Nonclinical Profile of BLZ-100, a Tumor-Targeting Fluorescent Imaging Agent.

BLZ-100 is a single intravenous use, fluorescent imaging agent that labels tumor tissue to enable more complete and precise surgical resection. It is composed of a chlorotoxin peptide covalently bound to the near-infrared fluorophore indocyanine green. BLZ-100 is in clinical development for intraoperative visualization of human tumors. The nonclinical safety and pharmacokinetic (PK) profile of BLZ-100 was evaluated in mice, rats, canines, and nonhuman primates (NHP). Single bolus intravenous administration of BLZ-100 was well tolerated, and no adverse changes were observed in cardiovascular safety pharmacology, PK, and toxicology studies in rats and NHP. The single-dose no-observed-adverse-effect-levels (NOAELs) were 7 mg (28 mg/kg) in rats and 60 mg (20 mg/kg) in NHP, corresponding to peak concentration values of 89 400 and 436 000 ng/mL and area-under-the-curve exposure values of 130 000 and 1 240 000 h·ng/mL, respectively. Based on a human imaging dose of 3 mg, dose safety margins are >100 for rat and monkey. BLZ-100 produced hypersensitivity reactions in canine imaging studies (lethargy, pruritus, swollen muzzle, etc). The severity of the reactions was not dose related. In a follow-up study in dogs, plasma histamine concentrations were increased 5 to 60 minutes after BLZ-100 injection; this coincided with signs of hypersensitivity, supporting the conclusion that the reactions were histamine based. Hypersensitivity reactions were not observed in other species or in BLZ-100 human clinical studies conducted to date. The combined imaging, safety pharmacology, PK, and toxicology studies contributed to an extensive initial nonclinical profile for BLZ-100, supporting first-in-human clinical trials.

Preclinical safety, pharmacokinetics, and pharmacodynamics of recombinant human interleukin-21 in cynomolgus macaques (Macaca fascicularis).

Interleukin-21 (IL-21), a pleiotropic immunostimulatory type I cytokine, has anticancer effects in animal models. Preclinical studies designed to assess the safety of recombinant human IL-21 (rIL-21) for use in phase I oncology studies are described. The rIL-21 (≤3.0 mg/kg per dose) was given intravenously to cynomolgus monkeys (Macaca fascicularis) once daily for 5 days, followed by 9 nondosing days (1 cycle) for ≤4 cycles. The rIL-21 pharmacokinetics was dose-dependent. Accumulation was not observed after repeated dosing, consistent with the short elimination half-life (t (1/2,λz); 0.4-0.8 hours). Safety findings included cyclical anemia and thrombocytopenia, clinical pathology changes consistent with acute-phase response, leukocyte infiltrates in hepatic sinusoids, and sporadic serum transaminase elevations (typically <3 times upper-limit of normal); all were reversible upon cessation of treatment. Decreased pharmacodynamic responses with time corresponded to the development of anti-rIL-21 antibodies; effects varied among individuals and were dose-dependent. These studies demonstrated rIL-21 to be generally well-tolerated when administered to cynomolgus monkeys, and all adverse effects were reversible upon treatment cessation. However, development of anti-rIL-21 antibodies may limit the use of this species in long-term studies.

Phase 1b study of pegylated interferon lambda 1 with or without ribavirin in patients with chronic genotype 1 hepatitis C virus infection.

