The advent of ponatinib (Iclusig; Takeda) in combination with chemotherapy is poised to influence upcoming guidelines for Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL). This follows the FDA's accelerated approval of the dual therapy as a first-line treatment for patients with newly diagnosed Ph+ ALL earlier this year.
The phase 3 PhALLCON trial (NCT03589326), a randomized, multicenter, active-controlled, open-label study, highlighted the efficacy of ponatinib. The trial revealed that 30% of patients in the ponatinib arm achieved minimal residual disease (MRD)-negative complete remission (CR). In this study, patients were randomized to receive either oral ponatinib at 30 mg daily or oral imatinib at 600 mg daily. The risk difference favoring ponatinib was 0.18 (95% CI, 0.08-0.28; P = .0004).
Clinical Impact of Ponatinib
According to Elias Jabbour, MD, The University of Texas MD Anderson Cancer Center and lead investigator of the PhALLCON trial, "Ph+ ALL is an extremely aggressive cancer and patients with this disease suffer from poor outcomes. There has long been a need for a potent TKI that can suppress mutation development and elicit deep responses in the frontline."
During the trial, both groups underwent 3 cycles of induction chemotherapy with dexamethasone and vincristine, followed by 6 consolidation cycles alternating between cytarabine and methotrexate, and 11 maintenance cycles with prednisone and vincristine. Post MRD-negative CR, a reduction of ponatinib dosage to 15 mg daily is recommended.
Current Treatment Landscape
Existing guidelines for Ph+ ALL are generally consistent for adolescent and young adults (AYA; aged 15-39 years) and adults aged 40 years and older. Treatment strategies are largely dictated by the patient's Philadelphia chromosome status. First-line treatment typically involves a combination of chemotherapy and a TKI. Allogeneic stem cell transplant is recommended for AYA patients with a suitable donor, and should also be considered for adult patients with good performance status and minimal comorbidities.
Other FDA-approved TKIs for Ph+ ALL include dasatinib and imatinib, often administered with chemotherapy regimens like hyper-CVAD. Studies have shown that adding hyper-CVAD to imatinib can improve 3-year CR rates compared to imatinib alone (68% vs 24%). Dasatinib combined with hyper-CVAD has demonstrated CR rates as high as 94% in Ph+ ALL patients.
Ponatinib in Resistant Cases
Ponatinib has shown a major hematologic response in 41% of Ph+ ALL cases where patients were intolerant or unresponsive to other TKIs, such as dasatinib. However, it's important to note that ponatinib carries an increased risk of thromboembolic events and is often reserved as a monotherapy for patients with T3151 mutations or those who have not benefited from other TKIs.
Awny Farajallah, MD, chief medical officer, oncology at Takeda, stated, "We are thrilled that the FDA has recognized the potential of Iclusig to fill a large gap in care for these patients and look forward to seeing the impact this can have on people with this rare and aggressive form of cancer."
