Safety of Liposomal Cytarabine Prophylaxis in Pediatric Bone Marrow Transplant (BMT) Recipients with Acute Leukemia (AL) and Non Hodgkin Lymphoma (NHL) At High Risk of CNS Relapse

Liposomal Cytarabine is a derivative of cytarabine designed for intrathecal or intraomaya treatment of leukemia/lymphomatous meningitis (LLM). This formulation allows for sustained release with prolonged therapeutic concentration and drug exposure of 8 to 14 days in children and adults, respectively. Adult trials have shown liposomal cytarabine 50mg to be both safe and effective in the treatment of LLM (Glantz et al, JCO 1999). Bomgaars et al. investigated the use of liposomal cytarabine in children in a phase I dose escalation trial and demonstrated the maximal tolerated dose to be 35mg and that it was safe, well tolerated and effective (Bomgaars et al., JCO 2004). Comparisons of liposomal cytarabine use with conventional methotrexate prophylaxis suggest an improved quality adjusted survival benefit for patients where any possible additional toxicities are out measured by prolonged overall survival (Cole et al, Cancer 2003). However, there remains a paucity of data on the use of liposomal cytarabine prophylaxis to prevent LLM in pediatric patients, particularly in pediatric allogeneic stem cell (AlloSCT) recipients. Review of the literature reveals conflicting data concerning the efficacy of intrathecal chemoprophylaxis in children with leukemia/lymphoma after hematopoietic stem cell transplant. Recent multicenter trials suggest no statistically significant difference in the incidence of isolated or mixed CNS relapses between children receiving standard post-SCT intrathecal prophylaxis versus those that received no prophylaxis (Rubin et al., BMT 2011). This highlights the need to explore alternative chemoprophylaxis strategies in these high risk patients so that significant progress can be achieved.

We report on the safety and tolerability of liposomal cytarabine prior to and following allogeneic or autologous stem cell transplant in pediatric BMT recipients with AL and NHL.

Pediatric stem cell recipients with a history of AL or NHL and high risk of CNS disease received liposomal cytarabine 35mg (<21yr) or 50mg (>21yr) via lumbar puncture or omaya resevoir pre conditioning and approximately every 3months for 1–2yrs post stem cell transplant. No other intrathecal prophylaxis was administered. Patients received dexamethasone (0.15mg/kg/dose BID) concomitantly × 5days. Eight patients received a 9/10 or 10/10 matched unrelated donor transplant, 1 patient received an 8/10 matched unrelated donor. There were 9 matched related donor transplants and 3 autologous transplants. Twelve patients received a TBI (1200 cGy) based myeloablative conditioning regimen. Seven patients received an additional CNS boost of up to 1200 cGy during conditioning. All allogeneic SCT recipients received GVHD prophylaxis as previously described (Oswunko/Cairo, BBMT 2004; Bhatia et al, BBMT 2009) with tacrolimus and MMF.

To date there have been 21 patients: (12 ALL, 2 AML, 3 Burkitt, 3 DLBCL and 1 T-LL). At the time of transplant, 7 patients were CR1/PR1, 10 patients CR2 and 4 patients CR3. Among all patients, they have received a total of 46 doses (median=1, range 1–12). Median age: 12yr (range 6–22). Mean follow up: 517 days (median= 294days). Eight of 21 patients had a history of CNS AL/NHL involvement prior to AlloSCT. No patients had evidence of LLM at the time of AlloSCT. Two patients experienced Grade II-III headache. Grade II-III vomiting was also noted in 2 additional patients. Head CT scans that were done at the time of symptom occurrence were negative for any evidence of hydrocephalus, hemorrhage, infarct or inflammation in all patients. Patients were treated with supportive therapy and had complete resolution of symptoms. Seven patients developed relapsed systemic disease, but none relapsed in the CNS. An additional 3 patients are deceased secondary to multi organ failure and 2 patients from overwhelming infection. However, none of the above patients had CNS AL/NHL at time of death.

These preliminary results suggest that prophylactic liposomal cytarabine is tolerable and effective in pediatric AlloSCT and AutoSCT recipients at risk for CNS relapse. Larger studies are needed in the future to compare this to other CNS prophylaxis regimens post auto or AlloSCT. In addition, trials are in development to investigate the combination of intraomaya Rituximab followed by liposomal Cytarabine in children with recurrent/refractory CNS CD20+ AL/NHL.

No relevant conflicts of interest to declare.