FDA Grants Dasatinib Priority Review for Children With Ph+ Chronic Phase CML

Lia Gore, MD, associate professor in the division of oncology at the University of Colorado School of Medicine

Lia Gore, MD

The FDA has accepted a supplemental new drug application (sNDA) for dasatinib (Sprycel) for use in children with Philadelphia chromosome-positive chronic phase chronic myeloid leukemia (CP Ph+ CML).

The agency also granted priority review for a powder for oral suspension (PFOS) formulation of dasatinib, according to Bristol Myers-Squibb, the manufacturer of the tyrosine kinase inhibitor.

The FDA is expected to issue a final decision on the sNDAs by November 9, 2017. The agency’s decision was based on phase II results from the CA180-226 trial presented in June at the 22nd Congress of the European Hematology Association and the 2017 ASCO Annual Meeting.

Primary objectives were major cytogenetic response (MCyR) for refractory/intolerant patients and complete cytogenetic response (CCyR) for newly-diagnosed patients. MCyR >30% and CCyR >55% were considered of clinical interest.

More than half of patients (55%; 95% CI, 36-74) reached MCyR >30% within 3 months. “Median duration of response has not been attained on this cohort yet, and responses at 12 and 24 months exceeded 90%,” lead author Lia Gore, MD, associate professor in the division of oncology at the University of Colorado School of Medicine said when presenting the data at the 2017 ASCO Annual Meeting.

For newly diagnosed patients, 61% (95% CI, 46-74) of those assigned to tablets and 70% (95% CI, 51-84) of the PFOS group reached cumulative rate of CCyR >55% as early as 6 months. The median duration has not been reached and, like the refractory/intolerant group, response rates were greater than 90% at 12 and 24 months.

The cumulative rate of major molecular response (MMR) in the refractory/intolerant cohort was 41% at 12 months, 55% at 24 months, and continued increasing over time. At 12 months, MMR was 57% for newly-diagnosed patients assigned to tablets and 45% for those assigned to PFOS. Those responses increased to 75% and 64%, respectively, at 24 months.

At 48 months, the estimated progression-free survival (PFS) rate was 78% in the refractory/intolerant group and 93% for newly-diagnosed patients regardless of treatment formulation. Gore added that median PFS has not been reached because only 7 patients in each cohort have experienced progression.

“We believe our data suggest that dasatinib could be considered as a new standard of care for children with CML in chronic phase,” Gore said.

CA180-226 is an international, open-label nonrandomized prospective study conducted in 18 countries from March 2009 to September 2014. Gore presented results from pediatric patients with CML in chronic phase, one group with imatinib-refractory or -intolerant disease (n = 29) and the other with newly-diagnosed patients.

Patients in the relapsed/intolerant group were assigned to 60 mg/m² dasatinib tablets. Newly-diagnosed patients were divided into 2 treatment groups, one assigned to 60 mg/m2 dasatinib tablets (n = 51) and the other to 72 mg/m2 PFOS (n = 33). Gore said the groups were not designed to be compared with each other.

Treatment continued until progression, toxicity, or withdrawal.

Of patients treated, 48% of the refractory/intolerant group and 73% of the newly-diagnosed patients remain on-study. Ten percent of newly diagnosed patients assigned to tablets discontinued due to progression, compared with 3% of newly-diagnosed patients assigned to PFOS and 17% for refractory/intolerant patients. Patients assigned to PFOS could cross over to tablets after 12 months of treatment, and 22 patients did so.

Median duration of treatment for refractory/intolerant patients was 49.91 months and median follow-up was 62.4 months. For newly diagnosed patients treated with tablets, median duration of treatment was 52.24 months and median follow-up was 54.3 months. For the PFOS newly diagnosed group, median duration of treatment was 27.40 months and median follow-up was 32.5 months. Gore said the PFOS group began enrollment after the other 2 cohorts.

One patient in the refractory/intolerant group who discontinued for progression died of a gastrointestinal bleed a year after going off treatment.

Overall, only 2 patients in the study experienced grade 3/4 adverse events: 1 patient in the refractory/intolerant cohort experienced myalgia/arthralgia and 1 newly-diagnosed patient assigned to tablets experienced hemorrhage.

“There were no occurrences of pleural effusion, pericardial effusion, pulmonary edema, pulmonary hypertension, or any vascular occlusive events in patients noted on this trial,” Gore said.

She added that investigators observed only 5 growth and development events, and all were grade 1/2.

Gore L, Kearns P, Lee ML, et al. Phase II trial of dasatinib in pediatric patients with Chronic Myeloid Leukemia in chronic phase. J Clin Oncol 35, 2017 (suppl; abstr 10511).