UNLABELLED: Interferon lambda 1 (IFN-lambda1) is a type III IFN that produces intracellular responses similar to those of IFN-alpha but in fewer cell types because of differences in the receptor distribution pattern, and this could potentially result in an improved safety profile. This was an open-label three-part study of patients with chronic hepatitis C virus (HCV) genotype 1 infection. Part 1 evaluated single-agent pegylated interferon lambda (PEG-IFN-lambda) at 1.5 or 3.0 microg/kg administered every 2 weeks or weekly for 4 weeks in patients who had relapsed after previous IFN-alpha-based treatment. Part 2 evaluated weekly doses of PEG-IFN-lambda ranging from 0.5 to 2.25 microg/kg in combination with ribavirin (RBV) for 4 weeks in treatment-relapse patients. Part 3 evaluated weekly PEG-IFN-lambda at 1.5 microg/kg in combination with RBV for 4 weeks in treatment-naive patients. Fifty-six patients were enrolled: 24 patients in part 1, 25 patients in part 2, and 7 patients in part 3. Antiviral activity was observed at all PEG-IFN-lambda dose levels (from 0.5 to 3.0 microg/kg). Two of seven treatment-naive patients (29%) achieved rapid virological response. Treatment was well tolerated with minimal flu-like symptoms and no significant hematologic changes other than RBV-associated decreases in hemoglobin. The most common adverse events were fatigue (29%), nausea (12%), and myalgia (11%). Six patients experienced increases in aminotransferases that met protocol-defined criteria for dose-limiting toxicity (DLT) or temporarily holding therapy with PEG-IFN-lambda. Most DLT occurred in patients with high PEG-IFN-lambda exposure. CONCLUSION: Weekly PEG-IFN-lambda with or without daily RBV for 4 weeks is well tolerated with minimal adverse events and hematologic effects and is associated with clear antiviral activity across a broad range of doses in patients with chronic HCV.

Recombinant soluble human FcgammaR1A (CD64A) reduces inflammation in murine collagen-induced arthritis.

Binding of immune complexes to cellular FcgammaRs can promote cell activation and inflammation. In previous studies, a recombinant human (rh) soluble FcgammaR, rh-FcgammaRIA (CD64A), was shown to block inflammation in passive transfer models of immune complex-mediated disease. To assess whether rh-FcgammaRIA could block inflammation in a T cell- and B cell-dependent model of immune complex-mediated disease, the efficacy of rh-FcgammaRIA in collagen-induced arthritis was evaluated. Mice with established arthritis were treated with a single s.c. injection of rh-FcgammaRIA (0.2-2.0 mg/dose) given every other day for 11 days. Relative to mice injected with vehicle alone, mice treated with rh-FcgammaRIA exhibited lower serum concentrations of IL-6, anti-type II collagen Abs, and total IgG2a. These changes were correlated with lower levels of paw swelling and joint damage in the rh-FcgammaRIA-treated mice and occurred in the presence of a significant murine Ab response to rh-FcgammaRIA. Comparison of the serum rh-FcgammaRIA concentration vs time profiles for rh-FcgammaRIA administered at two dose levels by i.v. and s.c. injection revealed that the bioavailabilty of s.c. administered rh-FcgammaRIA was 27-37%. Taken together, these data show that rh-FcgammaRIA is an effective inhibitor of inflammation in a model of established arthritis in mice.

A first-in-human study of BLZ-100 (tozuleristide) demonstrates tolerability and safety in skin cancer patients.

BLZ-100 (tozuleristide) is an intraoperative fluorescent imaging agent that selectively detects malignant tissue and can be used in real time to guide tumor resection. The purpose of this study was to assess the safety, tolerability, and pharmacokinetics of BLZ-100 and to explore the pharmacodynamics of fluorescence imaging of skin tumors. In this first-in-human study, BLZ-100 was administered intravenously to 21 adult patients 2 days before excising known or suspected skin cancers. Doses were 1, 3, 6, 12, and 18 mg, with 3-6 patients/cohort. Fluorescence imaging was conducted before and up to 48 h after dosing. BLZ-100 was well tolerated. There were no serious adverse events, deaths, or discontinuations due to adverse events, and no maximum tolerated dose (MTD) was identified. Headache (n = 2) and nausea (n = 2) were the only BLZ-100 treatment-related adverse events reported for >1 patient. Median time to maximal serum concentration was <0.5 h. Exposure based on maximal serum concentrations increased in a greater than dose-proportional manner. For intermediate dose-levels (3-12 mg), 4 of 5 basal cell carcinomas and 4 of 4 melanomas were considered positive for BLZ-100 fluorescence. BLZ-100 was well tolerated at all dose levels tested and these results support further clinical testing of this imaging agent in surgical oncology settings. Clinicaltrials.gov: NCT02097875.

