6 research outputs found
High-Throughput, Multispecies, Parallelized Plasma Stability Assay for the Determination and Characterization of Antibody–Drug Conjugate Aggregation and Drug Release
The stability of
antibody–drug conjugates (ADCs) in circulation
is critical for maximum efficacy and minimal toxicity. An ADC reaching
the intended target intact can deliver the highest possible drug load
to the tumor and reduce off-target toxicity from free drug in the
blood. As such, assessment of ADC stability is a vital piece of data
during development. However, traditional ADC stability assays can
be manually intensive, low-throughput, and require large quantities
of ADC material. Here, we introduce an automated, high-throughput
plasma stability assay for screening drug release and aggregation
over 144 h for up to 40 ADCs across five matrices simultaneously.
The amount of ADC material during early drug development is often
limited, so this assay was implemented in 384-well format to minimize
material requirements to <100 μg of each ADC and 100 μL
of plasma per species type. Drug release and aggregation output were
modeled using nonlinear regression equations to calculate formation
rates for each data type. A set of 15 ADCs with different antibodies
and identical valine–citrulline–<i>p</i>-aminobenzylcarbamate–monomethylauristatin
E linker-drug payloads was tested and formation rates were compared
across ADCs and between species, revealing several noteworthy trends.
In particular, a wide range in aggregation was found when altering
only the antibody, suggesting a key role for plasma stability screening
early in the development process to find and remove antibody candidates
with the potential to create unstable ADCs. The assay presented here
can be leveraged to provide stability data on new chemistry and antibody
screening initiatives, select the best candidate for in vivo studies,
and provide results that highlight stability issues inherent to particular
ADC designs throughout all stages of ADC development
Pharmaceutical Development Challenges in a Beyond Rule of Five Prodrug: Case Study of ABBV-167, Phosphate Prodrug of Venetoclax
ABBV-167,
a phosphate prodrug of BCL-2 inhibitor venetoclax, was
recently progressed into the clinic as an alternative means of reducing
pill burden for patients in high-dose indications. The dramatically
enhanced aqueous solubility of ABBV-167 allowed for high drug loading
within a crystalline tablet and, when administered in phase I clinical
study, conferred venetoclax exposure commensurate with the equivalent
dose administered as an amorphous solid dispersion. In enabling the
progression into the clinic, we performed a comprehensive evaluation
of the CMC development aspects of this beyond the rule of five (bRo5)
prodrug. Adding a phosphate moiety resulted in excessively complex
chemical speciation and solid form landscapes with significant physical-chemical
stability liabilities. A combination of experimental and computational
methods including microelectron diffraction (MicroED), total scattering,
tablet colorimetry, finite element, and molecular dynamics modeling
were used to understand CMC developability across drug substance and
product manufacture and storage. The prodrug’s chemical structural
characteristics and loose crystal packing were found to be responsible
for the loss of crystallinity during its manufacturing, which in turn
led to high solid-state chemical reactivity and poor shelf life stability.
The ABBV-167 case exemplifies key CMC development challenges for complex
chemical matter such as bRo5 phosphate prodrugs with significant ramifications
during drug substance and drug product manufacturing and storage
ABT-199, a potent and selective BCL-2 inhibitor, achieves antitumor activity while sparing platelets
Proteins in the B cell CLL/lymphoma 2 (BCL-2) family are key regulators of the apoptotic process. This family comprises proapoptotic and prosurvival proteins, and shifting the balance toward the latter is an established mechanism whereby cancer cells evade apoptosis. The therapeutic potential of directly inhibiting prosurvival proteins was unveiled with the development of navitoclax, a selective inhibitor of both BCL-2 and BCL-2-like 1 (BCL-X L), which has shown clinical efficacy in some BCL-2-dependent hematological cancers. However, concomitant on-target thrombocytopenia caused by BCL-X L inhibition limits the efficacy achievable with this agent. Here we report the re-engineering of navitoclax to create a highly potent, orally bioavailable and BCL-2-selective inhibitor, ABT-199. This compound inhibits the growth of BCL-2-dependent tumors in vivo and spares human platelets. A single dose of ABT-199 in three patients with refractory chronic lymphocytic leukemia resulted in tumor lysis within 24 h. These data indicate that selective pharmacological inhibition of BCL-2 shows promise for the treatment of BCL-2-dependent hematological cancers.close20113
Discovery of a Potent and Selective BCL‑X<sub>L</sub> Inhibitor with <i>in Vivo</i> Activity
A-1155463, a highly potent and selective
BCL-X<sub>L</sub> inhibitor,
was discovered through nuclear magnetic resonance (NMR) fragment screening
and structure-based design. This compound is substantially more potent
against BCL-X<sub>L</sub>-dependent cell lines relative to our recently
reported inhibitor, WEHI-539, while possessing none of its inherent
pharmaceutical liabilities. A-1155463 caused a mechanism-based and
reversible thrombocytopenia in mice and inhibited H146 small cell
lung cancer xenograft tumor growth <i>in vivo</i> following
multiple doses. A-1155463 thus represents an excellent tool molecule
for studying BCL-X<sub>L</sub> biology as well as a productive lead
structure for further optimization