CDK4/6 Inhibitors in Advanced HR+/HER2 - Breast Cancer: A Multicenter Real-World Data Analysis.

Purpose: CDK4/6 inhibitors (CDK4/6i) combined with endocrine therapy are considered standard-of-care for first-line therapy of patients with hormone receptor positive, HER2 negative, advanced breast cancer (HR+/HER2- ABC). Superiority of combination therapy over endocrine monotherapy has been demonstrated in a multitude of randomized controlled trials (RCTs) in phase III and IV. However, RCTs reflect clinical reality only to a limited extent, as narrow inclusion criteria lead to a selected patient collective. Here, we present real-world data (RWD) on CDK4/6i treatment in patients with HR+/HER2- ABC at four certified German university breast cancer centers. Methods: Patients diagnosed with HR+/HER2- ABC who were treated in clinical routine with CDK4/6i between November 2016 and December 2020 at four certified German university breast cancer centers (Saarland University Medical Center, University Medical Center Charité Berlin, University Medical Center Bonn, and University Medical Center Hospital Schleswig-Holstein, Campus Kiel) were identified and enrolled in this retrospective study. Clinicopathological characteristics and clinical outcomes were recorded with particular emphasis on CDK4/6i therapy course [progression-free survival (PFS) following treatment initiation, toxicity, dose reduction, therapy discontinuation, prior and subsequent therapy line]. Results: Data from n = 448 patients were evaluated. The mean patient age was 63 (±12) years. Of these patients, n = 165 (36.8%) were primarily metastasized, and n = 283 (63.2%) had secondary metastatic disease. N = 319 patients (71.3%) received palbociclib, n = 114 patients (25.4%) received ribociclib, and n = 15 patients (3.3%) received abemaciclib, respectively. Dose reduction was performed in n = 132 cases (29.5%). N = 57 patients (12.7%) discontinued the treatment with CDK4/6i due to side effects. N = 196 patients (43.8%) experienced disease progression under CDK4/6i treatment. The median PFS was 17 months. Presence of hepatic metastases and prior therapy lines were associated with shorter PFS, whereas estrogen positivity and dose reduction due to toxicity were positively associated with PFS. Presence of bone and lung metastases, progesterone positivity, Ki67 index, grading, BRCA1/2 and PIK3CA mutation status, adjuvant endocrine resistance, and age did not significantly impact on PFS. Conclusion: Our RWD analysis on CDK4/6i treatment in Germany supports data from RCTs regarding both treatment efficacy and safety of CDK4/6i for treatment of patients with HR+/HER2- ABC. In comparison to data from the pivotal RCTs, median PFS was lower but within the expected range for RWD, which could result from inclusion of patients with more advanced diseases (i.e., higher therapy lines) to our dataset.

Endogenous TRAIL-R4 critically impacts apoptotic and non-apoptotic TRAIL-induced signaling in cancer cells.

Binding of TRAIL to its death domain-containing receptors TRAIL-R1 and TRAIL-R2 can induce cell death and/or pro-inflammatory signaling. The importance of TRAIL and TRAIL-R1/R2 in tumor immune surveillance and cancer biology has meanwhile been well documented. In addition, TRAIL has been shown to preferentially kill tumor cells, raising hope for the development of targeted anti-cancer therapies. Apart from death-inducing receptors, TRAIL also binds to TRAIL-R3 and TRAIL-R4. Whereas TRAIL-R3 is lacking an intracellular domain entirely, TRAIL-R4 contains a truncated death domain but still a signaling-competent intracellular part. It is assumed that these receptors have anti-apoptotic, yet still not well understood regulatory functions. To analyze the significance of the endogenous levels of TRAIL-R4 for TRAIL-induced signaling in cancer cells, we stably knocked down this receptor in Colo357 and MDA-MB-231 cells and analyzed the activation of apoptotic and non-apoptotic pathways in response to treatment with TRAIL. We found that TRAIL-R4 affects a plethora of signaling pathways, partly in an opposite way. While knockdown of TRAIL-R4 in Colo357 strongly increased apoptosis and reduced clonogenic survival, it inhibited cell death and improved clonogenic survival of MDA-MB-231 cells after TRAIL treatment. Furthermore, TRAIL-R4 turned out to be an important regulator of the expression of a variety of anti-apoptotic proteins in MDA-MB-231 cells since TRAIL-R4-KD reduced the cellular levels of FLIPs, XIAP and cIAP2 but upregulated the levels of Bcl-xL. By inhibiting Bcl-xL with Navitoclax, we could finally show that this protein mainly accounts for the acquired resistance of MDA-MB-231 TRAIL-R4-KD cells to TRAIL-induced apoptosis. Analyses of non-apoptotic signaling pathways revealed that in both cell lines TRAIL-R4-KD resulted in a constitutively increased activity of AKT and ERK, while it reduced AKT activity after TRAIL treatment. Furthermore, TRAIL-R4-KD potentiated TRAIL-induced activation of ERK and p38 in Colo357, and NF-κB in MDA-MB-231 cells. Importantly, in both cell lines the activity of AKT, ERK, p38 and NF-κB after TRAIL treatment was higher in TRAIL-R4-KD cells than in respective control cells. Thus, our data provide evidence for the important regulatory functions of endogenous TRAIL-R4 in cancer cells and improve our understanding of the very complex human TRAIL/TRAIL-R system.