A potent peptide-steroid conjugate accumulates in cartilage and reverses arthritis without evidence of systemic corticosteroid exposure.

On-target, off-tissue toxicity limits the systemic use of drugs that would otherwise reduce symptoms or reverse the damage of arthritic diseases, leaving millions of patients in pain and with limited physical mobility. We identified cystine-dense peptides (CDPs) that rapidly accumulate in cartilage of the knees, ankles, hips, shoulders, and intervertebral discs after systemic administration. These CDPs could be used to concentrate arthritis drugs in joints. A cartilage-accumulating peptide, CDP-11R, reached peak concentration in cartilage within 30 min after administration and remained detectable for more than 4 days. Structural analysis of the peptides by crystallography revealed that the distribution of positive charge may be a distinguishing feature of joint-accumulating CDPs. In addition, quantitative whole-body autoradiography showed that the disulfide-bonded tertiary structure is critical for cartilage accumulation and retention. CDP-11R distributed to joints while carrying a fluorophore imaging agent or one of two different steroid payloads, dexamethasone (dex) and triamcinolone acetonide (TAA). Of the two payloads, the dex conjugate did not advance because the free drug released into circulation was sufficient to cause on-target toxicity. In contrast, the CDP-11R-TAA conjugate alleviated joint inflammation in the rat collagen-induced model of rheumatoid arthritis while avoiding toxicities that occurred with nontargeted steroid treatment at the same molar dose. This conjugate shows promise for clinical development and establishes proof of concept for multijoint targeting of disease-modifying therapeutic payloads.

Phase 1 Safety, Pharmacokinetics, and Fluorescence Imaging Study of Tozuleristide (BLZ-100) in Adults With Newly Diagnosed or Recurrent Gliomas.

BACKGROUND: Fluorescence-guided surgery (FGS) can improve extent of resection in gliomas. Tozuleristide (BLZ-100), a near-infrared imaging agent composed of the peptide chlorotoxin and a near-infrared fluorophore indocyanine green, is a candidate molecule for FGS of glioma and other tumor types. OBJECTIVE: To perform a phase 1 dose-escalation study to characterize the safety, pharmacokinetics, and fluorescence imaging of tozuleristide in adults with suspected glioma. METHODS: Patients received a single intravenous dose of tozuleristide 3 to 29 h before surgery. Fluorescence images of tumor and cavity in Situ before and after resection and of excised tissue ex Vivo were acquired, along with safety and pharmacokinetic measures. RESULTS: A total of 17 subjects received doses between 3 and 30 mg. No dose-limiting toxicity was observed, and no reported adverse events were considered related to tozuleristide. At doses of 9 mg and above, the terminal serum half-life for tozuleristide was approximately 30 min. Fluorescence signal was detected in both high- and low-grade glial tumors, with high-grade tumors generally showing greater fluorescence intensity compared to lower grade tumors. In high-grade tumors, signal intensity increased with increased dose levels of tozuleristide, regardless of the time of dosing relative to surgery. CONCLUSION: These results support the safety of tozuleristide at doses up to 30 mg and suggest that tozuleristide imaging may be useful for FGS of gliomas.

Sex differences in (+)-amphetamine- and (+)-methamphetamine-induced behavioral response in male and female Sprague-Dawley rats.

