Alexander B. Stillebroer

Prostate Cancer Gene 3 (PCA3): Development and Internal Validation of a Novel Biopsy Nomogram

BACKGROUND Urinary prostate cancer gene 3 (PCA3) represents a promising novel marker of prostate cancer detection. OBJECTIVE To test whether urinary PCA3 assay improves prostate cancer (PCa) risk assessment and to construct a decision-making aid in a multi-institutional cohort with pre-prostate biopsy data. DESIGN, SETTING, AND PARTICIPANTS PCA3 assay cut-off threshold analyses were followed by logistic regression models which used established predictors to assess PCa-risk at biopsy in a large multi-institutional data set of 809 men at risk of harboring PCa. MEASUREMENTS Regression coefficients were used to construct four sets of nomograms. Predictive accuracy (PA) estimates of biopsy outcome predictions were quantified using the area under the curve of the receiver operator characteristic analysis in models with and without PCA3. Bootstrap resamples were used for internal validation and to reduce overfit bias. The extent of overestimation or underestimation of the observed PCa rate at biopsy was explored graphically using nonparametric loss-calibration plots. Differences in PA were tested using the Mantel-Haenszel test. Finally, nomogram-derived probability cut-offs were tested to assess the ability to identify patients with or without PCa. RESULTS AND LIMITATIONS PCA3 was identified as a statistically independent risk factor of PCa at biopsy. Addition of a PCA3 assay improved bootstrap-corrected multivariate PA of the base model between 2% and 5%. The highest increment in PA resulted from a PCA3 assay cut-off threshold of 17, where a 5% gain in PA (from 0.68 to 0.73, p=0.04) was recorded. Nomogram probability-derived risk cut-off analyses further corroborate the superiority of the PCA3 nomogram over the base model. CONCLUSIONS PCA3 fulfills the criteria for a novel marker capable of increasing PA of multivariate biopsy models. This novel PCA3-based nomogram better identifies men at risk of harboring PCa and assists in deciding whether further evaluation is necessary.

Carbonic Anhydrase IX in Renal Cell Carcinoma: Implications for Prognosis, Diagnosis, and Therapy

CONTEXT The clinical management of patients with renal cell carcinoma (RCC) remains difficult, and the development of new diagnostic, prognostic, and therapeutic tools is still required. OBJECTIVE To review the current knowledge on the RCC-associated antigen carbonic anhydrase IX (CAIX) and provide evidence for how this antigen may aid in the clinical management of RCC. EVIDENCE ACQUISITION Clinical papers describing diagnostic, prognostic, and/or therapeutic applications of CAIX in RCC were selected from the Pubmed database. The search was manually augmented by reviewing the reference lists of articles. EVIDENCE SYNTHESIS Expression of CAIX is regulated by the Von Hippel Lindau (VHL) protein (pVHL). Because of the invariable VHL mutational loss in clear-cell RCC (ccRCC) patients, CAIX expression is ubiquitous in ccRCC. Determination of CAIX expression in nephrectomy specimens of RCC patients improves prognostic accuracy; high CAIX expression appears to correlate with a favourable prognosis and a greater likelihood of response to systemic treatment for metastatic disease. Therefore, CAIX expression might be used to stratify metastatic ccRCC (mRCC) patients for systemic treatment. When incorporated into the RCC nomogram, CAIX expression seems to improve diagnostic accuracy for primary RCC as well as mRCC patients, but further evidence is required. Clinical studies with the CAIX-specific monoclonal antibody (mAb) cG250 have provided unequivocal evidence that ccRCC lesions can be imaged with radiolabeled cG250. Results are awaited of a large, randomised trial that aims to establish the value of cG250 imaging for primary RCC. The outcome of another large, placebo-controlled study is awaited to establish the usefulness of CAIX-targeted therapy in the adjuvant setting. Therapeutic trials with high-dose radiolabeled cG250 and CAIX-loaded dendritic cells in mRCC patients are still in phase 1 or 2. CONCLUSIONS CAIX improves diagnostic accuracy and is an attractive target for imaging of and therapy for ccRCC.

The prostate cancer gene 3 (PCA3) urine test in men with previous negative biopsies: does free-to-total prostate-specific antigen ratio influence the performance of the PCA3 score in predicting positive biopsies?

