Differentiation therapy in poor risk myeloid malignancies: Results of companion phase II studies.

Pre-clinical data in non-M3 AML supports the use of differentiation therapy, but clinical activity has been limited. Myeloid growth factors can enhance anti-leukemic activity of differentiating agents in vitro. We conducted companion phase II trials investigating sargramostim (GM-CSF) 125µg/m(2)/day plus 1) bexarotene (BEX) 300mg/m(2)/day or 2) entinostat (ENT) 4-8mg/m(2)/week in patients with MDS or relapsed/refractory AML. Primary endpoints were response after at least two treatment cycles and toxicity. 26 patients enrolled on the BEX trial had a median of 2 prior treatments and 24 enrolled on the ENT trial had a median of 1. Of 13 response-evaluable patients treated with BEX, the best response noted was hematologic improvement in neutrophils (HI-N) seen in 4 (31%) patients; none achieved complete (CR) or partial remission (PR). Of 10 treated with ENT, there was 1 (10%) partial remission (PR) and 2 (20%) with HI-N. The secondary endpoint responses of HI-N with each combination were accompanied by a numerical increase in ANC (BEX: 524 to 931 cells/mm(3), p=0.096; ENT: 578 to 1 137 cells/mm(3), p=0.15) without increasing marrow blasts. Shared grade 3-4 non-hematologic toxicities included febrile neutropenia, bone pain, fatigue, and dyspnea. GM-CSF plus either BEX or ENT are well tolerated in resistant and refractory MDS and AML and showed modest clinical and biologic activity, most commonly HI-N.

Metronidazole lacks activity against Mycobacterium tuberculosis in an in vivo hypoxic granuloma model of latency.

During human latent tuberculosis (TB) infection, dormant bacilli putatively reside within the hypoxic environment of caseating lung granulomas. The anaerobic drug metronidazole has antituberculous activity under hypoxic conditions in vitro but lacks activity against murine TB. In the present study, we used the hypoxia marker pimonidazole to demonstrate the presence of hypoxia in a novel in vivo granuloma model of Mycobacterium tuberculosis latency. We also used a high-throughput, microarray-based technique to identify mycobacterial genes essential to hypoxia and showed that this in vivo model correctly identified 51% of hypoxia-attenuated mutants, a significantly larger percentage than that identified by the mouse (29%) and guinea pig (29%) aerosol models of TB. Although isoniazid showed activity during the first 28 days of therapy and rifampin was active against dormant bacilli after the establishment of hypoxia, metronidazole showed no antituberculous activity in this in vivo hypoxic granuloma model of M. tuberculosis dormancy.