ABSTRACT
Background: Diffuse intrinsic pontine glioma (DIPG) is the most common and deadliest pediatric brainstem tumor and is difficult to treat with chemotherapy in part due to the blood-brain barrier (BBB). Focused ultrasound (FUS) and microbubbles (MBs) have been shown to cause BBB opening, allowing larger chemotherapeutics to enter the parenchyma. Panobinostat is an example of a promising in vitro agent in DIPG with poor clinical efficacy due to low BBB penetrance. In this study, we hypothesized that using FUS to disrupt the BBB allows higher concentrations of panobinostat to accumulate in the tumor, providing a therapeutic effect. Methods: Mice were orthotopically injected with a patient-derived diffuse midline glioma (DMG) cell line, BT245. MRI was used to guide FUS/MB (1.5 MHz, 0.615 MPa peak negative pressure, 1 Hz pulse repetition frequency, 10-ms pulse length, 3 min treatment time)/(25 µL/kg, i.v.) targeting to the tumor location. Results: In animals receiving panobinostat (10 mg/kg, i.p.) in combination with FUS/MB, a 3-fold increase in tumor panobinostat concentration was observed, without significant increase of the drug in the forebrain. In mice receiving 3 weekly treatments, the combination of panobinostat and FUS/MB led to a 71% reduction of tumor volumes (P = .01). Furthermore, we showed the first survival benefit from FUS/MB improved delivery increasing the mean survival from 21 to 31 days (P < .0001). Conclusions: Our study demonstrates that FUS-mediated BBB disruption can increase the delivery of panobinostat to an orthotopic DMG tumor, providing a strong therapeutic effect and increased survival.
ABSTRACT
Diffuse intrinsic pontine glioma (DIPG) is the most common and deadliest pediatric brainstem tumor and is difficult to treat with chemotherapy in part due to the blood-brain barrier (BBB). Focused ultrasound (FUS) and microbubbles (MBs) have been shown to cause BBB disruption (BBBD), allowing larger chemotherapeutics to enter the parenchyma. Panobinostat is an example of a promising in vitro agent in DIPG with poor clinical efficacy due to low BBB penetrance. In this study, we hypothesized that using FUS to disrupt the BBB allows higher concentrations of panobinostat to accumulate in the tumor, providing a therapeutic effect. Mice were orthotopically injected with a patient-derived DMG cell line, BT-245. MRI was used to guide FUS/MB (1.5 MHz, 0.615 MPa PNP, 1 Hz PRF, 10 ms PL, 3 min treatment time) / (25 µL/kg, IV) targeting to the tumor location. In animals receiving panobinostat (10 mg/kg, IP) in combination with FUS/MB, a 3-fold increase in tumor panobinostat concentration was observed, with only insignificant increase of the drug in the forebrain. In mice receiving three weekly treatments, the combination of panobinostat and FUS/MB led to a 71% reduction of tumor volumes by MRI ( p = 0.01). Furthermore, FUS/MB improved the mean survival from 21 to 31 days ( p < 0.0001). Our study demonstrates that FUS-mediated BBBD can increase the delivery of panobinostat to an orthotopic DMG tumor, providing a strong therapeutic effect and increased survival. One Sentence Summary: FUS and microbubbles can increase the delivery of panobinostat to a patient-derived xenograft (PDX) orthotopic DMG tumor, providing a strong therapeutic effect and increased survival.
ABSTRACT
A triply convergent synthetic approach which culminates in the enantioselective syntheses of the C(1)-C(9) and C(12)-C(26) subunits of the macrolide antitumor agent rhizoxin is described. The central C(12)-C(20) subunit 4 has been prepared efficiently via diastereoselective enzymatic acetate hydrolysis of 15 with porcine pancreatic lipase, a chelation-controlled Ireland-Claisen rearrangement (10 --> 12) combined with kinetic bromolactonization (12 --> 14), and Mitsunobu inversion (23 --> 26) to introduce the three contiguous C(15)-C(17) stereocenters. Formation of the C(18)-C(19) trisubstituted (E)-olefin was achieved by a stereoselective Horner-Wadsworth-Emmons reaction. The central segment 4 and the oxazole chromophore side chain 3 were coupled using another highly stereoselective Horner-Wadsworth-Emmons reaction. Two different lactone subunits [C(1)-C(9) segment 5 and C(3)-C(10) segment 47] were also prepared, employing a thermodynamically controlled diastereotopic group differentiation tactic for establishing the C(5) stereochemistry.
