Development and evaluation of peptidic ligands targeting tumour-associated urokinase plasminogen activator receptor (uPAR) for use in α-emitter therapy for disseminated ovarian cancer

Purpose

Among gynecologic malignancies, ovarian cancer has the highest mortality due to rapid peritoneal dissemination. Treatment failure particularly arises from failure to eliminate disseminated cells. Our aim was to develop peptidic radioligands targeting tumour cell-associated urokinase receptor (uPAR, CD87) for α-emitter therapy for advanced ovarian cancer.

Methods

DOTA-conjugated, uPAR-directed ligands were synthesised on solid-phase. Binding of peptides to human cells expressing uPAR was assayed by flow cytofluorometry or, in case of ²¹³Bi-labelled peptides, by measuring cell-bound radioactivity. Bio-distribution of the ²¹³Bi-labelled peptide P-P4D was analysed in nude mice 28 days after intraperitoneal inoculation of OV-MZ-6 ovarian cancer cells in the absence or presence of the plasma expander gelofusine.

Results

uPAR-selective ligands were developed based on published high-affinity uPAR-binding peptides. For preparation of N-terminally cross-linked divalent ligands, a novel solid-phase procedure was developed. Specific binding of ²¹³Bi-labelled peptides to monocytoid U937 and OV-MZ-6 cells was demonstrated using the natural ligand of uPAR, pro-uPA, or a soluble form of uPAR, suPAR, as competitors. The pseudo-symmetrical covalent dimer ²¹³Bi-P-P4D displayed superior binding to OV-MZ-6 cells in vitro. Accumulation of ²¹³Bi-P-P4D in tumour tissue was demonstrated by bio-distribution analysis in nude mice bearing intraperitoneal OV-MZ-6-derived tumours. Gelofusine reduced kidney uptake of ²¹³Bi-P-P4D by half.

Conclusion

Ovarian cancer cells overexpressing uPAR were specifically targeted in vitro and in vivo by ²¹³Bi-P-P4D. Kidney uptake of ²¹³Bi-P-P4D was distinctly reduced using gelofusine. Thus, this radiopeptide may represent a promising option for therapy for disseminated ovarian cancer.     

213Bi-DOTATOC receptor-targeted alpha-radionuclide therapy induces remission in neuroendocrine tumours refractory to beta radiation: a first-in-human experience

Purpose

Radiopeptide therapy using a somatostatin analogue labelled with a beta emitter such as ⁹⁰Y/¹⁷⁷Lu-DOTATOC is a new therapeutic option in neuroendocrine cancer. Alternative treatments for patients with refractory disease are rare. Here we report the first-in-human experience with ²¹³Bi-DOTATOC targeted alpha therapy (TAT) in patients pretreated with beta emitters.

Methods

Seven patients with progressive advanced neuroendocrine liver metastases refractory to treatment with ⁹⁰Y/¹⁷⁷Lu-DOTATOC were treated with an intraarterial infusion of ²¹³Bi-DOTATOC, and one patient with bone marrow carcinosis was treated with a systemic infusion of ²¹³Bi-DOTATOC. Haematological, kidney and endocrine toxicities were assessed according to CTCAE criteria. Radiological response was assessed with contrast-enhanced MRI and ⁶⁸Ga-DOTATOC-PET/CT. More than 2 years of follow-up were available in seven patients.

Results

The biodistribution of ²¹³Bi-DOTATOC was evaluable with 440 keV gamma emission scans, and demonstrated specific tumour binding. Enduring responses were observed in all treated patients. Chronic kidney toxicity was moderate. Acute haematotoxicity was even less pronounced than with the preceding beta therapies.

Conclusion

TAT can induce remission of tumours refractory to beta radiation with favourable acute and mid-term toxicity at therapeutic effective doses.     

