| Ponatinib vs Imatinib in Frontline Philadelphia Chromosome–Positive Acute Lymphoblastic Leukemia: A Randomized Clinical Trial |
| Design |
Phase 3, open-label, global, randomized clinical trial (PhALLCON)
N= 232 (intention-to-treat population)
|
| Objective |
To compare frontline ponatinib vs imatinib in adults with newly diagnosed Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL) |
| Study Groups |
Ponatinib (n= 154)
Imatinib (n= 78)
|
| Inclusion Criteria |
Patients ≥18 years with newly diagnosed Ph+ ALL, verified p190 or p210 dominant isoforms, and an Eastern Cooperative Oncology Group (ECOG) performance status score 2 or better, bilirubin ≤1.5x the ULN, ALT or AST ≤2.5x ULN, SCr ≤1.5x ULN and estimated CrCl ≥30 mL/min, serum lipase and amylase ≤1.5x ULN, QT interval ≤450 ms (males) or ≤470 ms (females) |
| Exclusion Criteria |
History or current diagnosis of chronic-phase, accelerated-phase, or blast-phase chronic myeloid leukemia, prior/current systemic anticancer therapy and/or radiotherapy for ALL, taking drugs with a known risk of causing prolonged QT corrected interval or torsades de pointe, taking medications or herbal supplements known to be strong inhibitors or strong inducers of cytochrome P450 3A4 ≤14 days before first dose of study drug, history of acute pancreatitis in ≤1 y of screening or history of chronic pancreatitis, triglycerides >450 mg/dL, history/presence of clinically relevant CNS pathology, CNS or extramedullary involvement with ALL other than lymphadenopathy or hepatosplenomegaly, poorly controlled diabetes, clinically significant or uncontrolled cardiovascular disease, cerebrovascular, or peripheral vascular disease, or history of or active VTE disease, lactating, breastfeeding, pregnant |
| Methods |
Patients received ponatinib (30 mg/d) or imatinib (600 mg/d) with reduced-intensity chemotherapy, followed by single-agent ponatinib or imatinib after cycle 20. Ponatinib dose was reduced to 15 mg upon achieving MRD-negative complete remission. Patients continued treatment until loss of efficacy, unacceptable toxicity, or proceeding to hematopoietic stem cell transplant (HSCT).
Intrathecal therapy (methotrexate, cytarabine, and corticosteroids) was given twice monthly for the first 6 cycles for central nervous system disease prophylaxis.
|
| Duration |
January 2019 to May 2022, with follow-up until August 12, 2022 |
| Outcome Measures |
Primary: MRD-negative complete remission rate at the end of induction
Secondary: Event-free survival, duration of complete remission and MRD-negative complete remission, MRD negativity (MR4), BCR::ABL1IS ≤0.0032% (MR4.5), time to treatment failure, overall survival, adverse events
|
| Baseline Characteristics |
|
Ponatinib (n= 164) |
Imatinib (n= 81) |
| Age, median (range), years |
54 (19-82) |
52 (19-75) |
| Age ≥60 |
61 (37.2%) |
30 (37.0%) |
| Female |
90 (54.9%) |
43 (53.1%) |
|
ECOG score
0 (best)
1
2 (worst)
|
72 (43.9%)
85 (51.8%)
7 (4.3%)
|
33 (40.7%)
43 (53.1%)
5 (6.2%)
|
|
Central nervous system disease/extramedullary disease
|
10 (6.1%)
|
3 (3.7%)
|
|
BCR::ABL1 dominant isoform
p190
p210
|
114 (69.5%)
40 (24.4%)
|
53 (65.4%)
25 (30.9%)
|
|
Cardiovascular comorbidities
≥1
≥2
Hypertension
Diabetes
Obesity
Dyslipidemia
History of smoking
|
92 (56.4%)
45 (27.6%)
58 (35.6%)
39 (23.9%)
33 (20.2%)
29 (17.8%)
44 (27.0%)
|
52 (64.2%)
27 (33.3%)
30 (37.0%)
24 (29.6%)
19 (23.5%)
23 (28.4%)
26 (32.1%)
|
| Results |
|
Ponatinib (n= 154) |
Imatinib (n= 78) |
p-value |
| MRD-negative complete remission rate |
53 (34.4%) |
13 (16.7%) |
0.002 |
| Event-free survival, median, months |
Not reached |
29 |
- |
| Duration of MRD-negative complete remission, median (95% CI), months |
NE (16.6-NE) |
18.0 (8.4-27.8) |
- |
| MR4 |
61 (43.0%) |
15 (22.1%) |
0.002 |
| MR4.5 |
26.8% |
14.7% |
- |
| Time to treatment failure, median, months |
Not reached |
21.9 |
- |
| Overall survival |
Not reached |
Not reached |
- |
| NE= not estimable. |
| Adverse Events |
Adverse events were similar between treatment groups.
Arterial occlusive events: ponatinib, 2.5%; imatinib, 1.2%.
VTE events: ponatinib, 11.7%; imatinib, 12.3%.
|
| Study Author Conclusions |
Ponatinib demonstrated a superior rate of MRD-negative complete remission at the end of induction vs imatinib when combined with reduced-intensity chemotherapy in adults with newly diagnosed Ph+ ALL. The safety profile of ponatinib was comparable with imatinib. |
| Critique |
The study's strengths include its randomized design and the use of a global, multicenter approach, which enhances the generalizability of the findings. However, the short duration of follow-up limits the ability to assess long-term survival outcomes. Additionally, the comparator, imatinib, is not the current standard of care in all regions, which may affect the applicability of the results in settings where second-generation tyrosine kinase inhibitors are more commonly used. |