Vascular endothelial growth factor (VEGF)-A is overexpressed in most malignant and premalignant breast lesions. VEGF-A can be visualized noninvasively with PET imaging and using the tracer 89 Zr-labeled bevacizumab. In this clinical feasibility study, we assessed whether VEGF-A in primary breast cancer can be visualized by 89 Zr-bevacizumab PET. Methods: Before surgery, breast cancer patients underwent a PET/CT scan of the breasts and axillary regions 4 d after intravenous administration of 37 MBq of 89 Zr-bevacizumab per 5 mg. PET images were compared with standard imaging modalities. 89 Zr-bevacizumab uptake was quantified as the maximum standardized uptake value (SUV max ). VEGF-A levels in tumor and normal breast tissues were assessed with enzyme-linked immunosorbent assay. Data are presented as mean 6 SD. Results: Twenty-five of 26 breast tumors (mean size 6 SD, 25.1 6 19.8 mm; range, 4-80 mm) in 23 patients were visualized. SUV max was higher in tumors (1.85 6 1.22; range, 0.52-5.64) than in normal breasts (0.59 6 0.37; range, 0.27-1.69; P , 0.001). The only tumor not detected on PET was 10 mm in diameter. Lymph node metastases were present in 10 axillary regions; 4 could be detected with PET (SUV max , 2.66 6 2.03; range, 1.32-5.68). VEGF-A levels in the 17 assessable tumors were higher than in normal breast tissue in all cases (VEGF-A/mg protein, 184 6 169 pg vs. 10 6 21 pg; P 5 0.001), whereas 89 Zr-bevacizumab tumor uptake correlated with VEGF-A tumor levels (r 5 0.49). Conclusion: VEGF-A in primary breast cancer can be visualized by means of 89 Zr-bevacizumab PET.

Mesothelin is a tumor differentiation antigen expressed by epithelial tumors, including pancreatic cancer. Currently, mesothelin is being targeted with an antibody-drug conjugate (ADC) consisting of a mesothelin-specific antibody coupled to a highly potent chemotherapeutic drug. Considering the toxicity of the ADC and reduced accessibility of pancreatic tumors, non-invasive imaging could provide necessary information. We therefore developed a zirconium-89 (89Zr) labeled anti-mesothelin antibody (89Zr-AMA) to study its biodistribution in human pancreatic tumor bearing mice. Biodistribution and dose-finding of 89Zr-AMA were studied 144 h after tracer injection in mice with subcutaneously xenografted HPAC. MicroPET imaging was performed 24, 72 and 144 h after tracer injection in mice bearing HPAC or Capan-2. Tumor uptake and organ distribution of 89Zr-AMA were compared with nonspecific 111In-IgG. Biodistribution analyses revealed a dose-dependent 89Zr-AMA tumor uptake. Tumor uptake of 89Zr-AMA was higher than 111In-IgG using the lowest tracer dose. MicroPET showed increased tumor uptake over 6 days, whereas activity in blood pool and other tissues decreased. Immunohistochemistry showed that mesothelin was expressed by the HPAC and CAPAN-2 tumors and fluorescence microscopy revealed that AMA-800CW was present in tumor cell cytoplasm. 89Zr-AMA tumor uptake is antigen-specific in mesothelin-expressing tumors. 89Zr-AMA PET provides non-invasive, real-time information about AMA distribution and tumor targeting.

The humanized monoclonal antibody with high affinity for the human epidermal growth factor receptor (HER) 3, RG7116, is a glycoengineered, IgG1 class antibody. By labeling RG7116 with zirconium-89 ((89)Zr) we aimed to visualize in vivo HER3 expression and study the biodistribution of this antibody in human tumor-bearing mice. Biodistribution of (89)Zr-RG7116 was studied in subcutaneously xenografted FaDu tumor cells (HER3-positive). Dose-dependency of (89)Zr-RG7116 organ distribution and specific tumor uptake was assessed by administering doses ranging from 0.05 to 10 mg/kg RG7116 to SCID/Beige mice. Biodistribution was analyzed at 24 and 144 h after injection. MicroPET imaging was performed at 1, 3, and 6 days after injection of 1.0 mg/kg (89)Zr-RG7116 in the FaDu, H441, QG-56 and Calu-1 xenografts with varying HER3 expression. The excised tumors were analyzed for HER3 expression. Biodistribution analyses showed a dose- and time-dependent (89)Zr-RG7116 tumor uptake in FaDu tumors. The highest tumor uptake of (89)Zr-RG7116 was observed in the 0.05 mg/kg dose group with 27.5%ID/g at 144 h after tracer injection. MicroPET imaging revealed specific tumor uptake of (89)Zr-RG7116 in FaDu and H441 models with an increase in tumor uptake over time. Biodistribution data was consistent with the microPET findings in FaDu, H441, QG56 and Calu-1 xenografts, which correlated with HER3 expression levels. In conclusion, (89)Zr-RG7116 specifically accumulates in HER3 expressing tumors. PET imaging with this tracer provides real-time non-invasive information about RG7116 distribution, tumor targeting and tumor HER3 expression levels.