Therapeutic efficacy and toxicity of <Superscript>225</Superscript>Ac-labelled vs. <Superscript>213</Superscript>Bi-labelled tumour-homing peptides in a preclinical mouse model of peritoneal carcinomatosis

Purpose  

Targeted delivery of alpha-particle-emitting radionuclides is a promising novel option in cancer therapy. We generated stable conjugates of the vascular tumour-homing peptide F3 both with ²²⁵Ac and ²¹³Bi that specifically bind to nucleolin on the surface of proliferating tumour cells. The aim of our study was to determine the therapeutic efficacy of ²²⁵Ac-DOTA-F3 in comparison with that of ²¹³Bi-DTPA-F3.     

Beckenwandrezidive des Zervixkarzinoms

Purpose

The prognosis of patients with pelvic wall recurrences after primary therapy of cervical cancer is bad. In selected patients treated exclusively by surgery as primary therapy the 5-year survival rate was between 5 and 25%. Additionally the combination of operation and radiotherapy (CORT) improved the survival so far. We developed a new concept for the treatment of pelvic wall recurrences. This concept includes the combination of radical surgery, interstitial radiation and chemotheray — CORCT (combined operative- and radiochemotherapy).

Patients and Methods

After radical surgery, interstitial HDR (Ir-192) brachytherapy in afterloading technique (2.5 Gy, 2 fractions/day in 5 days) was performed. Additionally a chemotherapy with cisplatin 25 mg/m²/day in 5 days and 5-fluorouracil 1000 mg/day in 5 days was applicated.

Results

After combined operative- and radiotherapy 3 of 3 patients died after treatment within 8 months (median) because of distant metastases. After additive radiochemotherapy 3 of 4 patients had no evidence of disease (NED) after a follow-up period of 14 (12 to 30) months.

Conclusion

The first treatment results of the new designed combined operative- and radiochemotherapy concept (CORCT) led us to expect an improvement of the prognosis of patients with recurrences of cervical cancer at the pelvic wall.     

Spectral CT evaluation of interstitial brachytherapy in pancreatic carcinoma xenografts: preliminary animal experience

Objectives

We sought to evaluate the capability of spectral CT to detect the therapeutic response to ¹²⁵I interstitial brachytherapy in a pancreatic carcinoma xenograft nude mouse model.

Methods

Twenty mice bearing SWl990 human pancreatic cancer cell xenografts were randomly separated into two groups: experimental (n?=?10; 1.0 mCi) and control (n?=?10; 0 mCi). After a two-week treatment, spectral CT was performed. Contrast-to-noise ratio (CNR) and iodine concentration (IC) in the lesions were measured and normalized to the muscle tissue, and nIC CD31 immunohistochemistry was used to measure microvessel density (MVD). The relationships between the nIC and MVD of the tumours were analysed.

Results

The nIC of the experimental group was significantly lower than that of the control group during the multiphase examination. A significant difference in the MVD was observed between the two groups (P <0.001). The nIC values of the three-phase scans have a certain positive correlation with MVD (r?=?0.57, p?Conclusions Spectral CT can be a useful non-invasive imaging modality in evaluating the therapeutic effect of ¹²⁵I interstitial brachytherapy to a pancreatic carcinoma.

Key Points

? Spectral CT offers opportunities to assess therapeutic response in pancreatic cancer cases. ? Spectral CT findings correlated with vascular changes associated with ¹²⁵I seed implantation. ? Spectral CT with monochromatic imaging removed most ¹²⁵I seed artefacts.     

The effect of paclitaxel on the radiosensitivity of gynecological tumor cells

Background

Paclitaxel, a natural product from Taxus brevifolia, is a microtubule stabilizing agent, which has been shown to block different cells in the G2/M phase of the cell cycle and consequently, to modulate their radioresponsiveness. Our aim was to test the cytotoxic and radiosensitizing potential of paclitaxel, with respect to different gynecological tumors with varying radiosensitivities.

Material and Method

We performed clonogenic assays and flow cytometry on 2 cell lines, MCF-7 (breast) and CaSki (cervix) cells, and on 2 primary ovarian tumor samples (OC-I and OC-II). The cells were irradiated with 200 kV X-rays, radiation doses of up to 8 Gy were applied either as single doses or in 2 Gy fractions. Paclitaxel concentrations varied from 0.07 to 700 nM, incubation times varied from 3 to 120 h.

