Peptide-mediated targeting of cytokines to tumor vasculature: the NGR-hTNF example.

A growing body of evidence suggests that the efficacy of cytokines in cancer therapy can be increased by targeting strategies based on conjugation with ligands that recognize receptors expressed by tumor cells or elements of the tumor microenvironment, including the tumor vasculature. The targeting approach is generally conceived to permit administration of low, yet pharmacologically active, doses of drugs, thereby avoiding toxic reactions. However, it is becoming clear that, in the case of cytokines, this strategy has another inherent advantage, i.e. the possibility of administering extremely low doses that do not activate systemic counter-regulatory mechanisms, which may limit their potential therapeutic effects. This review is focused on the use of tumor vasculature-homing peptides as vehicles for targeted delivery of cytokines to tumor blood vessel. In particular, we provide an overview of peptide-cytokine conjugates made with peptides containing the NGR, RGD, isoDGR or RGR sequences and describe, in more details, the biological and pharmacological properties of NGR-hTNF, a peptide-tumor necrosis factor-α conjugate that is currently being tested in phase II and III clinical studies. The results of preclinical and clinical studies performed with these products suggest that peptide-mediated vascular-targeting is indeed a viable strategy for delivering bioactive amounts of cytokines to tumor endothelial cells without causing the activation of counter-regulatory mechanisms and toxic reactions.

Re-challenge with pemetrexed in advanced mesothelioma: a multi-institutional experience.

BACKGROUND: Although first-line therapy for patients affected by advanced mesothelioma is well established, there is a lack of data regarding the impact of second-line treatment. METHODS: We retrospectively collected data of patients affected by advanced mesothelioma, already treated with first-line therapy based on pemetrexed and platin, with a response (partial response or stable disease) lasting at least 6 months, and re-treated with a pemetrexed-based therapy at progression. The primary objective was to describe time to progression and overall survival after re-treatment. RESULTS: Overall across several Italian oncological Institutions we found 30 patients affected by advanced mesothelioma, in progression after a 6-month lasting clinical benefit following a first-line treatment with cisplatin and pemetrexed, and re-challenged with a pemetrexed-based therapy. In these patients we found a disease control rate of 66%, with reduction of pain in 43% of patients. Overall time to progression and survival were promising for a second-line setting of patients with advanced mesothelioma, being 5.1 and 13.6 months, respectively. CONCLUSIONS: In our opinion, when a patient has a long-lasting benefit from previous treatment with pemetrexed combined with a platin compound, the same treatment should be offered at progression.

Phase I study of NGR-hTNF, a selective vascular targeting agent, in combination with cisplatin in refractory solid tumors.

PURPOSE: NGR-hTNF exploits the tumor-homing peptide asparagine-glycine-arginine (NGR) for selectively targeting TNF-α to an aminopeptidase N overexpressed on cancer endothelial cells. Preclinical synergism with cisplatin was displayed even at low doses. This study primarily aimed to explore the safety of low-dose NGR-hTNF combined with cisplatin in resistant/refractory malignancies. Secondary aims included pharmacokinetics (PKs), pharmacodynamics, and activity. EXPERIMENTAL DESIGN: NGR-hTNF was escalated using a doubling-dose scheme (0.2-0.4-0.8-1.6 µg/m(2)) in combination with fixed-dose of cisplatin (80 mg/m(2)), both given intravenously once every three weeks. PKs and circulating TNF-receptors (sTNF-Rs) were assessed over the first three cycles. RESULTS: Globally, 22 patients (12 pretreated with platinum) received a range of one to ten cycles. Consistently with the low-dose range tested, maximum-tolerated dose was not reached. No dose-limiting toxicities (DLTs) were observed at 0.2 (n = 4) and 0.4 µg/m(2) (n = 3). One DLT (grade 3 infusion-related reaction) was observed at 0.8 µg/m(2). This dose cohort was expanded to six patients without further DLTs. No DLTs were noted also at 1.6 µg/m(2) (n = 3). NGR-hTNF exposure increased dose-proportionally without apparent PK interactions with cisplatin. No shedding of sTNF-Rs was detected up to 0.8 µg/m(2). At the dose level of 0.8 µg/m(2), expanded to 12 patients for activity assessment, a platinum-pretreated lung cancer patient achieved a partial response lasting more than six months and five patients maintained stable disease for a median time of 5.9 months. CONCLUSIONS: The combination of NGR-hTNF 0.8 µg/m(2) with cisplatin 80 mg/m(2) showed favorable toxicity profile and promising antitumor activity.

