Optimization of therapeutic antibodies for reduced self-association and non-specific binding via interpretable machine learning.

Antibody development, delivery, and efficacy are influenced by antibody-antigen affinity interactions, off-target interactions that reduce antibody bioavailability and pharmacokinetics, and repulsive self-interactions that increase the stability of concentrated antibody formulations and reduce their corresponding viscosity. Yet identifying antibody variants with optimal combinations of these three types of interactions is challenging. Here we show that interpretable machine-learning classifiers, leveraging antibody structural features descriptive of their variable regions and trained on experimental data for a panel of 80 clinical-stage monoclonal antibodies, can identify antibodies with optimal combinations of low off-target binding in a common physiological-solution condition and low self-association in a common antibody-formulation condition. For three clinical-stage antibodies with suboptimal combinations of off-target binding and self-association, the classifiers predicted variable-region mutations that optimized non-affinity interactions while maintaining high-affinity antibody-antigen interactions. Interpretable machine-learning models may facilitate the optimization of antibody candidates for therapeutic applications.

ImmTOR nanoparticles enhance AAV transgene expression after initial and repeat dosing in a mouse model of methylmalonic acidemia.

A major barrier to adeno-associated virus (AAV) gene therapy is the inability to re-dose patients due to formation of vector-induced neutralizing antibodies (Nabs). Tolerogenic nanoparticles encapsulating rapamycin (ImmTOR) provide long-term and specific suppression of adaptive immune responses, allowing for vector re-dosing. Moreover, co-administration of hepatotropic AAV vectors and ImmTOR leads to an increase of transgene expression even after the first dose. ImmTOR and AAV Anc80 encoding the methylmalonyl-coenzyme A (CoA) mutase (MMUT) combination was tested in a mouse model of methylmalonic acidemia, a disease caused by mutations in the MMUT gene. Repeated co-administration of Anc80 and ImmTOR was well tolerated and led to nearly complete inhibition of immunoglobulin (Ig)G antibodies to the Anc80 capsid. A more profound decrease of plasma levels of the key toxic metabolite, plasma methylmalonic acid (pMMA), and disease biomarker, fibroblast growth factor 21 (FGF21), was observed after treatment with the ImmTOR and Anc80-MMUT combination. In addition, there were higher numbers of viral genomes per cell (vg/cell) and increased transgene expression when ImmTOR was co-administered with Anc80-MMUT. These effects were dose-dependent, with the higher doses of ImmTOR providing higher vg/cell and mRNA levels, and an improved biomarker response. Combining of ImmTOR and AAV can not only block the IgG response against capsid, but it also appears to potentiate transduction and enhance therapeutic transgene expression in the mouse model.

Enhancement of liver-directed transgene expression at initial and repeat doses of AAV vectors admixed with ImmTOR nanoparticles.

Systemic AAV (adeno-associated virus) gene therapy is a promising approach for the treatment of inborn errors of metabolism, but questions remain regarding its potency and durability. Tolerogenic ImmTOR nanoparticles encapsulating rapamycin have been shown to block the formation of neutralizing anti-capsid antibodies, thereby enabling vector re-administration. Here, we further demonstrate that ImmTOR admixed with AAV vectors also enhances hepatic transgene expression at the initial dose of AAV vector, independent of its effects on adaptive immunity. ImmTOR enhances AAV trafficking to the liver, resulting in increased hepatic vector copy numbers and transgene mRNA expression. Enhanced transgene expression occurs through a mechanism independent of the AAV receptor and cannot be replicated in vivo with free rapamycin or empty nanoparticles. The multipronged mechanism of ImmTOR action makes it an attractive candidate to enable more efficient transgene expression at first dose while simultaneously inhibiting adaptive responses against AAV to enable repeat dosing.

Thrombocytosis during antifungal therapy of candidemia.

BACKGROUND: Secondary, "reactive," thrombocytosis has been attributed to bacterial infection and treatment with multiple pharmaceuticals and may be associated with an increase in the incidence of gastrointestinal tract bleeding and thrombotic events (eg, stroke). OBJECTIVE: To characterize the dynamics of thrombocytosis in patients with candidemia receiving antifungal therapy. METHODS: We initiated a retrospective observational description of patients with candidemia who were treated with antifungal agents. A total of 108 patients diagnosed with candidemia between August 1995 and September 2003 at our teaching hospital were enrolled. Three groups (candidemia with antifungal therapy, candidemia without antifungal therapy, antifungal therapy without candidemia) of patients >18 years of age were evaluated for the presence of thrombocytosis. Platelet administration, pharmacologic or pathologic contributors to thrombocytosis, and other pertinent details related to an elevation of platelet counts were scrutinized. RESULTS: Reactive thrombocytosis was observed in approximately 10% of treated patients with candidemia. Within the subgroup developing reactive thrombocytosis, life-threatening thrombotic complications were uncommon. Mean baseline platelet counts were 393 x 10(3)/mm3, with a mean peak (695 x 10(3)/mm3) occurring an average of 13 days after initiation of therapy. All patients had resolution within 7 days after therapy. The maximum peak (1056 x 10(3)/mm3) was observed in a patient after 14 days of antifungal therapy. The onset of thrombocytosis in this patient was 4 days and lasted 4 days after therapy. CONCLUSIONS: Reactive thrombocytosis occurs during treatment of candidemia. The causative agent (drug vs disease), the risk associated with this reaction, and evaluation of treatment need to be elucidated by a larger epidemiologic study or controlled, prospective clinical trial.

Unusual skin lesions in chronic myelomonocytic leukemia.

Chronic myelomonocytic leukemia (CMML) is a relatively rare, heterogeneous syndrome classified as a myelodysplastic syndrome according to the French-American-British classification system. The patient's presenting symptom was a pigmented skin nodule that, although common for cases of acute monoblastic leukemia, is peculiar for CMML. This case should increase awareness of the inclusion of CMML in the differential diagnosis of a discolored nodule and highlight the clinicopathologic considerations and therapeutic challenges consistent with the diagnosis of CMML.