Study Type – Diagnosis (exploratory cohort)
Level of Evidence 2b

Phase 1 Radioimmunotherapy Study with Lutetium 177–labeled Anti-Carbonic Anhydrase IX Monoclonal Antibody Girentuximab in Patients with Advanced Renal Cell Carcinoma

BACKGROUND Patients with metastatic clear cell renal cell carcinoma (ccRCC) have a dismal prognosis. Therefore, new and less toxic treatments are needed. OBJECTIVE We determined the maximum tolerated dose (MTD) and potential therapeutic efficacy of multiple infusions of lutetium 177 ((177)Lu)-girentuximab (cG250) on various dose levels in a phase 1 trial in patients with progressive metastasized ccRCC. DESIGN, SETTING, AND PARTICIPANTS In this uncontrolled case series in 23 patients with progressive ccRCC metastases, cG250 accumulation was verified by diagnostic indium 111-cG250 imaging. Patients then received a high-activity dose of (177)Lu-cG250. INTERVENTION Groups of three patients received (177)Lu-cG250, starting at a dose level of 1110 MBq/m(2)(177)Lu-cG250, with dose increments of 370 MBq/m(2) per group. In the absence of persistent toxicity, progressive disease, and accelerated blood clearance, patients were eligible for retreatment after 3 mo with 75% of the previous activity dose. Patients could receive a total of three treatment cycles. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS Determination of the MTD was the primary and therapeutic efficacy was the secondary outcome measurement of the study. RESULTS AND LIMITATIONS The MTD was 2405 MBq/m(2) because higher doses resulted in dose-limiting myelotoxicity. Some patients received second (13 of 23 [56%]) and third (4 of 23 [17%]) treatment cycles. Most patients (17 of 23 [74%]) demonstrated stable disease 3 mo after the first treatment, and one patient showed a partial response that lasted for 9 mo. Mean growth of target tumor lesions was reduced from 40.4% (95% confidence interval [CI], ± 17.0) during the last 3 mo before study entry to 5.5% (95% CI, ± 5.3; p<0.001) at 3 mo after the first treatment cycle. No major nonhematologic side effects were observed. CONCLUSIONS (177)Lu-cG250 radioimmunotherapy in metastatic ccRCC patients is well tolerated at an activity dose level as high as 2405 MBq/m(2) (MTD). Radioimmunotherapy with (177)Lu-cG250 may stabilize previously progressive metastatic ccRCC.

The reverse side of the victory: Flare up of symptoms after discontinuation of sunitinib or sorafenib in renal cell cancer patients. A report of three cases

activation of psoriasis and spontaneous regression of metastases. Similar observation has recently been reported in a patient with rheumatoid arthritis and marginal zone B cell lymphoma treated with infliximab and methotrexate [8]. In that case spontaneous remission was noted after the withdrawal of infliximab and methotrexate. Allogeneic hematopoietic stem cell transplantation may be viewed as adoptive immunotherapy, and is frequently accompanied by graftversus-host disease. A case of graft-versus-host disease manifesting as with psoriatic skin lesions has been described [9]. We can only speculate about the mechanism(s) of association between the course of psoriasis and metastatic RCC in the present patient. T lymphocytes isolated from psoriatic lesions exhibit cross reactivity to microbial and self antigens [7]. It is possible that similar cross reactivity exists between the putative tumor antigens responsible for tumor rejection and autoantigens in the skin, but this hypothesis remains speculative. The risk of cancer may be increased in patients with psoriasis, possibly as the result of therapy [10], but increased incidence of RCC has not been observed and RCC is a rare event in patients with psoriasis. In conclusion, this case report presents further indication that immune response may play a role in spontaneous regression of RCC metastases after nephrectomy.

111In-Bevacizumab Imaging of Renal Cell Cancer and Evaluation of Neoadjuvant Treatment with the Vascular Endothelial Growth Factor Receptor Inhibitor Sorafenib

Clear cell renal cell cancer (ccRCC) prominently expresses vascular endothelial growth factor-A (VEGF-A), and new treatment strategies for renal cell cancer (RCC) aim at the inhibition of VEGF–VEGF receptor signaling. This study explores the ability of 111In-bevacizumab scintigraphy to depict RCC and to evaluate response to neoadjuvant treatment with sorafenib, a VEGF receptor inhibitor. Methods: The ability to depict RCC with 111In-bevacizumab scintigraphy was tested in 14 patients scheduled to undergo a tumor nephrectomy; of these, 9 RCC patients were treated in a neoadjuvant setting with sorafenib (400 mg orally twice a day). In the latter group, baseline and posttreatment 111In-bevacizumab scans were compared. The intratumoral distribution of 111In-bevacizumab was determined scintigraphically ex vivo in a 1-cm lamella of the resected tumorous kidney. Expression of VEGF-A, glucose transporter-1, carbonic anhydrase IX, α-smooth-muscle actin, and Ki67 was determined by immunohistochemistry and compared with the local concentration of 111In-bevacizumab. Additionally, the VEGF-A content in tumor samples was determined quantitatively by enzyme-linked immunosorbent assay. Results: In all 5 non–neoadjuvant-treated patients, preferential accumulation of 111In-bevacizumab was observed in the tumors. All ccRCC lesions with enhanced 111In-bevacizumab targeting expressed high levels of VEGF-A. Treatment with sorafenib resulted in a significant decrease of 111In-bevacizumab uptake in the tumor in the patients with ccRCC (mean change, −60.5%; range, +1.5% to −90.1%). The decrease in uptake was due to destruction of the tumor neovasculature, whereas the VEGF-A expression remained intact. In the patient with papillary RCC, limited uptake without change after sorafenib was observed. Conclusion: RCC lesions were clearly delineated with 111In-bevacizumab scintigraphy. Neoadjuvant treatment with sorafenib resulted in a significant decrease of 111In-bevacizumab uptake in RCC. 111In-bevacizumab scintigraphy can be an attractive biomarker for response and needs further study.