(+)-Methamphetamine (METH) and (+)-amphetamine (AMP) are structurally similar drugs that are reported to induce similar pharmacological effects in rats of the same sex. Because pharmacokinetic data suggest female rats should be more affected than males, the current studies sought to test the hypothesis that the behavioral and temporal actions of METH and AMP should be greater in female Sprague-Dawley rats than in males. Using a dosing regimen designed to reduce the possibility of tolerance and sensitization, rats were administered 1.0 and 3.0 mg/kg intravenous drug doses. Distance traveled, rearing events and focal stereotypies (e.g., head weaving, sniffing) were measured. Female rats traveled significantly greater distances and displayed a greater number of rearing events than males after both doses. Analysis of stereotypy ratings after 3.0 mg/kg revealed that focal stereotypies were more pronounced and lasted longer in females. The second study compared the potencies of METH and AMP in inducing locomotor activity and focal stereotypies in each sex. No differences in potency were found when METH and AMP effects were compared within males or females. In summary, these studies showed female rats displayed greater and longer-lasting locomotor activity and more stereotypic behaviors, supporting earlier evidence of significant sexual dimorphism in pharmacokinetics.

Monoclonal IgG affinity and treatment time alters antagonism of (+)-methamphetamine effects in rats.

The roles of monoclonal antibody affinity and treatment time of (+)-methamphetamine-induced pharmacological effects in rats were studied using two anti-(+)-methamphetamine monoclonal antibodies. These studies tested the preclinical protective effects of monoclonal antibody antagonists in (+)-methamphetamine overdose and pretreatment scenarios. The higher affinity antibody (mAb6H4; KD=11 nM for (+)-methamphetamine) more effectively antagonized (+)-methamphetamine-induced behavioral effects (distance and rearing) than the low affinity antibody (designated mAb6H8; KD=250 nM) and had a longer duration of action. Both antibodies more effectively reduced (+)-methamphetamine effects in the overdose model than in the pretreatment model. (+)-Methamphetamine pharmacokinetic studies showed the mAb6H4 significantly reduced brain concentrations over time in both models. However, while mAb6H4 immediately reduced brain concentrations in the overdose model, it did not prevent the initial distribution of (+)-methamphetamine into the brain in the pretreatment model. Thus, anti-(+)-methamphetamine monoclonal antibody affinity and administration time (relative to (+)-methamphetamine dosing) are critical determinants of therapeutic success.

Pharmacodynamic mechanisms of monoclonal antibody-based antagonism of (+)-methamphetamine in rats.

Our studies examined pharmacokinetic mechanisms involved in high-affinity (K(d) approximately 11 nM) monoclonal antibody-based antagonism of (+)-methamphetamine-induced locomotor effects. Male rats received (+)-methamphetamine (0.3, 1, or 3 mg/kg i.v.) followed 30 min later by saline or anti-(+)-methamphetamine monoclonal antibody. All groups received a constant dose of monoclonal antibody that was equimolar in binding sites to the body burden of a 1 mg/kg i.v. (+)-methamphetamine dose 30 min after administration. The monoclonal antibody antagonized locomotor effects due to 0.3 and 1 mg/kg (+)-methamphetamine. In contrast, monoclonal antibody treatment increased locomotor activity due to 3 mg/kg (+)-methamphetamine. We also investigated the serum and brain pharmacokinetics of (+)-methamphetamine without and with the monoclonal antibody. Rats received (+)-methamphetamine (1 mg/kg i.v.) followed by saline or monoclonal antibody treatment at 30 min. The monoclonal antibody significantly increased serum methamphetamine concentrations and significantly decreased brain methamphetamine concentrations. These data indicate that anti-(+)-methamphetamine monoclonal antibody-induced pharmacodynamics are complex, but are related to time-dependent changes in (+)-methamphetamine brain distribution.

Recombinant interleukin-21 plus sorafenib for metastatic renal cell carcinoma: a phase 1/2 study.

