Increments in DNA-thioguanine level during thiopurine-enhanced maintenance therapy of acute lymphoblastic leukemia.

Maintenance therapy containing methotrexate and 6-mercapto - purine is essential to cure acute lymphoblastic leukemia (ALL). Cytotoxicity is elicited by incorporation of thioguanine nucleotides into DNA (DNA-TG), and higher leukocyte DNA-TG is associated with increased relapse-free survival. As 6-thioguanine provides 6- fold higher cytosolic levels of thioguanine nucleotides than does 6- mercapto purine, we added low-dose 6-thioguanine to methotrexate/6- mercapto purine maintenance therapy to explore if this combination results in significantly higher DNA-TG. The target population of the "Thiopurine Enhanced ALL Maintenance therapy" (TEAM) study was 30 patients with non-high-risk ALL, aged 1-45 years on methotrexate/6-mercaptopurine maintenance therapy receiving no other systemic chemotherapy. Incremental doses of 6-thioguanine were added to methotrexate/6-mercaptopurine maintenance therapy (starting 6-thioguanine dose: 2.5 mg/m2/day, maximum: 12.5 mg/m2/day). The primary endpoint was DNA-TG increments. Thirty-four patients were included, and 30 patients completed maintenance therapy according to the TEAM strategy. Of these 30 patients, 26 (87%) tolerated 10.0-12.5 mg/m2/day as the maximum 6-thioguanine dose. TEAM resulted in significantly higher DNA-TG levels compared to those in both TEAM patients before their inclusion in TEAM (on average 251 fmol/mg DNA higher [95% confidence interval: 160-341; P<0.0001]), and with historical patients receiving standard methotrexate/6-mercapto - purine maintenance therapy (on average 272 fmol/mg DNA higher [95% confidence interval: 147-398; P<0.0001]). TEAM did not increase myelotoxicity or hepatotoxicity. In conclusion, TEAM is an innovative and feasible approach to improve maintenance therapy and results in higher DNA-TG levels without inducing additional toxicity. It may therefore be an effective strategy to reduce the risk of ALL relapse through increased DNA-TG. This will be tested in a randomized ALLTogether-1 substudy.

Serial Ultrasound Monitoring for Early Recognition of Asparaginase Associated Pancreatitis in Children With Acute Lymphoblastic Leukemia.

BACKGROUND: Acute lymphoblastic leukemia (ALL) is the most common cancer in children and L-asparaginase is an essential component of the treatment. Cessation of L-asparaginase decreases event free survival. Acute pancreatitis is the toxicity that most commonly results in cessation of L-asparaginase. We tested whether serial ultrasound examinations could predict asparaginase-associated pancreatitis (AAP). METHODS: Children (aged 1.0-17.9 years) with childhood ALL treated at the University Hospital Rigshopitalet, Copenhagen, according to the standard or intermediate risk arms of the NOPHO ALL2008 protocol, with PEG-asparaginase of 2 or 6 week intervals, for 30 weeks had their pancreas monitored using serial ultrasound in order to detect early signs of inflammation. RESULTS: Nineteen of 31 eligible patients were included. Three of the included patients developed AAP. None of the patients, including the three patients that developed AAP, had signs of inflammatory edema or pancreas enzymes above three times the upper normal limit prior to AAP. CONCLUSION: We found no signs of inflammatory edema within the pancreas on ultrasound during treatment with PEG-asparginase in our cohort prior to development of AAP or in patients that did not develop AAP.