First-in-human trial of the safety, pharmacokinetics and immunogenicity of a PEGylated anti-CD40L antibody fragment (CDP7657) in healthy individuals and patients with systemic lupus erythematosus

OBJECTIVE

The objective of this paper is to investigate the safety, pharmacokinetics (PK) and immunogenicity of CDP7657, a PEGylated anti-CD40L antibody fragment, in healthy individuals and patients with systemic lupus erythematosus (SLE).

METHODS

This randomized, double-blind, single-dose, dose-escalation phase I study consisted of two parts. In part 1, 28 healthy individuals received CDP7657 IV (0.004-5 mg/kg) or placebo. In part 2, 17 patients with SLE received CDP7657 IV (5-60 mg/kg) or placebo. The CDP7657:placebo ratio was 3:1.

RESULTS

Adverse events (AEs) were reported by 76% of healthy individuals and 100% of patients with SLE treated with CDP7657; most were mild or moderate in intensity. Two healthy individuals reported serious AEs (SAEs), one of which was considered treatment related (infusion-related reaction; 5 mg/kg cohort). One patient with SLE (60 mg/kg cohort) experienced three SAEs, one of which was considered treatment related (herpes zoster infection). No thromboembolic events were reported. CPD7657 exposure increased in a dose-proportional manner. Low anti-CDP7657 antibody titres were detected in the majority of CDP7657-treated participants with no apparent impact on the PK of CDP7657.

CONCLUSION

Single doses of CDP7657 showed predictable PK in healthy individuals and patients with SLE and were well tolerated, with no safety signals of concern. These findings support further investigation of CDP7657 as a therapy for SLE.

Phase I and DCE-MRI evaluation of CDP791, a di-Fab PEG conjugate that inhibits VEGFR2

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Background: VEGF inhibitors are of proven clinical value. However, very few drugs specifically inhibit VEGFR2. CDP791 is a di-Fab PEG conjugate that binds VEGFR2 with a Kd of 49pM. Methods: We performed a single site, open label, dose-escalation study of CDP791. Cohorts of patients received between 0.3 and 30 mg/kg every 3 weeks until disease progression. DCE-MRI was performed at each dose level. Results: Thirty-one patients with colorectal, ovarian or renal cancer or other tumors were treated. There was no observed dose limiting toxicity or maximum tolerated dose. At doses of 10mg/kg or above, 7/16 patients developed cutaneous hemangiomata that regressed upon drug withdrawal. Biopsy of these confirmed that CDP791 was co-located with unphosphorylated VEGFR2. DCE-MRI revealed a dose- dependent inhibition of tumor growth over 20 days post-treatment, although there was no measurable change in Ktrans, an indicator of blood flow and capillary permeability. Fourteen patients received extended treatment and 5 (with renal (x2), colorectal, endometrial cancer and melanoma) had stable disease after 6 cycles. Plasma concentrations of CDP791 >10mcg/mL were sustained across the 21-day cycle for doses 10mg/kg and above. Conclusions: CDP791 is a pure VEGFR2 antagonist that is well tolerated up to doses of 30mg/kg. The drug is mechanistically active, associated with hemangiomata and dose-level dependent inhibition of tumor growth but not with reduction in vascular permeability or blood flow on DCE-MRI. These data imply that the drug is active in patients but challenge our understanding of the regulation of tumor vascular permeability. In addition, they suggest that serial 3-dimensional measurements of short-term tumor growth patterns are a sensitive method to detect biological therapy-related tumor growth inhibition.

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The effect of post-irradiation anisotonic treatment on cell survival and repair of DNA damage

V79 379A cells were irradiated and then exposed to anisotonic PBS for 20 min. This enhanced the radiation effect resulting from the fixation of potentially lethal damage. The induction of DNA single- and double-strand breaks is not increased by this treatment. Anisotonic treatment delayed the onset of repair of DNA damage. However when cells were returned to normal medium, they repaired the damage to a similar extent as cells not exposed to the anisotonic treatment. We suggest that the fixation of damage by post-irradiation anisotonic treatment is mediated through an increased probability of misrepair of DNA damage due to the delay in the onset of repair. This is supported by the observation that there is a reduced effect of post-irradiation anisotonic treatment on cells that have a markedly reduced ability to repair double-strand breaks.

The RBE for renal damage after irradiation with 3 MeV neutrons

Mouse kidneys were locally irradiated with single doses or up to 8 fractions of 240 kV X rays or 3 MeV neutrons. Damage was assessed from measurements of urine output, isotope clearance or haematocrit levels. All three assays gave steep dose-response curves by 4-5 months after irradiation. The repair capacity of the kidney was considerable after X-irradiation but was very small after irradiation with neutrons. Thus the RBE increased sharply with increasing fractionation. After large doses, an RBE of 2.3-2.5 was measured, rising to 4.5-5.1 after 8 fractions of 4 to 5 Gy X rays. Linear-quadratic analysis of these data has allowed RBE's to be calculated outside the measured dose range. The limiting RBE predicted at very low doses per fraction is 20 to 26, whereas at extremely high doses it would be as low as 1.2 to 1.4. This indicates that high RBE values may be seen in a slow turnover tissue after low doses per fraction (within the clinically relevant range) although this may not be evident after larger doses. Such high RBE's arise because of the shape of the underlying X-ray dose-response curve rather than the shape of the neutron curve.

Increased collagen and fluid content of mouse kidneys at 9 months after single or fractionated X irradiation

Mouse kidneys have been analyzed at sacrifice, 9 months after single-dose and fractionated irradiation, using wet and dry weight, a biochemical determination of hydroxyproline, and quantitation of dilated renal tubules in histological preparations. Dose-response curves have been constructed to determine the sensitivity and precision of the assays and to study the influence of dose fractionation on a variety of radiation responses of the kidney. There was a marked loss of kidney weight, measured either wet or dry, with maximum changes from control values by factors of 3 and 5, respectively. The wet:dry weight ratio increased with X-ray dose, indicating that relative fluid content was increased even 9 months after irradiation. This could be partly attributed to dilated renal tubules. Total collagen content per kidney, determined by a hydroxyproline assay, showed a less marked dose dependence, with a maximum increase of a factor of 1.4. However, hydroxyproline per dry weight increased by a factor of 7, and this ratio proved to be the most sensitive and precise measure of radiation damage. The "fibrosis" that is detected in histological sections appears to be more a relative than an absolute alteration in connective tissue. The loss of parenchymal cell mass, particularly in the proximal tubules, is the predominant factor; the increase in the absolute amount of collagen per kidney contributes to a lesser degree. The influence of radiation dose fractionation was analyzed using a linear-quadratic response model. The alpha/beta ratios were between 0.9 and 2.9 Gy.