Results

Paclitaxel alone changed the cell cycle distribution of the cells tested and was cytotoxic in a time and concentration dependent manner. When combined with radiation, most schedules resulted in additive effects of the combined treatments. However, for MCF-7 cells, when 7 nM paclitaxel, applied 24 h before irradiation, were combined with fractionated irradiation a supra-additive effect with a SER of 1.2 was found. For CaSki cells, under comparable conditions the SER was 1.13 but the effects were not statistically significant.

Conclusion

Under specific conditions, paclitaxel exerted a weak radiosensitizing effect on breast and cervical carcinoma cells. A therapeutic gain may be possible on the basis of an optimal paclitaxel/radiation scheduling.     

[11C]Choline as pharmacodynamic marker for therapy response assessment in a prostate cancer xenograft model

Purpose

[¹¹C]Choline has been established as a PET tracer for imaging prostate cancer. The aim of this study was to determine whether [¹¹C]choline can be used for monitoring the effects of therapy in a prostate cancer mouse xenograft model.

Methods

The androgen-independent human prostate cancer cell line PC-3 was implanted subcutaneously into the flanks of 13 NMRI (nu/nu) mice. All mice were injected 4–6 weeks after xenograft implantation with 37 MBq [¹¹C]choline via a tail vein. Dynamic imaging was performed for 60 min with a small-animal PET/CT scanner (Siemens Medical Solutions). Six mice were subsequently injected intravenously with docetaxel twice (days 1 and 5) at a dose of 3 mg/kg body weight. Seven mice were treated with PBS as a control. [¹¹C]Choline imaging was performed prior to and 1, 2 and 3 weeks after treatment. To determine choline uptake the images were analysed in terms of tumour-to-muscle (T/M) ratios. Every week the size of the implanted tumour was determined with a sliding calliper.

Results

The PC-3 tumours could be visualized by [¹¹C]choline PET. Before treatment the T/M_mean ratio was 1.6±0.5 in the control group and 1.8±0.4 in the docetaxel-treated group (p=0.65). There was a reduction in the mean [¹¹C]choline uptake after docetaxel treatment as early as 1 week after initiation of therapy (T/M ratio 1.8±0.4 before treatment, 0.9±0.3 after 1 week, 1.1±0.3 after 2 weeks and 0.8±0.2 after 3 weeks). There were no decrease in [¹¹C]choline uptake in the control group following treatment (T/M ratio 1.6±0.5 before treatment, 1.7±0.4 after 1 week, 1.8±0.7 after 2 weeks and 1.7±0.4 after 3 weeks). For analysis of the dynamic data, a generalized estimation equation model revealed a significant decrease in the T/M_dyn ratios 1 week after docetaxel treatment, and the ratio remained at that level through week 3 (mean change ?0.93±0.24, p<0.001, after 1  week; ?0.78±0.21, p<0.001, after 2 weeks; ?1.08±0.26, p<0.001, after 3 weeks). In the control group there was no significant decrease in the T/M_dyn ratios (mean change 0.085±0.39, p=0.83, after 1 week; 0.31±0.48, p=0.52, after 2 weeks; 0.11±0.30, p=0.72, after 3 weeks). Metabolic changes occurred 1 week after therapy and preceded morphological changes of tumour size during therapy.

Conclusion

Our results demonstrate that [¹¹C]choline has the potential for use in the early monitoring of the therapeutic effect of docetaxel in a prostate cancer xenograft animal model. The results also indicate that PET with radioactively labelled choline derivatives might be a useful tool for monitoring responses to taxane-based chemotherapy in patients with advanced prostate cancer.     

