Immunohistochemical expression of carbonic anhydrase IX assessed over time and during treatment in renal cell carcinoma

Format-tuning of in vivo-launched bispecific T cell engager enhances efficacy against renal cell carcinoma

BACKGROUND

Advanced clear cell renal cell carcinoma (ccRCC) is a prevalent kidney cancer for which long-term survival rates are abysmal, though immunotherapies are showing potential. Not yet clinically vetted are bispecific T cell engagers (BTEs) that activate T cell-mediated cancer killing through intercellular synapsing. Multiple BTE formats exist, however, with limited cross-characterizations to help optimize new drug design. Here, we developed BTEs to treat ccRCC by targeting carbonic anhydrase 9 (CA9) while characterizing the persistent BTE (PBTE) format and comparing it to a new format, the persistent multivalent T cell engager (PMTE). These antibody therapies against ccRCC are developed as both recombinant and synthetic DNA (synDNA) medicines.

METHODS

Antibody formatting effects on binding kinetics were assessed by flow cytometry and intercellular synaptic strength assays while potency was tested using T-cell activation and cytotoxicity assays. Mouse models were used to study antibody plasma and tumor pharmacokinetics, as well as antitumor efficacy as both recombinant and synDNA medicines. Specifically, three models using ccRCC cell line xenografts and human donor T cells in immunodeficient mice were used to support this study.

RESULTS

Compared with a first-generation BTE, we show that the PBTE reduced avidity, intercellular synaptic strength, cytotoxic potency by as much as 33-fold, and ultimately efficacy against ccRCC tumors in vivo. However, compared with the PBTE, we demonstrate that the PMTE improved cell avidity, restored intercellular synapses, augmented cytotoxic potency by 40-fold, improved tumor distribution pharmacokinetics by 2-fold, and recovered synDNA efficacy in mouse tumor models by 20-fold. All the while, the PMTE displayed a desirable half-life of 4 days in mice compared with the conventional BTE's 2 hours.

CONCLUSIONS

With impressive efficacy, the CA9-targeted PMTE is a promising new therapy for advanced ccRCC, which can be effectively delivered through synDNA. The highly potent PMTE format itself is a promising new tool for future applications in the multispecific antibody space.

Intrinsically disordered features of carbonic anhydrase IX proteoglycan-like domain

hCA IX is a multi-domain protein belonging to the family of hCAs which are ubiquitous zinc enzymes that catalyze the reversible hydration of CO2 to HCO3- and H+. hCA IX is a tumor-associated enzyme with a limited distribution in normal tissues, but over-expressed in many tumors, and is a promising drug target. Although many studies concerning the CA IX catalytic domain were performed, little is known about the proteoglycan-like (PG-like) domain of hCA IX which has been poorly investigated so far. Here we attempt to fill this gap by providing an overview on the functional, structural and therapeutic studies of the PG-like domain of hCA IX which represents a unique feature within the CA family. The main studies and recent advances concerning PG role in modulating hCA IX catalytic activity as well as in tumor spreading and migration are here reported. Special attention has been paid to the newly discovered disordered features of the PG domain which open new perspectives about its molecular mechanisms of action under physiological and pathological conditions, since disorder is likely involved in mediating interactions with partner proteins. The emerged disordered features of PG domain will be explored for putative diagnostic and therapeutic applications involving CA IX targeting in tumors.

ImmunoPET: Concept, Design, and Applications

Immuno-positron emission tomography (immunoPET) is a paradigm-shifting molecular imaging modality combining the superior targeting specificity of monoclonal antibody (mAb) and the inherent sensitivity of PET technique. A variety of radionuclides and mAbs have been exploited to develop immunoPET probes, which has been driven by the development and optimization of radiochemistry and conjugation strategies. In addition, tumor-targeting vectors with a short circulation time (e.g., Nanobody) or with an enhanced binding affinity (e.g., bispecific antibody) are being used to design novel immunoPET probes. Accordingly, several immunoPET probes, such as ⁸⁹Zr-Df-pertuzumab and ⁸⁹Zr-atezolizumab, have been successfully translated for clinical use. By noninvasively and dynamically revealing the expression of heterogeneous tumor antigens, immunoPET imaging is gradually changing the theranostic landscape of several types of malignancies. ImmunoPET is the method of choice for imaging specific tumor markers, immune cells, immune checkpoints, and inflammatory processes. Furthermore, the integration of immunoPET imaging in antibody drug development is of substantial significance because it provides pivotal information regarding antibody targeting abilities and distribution profiles. Herein, we present the latest immunoPET imaging strategies and their preclinical and clinical applications. We also emphasize current conjugation strategies that can be leveraged to develop next-generation immunoPET probes. Lastly, we discuss practical considerations to tune the development and translation of immunoPET imaging strategies.