BACKGROUND: Despite the positive impact of targeted therapies on metastatic renal cell carcinoma (mRCC), durable responses are infrequent and an unmet need exists for novel therapies with distinct mechanisms of action. We investigated the combination of recombinant Interleukin 21 (IL-21), a cytokine with unique immunostimulatory properties, plus sorafenib, a VEGFR tyrosine kinase inhibitor. METHODS: In this phase 1/2 study, 52 mRCC patients received outpatient treatment with oral sorafenib 400 mg twice daily plus intravenous IL-21 (10-50 mcg/kg) on days 1-5 and 15-19 of each 7-week treatment course. The safety, antitumor activity, pharmacokinetic and pharmacodynamic effects of the combination were evaluated. RESULTS: In phase 1 (n = 19), the maximum tolerated dose for IL-21 with the standard dose of sorafenib was determined to be 30 mcg/kg/day; grade 3 skin rash was the only dose-limiting toxicity. In phase 2, 33 previously-treated patients tolerated the combination therapy well with appropriate dose reductions; toxicities were mostly grade 1 or 2. The objective response rate was 21% and disease control rate was 82%. Two patients have durable responses that are ongoing, despite cessation of both IL-21 and sorafenib, at 41+ and 30+ months, respectively. The median progression-free survival in phase 2 was 5.6 months. The pharmacokinetic and pharmacodynamic properties of IL-21 appeared to be preserved in the presence of sorafenib. CONCLUSION: IL-21 plus sorafenib has antitumor activity and acceptable safety in previously treated mRCC patients. IL-21 may represent a suitable immunotherapy in further exploration of combination strategies in mRCC. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT00389285.

Pharmacokinetics and pharmacodynamics of pegylated interferon lambda-1 in cynomolgus monkeys.

Type III lambda interferons (IFNs) have activity similar to type I IFNs, but a more restricted receptor distribution. A pegylated human IFN lambda-1 (pegIFNλ) is under development for chronic hepatitis C. Induction of receptor signaling (STAT1 phosphorylation) and expression of interferon-stimulated genes (ISGs) by pegIFNλ were assessed in, respectively, cynomolgus monkey leukocyte subsets and hepatocytes stimulated in vitro. ISG induction by pegIFNλ or IFNα was also assessed in peripheral leukocytes and liver biopsies after single and repeat (x3) dosing of pegIFNλ (0.03, 0.3, 3.0 mg/kg) or unpegylated IFNα-2b (10(7) IU/kg). Single-dose pharmacokinetics of pegIFNλ were evaluated. Strong ISG induction occurred in cultured hepatocytes and liver biopsies with both pegIFNλ and IFNα. However, STAT1 phosphorylation, MHC class 1 upregulation, and ISG induction in leukocytes only occurred with IFNα. Serum neopterin was unaffected by pegIFNλ; however, ß-2-microglobulin was elevated at all doses. The terminal half-life of pegIFNλ was 23 h with a 59 mL/kg volume of distribution, consistent with other pegylated IFNs. Serum exposure was dose-proportional across the dosing range. These data demonstrate the suitability of cynomolgus monkeys for the preclinical evaluation of pegIFNλ. Additionally, the absence of pegIFNλ pharmacologic activity in leukocytes is consistent with its low receptor expression in blood.

Engineering of stable bispecific antibodies targeting IL-17A and IL-23.

Bispecific antibodies (bsAbs) present an attractive opportunity to combine the additive and potentially synergistic effects exhibited by combinations of monoclonal antibodies (mAbs). Current challenges for engineering bsAbs include retention of the binding affinity of the parent mAb or antibody fragment, the ability to bind both targets simultaneously, and matching valency with biology. Other factors to consider include structural stability and expression of the recombinant molecule, both of which may have significant impact on its development as a therapeutic. Here, we incorporate selection of stable, potent single-chain variable fragments (scFvs) early in the engineering process to assemble bsAbs for therapeutic applications targeting the cytokines IL-17A/A and IL-23. Stable scFvs directed against human cytokines IL-23p19 and IL-17A/A were isolated from a human Fab phage display library via batch conversion of panning output from Fabs to scFvs. This strategy integrated a step for shuffling V regions during the conversion and permitted the rescue of scFv molecules in both the V(H)V(L) and the V(L)V(H) orientations. Stable scFvs were identified and assembled into several bispecific formats as fusions to the Fc domain of human IgG1. The engineered bsAbs are potent neutralizers of the biological activity of both cytokines (IC(50) < 1 nM), demonstrate the ability to bind both target ligands simultaneously and display stability and productivity advantageous for successful manufacture of a therapeutic molecule. Pharmacokinetic analysis of the bsAbs in mice revealed serum half-lives similar to human mAbs. Assembly of bispecific molecules using stable antibody fragments offers an alternative to reformatting mAbs and minimizes subsequent structure-related and manufacturing concerns.