Prolonged survival in secondary glioblastoma following local injection of targeted alpha therapy with <Superscript>213</Superscript>Bi-substance P analogue

Background

Glioblastoma multiforme (GBM), the most common malignant brain tumor, mainly manifests as a primary de novo and less frequently as a secondary glial neoplasm. GBM has been demonstrated to overexpress the NK-1 receptor and substance P can be used as a ligand for targeted therapy. Alpha emitters, e.g. ²¹³Bi, that deposit their high energy within a short range allow the selective irradiation of tumor cells while sparing adjacent neuronal structures.

Material and methods

Among 50 glioma patients of different subtypes that have to date been treated with targeted alpha therapy at the Medical University Warsaw, we report here the data on nine patients with secondary GBM. Following surgery, chemo- and radiotherapy, recurrent GBM was treated by intracavitary injection of 1–6 doses of 0.9–2.3 GBq ²¹³Bi- DOTA-[Thi⁸,Met(O₂)¹¹]-substance P (²¹³Bi-DOTA-SP) in 2-month intervals. ⁶⁸Ga-DOTA-[Thi⁸,Met(O₂)¹¹]-substance P (⁶⁸Ga-DOTA-SP) was co-injected with the therapeutic doses to assess biodistribution using PET/CT. Therapeutic response was monitored with MRI.

Results

Treatment with activities ranging from 1.4 to 9.7 (median 5.8) GBq ²¹³Bi- DOTA-SP was well tolerated with only mild transient adverse reactions, mainly headaches due to a transient perfocal edema reaction. The median progression free survival and overall survival time following the initiation of alpha therapy was 5.8 and 16.4 months, respectively. The median overall survival time from the first diagnosis was 52.3 months. Two out of nine patients are still alive 39 and 51 months, respectively, after the initiation of the therapy.

Conclusions

Targeted alpha therapy of secondary GBM with ²¹³Bi-DOTA-SP is safe and well tolerated and may evolve as a promising novel therapeutic option for secondary GBM.

     

Nachweis einer strahleninduzierten Produktion von Tumor-Nekrose-Faktor alpha im Ewing-Sarkom RM 82 in vitro und in vivo

Aim

The expression of cytokines plays an important role in the transmission of the effects of ionizing radiation to tumor cells and normal tissue. Tumor necrosis factor alpha (TNF α), a pleiotropic monokine, is of special interest because of its cytotoxic effect on tumor cells and the induction of hemorrhagic necrosis in tumors. We examined the influence of ionizing radiation on TNF α production in a human Ewing’s sarcoma cell line in vitro and in vivo.

Methods

The protein and mRNA levels of the Ewing’s sarcoma cell line RM 82 were examined in vitro with ?Enhanced Amplified Sensitivity Immunoassay” (EASIA) and semiquantitative RT-PCR before and after treatment with single doses of 2 to 40 Gy, 1 to 72 hours after irradiation. After successful transplantation to nude mice, the time and dose correlation of TNF α mRNA production was examined in vivo.

Results

In vitro, RM 82 had a basal protein level of TNF α of 20.1±4.3 pg/ml/10⁶ cells. We observed a time- and dose-dependent increase of TNF α expression with a maximum of 125 pg/ml/10⁶ (5.9fold) 24 hours after irradiation with 20 Gy. At the mRNA level, the maximal up-regulation occurred 6 to 12 hours after 10 Gy. In vivo, the xenograft tumor maintained the capacity of TNF α expression. Time-and dose-dependency in mRNA production showed a maximum increase 6 hours after treatment with 10 Gy.

Conclusions

The presented experiments show in vitro a dose- and time-dependent up-regulation of TNF α in the Ewing’s sarcoma cell line RM 82 on protein and mRNA level. For the first time this phenomenon was also observed in vivo in a human xenograft tumor. This tumor model could be used for further experiments to examine the role of TNF α as a biologic radiation response modifier in human tumors.     

Pretargeted immuno-PET and radioimmunotherapy of prostate cancer with an anti-TROP-2 x anti-HSG bispecific antibody

Purpose

TF12 is a trivalent bispecific antibody that consists of two anti-TROP-2 Fab fragments and one anti-histamine-succinyl-glycine (HSG) Fab fragment. The TROP-2 antigen is found in many epithelial cancers, including prostate cancer (PC), and therefore this bispecific antibody could be suitable for pretargeting in this cancer. In this study, the characteristics and the potential for pretargeted radioimmunoimaging and radioimmunotherapy with TF12 and the radiolabeled di-HSG peptide IMP288 in mice with human PC were investigated.