Inhibition of carbonic anhydrase IX targets primary tumors, metastases, and cancer stem cells: Three for the price of one

Human carbonic anhydrase (CA) IX is a tumor-associated protein, since it is scarcely present in normal tissues, but highly overexpressed in a large number of solid tumors, where it actively contributes to survival and metastatic spread of tumor cells. Due to these features, the characterization of its biochemical, structural, and functional features for drug design purposes has been extensively carried out, with consequent development of several highly selective small molecule inhibitors and monoclonal antibodies to be used for different purposes. Aim of this review is to provide a comprehensive state-of-the-art of studies performed on this enzyme, regarding structural, functional, and biomedical aspects, as well as the development of molecules with diagnostic and therapeutic applications for cancer treatment. A brief description of additional pharmacologic applications for CA IX inhibition in other diseases, such as arthritis and ischemia, is also provided.

Carbonic anhydrase-IX score is a novel biomarker that predicts recurrence and survival for high-risk, nonmetastatic renal cell carcinoma: Data from the phase III ARISER clinical trial

INTRODUCTION AND OBJECTIVE

With a limited number of prognostic and predictive biomarkers available, carbonic anhydrase-IX (CAIX) has served as an important prognostic biomarker for patients with clear cell renal cell carcinoma (ccRCC). However, studies have recently called into question the role of CAIX as a biomarker for ccRCC. To investigate this uncertainty, we quantified the association of CAIX with lymphatic involvement and survival using data from ARISER study (WX-2007-03-HR)--a prospective trial involving subjects with high-risk nonmetastatic ccRCC.

METHODS AND MATERIALS

We reviewed the records of 813 patients enrolled in the ARISER study. Central review of histology, grade, and CAIX staining (frequency and intensity) was performed. CAIX score was derived by multiplying the staining intensity (1-3) by percent positive cells (0%-100%), yielding a range of 0 to 300. We quantified the association of CAIX expression and score with lymphatic spread and survival (disease-free survival [DFS] and overall survival [OS]) using Kaplan-Meier and multivariable propensity score adjusted Cox regression analyses.

RESULTS

Median follow-up of the cohort was 54.2 months. Although 56% of subjects with lymphatic involvement had CAIX>85%, only 33% had CAIX score ≥ 200. On multivariable analysis, CAIX>85% was not a statistically significant predictor of DFS and OS (P = 0.06 and P = 0.15, respectively). However, CAIX score ≥ 200, when compared with CAIX score ≤ 100, was associated with improved DFS and OS (P = 0.01 and P = 0.01, respectively) on multivariable analysis.

CONCLUSIONS

The largest, multicenter, prospective analysis of patients with high-risk nonmetastatic ccRCC demonstrates the utility of CAIX score as a statistically significant prognostic biomarker for survival. We recommend that CAIX score be quantified for all patients with high-risk disease after nephrectomy.

Prognostic value of carbonic anhydrase IX immunohistochemical expression in renal cell carcinoma: a meta-analysis of the literature

Background

Carbonic anhydrase IX (CAIX) protein has been correlated with progression and survival in patients with renal cell carcinoma (RCC). The prognostic value of CAIX in RCC however, remains inconclusive according to published works. This study aimed to analyze CAIX as a biological marker to predict RCC patient prognosis.

Methods

A literature search of the PubMed and Web of Knowledge databases was performed to retrieve original studies from their inception to December of 2013. Fifteen studies, collectively including a total of 2611 patients with renal cell carcinoma, were carefully reviewed. Standard meta-analysis methods were applied to evaluate the prognostic impact of CAIX expression on patient prognosis. The hazard ratio (HR) and its 95% confidence interval (CI) were recorded for the relationship between CAIX expression and survival, and the data were analyzed using Review Manager 5.2 software and Stata software 11.0.

Results

In patients with RCC, low CAIX expression was associated with poor disease-specific survival (HR = 1.89, 95% CI: 1.20–2.98, P = 0.006), unfavorable progression-free survival (HR = 2.62, 95% CI: 1.14–6.05, P = 0.02) and worse overall survival (HR = 2.03, 95% CI: 1.28–3.21, P = 0.002). Furthermore, low CAIX expression was significantly associated with the presence of lymph node metastases (odds ratio (OR) = 0.31, 95% CI = 0.15–0.62, P = 0.0009) and distant metastases (OR = 0.66, 95% CI = 0.46–0.96, P = 0.03) and predicted a higher tumor grade (OR = 0.41, 95% CI = 0.31–0.54, P<0.00001).

Conclusions

Low CAIX expression most likely indicates poor prognosis in RCC patients. Moreover, low CAIX expression was significantly associated with unfavorable clinicopathological factors. To strengthen our findings, further well-designed prospective studies should be conducted to investigate the role of CAIX expression in RCC.

