Translational PK/PD Modeling of Tumor Growth Inhibition and Target Inhibition to Support Dose Range Selection of the LMP7 Inhibitor M3258 in Relapsed/Refractory Multiple Myeloma.

M3258 is an orally bioavailable, potent, selective, reversible inhibitor of the large multifunctional peptidase 7 (LMP7, ß5i, PSMB8) proteolytic subunit of the immunoproteasome, a component of the cellular protein degradation machinery, highly expressed in malignant hematopoietic cells including multiple myeloma. Here we describe the fit-for-purpose pharmacokinetic (PK)/pharmacodynamic (PD)/efficacy modeling of M3258 based on preclinical data from several species. The inhibition of LMP7 activity (PD) and tumor growth (efficacy) were tested in human multiple myeloma xenografts in mice. PK and efficacy data were correlated yielding a free M3258 concentration of 45 nM for half-maximal tumor growth inhibition (KC50). As M3258 only weakly inhibits LMP7 in mouse cells, both in vitro and in vivo bridging studies were performed in rats, monkeys, and dogs for translational modeling. These data indicated that the PD response in human xenograft models was closely reflected in dog PBMCs. A PK/PD model was established, predicting a free IC50 value of 9 nM for M3258 in dogs in vivo, in close agreement with in vitro measurements. In parallel, the human PK parameters of M3258 were predicted by various approaches including in vitro extrapolation and allometric scaling. Using PK/PD/efficacy simulations, the efficacious dose range and corresponding PD response in human were predicted. Taken together, these efforts supported the design of a phase Ia study of M3258 in multiple myeloma patients (NCT04075721). At the lowest tested dose level, the predicted exposure matched well with the observed exposure while the duration of LMP7 inhibition was underpredicted by the model. SIGNIFICANCE STATEMENT: M3258 is a novel inhibitor of the immunoproteasome subunit LMP7. The human PK and human efficacious dose range of M3258 were predicted using in vitro-in vivo extrapolation and allometric scaling methods together with a fit-for-purpose PK/PD and efficacy model based on data from several species. A comparison with data from the Phase Ia clinical study showed that the human PK was accurately predicted, while the extent and duration of PD response were more pronounced than estimated.

Pharmacodynamic biomarkers of long-term interferon beta-1a therapy in REFLEX and REFLEXION.

This post-hoc analysis evaluated candidate biomarkers of long-term efficacy of subcutaneous interferon beta-1a (sc IFN ß-1a) in REFLEX/REFLEXION studies of clinically isolated syndrome. Samples from 507 REFLEX and 287 REFLEXION study participants were analyzed. All investigated biomarkers were significantly upregulated 1.5-4-fold in response to sc IFN ß-1a treatment versus baseline (p ≤ 0.008). The validity of MX1, 2'5'OAS, and IL-1RA as biomarkers of response to sc IFN ß-1a was confirmed in this large patient cohort, with biomarkers consistently upregulated in a dose-dependent manner. Neopterin, TRAIL, and IP-10 were confirmed as biomarkers associated with long-term sc IFN ß-1a treatment efficacy over 5 years.

Improved production of A40926 by Nonomuraea sp. through deletion of a pathway-specific acetyltransferase.

Nonomuraea strain ATCC 39727 produces the glycopeptide A40926, used for manufacturing dalbavancin, currently in advanced clinical trials. From the gene cluster involved in A40926 biosynthesis, a strain deleted in dbv23 was constructed. This mutant can produce only the glycopeptides lacking the O-linked acetyl residue at position 6 of the mannose moiety, while, under identical fermentation conditions, the wild-type strain produces mostly glycopeptides carrying an acetylated mannose. Furthermore, the total amount of glycopeptides produced by the mutant strain was found to be approximately twice that of the wild type. The reduced level of glycopeptides observed in the wild-type strain may be due to an inhibitory effect exerted by the acetylated compound on the biosynthesis of A40926. Indeed, spiking production cultures with > or =1 microg/ml of the acetylated glycopeptide inhibited A40926 production in the mutant strain.

A derivative of the glycopeptide A40926 produced by inactivation of the beta-hydroxylase gene in Nonomuraea sp. ATCC39727.

The actinomycete Nonomuraea sp. ATCC39727 produces the glycopeptide A40926. In the corresponding dbv cluster, ORF28 encodes a putative hydroxylase. A gene replacement mutant of ORF28 in Nonomuraea produces a small amount of an A40926-related metabolite, 16 amu smaller than the parent compound, which was identified as the desoxyderivative of A40926 lacking the beta-hydroxyl group on the tyrosine moiety. This result demonstrates that ORF28 is actually involved in the formation of the beta-hydroxytyrosine residue present in A40926. The formation of an altered glycopeptide and the inability to rescue A40926 production upon feeding free beta-hydroxytyrosine are consistent with the possibility that, in contrast to balhimycin formation, hydroxylation occurs after tyrosine activation by the nonribosomal peptide synthetase.

A gene transfer system for the glycopeptide producer Nonomuraea sp. ATCC39727.

The filamentous actinomycete Nonomuraea sp. ATCC39727 produces the industrially important glycopeptide antibiotic A40926. We developed a gene transfer system based on intergeneric conjugation from Escherichia coli. Analysis of the ex-conjugants revealed that the incoming plasmid pSET152 had integrated at two sites in the Nonomuraea genome. One of these was characterized and found to be highly related to other PhiC31 attB sites described in Streptomyces spp., including the core TTS sequence, where crossover occurs. Surprisingly, pSET152 was also found in episomic form in the Nonomuraea ex-conjugants.

The gene cluster for the biosynthesis of the glycopeptide antibiotic A40926 by nonomuraea species.

The glycopeptide A40926 is the precursor of dalbavancin, a second-generation glycopeptide currently under clinical development. The dbv gene cluster, devoted to A40926 biosynthesis, was isolated and characterized from the actinomycete Nonomuraea species ATCC39727. From sequence analysis, 37 open reading frames (ORFs) participate in A40926 biosynthesis, regulation, resistance, and export. Of these, 27 ORFs find a match in at least one of the previously characterized glycopeptide gene clusters, while 10 ORFs are, so far, unique to the dbv cluster. Putative genes could be identified responsible for some of the tailoring steps (attachment of glucosamine, sugar oxidation, and mannosylation) expected during A40926 biosynthesis. After constructing a Nonomuraea mutant by deleting dbv ORFs 8 to 10, the novel compound dechloromannosyl-A40926 aglycone was isolated.