Methods

The optimal TF12 protein dose, IMP288 peptide dose, and dose interval for PC targeting were assessed in nude mice with s.c. PC3 xenografts. Immuno-positron emission tomography (PET)/CT was performed using TF12/⁶⁸Ga-IMP288 at optimized conditions. The potential of pretargeted radioimmunotherapy (PRIT) using the TF12 pretargeted ¹⁷⁷Lu-IMP288 was determined.

Results

TF12 and ¹¹¹In-IMP288 showed high and fast accumulation in the tumor [20.4?±?0.6 %ID/g at 1 h post-injection (p.i.)] at optimized conditions, despite the internalizing properties of TF12. The potential for PRIT was shown by retention of 50 % of the ¹¹¹In-IMP288 in the tumor at 48 h p.i. One cycle of treatment with TF12 and ¹⁷⁷Lu-IMP288 showed significant improvement of survival compared to treatment with ¹⁷⁷Lu-IMP288 alone (90 vs. 67 days, p?<?0.0001) with no renal or hematological toxicity.

Conclusion

TROP-2-expressing PC can be pretargeted efficiently with TF12, with very rapid uptake of the radiolabeled hapten-peptide, IMP288, sensitive immuno-PET, and effective therapy.     

MR-guided radiofrequency ablation using a wide-bore 1.5-T MR system: clinical results of 213 treated liver lesions

Objective

To evaluate the technical effectiveness, technical success and patient safety of MR-guided radiofrequency (RF) ablation of liver malignancies using a wide-bore 1.5-T MR system.

Methods

In 110 patients, 56 primary liver lesions and 157 liver metastases were treated in 157 sessions using percutaneous RF ablation. Mean lesion diameter was 20?mm (range 4–54?mm). All planning, procedural and post-interventional control MR investigations were carried out using a wide-bore 1.5-T MR system. Technical success was assessed by a contrast-enhanced MR liver examination immediately after the intervention. Technique effectiveness was assessed by dynamic hepatic MR study 1?month post ablation; mean follow-up period was 24.2?months (range 5–44).

Results

Technical success and technique effectiveness were achieved in 210/213 lesions (98.6?%). In 18/210 lesions (8.6?%), local tumour progression occurred 4–28?months after therapy. Seven of these 18 lesions were treated in a second session achieving complete ablation, 6 other lesions were referred to surgery. Overall RF effectiveness rate was 199/213 (93.4?%); overall therapy success (including surgery) was 205/213 (96.2?%). Two major complications (1.3?%) (bleeding and infected biloma) and 14 (8.9?%) minor complications occurred subsequent to 157 interventions.

Conclusion

Wide-bore MR-guided RF ablation is a safe and effective treatment option for liver lesions.

Key Points

? Magnetic resonance-guided radiofrequency ablation offers various options for monitoring therapy. ? All steps of RF ablation carried out in 1.5-T wide-bore system. ? Therapeutic decisions were based on T1-weighted imaging. ? Technical success and technical effectiveness were high. ? Local tumour progression rate was 8.6?% over a 24-month mean follow-up.     

High treatment efficacy by dual targeting of Burkitt’s lymphoma xenografted mice with a <Superscript>177</Superscript>Lu-based CD22-specific radioimmunoconjugate and rituximab

Purpose

Dual-targeted therapy has been shown to be a promising treatment option in recurrent and/or refractory B-cell non-Hodgkin’s lymphoma (B-NHL). We generated radioimmunoconjugates (RICs) comprising either a novel humanized anti-CD22 monoclonal antibody, huRFB4, or rituximab, and the low-energy β-emitter ¹⁷⁷Lu. Both RICs were evaluated as single agents in a human Burkitt’s lymphoma xenograft mouse model. To increase the therapeutic efficacy of the anti-CD22 RIC, combination therapy with unlabelled anti-CD20 rituximab was explored.

