Focal Adhesion Kinase (FAK) is a non-receptor tyrosine kinase that plays a key role in cellular processes such as cell adhesion, migration, proliferation and survival. Recent studies have also implicated FAK in the regulation of cell-cell adhesion. Here, evidence is presented showing that siRNA-mediated suppression of FAK levels in NBT-II cells and expression of dominant negative mutants of FAK caused loss of epithelial cell morphology and inhibited the formation of cell-cell adhesions. Rac and Rho have been implicated in the regulation of cell-cell adhesions and can be regulated by FAK signaling. Expression of active Rac or Rho in NBT-II cells disrupted formation of cell-cell contacts, thus promoting a phenotype similar to FAK-depleted cells. The loss of intercellular contacts in FAK-depleted cells is prevented upon expression of a dominant negative Rho mutant, but not a dominant negative Rac mutant. Inhibition of FAK decreased tyrosine phosphorylation of p190RhoGAP and elevated the level of GTP-bound Rho. This suggests that FAK regulates cell-cell contact formation by regulation of Rho.

SummaryRecent studies using animal models have demonstrated an important role for FAK in the cardiovascular system. In particular, FAK is essential for angiogenesis in the embryo, functions in heart development and modulates the response of cardiomyocytes to pressure overload in adult mice. FAK function at the cellular level is discussed to provide insight into the mechanisms regulating these biological events and the role of FAK in controlling endothelial junctions and responses to mechanical stimulation are discussed. IUBMB Life, 59: 709-716, 2007

LBA602 Background: The increasing detection of renal masses presents a significant patient management challenge. Diagnostic options include cross-sectional imaging, which cannot reliably differentiate benign and malignant renal masses, and biopsy, which is invasive and subject to sampling errors. These limitations highlight the unmet need for accurate noninvasive techniques to guide patient management. Girentuximab is a monoclonal antibody that targets carbonic anhydrase IX (CAIX), an enzyme highly expressed in clear cell renal carcinoma (ccRCC). Radiolabeled 89Zr-DFO-girentuximab (TLX250-CDx) is highly specific for CAIX and can aid differentiation between ccRCCs and other renal lesions. The ZIRCON study evaluated the performance of TLX250-CDx PET/CT for detection of ccRCC in adult patients with indeterminate renal masses (IDRM). Methods: ZIRCON was an open-label, multicenter clinical trial. Patients with an IDRM (≤ 7 cm; tumor stage cT1) who were scheduled for partial nephrectomy within 90 days from planned TLX250-CDx administration were eligible. Enrolled patients received a single dose of TLX250-CDx IV (37 MBq ± 10%; 10 mg girentuximab) on Day 0 and underwent PET/CT imaging on Day 5 (± 2 days) prior to surgery. Blinded central histology review determined ccRCC status. The coprimary objectives were to evaluate both the sensitivity and specificity of TLX250-CDx PET/CT imaging in detecting ccRCC in patients with IDRM, using histology as the standard of truth. Key secondary objectives included sensitivity and specificity of TLX250-CDx PET/CT imaging in the subgroup of patients with IDRM ≤ 4 cm (cT1a). Other secondary objectives included positive and negative predictive values, safety, and tolerability. The Wilson 95% confidence intervals (CI) lower bound for sensitivity and specificity had to be > 70% and 68% respectively for ≥ 2 independent readers to declare the study successful. Results: 300 patients received TLX250-CDx; mean age was 62 ± 12 y; 71% were males. Of 288 patients with central histopathology of surgical samples, 193 (67%) had ccRCC, and 179 (62%) had CT1a; Of 284 evaluable patients included in primary analysis, the average across all 3 readers for sensitivity and specificity was 86% [80%, 90%] and 87% [79%, 92%] respectively for coprimary endpoints; and 85% [77%, 91%] and 90% [79%, 95%] respectively for key secondary endpoints. For all readers, the lower boundaries of 95% CI for coprimary and key secondary endpoints were > 75%. For all evaluable patients, positive and negative predictive values were ≥ 91.7% and ≥ 73.7%, respectively. Of 263 treatment-emergent adverse events (TEAEs), 2 TEAEs were treatment related. Conclusions: This study confirms that TLX250-CDx PET/CT is well tolerated and can accurately and noninvasively identify ccRCC, with promising utility for designing best management approaches for patients with IDRM. Clinical trial information: NCT03849118 .

TPS738 Background: Carbonic anhydrase IX (CAIX) is a cell surface antigen that is widely expressed in many cancers including clear cell renal cell carcinoma, urothelial and triple negative breast cancers, and thus is a potential target for imaging and therapy. 89Zr-DFO-girentuximab (hereafter referred to as TLX250-CDx) is a diagnostic radiopharmaceutical for PET imaging that targets CAIX and has demonstrated clinical success in ccRCC imaging. Genitourinary (GU) cancer types that express CAIX lack robust diagnostic and management options. To improve the morbidity and mortality, diagnostic and therapeutic innovation is needed; theranostics with TLX250-CDx may play an integral role. Moreover, TLX250-CDx could assist with patient selection for immuno-oncology therapy as CAIX tumoral expression is associated with resistance to immunotherapy. Finally, TLX250-CDx imaging could provide a cost-effective method for monitoring response to various therapies. In this pilot study, patients with different tumor types likely to express CAIX that lack effective therapies will be evaluated for TLX250-CDx tumor uptake. Methods: This is an open-label, non-randomized study to evaluate feasibility of targeting CAIX for potential diagnostic and therapeutic applications. Data gathered from this pilot study will support a larger trial with patients with the tumor types expressing the greatest avidity forTLX250-CDx, as well as therapeutic studies targeting CAIX. The study's primary objective is to noninvasively evaluate TLX250-CDx PET/CT imaging of CAIX tumoral expression in different solid tumors. The secondary objective is to evaluate tolerability and safety of TLX250-CDx administration in patients with different tumor types. Patients with cancer types including cervical and ovarian (minimum 5 patients per type) will be enrolled. Patients must have at least one non-central nervous system measurable target lesion (as per RECIST 1.1) documented by conventional imaging performed within 30 days before dosing. Patients will receive a single administration of TLX250-CDx (37 MBq [1mCi] ± 10%, containing 10 mg of girentuximab), and will undergo PET/CT imaging 5 ± 2 days later. Tumor uptake of TLX250-CDx will be assessed per lesion, up to the 10 most active lesions. Qualitative visual analysis (presence or absence of localized uptake associated with tumor, as seen on contrast-enhanced CT, MRI and/or FDG PET/CT), will be used to evaluate concordance of tumor lesion detection between TLX250-CDx PET/CT and conventional imaging according to RECIST 1.1. Patient safety will be evaluated based on incidence and nature of adverse events and clinically significant changes in laboratory test values, vital signs, or physical exam. Statistics will be descriptive with no formal hypothesis. The study is ongoing. Acknowledgements: Stefanie D. Martina, MS (Telix Pharmaceuticals) provided writing/editorial support. Clinical trial information: NCT05563272 .

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