Targeting immune complex-mediated hypersensitivity with recombinant soluble human FcgammaRIA (CD64A).

Binding of Ag-Ab immune complexes to cellular FcgammaR promotes cell activation, release of inflammatory mediators, and tissue destruction characteristic of autoimmune disease. To evaluate whether a soluble FcgammaR could block the proinflammatory effects of immune complexes, recombinant human (rh) versions of FcgammaRIA, FcgammaRIIA, and FcgammaRIIIA were prepared. Binding of rh-FcgammaRIA to IgG was of high affinity (KD=1.7x10(-10) M), whereas rh-FcgammaRIIA and rh-FcgammaRIIIA bound with low affinity (KD=0.6-1.9x10(-6) M). All rh-FcgammaR reduced immune complex precipitation, blocked complement-mediated lysis of Ab-sensitized RBC, and inhibited immune complex-mediated production of IL-6, IL-13, MCP-1, and TNF-alpha by cultured mast cells. Local or systemic delivery only of rh-FcgammaRIA, however, reduced edema and neutrophil infiltration in the cutaneous Arthus reaction in mice. 125I-labeled rh-FcgammaRIA was cleared from mouse blood with a rapid distribution phase followed by a slow elimination phase with a t1/2gamma of approximately 130 h. The highest percentage of injected radioactivity accumulated in blood approximately liver approximately carcass>kidney. s.c. dosing of rh-FcgammaRIA resulted in lower serum levels of inflammatory cytokines and prevented paw swelling and joint damage in a murine model of collagen Ab-induced arthritis. These data demonstrate that rh-FcgammaRIA is an effective inhibitor of type III hypersensitivity.

Use of anti-(+)-methamphetamine monoclonal antibody to significantly alter (+)-methamphetamine and (+)-amphetamine disposition in rats.

These studies examined the effects of a high-affinity anti-(+)-methamphetamine monoclonal antibody (mAb; KD = 11 nM) on (+)-methamphetamine [(+)-METH] and (+)-amphetamine [(+)-AMP] serum and tissue disposition and serum protein binding following i.v. (+)-METH administration. Male Sprague-Dawley rats were pretreated with a buffer solution (control rats) or with anti-(+)-METH mAb [equimolar in binding sites to the (+)-METH dose]. The next day, both groups received a 1 mg/kg i.v. (+)-METH dose. At various time points after (+)-METH administration, rats were sacrificed (n = 3 per time point), and serum and tissues were collected. (+)-METH serum protein binding was increased from approximately 5% in controls to approximately 88 to 99% in the mAb-treated rats. The (+)-METH area under the concentration versus time curves from 0 to 4.5 h (AUC0-4.5 h) in mAb-treated rats showed an increase of >6600% for serum and a decrease of >60% for brain, compared with buffer-treated controls. Differential effects of anti-METH mAb on (+)-METH concentrations were observed in other tissues. For example, in the liver, anti-(+)-METH mAb caused significant increases in (+)-METH concentrations. The AUC0-4.5 h for (+)-AMP, a pharmacologically active metabolite, was decreased by approximately 50% in all tissues examined. These data show that pretreatment with an anti-(+)-METH mAb can significantly alter the disposition of (+)-METH and (+)-AMP in rats. Since the mAb has no significant cross-reactivity with (+)-AMP, the data suggest that the mAb reduced (+)-METH metabolic clearance through high-affinity binding to (+)-METH. Finally, rapidly equilibrating tissues, like the brain, appear to be preferentially protected by the mAb.