Methods

The binding activity of CHX-A″-DTPA-conjugated antibodies to target cells was analysed by flow cytometry. To assess tumour targeting of ¹⁷⁷Lu-labelled antibodies, in vivo biodistribution experiments were performed. For radioimmunotherapy (RIT) studies, non-obese diabetic recombination activating gene-1 (NOD-Rag1 ^null ) interleukin-2 receptor common gamma chain (IL2rγ ^null ) null mice (NRG mice) were xenografted subcutaneously with Raji Burkitt’s lymphoma cells. ¹⁷⁷Lu-conjugated antibodies were administered at a single dose of 9.5 MBq per mouse. For dual-targeted therapy, rituximab was injected at weekly intervals (0.5 – 1.0 mg). Tumour accumulation of RICs was monitored by planar scintigraphy.

Results

Conjugation of CHX-A”-DTPA resulted in highly stable RICs with excellent antigen-binding properties. Biodistribution experiments revealed higher tumour uptake of the ¹⁷⁷Lu-labelled anti-CD22 IgG than of ¹⁷⁷Lu-labelled rituximab. Treatment with ¹⁷⁷Lu-conjugated huRFB4 resulted in increased tumour growth inhibition and significantly longer survival than treatment with ¹⁷⁷Lu-conjugated rituximab. The therapeutic efficacy of the anti-CD22 RIC could be markedly enhanced by combination with unlabelled rituximab.

Conclusion

These findings suggest that dual targeting with ¹⁷⁷Lu-based CD22-specific RIT in combination with rituximab is a promising new treatment option for refractory B-NHL.

     

Treatment with tandem [90Y]DOTA-TATE and [177Lu]DOTA-TATE of neuroendocrine tumours refractory to conventional therapy

Purpose

Peptide receptor radionuclide therapy (PRRT) with radiolabelled somatostatin analogues has been demonstrated to be an effective therapeutic option in patients with disseminated neuroendocrine tumours (NET). Treatment with tandem [⁹⁰Y]DOTA-TATE and [¹⁷⁷Lu]DOTA-TATE may improve the efficacy of PRRT without increasing the toxicity. In a phase II study we evaluated the feasibility of combined PPRT with a high-energy beta emitter (⁹⁰Y) and a medium-energy beta/gamma emitter (¹⁷⁷Lu) in patients with metastatic NET refractory to conventional therapy.

Methods

A group of 26 patients with metastatic NET were treated with four therapeutic cycles of alternating [¹⁷⁷Lu]DOTA-TATE (5.55 GBq) and [⁹⁰Y]DOTA-TATE (2.6 GBq). A dosimetric evaluation was carried out after administration of [¹⁷⁷Lu]DOTA-TATE to calculate the absorbed doses in healthy organs. The acute and long-term toxicities of repeated treatment were analysed. PRRT efficacy was evaluated according to RECIST.

Results

Administration of tandem [⁹⁰Y]DOTA-TATE and [¹⁷⁷Lu]DOTA-TATE induced objective responses in 42.3 % of patients with metastatic NET with a median progression-free survival longer than 24 months. Of patients with pretreatment carcinoid syndrome, 90 % showed a symptomatic response or a reduction in tumour-associated pain. The cumulative biologically effective doses (BED) were below the toxicity limit in the majority of patients, in the absence of renal function impairment

Conclusion

The results of our study indicates that combined [⁹⁰Y]DOTA-TATE and [¹⁷⁷Lu]DOTA-TATE therapy is a feasible and effective therapeutic option in NET refractory to conventional therapy. Furthermore, the absence of kidney damage and the evaluated cumulative BEDs suggest that increasing the number of tandem administrations is an interesting approach.     

Induction chemotherapy followed by simultaneous hyperfractionated radiochemotherapy in advanced head and neck cancer

Purpose

To evaluate the feasibility of induction chemotherapy followed by concomitant chemotherapy and hyperfractionated irradiation in locally advanced, inoperable head and neck cancer.