Dosimetric Analysis of 177Lu-cG250 Radioimmunotherapy in Renal Cell Carcinoma Patients: Correlation with Myelotoxicity and Pretherapeutic Absorbed Dose Predictions Based on 111In-cG250 Imaging

This study aimed to estimate the radiation absorbed doses to normal tissues and tumor lesions during radioimmunotherapy with 177Lu-cG250. Serial planar scintigrams after injection of 111In-cG250 or 177Lu-cG250 in patients with metastasized renal cell carcinoma were analyzed quantitatively. The estimated radiation doses were correlated with observed hematologic toxicity. In addition, the accuracy of the predicted therapeutic absorbed doses, based on diagnostic 111In-cG250 data, were determined. Methods: Twenty patients received a diagnostic tracer activity of 111In-cG250 (185 MBq), followed by radioimmunotherapy with 177Lu-cG250. The administered activity of 177Lu-cG250 was escalated by entering 3 patients at each activity level starting at 1,110 MBq/m2, with increments of 370 MBq/m2. After each diagnostic and therapeutic administration, whole-body scintigraphic images and pharmacokinetic data were acquired. Hematologic toxicity was graded using the Common Toxicity Criteria, version 3.0. Diagnostic 111In-cG250 data were used to simulate 177Lu and 90Y data by correcting for the difference in physical decay. Absorbed doses were calculated for the whole body, red marrow, organs, and tumor metastases for the therapeutic 177Lu-cG250, simulated 177Lu-cG250, and simulated 90Y-cG250 data. Results: Observed hematologic toxicity, especially platelet toxicity, correlated significantly with the administered activity (r = 0.85), whole-body absorbed dose (r = 0.65), and red marrow dose (r = 0.62 and 0.75). An inverse relationship between the mass and absorbed dose of the tumor lesions was observed. Calculated mean absorbed doses were similar for the simulated and measured 177Lu-cG250 data. Absorbed doses (whole body and red marrow) based on the simulated 177Lu-cG250 data correlated with the observed platelet toxicity (r = 0.65 and 0.82). The tumor–to–red marrow dose ratio was higher for radioimmunotherapy with 177Lu-cG250 than for radioimmunotherapy with 90Y-cG250, indicating that 177Lu has a wider therapeutic window for radioimmunotherapy with cG250 than 90Y. Conclusion: In patients with metastasized renal cell carcinoma, hematologic toxicity after treatment with 177Lu-cG250 can be predicted on the basis of administered activity and whole-body and red marrow–absorbed dose. Diagnostic 111In-cG250 data can be used to accurately predict absorbed doses and myelotoxicity of radioimmunotherapy with 177Lu-cG250. These estimations indicate that in these patients, higher radiation doses can be guided to the tumors with 177Lu-cG250 than with 90Y-cG250.

Tyrosine Kinase Inhibitor Sorafenib Decreases 111In-Girentuximab Uptake in Patients with Clear Cell Renal Cell Carcinoma

Tyrosine kinase inhibitors (TKIs) have revolutionized the treatment of metastatic clear cell renal cell carcinoma (RCC). Although TKIs have demonstrated good clinical efficacy, the lack of complete responses, the chronic nature of the treatment, and the side effects are clear disadvantages. An interesting new approach in the treatment of clear cell RCC is antibody-mediated therapy with the chimeric anti–carbonic anhydrase IX (CAIX) antibody girentuximab (cG250). As the results of several girentuximab trials become available, the question arises of whether TKI treatment can be combined with girentuximab-based therapy. In this study, we assessed the effect of the widely used TKI sorafenib on the tumor-targeting potential of 111In-labeled girentuximab. Methods: 111In-girentuximab imaging was performed on 15 patients suspected of having a renal malignancy, with surgery being part of their treatment plan. Of these, 10 patients were treated in a neoadjuvant setting with sorafenib (400 mg orally twice daily). Five patients received treatment during 1 wk, and 5 patients received treatment during 4 wk. In both sorafenib-treated groups, baseline and posttreatment tumor targeting of 111In-girentuximab were compared. Surgery was performed 3 d after the last image acquisition. Five additional patients were included as a control group and had only a single 111In-girentuximab injection and scintigraphy without any treatment. Distribution of 111In-girentuximab was determined scintigraphically ex vivo in a 1-cm lamella of the resected tumorous kidney. Expression of CAIX and of the vascular marker CD31 was determined immunohistochemically on specimens of both tumor and normal kidney tissue. Results: Treatment with sorafenib resulted in a marked decrease of 111In-girentuximab uptake in the tumor in clear cell RCC patients, especially in the group treated for 4 wk (mean change in both sorafenib-treated groups, −38.4%; range, +9.1% to −79.4%). Immunohistochemical analysis showed markedly reduced CD31 expression and vessel density in the sorafenib-treated groups but no differences in CAIX expression between the sorafenib-treated groups and the nontreated patients. Conclusion: Treatment with sorafenib resulted in a treatment duration–dependent significantly decreased uptake of 111In-girentumab in clear cell RCC lesions. These results indicate that the efficacy of antibody-mediated treatment or diagnosis modalities is hampered by TKI treatment.

