini: Bristol-Myers Squibb: Consultancy ; Ariad: Consultancy ; Novartis: Consultancy . Castagnetti: BMS: Consultancy , Honoraria ; Novartis: Consultancy , Honoraria ; Pfizer: Consultancy , Honoraria ; ARIAD: Consultancy , Honoraria . Bonifacio: Ariad Pharmaceuticals: Consultancy ; Amgen: Consultancy ; Pfizer: Consultancy ; Novartis Farma: Research Funding . Saglio: Bristol-Myers Squibb: Consultancy , Honoraria ; Pfizer: Consultancy , Honoraria ; ARIAD: Consultancy , Honoraria ; Novartis Pharmaceutical Corporation: Consultancy , Honoraria . Rosti: Novartis: Honoraria , Research Funding , Speakers Bureau ; Bristol Myers Squibb: Honoraria , Research Funding , Speakers Bureau . Baccarani: NOVARTIS: Honoraria , Membership on an entity’s Board of Directors or advisory committees , Speakers Bureau ; Bristol-Myers Squibb: Honoraria , Membership on an entity’s Board of Directors or advisory committees , Speakers Bureau ; ARIAD Pharmaceuticals, Inc.: Honoraria , Membership on an entity’s Board of Directors or advisory committees , Speakers Bureau ; PFIZER: Honoraria , Membership on an entity’s Board of Directors or advisory committees , Speakers Bureau . Martinelli: Pfizer: Consultancy ; Novartis: Consultancy , Speakers Bureau ; ROCHE: Consultancy ; BMS: Consultancy , Speakers Bureau ; AMGEN: Consultancy ; MSD: Consultancy ; Ariad: Consultancy .
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