Methods

A pilot study was undertaken comprising 3 cycles of cisplatinum (100 mg/m², day 1) and 5-fluorouracil (1000 mg/m² in continuous intravenous infusion over the first 120 h) followed by bifractionated radiotherapy applied to tumor/involved lymph nodes up to the dose of 74.4 Gy given in 2 fractions of 1.2 Gy daily for 5 days a week combined with concomitant weekly cisplatinum infusion (50 mg/m²).

Results

Six patients were enrolled in the study. All of them completed the protocol therapy. Severe mucositis and myelotoxicity were the most common acute side effects observed in all and in 5 of the patients, respectively. Acute toxicity required interruption of concomitant chemotherapy in 5 cases and in 2 interruption of radiotherapy was necessary. Opioid analgesic parenteral therapy was administered in 4 patients. Three of them had to be hospitalized. One patient experienced cerebral stroke 1 day after the completion of therapy and died 7 days later. Due to high acute toxicity, patient accrual was terminated after 6 patients. At the mean follow-up of 17 months, 4 patients are alive, 3 of them are free of disease and in 1 local progression has been diagnosed.

Conclusions

High acute toxicity of induction cisplatinum and 5-fluorouracil followed by concomitant cisplatinum and hyperfractionated irradiation calls for less toxic treatment schedules in locally advanced inoperable head and neck cancer.     

Pairwise comparison of 89Zr- and 124I-labeled cG250 based on positron emission tomography imaging and nonlinear immunokinetic modeling: in vivo carbonic anhydrase IX receptor binding and internalization in mouse xenografts of clear-cell renal cell carcinoma

Purpose

The PET tracer, ¹²⁴I-cG250, directed against carbonic anhydrase IX (CAIX) shows promise for presurgical diagnosis of clear-cell renal cell carcinoma (ccRCC) (Divgi et al. in Lancet Oncol 8:304–310, 2007; Divgi et al. in J Clin Oncol 31:187–194, 2013). The radiometal ⁸⁹Zr, however, may offer advantages as a surrogate PET nuclide over ¹²⁴I in terms of greater tumor uptake and retention (Rice et al. in Semin Nucl Med 41:265–282, 2011). We have developed a nonlinear immunokinetic model to facilitate a quantitative comparison of absolute uptake and antibody turnover between ¹²⁴I-cG250 and ⁸⁹Zr-cG250 using a human ccRCC xenograft tumor model in mice. We believe that this unique model better relates quantitative imaging data to the salient biological features of tumor antibody–antigen binding and turnover.

Methods

We conducted experiments with ⁸⁹Zr-cG250 and ¹²⁴I-cG250 using a human ccRCC cell line (SK-RC-38) to characterize the binding affinity and internalization kinetics of the two tracers in vitro. Serial PET imaging was performed in mice bearing subcutaneous ccRCC tumors to simultaneously detect and quantify time-dependent tumor uptake in vivo. Using the known specific activities of the two tracers, the equilibrium rates of antibody internalization and turnover in the tumors were derived from the PET images using nonlinear compartmental modeling.

Results

The two tracers demonstrated virtually identical tumor cell binding and internalization but showed markedly different retentions in vitro. Superior PET images were obtained using ⁸⁹Zr-cG250, owing to the more prolonged trapping of the radiolabel in the tumor and simultaneous washout from normal tissues. Estimates of cG250/CAIX complex turnover were 1.35 – 5.51?×?10¹² molecules per hour per gram of tumor (20 % of receptors internalized per hour), and the ratio of ¹²⁴I/⁸⁹Zr atoms released per unit time by tumor was 17.5.

Conclusion

Pairwise evaluation of ⁸⁹Zr-cG250 and ¹²⁴I-cG250 provided the basis for a nonlinear immunokinetic model which yielded quantitative information about the binding and internalization of radioantibody bound to CAIX on tumor cells in vivo. ⁸⁹Zr-cG250 is likely to provide high-quality PET images and may be a useful tool to quantify CAIX/cG250 receptor turnover and cG250-accessible antigen density noninvasively in humans.     

