Elsevier

European Journal of Cancer

Volume 46, Issue 16, November 2010, Pages 2926-2935
European Journal of Cancer

The tumour-targeting human L19-IL2 immunocytokine: Preclinical safety studies, phase I clinical trial in patients with solid tumours and expansion into patients with advanced renal cell carcinoma

https://doi.org/10.1016/j.ejca.2010.07.033Get rights and content

Abstract

Background

L19-IL2, a tumour-targeting immunocytokine composed of the recombinant human antibody fragment L19 (specific to the alternatively-spliced EDB domain of fibronectin, a well characterised marker of tumour neo-vasculature) and of human IL2, has demonstrated strong therapeutic activity in animal cancer models. This phase I/II trial was performed to evaluate safety, tolerability, recommended phase II dose (RD) and early signs of activity of L19-IL2.

Patients and methods

Five cohorts of patients with progressive solid tumours (n = 21) received an intravenous infusion of L19-IL2 (from 5 to 30 Mio IU IL2 equivalent dose) on days 1, 3 and 5 every 3 weeks. This treatment cycle was repeated up to six times. In the following expansion phase, patients with metastatic renal cell carcinoma (RCC) (n = 12) were treated at the RD of L19-IL2. Clinical data and laboratory findings were analysed for safety, tolerability and activity.

Results

Preclinical studies in rats and monkeys did not raise any safety concerns. The RD was defined to be 22.5 Mio IU IL2 equivalent. Pharmacokinetics of L19-IL2 was dose proportional over the tested range, with a terminal half-life of 2–3 h. Toxicities were manageable and reversible with no treatment-related deaths. We observed stable disease in 17/33 patients (51%) and 15/18 with mRCC (83%) after two cycles. Median progression-free survival of RCC patients in the expansion phase of the study was 8 months (1.5–30.5).

Conclusions

L19-IL2 can be safely and repeatedly administered at the RD of 22.5 Mio IU IL2 equivalent in advanced solid tumours. Preliminary evaluation suggests clinical activity of L19-IL2 in patients with mRCC.

Introduction

One of the most promising new avenues for the development of more selective and efficacious cancer therapies relies on antibody-mediated targeted delivery of bioactive agents to the tumour environment.1, 2 The antibody-based targeted delivery of therapeutics such as cytokines to antigens located within tumour stroma appears to be particularly attractive. The alternatively-spliced extra-domain B (EDB) of fibronectin is an excellent target for such a strategy because it is virtually undetectable in normal healthy adults (exception made for the endometrium in the proliferative phase), but is strongly expressed in stromal and neo-vascular structures during cancer progression.3

L19-IL2 is a recombinant fusion protein consisting of human interleukin-2 (IL2) fused to single chain fragment variable [scFv(L19), an antibody fragment specific to EDB.4, 5, 6 ScFv(L19) selectively localises to tumour tissues in animal models of cancer5, 7, 8, 9, 10, 11 and its ability to target solid tumours and lymphomas in humans has been demonstrated in two immunoscintigraphic clinical studies in patients with cancer.12, 13 Preclinical biodistribution studies with human and murine tumour-bearing animals showed that L19-IL2 is selectively delivered to the tumour tissue and deposited at high local concentrations over an extended time period (beyond 72 h), resulting in a dramatic enhancement of the therapeutic properties of IL2.7, 14, 15 In these models, the inhibitory effects of L19-IL2 on tumour growth were much stronger and more sustained as compared with a control IL2 fusion protein not containing L19 and a free IL2 plus the L19 antibody in an equimolar mixture.7, 14, 15 In tumour-bearing mice, the anticancer activity was shown to be mainly mediated by natural killer (NK) cells.7, 14

Preclinical toxicology studies performed in primates and rats with L19-IL2 are in complete agreement with the results described for human recombinant IL2, and overall they did not raise any safety concerns.

This is the first clinical study of L19-IL2 conducted in cancer patients. Because of known activity of recombinant human IL2 in advanced renal cell carcinoma (RCC) patients, and as EDB is strongly expressed in this tumour type, RCC was considered a relevant target for treatment with L19-IL2.16

Section snippets

Study design and treatment

This was an open-label, non-randomised, multicentre, phase I/II study. In the dose escalation part of the study, 3–6 patients with advanced solid tumours were recruited into five dosing cohorts according to the modified Fibonacci scheme. The cohorts were sequentially enrolled and doses were escalated according to the following scheme: 5, 10, 15, 22.5 and 30 Mio IU IL2 equivalent (IL2e), corresponding to L19-IL2 doses of 0.835, 1.67, 2.51, 2.76 and 3.01 mg, respectively.7 In the second part of

EDB expression in RCC

Prior to study initiation, the L19 antibody11, 19 was used to investigate the expression of the alternatively-spliced EDB domain of fibronectin in frozen specimens of human RCC. Clear cell renal cell carcinomas consistently showed strong EDB expression, both in the immunohistochemical and in the immunofluorescence analysis. L19 staining was particularly intense around tumour blood vessels (Supplementary Fig. 1). L19 exhibits no detectable staining in a panel of normal human tissues, exception

Discussion

This is the ‘first-in-man’ study of L19-IL2. The results of this study demonstrate that L19-IL2 can be safely administered at 22.5 Mio IU IL2 equivalent dose corresponding to 3.75 mg of fusion protein. All reported toxicities were temporary and resolved completely within a few hours or days of L19-IL2 administration. There was no evidence of motor neuropathy or allergic reactions associated with L19-IL2. All frequent toxicities observed with L19-IL2, except for pain at the tumour site, are

Sources of support

Drug supply, equipment, pharmacokinetic, pharmacodynamic and human anti-fusion protein antibodies analyses were provided by Philogen, Siena, Italy and Bayer Schering Pharma, Berlin, Germany.

The research activity of D.N. is funded by the ETH Zurich, the Swiss National Science Foundation, the European Union (ADAMANT Project), the Swiss Cancer League, the SwissBridge Foundation and the Stammbach Foundation.

Role of funding source

Bayer Schering Pharma AG contributed to the study design, the collection, analysis and interpretation of data, the writing of the manuscript and the decision to submit the manuscript for publication.

Philogen S.p.A contributed to the study design, the collection, analysis and interpretation of data, the writing of the manuscript and the decision to submit the manuscript for publication.

Conflict of interest statement

Manfred Johannsen has received honoraria from Pfizer, Germany, Roche Pharma, Wyeth, Bayer AG and Novartis, Germany; Jan Roigas has received honoraria from Pfizer, Germany, Bayer AG, Wyeth and Roche Pharma; Steffen Weikert has received honoraria from Pfizer, Germany, Wyeth and Novartis, Germany; Kurt Miller is a consultant for Sanofi-Aventis, Novartis, Germany and AstraZeneca, Germany; Valeria Lovato, Eveline Trachsel, Manuela Kaspar are employees of Philochem AG, Zurich, Switzerland; Reinerio

Acknowledgements

The authors thank Ulf Harnack for the FACScan analysis of lymphocyte populations and Treg cell frequencies in blood from L19-IL2 treated RCC patients, and Tom Osmon for putting together and analysing the flow cytometry spread sheets.

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