Phase II study of asparagine-glycine-arginine-human tumor necrosis factor alpha, a selective vascular targeting agent, in previously treated patients with malignant pleural mesothelioma.

PURPOSE: NGR-hTNF consists of human tumor necrosis factor alpha (hTNF-alpha) fused to the tumor-homing peptide asparagine-glycine-arginine (NGR) able to selectively bind an aminopeptidase N isoform overexpressed on tumor blood vessels. Hypervascularity is a prominent and poor-prognosis feature of malignant pleural mesothelioma (MPM). Currently, there are no standard options for patients with MPM who are failing a front-line pemetrexed-based regimen. We explored safety and efficacy of NGR-hTNF in this setting. PATIENTS AND METHODS: Eligible patients had radiologically documented tumor progression and performance status < or = 2. Primary study aim was progression-free survival (PFS). NGR-hTNF 0.8 microg/m(2) was given intravenously every 3 weeks. A subsequent cohort of patients received 0.8 microg/m(2) on a weekly basis. RESULTS: In the triweekly cohort (n = 43), only one grade 3 drug-related toxicity was noted, and the most common grades 1 to 2 were short-lived chills (71%). The median PFS was 2.8 months (95% CI, 2.3 to 3.3 months). Nineteen patients (44%) had disease control (one had partial response, and 18 had stable diseases) and experienced a median progression-free time of 4.4 months. In the weekly cohort (n = 14), there was no higher toxicity, and median PFS was 3.0 months (95% CI, 1.9 to 4.1 months). Seven patients (50%) had disease control (all stable diseases) and had a median progression-free interval of 9.1 months. In the overall study population (N = 57), median PFS was 2.8 months. Median progression-free time was 4.7 months in twenty-six patients (46%) who achieved disease control. Median survival was 12.1 months. CONCLUSION: The tolerability and disease control of NGR-hTNF 0.8 microg/m(2) weekly warrant additional evaluation in patients with advanced MPM.

Defining the optimal biological dose of NGR-hTNF, a selective vascular targeting agent, in advanced solid tumours.

BACKGROUND: NGR-hTNF consists of human tumour necrosis factor-alpha (hTNF-alpha) fused to the tumour-homing peptide NGR, a ligand of an aminopeptidase N/CD13 isoform, which is overexpressed on endothelial cells of newly formed tumour blood vessels. NGR-TNF showed a biphasic dose-response curve in preclinical models. This study exploring the low-dose range aimed to define safety and optimal biological dose of NGR-hTNF. PATIENTS AND METHODS: Pharmacokinetics, plasma biomarkers and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) were evaluated at baseline and after each cycle in 16 patients enrolled at four doubling-dose levels (0.2-0.4-0.8-1.6 microg/m(2)). NGR-hTNF was given intravenously as 1-h infusion every 3 weeks (q3w). Tumour response was assessed q6w. RESULTS: Eighty-three cycles (median, 2; range, 1-29) were administered. Most frequent treatment-related toxicity was grade 1-2 chills (69%), occurring during the first infusions. Only one patient treated at 1.6 microg/m(2) had a grade 3 drug-related toxicity (chills and dyspnoea). Both C(max) and AUC increased proportionally with dose. No shedding of soluble TNF-alpha receptors was observed up to 0.8 microg/m(2). Seventy-five percent of DCE-MRI assessed patients showed a decrease over time of K(trans), which was more pronounced at 0.8 microg/m(2). Seven patients (44%) had stable disease for a median time of 5.9 months, including a colon cancer patient who experienced an 18-month progression-free time. CONCLUSION: Based on tolerability, soluble TNF-receptors kinetics, anti-vascular effect and disease control, NGR-hTNF 0.8 microg/m(2) will be further developed either as single-agent or with standard chemotherapy.