ImmunoPET Imaging of Renal Cell Carcinoma with (124)I- and (89)Zr-Labeled Anti-CAIX Monoclonal Antibody cG250 in Mice

INTRODUCTION Monoclonal antibody (mAb) cG250 recognizes carbonic anhydrase IX (CAIX), overexpressed on clear cell renal cell carcinoma (ccRCC). (124)I-cG250 is currently under clinical investigation for the detection of ccRCC. However, the (124)I label is rapidly excreted from the tumor cells after internalization of the radiolabeled mAb. We hypothesized that labeling cG250 with the residualizing positron emitter (89)Zr would lead to higher tumor uptake and more sensitive detection of ccRCC lesions. MATERIALS AND METHODS Nude mice with CAIX-expressing ccRCC xenografts (SK-RC-52 or NU-12) were i.v. injected with (89)Zr-cG250 or (124)I-cG250. To determine specificity of (89)Zr-cG250 uptake in ccRCC, one control group was i.v. injected with (89)Zr-MOPC21 (irrelevant mAb). PET images were acquired using a small animal PET camera and the biodistribution of the radiolabeled mAb was determined. RESULTS The ccRCC xenografts were clearly visualized after injection of (89)Zr-cG250 and (124)I-cG250. Tumor uptake of (89)Zr-cG250 was significantly higher compared with (124)I-cG250 in the NU-12 tumor model (114.7% ± 25.2% injected dose per gram (%ID/g) vs. 38.2 ± 18.3%ID/g, p=0.029), but in the SK-RC-52 the difference in tumor uptake was not significant (48.7 ± 15.2%ID/g vs. 32.0 ± 22.9%ID/g, p=0.26). SK-RC-52 tumors were not visualized with (89)Zr-MOPC21 (tumor uptake 3.0%ID/g). Intraperitoneal SK-RC-52 lesions as small as 7 mm(3) were visualized with (89)Zr-cG250 PET. CONCLUSION ImmunoPET imaging with cG250 visualized s.c. and i.p. ccRCC lesions in murine models. This confirms the potential of cG250 immunoPET in the diagnosis and (re)staging of ccRCC. PET imaging of ccRCC tumors with (89)Zr-cG250 could be more sensitive than (124)I-cG250-PET.

Radiolabeled antibodies in renal cell carcinoma

Abstract Renal cell carcinoma (RCC) is a radio- and chemotherapy resistant tumor, which has a very high morbidity and mortality when metastasized. The current treatment options demonstrate limited efficacy and severe side-effects. Therefore, there is a need for new therapeutic strategies for RCC. As for other malignancies, monoclonal antibodies (mAbs) targeting tumor-associated antigens have been developed for RCC. One of these, mAb G250, targets the MN/CAIX/G250 antigen, which is ubiquitously expressed in clear cell RCC (ccRCC). ccRCC is the most common form of RCC with a prevalence of 80%. Expression of G250 in normal tissue is restricted to the gastrointestinal mucosa and related structures, thereby making it a suitable candidate for targeting ccRCC. In several clinical studies the efficient accumulation of mAb G250 in ccRCC has been demonstrated, resulting in high contrast images. G250-imaging could prove to be a valuable tool in diagnosing metastases in patients with a G250-antigen positive primary tumor and/or in the differential diagnosis of suspect kidney lesions. Furthermore, the therapeutic efficacy of radiolabeled G250 has been investigated in a series of studies. Thus far, most efforts have been devoted to G250 labeled with high doses of 131I. Other radionuclides which may enhance the therapeutic index of this radiolabeled mAb are currently under investigation. In our institution, an activity dose escalation study is currently ongoing to investigate the therapeutic potential of 177Lu-labeled G250 in metastatic ccRCC patients. In this review, the current status of the diagnostic and therapeutic properties of radiolabeled antibodies in RCC is described.