Carbonic anhydrase 9 in clear cell renal cell carcinoma: a marker for diagnosis, prognosis and treatment

Carbonic anhydrase 9 (CA9) is a transmembrane member of the carbonic anhydrase family. It catalyses the reversible hydration of carbon dioxide into bicarbonate and a proton, thus enabling tumour cells to maintain a neutral pH despite an acidic microenvironment. CA9 is not expressed in healthy renal tissue but is expressed in most clear cell renal cell carcinomas (CCRCC) through HIF-1α accumulation driven by hypoxia and inactivation of the VHL gene. CA9 expression can be detected in the tumour by immunohistochemistry (IHC), in blood and tissue by ELISA assay and RT-PCR. It has a 100% diagnostic specificity in solid renal tumours, while ELISA assays on aspiration fluids may help in atypical cysts. Blood-based assays, ELISA for CA9 antigen and RT-PCR for CA9 mRNA are promising for the prognosis and follow-up of localised CCRCC. In metastatic disease, high CA9 expression by IHC was reported to be a powerful prognostic marker with better survival and sensitivity to IL-2, but this is still debated. Almost no data are currently available on the association of CA9 expression and outcome to targeted drugs. The prognostic value of CA9 in CCRCC could be explained by the frequent VHL gene inactivation driving an early activation of the HIF pathway. The poorer prognosis associated with low CA9 expressing tumours could be due to the simultaneous overexpression of EGFR contributing to the activation of AkT and mTOR pathways. Targeting CA9 by inhibitors, radioimmunotherapy, monoclonal antibodies or vaccination is promising and offers new avenues for clinical research.

'Image and treat': an individualized approach to urological tumors

PURPOSE OF REVIEW

The current treatment options for advanced urologic cancers demonstrate limited efficacy. To obtain optimal clinical results, there is a need for new, individualized, therapeutic strategies, which have only recently been applied to these malignancies. Nuclear medicine plays an important role in establishing imaging biomarkers necessary for personalized medicine. This review focuses on the current status of the 'image and treat' approach combining molecular imaging with targeted radionuclide therapy of urological malignancies

RECENT FINDINGS

Tumor-specific targets in uro-oncology are showing promising results for development of personalized therapy using positron emission tomography/computed tomography (PET/CT) molecular imaging and radioimmunotherapy. The antibody cG250, which binds to carbonic anhydrase IX, is being evaluated as a radiolabeled imaging and therapeutic agent in clear-cell renal cell carcinoma. I-cG250 PET/CT has demonstrated excellent targeting of clear-cell renal cell carcinoma. Prostate-specific membrane antigen is a promising target for both PET/CT and radioimmunotherapy of prostate cancer. HER2 may be another potential target in bladder and prostate cancer.

SUMMARY

Tumor-specific targets and biomarkers are being studied for PET/CT and radioimmunotherapy. This may lead to development of new therapeutic strategies. However, considerable investment in new research will be required for personalized medicine to be routinely used in uro-oncology.

Presence of intratumoral neutrophils is an independent prognostic factor in localized renal cell carcinoma

PURPOSE

We have previously demonstrated a significant negative impact of intratumoral neutrophils in metastatic renal cell carcinoma. This study assessed intratumoral neutrophils in localized clear cell renal cell carcinoma (RCC).

PATIENTS AND METHODS

The study comprised 121 consecutive patients who had a nephrectomy for localized RCC. Biomarkers (intratumoral CD8+, CD57+ immune cells, CD66b+ neutrophils, and carbonic anhydrase IX [CA IX]) were assessed by immunohistochemistry, and the relationship with clinical and histopathologic features and patient outcome was evaluated.

RESULTS

The intratumoral neutrophils ranged from zero to 289 cells/mm(2) tumor tissue. The presence of intratumoral neutrophils was statistically significantly associated with increasing tumor size, low hemoglobin, high creatinine, and CA IX < or = 85%. In multivariate analysis, the presence of intratumoral neutrophils (hazard ratio [HR], 3.0; 95% CI, 1.7 to 5.4; P < .0001), pT stage T3b/T4 (HR, 2.1; 95% CI, 1.2 to 3.6; P = .007), and low hemoglobin (HR, 1.8; 95% CI, 1.0 to 3.1; P = .03) were independent prognostic factors significantly associated with short recurrence-free survival. The presence of intratumoral neutrophils was also an independent prognostic factor for cancer-specific survival (HR, 3.5; 95% CI, 1.9 to 6.4; P < .0001) and overall survival (HR, 3.1; 95% CI, 1.9 to 5.0; P < .0001). Applying the prognostic value of intratumoral neutrophils to the Leibovich low-/intermediate-risk group (n = 78) showed a 5-year recurrence-free survival of 53% (95% CI, 34.6% to 71.8%; presence of intratumoral neutrophils) versus 87% (95% CI, 77.8% to 96.8%; absence of intratumoral neutrophils). The estimated concordance index was 0.74 using the Leibovich risk score and 0.80 when intratumoral neutrophils were added.

CONCLUSION

The presence of intratumoral neutrophils is a new, strong, independent prognostic factor for short recurrence-free, cancer-specific, and overall survival in localized clear cell RCC.