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Author(s): Arrieta, Antonio C; Sung, Lillian; Bradley, John S; Zwaan, C Michel; Gates, Davis; Waskin, Hetty; Carmelitano, Patricia; Groll, Andreas H; Lehrnbecher, Thomas; Mangin, Eric; Joshi, Amita; Kartsonis, Nicholas A; Walsh, Thomas J; Paschke, Amanda | Abstract: BACKGROUND:Posaconazole (POS) is a potent triazole antifungal agent approved in adults for treatment and prophylaxis of invasive fungal infections (IFIs). The objectives of this study were to evaluate the pharmacokinetics (PK), safety, and tolerability of POS oral suspension in pediatric subjects with neutropenia. METHODS:This was a prospective, multicenter, sequential dose-escalation study. Enrolled subjects were divided into 3 age groups: AG1, 7 to l18 years; AG2, 2 to l7 years; and AG3, 3 months to l2 years. AG1 and AG2 were divided into 3 dosage cohorts: DC1, 12 mg/kg/day divided twice daily (BID); DC2, 18 mg/kg/day BID; and DC3, 18 mg/kg/day divided thrice daily (TID). AG3 was also divided into DC1 and DC2; however, no subjects were enrolled in DC2. Subjects received 7-28 days of POS oral suspension. PK samples were collected at predefined time points. The POS PK target was predefined as ~90% of subjects with Cavg (AUC /dosing interval) between 500 and 2500 ng/mL, with an anticipated mean steady state Cavg exposure of ~1200 ng/mL. RESULTS:The percentage of subjects meeting the PK target was l90% across all age groups and dosage cohorts (range: 31% to 80%). The percentage of subjects that achieved the Cavg target of 500 to 2500 ng/mL on Day 7 ranged from 31% to 80%, with the lowest proportion in subjects 2 to l7 years receiving 12 mg/kg/day BID (AG2/DC1) and the highest proportion in subjects 7 to l18 years receiving 18 mg/kg/day TID (AG1/DC3). At all three dose levels (12 mg/kg/day BID, 18 mg/kg/day BID and 18 mg/kg/day TID), subjects in AG1 (7 to l18 years old) had higher mean PK exposures at steady state than those in AG2. High variability in exposures was observed in all groups. POS oral suspension was generally well tolerated and most of the reported adverse events were related to the subjects' underlying diseases. CONCLUSION:The POS PK target of 90% of subjects with Cavg between 500 and 2500 ng/mL was not achieved in any of the age groups across the different dosage cohorts. New formulations of the molecule with a greater potential to achieve the established PK target are currently under investigation. TRIAL REGISTRATION:ClinicalTrials.gov identifier: NCT01716234.

Background: Recent studies show the importance of interactions between CD47 expressed on acute myeloid leukemia (AML) cells and the inhibitory immunoreceptor, signal regulatory protein-alpha (SIRP alpha) on macrophages. Although AML cells express SIRP alpha, its function has not been investigated in these cells. In this study we aimed to determine the role of the SIRP alpha in acute myeloid leukemia.Design and Methods: We analyzed the expression of SIRP alpha, both on mRNA and protein level in AML patients and we further investigated whether the expression of SIRP alpha on two low SIRP alpha expressing AML cell lines could be upregulated upon differentiation of the cells. We determined the effect of chimeric SIRP alpha expression on tumor cell growth and programmed cell death by its triggering with an agonistic antibody in these cells. Moreover, we examined the efficacy of agonistic antibody in combination with established antileukemic drugs.Results: By microarray analysis of an extensive cohort of primary AML samples, we demonstrated that SIRP alpha is differentially expressed in AML subgroups and its expression level is dependent on differentiation stage, with high levels in FAB M4/M5 AML and low levels in FAB M0-M3. Interestingly, AML patients with high SIRP alpha expression had a poor prognosis. Our results also showed that SIRP alpha is upregulated upon differentiation of NB4 and Kasumi cells. In addition, triggering of SIRP alpha with an agonistic antibody in the cells stably expressing chimeric SIRP alpha, led to inhibition of growth and induction of programmed cell death. Finally, the SIRP alpha-derived signaling synergized with the activity of established antileukemic drugs.Conclusions: Our data indicate that triggering of SIRP alpha has antileukemic effect and may function as a potential therapeutic target in AML.

Development of relapse remains a problem for further improvements in the survival of pediatric AML patients. While virtually all patients show a good response to initial treatment, more patients respond poorly when treated at relapse. The cellular characteristics of leukemic blast cells that allow survival of initial treatment, relapse development and subsequent resistance to salvage treatment remain largely elusive. Therefore, we studied if leukemic blasts at relapse biologically resemble their initial diagnosis counterparts. We performed microarray gene expression profiling on paired initial and relapse samples of 23 pediatric AML patients. In 11 out of 23 patients, gene expression profiles of initial and corresponding relapse samples end up in different clusters in unsupervised analysis, indicating altered gene expression profiles. In addition, shifts in type I/II mutational status were found in 5 of these 11 patients, while shifts were found in 3 of the remaining 12 patients. Although differentially expressed genes varied between patients, they were commonly related to hematopoietic differentiation, encompassed genes involved in chromatin remodeling and showed associations with similar transcription factors. The top five were CEBPA, GFI1, SATB1, KLF2 and TBP. In conclusion, the leukemic blasts at relapse are biologically different from their diagnosis counterparts. These differences may be exploited for further development of novel treatment strategies. OA gold