Re-irradiation combined with capecitabine in locally recurrent squamous cell carcinoma of the head and neck

Background

We performed a prospective phase II trial to investigate the safety and efficacy of radiotherapy combined with capecitabine in patients suffering from a recurrence of a squamous cell carcinoma of the head and neck (SCCHN) within a previously irradiated field.

Patients and methods

A total of 31 evaluable patients with recurrent SCCHN received re-irradiation with a total dose of 50?Gy (25 fractions over 5?weeks) up to a maximum of 60?Gy combined with 900?mg/m²/day capecitabine given on the days of radiotherapy.

Results

The median time to relapse after the first course of radiotherapy was 15?months. The overall response rate in our study was 68% including 6?patients with a complete response. The median overall survival was 8.4?months. Grade 3 or 4 mucositis occurred in 4?patients and 1?patient, respectively. No grade 4 hematological toxicities were observed; 1?patient had grade 3 anemia. The cumulative median lifetime dose was 116?Gy.

Conclusion

Capecitabine combined with re-irradiation is a well-tolerated treatment in patients with recurrent SCCHN. In light of its good tolerability, it appears to be a potential option for patients with a reduced performance status and may also serve as a basis for novel treatment concepts, such as in combination with targeted therapies.     

Carboplatin and etoposide combined with radiotherapy for limited-stage small-cell esophageal carcinoma: three cases and review of the literature

Purpose

Small-cell esophageal carcinoma (SCEC) is a rare disease for which standard therapy has not yet been established. We report the results of three cases of limited-stage SCEC treated with combination therapy using carboplatin (CBDCA) and etoposide (VP-16) and radiotherapy.

Materials and methods

The clinical stage according to the Japanese Classification of Esophageal Cancer 7th ed. was stage III in 2 cases and stage IVa in 1. These patients with limited-stage SCEC were treated at our institution with four cycles of CBDCA and VP-16, either concurrent with radiotherapy for the second two cycles (n = 2) or followed by radiotherapy after the last cycle (n = 1).

Results

A complete response (CR) was obtained for all three patients, resulting in a response rate of 100%. Two patients are alive at 16.4 and 22.5 months after initial treatment. One patient died with myeloid leukemia at 43.5 months after initial treatment. None of the patients had loco-regional recurrence. Brain metastasis was detected in one patient at 7 months after initial therapy and was treated with stereotactic radiotherapy combined with whole brain irradiation.

Conclusion

CBDCA and VP-16 in combination with radiotherapy should be considered an important treatment option for SCEC.     

In vivo imaging of T cells loaded with gold nanoparticles: a pilot study

Purpose

Malignant tumours develop strategies to avoid immune recognition and elimination by T cells, even in individuals with a fully functioning immune system. To explore the treatment approach of adoptive immunotherapy, we exploited T cells loaded with radiolabelled gold nanoparticles (AuNPs) to track T cells in vivo.

Materials and methods

Surface-modified AuNPs were radiolabelled with ¹¹¹In or ⁶⁴Cu. They were then transferred into T cells via electroporation. To evaluate the effectiveness of this process, T cells loaded with ¹¹¹In-radiolabelled AuNPs were injected directly into the right lung of nude mice for in vivo imaging by micro-SPECT/CT. T cells loaded with ⁶⁴Cu-radiolabelled AuNPs were then injected into the tail vein of nude mice and imaged by micro-PET/CT.

Results

High uptake signals were observed in the right lung following the direct injection of T cells containing ¹¹¹In-labelled AuNPs. Imaging showed a marked difference in the dynamic biodistribution of T cells containing ⁶⁴Cu-labelled AuNPs when compared with ⁶⁴Cu-labelled AuNPs alone.

Conclusions

This study demonstrated the feasibility of the in vivo imaging of T cells loaded with radiolabelled AuNPs.