A Phase I Open-Label Clinical Trial Evaluating the Therapeutic Vaccine hVEGF26–104/RFASE in Patients with Advanced Solid Malignancies

Lessons Learned: The novel therapeutic vaccine hVEGF26–104/RFASE was found to be safe and well tolerated in patients with cancer. hVEGF26–104/RFASE failed to induce seroconversion against native hVEGF165 and, accordingly, neither a decrease in circulating vascular endothelial growth factor (VEGF) levels nor clinical benefit was observed. Remarkably, hVEGF26–104/RFASE induced VEGF165-neutralizing antibodies in a nonhuman primate model. The absence of seroconversion in human calls for caution in the interpretation of efficacy of human vaccines in nonhuman primates. Background: Targeting vascular endothelial growth factor-A (VEGF) is a well-established anticancer therapy. We designed a first-in-human clinical trial to investigate the safety and immunogenicity of the novel vaccine hVEGF26–104/RFASE. Methods: Patients with advanced solid malignancies with no standard treatment options available were eligible for this phase I study with a 3+3 dose-escalation design. On days 0, 14, and 28, patients received intramuscular hVEGF26–104, a truncated synthetic three-dimensional (3D)-structured peptide mimic covering the amino acids 26–104 of the human VEGF165 isoform, emulsified in the novel adjuvant Raffinose Fatty Acid Sulphate Ester (RFASE), a sulpholipopolysaccharide. Objectives were to determine safety, induction of VEGF-neutralizing antibodies, and the maximum tolerated dose. Blood was sampled to measure VEGF levels and antibody titers. Results: Eighteen of 27 enrolled patients received three immunizations in six different dose-levels up to 1,000 μg hVEGF26–104 and 40 mg RFASE. No dose-limiting toxicity was observed. Although in four patients an antibody titer against hVEGF26–104 was induced (highest titer: 2.77 10log), neither a reduction in VEGF levels nor neutralizing antibodies against native VEGF165 were detected. Conclusion: Despite having an attractive safety profile, hVEGF26–104/RFASE was not able to elicit seroconversions against native VEGF165 and, consequently, did not decrease circulating VEGF levels. Deficient RFASE adjuvant activity, as well as dominant immunoreactivity toward neoepitopes, may have impeded hVEGF26–104/RFASE's efficacy in humans

Phase I Study of Dalteparin in Combination With Sunitinib in Patients With Metastatic Clear Cell Renal Carcinoma

Background: Based on the tumor-driven concomitant activation of angiogenesis and coagulation we conducted a phase I combination study of sunitinib with the low molecular weight heparin dalteparin in patients with metastatic clear cell renal cell carcinoma (ccRCC). Materials and Methods: Patients received standard treatment with sunitinib (50 mg daily, 4 weeks on, 2 weeks off). During the second week of no sunitinib in the first cycle (week 6) patients received dalteparin monotherapy (in escalating doses). Combination therapy of the 2 agents was administered from the second cycle onward. Seventeen patients were enrolled at 3 dose levels of dalteparin. Results: Diarrhea and fatigue were the most frequent reported drug-related toxicities (41%). One dose-limiting toxicity (grade 3 anemia) was observed at the highest dose level of dalteparin. There were 4 partial responses (24%) and the median progression-free survival in this study was 14 months (95% confidence interval, 8.0-23.4). Anti-factor Xa levels were increased during combination therapy compared with dalteparin monotherapy. Conclusions: Combination therapy of sunitinib with therapeutic doses of dalteparin is safe and well tolerated. The increased anti-factor Xa levels during combination treatment suggest that sunitinib might increase the anticoagulation activity of dalteparin. The positive safety profile warrants prospective evaluation of the clinical benefit of this combination strategy in patients with ccRCC

Targeted vaccination against the bevacizumab binding site on VEGF using 3D-structured peptides elicits efficient antitumor activity

Therapeutic targeting of the VEGF signaling axis by the VEGFneutralizing monoclonal antibody bevacizumab has clearly demonstrated clinical benefit in cancer patients. To improve this strategy using a polyclonal approach, we developed a vaccine targeting VEGF using 3D-structured peptides that mimic the bevacizumab binding site. An in-depth study on peptide optimization showed that the antigen's 3D structure is essential to achieve neutralizing antibody responses. Peptide 1 adopts a clear secondary, native-like structure, including the typical cysteine-knot fold, as evidenced by CD spectroscopy. Binding and competition studies with bevacizumab in ELISA and surface plasmon resonance analysis revealed that peptide 1 represents the complete bevacizumab binding site, including the hairpin loop (β5-turn-β6) and the structure-supporting β2-α2-β3 loop. Vaccination with peptide 1 elicited high titers of cross-reactive antibodies to VEGF, with potent neutralizing activity. Moreover, vaccination-induced antisera displayed strong angiostatic and tumor-growth-inhibiting properties in a preclinical mouse model for colorectal carcinoma, whereas antibodies raised with peptides exclusively encompassing the β5-turn-β6 loop (peptides 15 and 20) did not. Immunization with peptide 1 or 7 (murine analog of 1) in combinationwith the potent adjuvant raffinose fatty acid sulfate ester (RFASE) showed significant inhibition of tumor growth in the B16F10 murine melanoma model. Based on these data, we conclude that this vaccination technology,which is currently being investigated in a phase I clinical trial (NCT02237638), can potentially outperform currently applied anti-VEGF therapeutics.</p