Under simulated hair dye use conditions, a significantly lower degree of cross-elicitation to ME-PPD (30%) was observed than previously reported for PPD (32 of 38, 84%). Additionally, a decreased cross-elicitation strength was observed across all three patch test grades, likely reflecting the reduced skin-sensitization properties of ME-PPD. Consequently, careful dermatological evaluation is required to assess cross-reactivity to ME-PPD in patients allergic to hair dyes.

Purpose: The mTOR pathway is frequently activated in ovarian cancers. mTOR inhibitors, such as everolimus, can reduce VEGF-A production by cancer cells. We investigated whether early everolimus treatment effects could be monitored by positron emission tomography (PET) with 89Zr-bevacizumab. Experimental Design: The effect of everolimus on VEGF-A secretion was determined in a panel of human ovarian cancer cell lines and in A2780luc+ ovarian cancer cells xenografted subcutaneously in BALB/c mice. Mice received daily 10 mg/kg everolimus intraperitoneally (i.p.) for 14 days. PET scans with the tracer 89Zr-labeled bevacizumab were conducted before and after treatment. Ex vivo89Zr-bevacizumab biodistribution and correlative tissue analyses were conducted. Tumor VEGF-A levels were measured with ELISA and mean vascular density (MVD) was determined with immunohistochemistry. Results: Everolimus treatment reduced VEGF-A levels in the supernatant of all cell lines. Everolimus lowered 89Zr-bevacizumab tumor uptake by 21.7% ± 4.0% [mean standardized uptake value (SUVmean) 2.3 ± 0.2 vs. 2.9 ± 0.2, P < 0.01]. Ex vivo biodistribution also showed lower tracer uptake in the tumors of treated as compared with control animals (7.8 ± 0.8%ID/g vs. 14.0 ± 1.7%ID/g, P < 0.01), whereas no differences were observed for other tissues. This coincided with lower VEGF-A protein levels in tumor lysates in treated versus untreated tumors (P = 0.04) and reduced MVD (P < 0.01). Conclusion: Tumor VEGF-A levels are decreased by everolimus. 89Zr-bevacizumab PET could be used to monitor tumor VEGF-A levels as an early biomarker of the antiangiogenic effect of mTOR inhibitor therapy. Clin Cancer Res; 18(22); 6306–14. ©2012 AACR.

SummaryAlthough p-phenylenediamine (PPD) has been recognized as an extreme sensitizer for many years, the exact mechanism of sensitization has not been elucidated yet. Penetration and the ability to bind to proteins are the first two hurdles that an allergen has to overcome to be able to sensitize. This review is an overview of studies regarding PPD penetration through skin (analogues) and studies on the amino acids that are targeted by PPD. To complete this review, the auto-oxidation and N -acetylation steps involved in PPD metabolism are described. In summary, under normal hair dyeing exposure conditions, <1% of the applied PPD dose penetrates the skin. The majority (>80%) of PPD that penetrates will be converted into the detoxification products monoacetyl-PPD and diacetyl-PPD by the N -acetyltransferase enzymes. The small amount of PPD that does not become N -acetylated is susceptible to auto-oxidation reactions, yielding proteinreactive PPD derivatives. These derivatives may bind to specific amino acids, and some of the formed adducts might be the complexes responsible for sensitization. However, true in vivo evidence is lacking, and further research to unravel the definite mechanism of sensitization is needed.Key words: haptenation; penetration; p-phenylenediamine; protein binding; sensitization.p-Phenylenediamine (PPD) is an aromatic amine known for its extreme sensitizing potency, and may cause severe allergic contact dermatitis. It is predominantly used as a precursor in oxidative hair dyes, but it can also be found in so-called 'temporary henna tattoos', despite the prohibition of this application in Europe and the United States (1, 2). Hair dyeing -in both consumer and occupational settings -has been shown to be a common cause of PPD sensitization (3). Whereas allergic contact dermatitis in consumers gives rise to erythema and oedema (sometimes severe) of the face, eyelids, scalp, and neck, the hands are most affected in hairdressers (4).Although allergic contact dermatitis caused by PPD has been studied extensively, the exact pathways of sensitization and elicitation are not yet completely unravelled. Nevertheless, as is generally known, in order to induce a T cell-mediated immune response, a chemical needs to undergo several steps. Briefly, a chemical has to penetrate the stratum corneum to reach the living epidermis. Here, the low molecular weight chemical, the hapten, will haptenate (i.e. be bound to) cutaneous protein. The hapten-protein complex will be formed inside the cell or be taken up and subsequently processed by antigen-presenting cells of the epidermis or dermis. These cells become activated and migrate to regional lymph nodes, where they may encounter and activate allergen-specific naïve T cells. Expanded progeny of these allergen-specific T cells, which are then turned into effector and memory T cells, will recirculate and migrate to the skin. On re-exposure to the initial allergen, the abovementioned process will recur, but now memory T cells can immediately release cytokines and chemo...

We have gained insights into the in vivo penetration of PPD in human skin by using non-invasive Raman spectroscopy. Penetration into the skin was fast, and the PPD concentrations detected in the stratum corneum were high. PPD was detected in both the stratum corneum and the viable epidermis. Oxidized or acetylated PPD derivatives could not be detected.

No abstract