ADAM17-A Potential Blood-Based Biomarker for Detection of Early-Stage Ovarian Cancer.

Ovarian cancer has the highest mortality rate among gynecological tumors. This is based on late diagnosis and the lack of early symptoms. To improve early detection, it is essential to find reliable biomarkers. The metalloprotease ADAM17 could be a potential marker, as it is highly expressed in many solid tumors, including ovarian and breast cancer. The aim of this work is to evaluate the relevance of ADAM17 as a potential diagnostic blood-based biomarker in ovarian cancer. Ovarian cancer cell lines IGROV-1 and A2780, as well as primary patient-derived tumor cells obtained from tumor tissue and ascitic fluid, were cultured to analyze ADAM17 abundance in the culture supernatant. In a translational approach, a cohort of 117 well-characterized ovarian cancer patients was assembled and ADAM17 levels in serum and corresponding ascitic fluid were determined at primary diagnosis. ADAM17 was quantified by enzyme-linked immunosorbent assay (ELISA). In the present study, ADAM17 was detected in the culture supernatant of ovarian cancer cell lines and primary cells. In addition, ADAM17 was found in serum and ascites of ovarian cancer patients. ADAM17 level was significantly increased in ovarian cancer patients compared to an age-matched control group (p < 0.0001). Importantly early FIGO I/II stages, which would not have been detected by CA-125, were associated with higher ADAM17 concentrations (p = 0.007). This is the first study proposing ADAM17 as a serum tumor marker in the setting of a gynecological tumor disease. Usage of ADAM17 in combination with CA-125 and other markers could help detect early stages of ovarian cancer.

Pharmacologically Inactive Bisphosphonates as an Alternative Strategy for Targeting Osteoclasts: In Vivo Assessment of 5-Fluorodeoxyuridine-Alendronate in a Preclinical Model of Breast Cancer Bone Metastases.

Bisphosphonates have effects that are antiresorptive, antitumor, and antiapoptotic to osteoblasts and osteocytes, but an effective means of eliciting these multiple activities in the treatment of bone metastases has not been identified. Antimetabolite-bisphosphonate conjugates have potential for improved performance as a class of bone-specific antineoplastic drugs. The primary objective of the study was to determine whether an antimetabolite-bisphosphonate conjugate will preserve bone formation concomitant with antiresorptive and antitumor activity. 5-FdU-ale, a highly stable conjugate between the antimetabolite 5-fluoro-2'-deoxyuridine and the bisphosphonate alendronate, was tested for its therapeutic efficacy in a mouse model of MDA-MB231 breast cancer bone metastases. In vitro testing revealed osteoclasts to be highly sensitive to 5-FdU-ale. In contrast, osteoblasts had significantly reduced sensitivity. Tumor cells were resistant in vitro but in vivo tumor burden was nevertheless significantly reduced compared with untreated mice. Sensitivity to 5-FdU-ale was not mediated through inhibition of farnesyl diphosphate synthase activity, but cell cycle arrest was observed. Although serum tartrate-resistant acid phosphatase (TRAP) levels were greatly reduced by both drugs, there was no significant decrease in the serum bone formation marker osteocalcin with 5-FdU-ale treatment. In contrast, there was more than a fivefold decrease in serum osteocalcin levels with alendronate treatment (p < 0.001). This finding is supported by time-lapse micro-computed tomography analyses, which revealed bone formation volume to be on average 1.6-fold higher with 5-FdU-ale treatment compared with alendronate (p < 0.001). We conclude that 5-FdU-ale, which is a poor prenylation inhibitor but maintains potent antiresorptive activity, does not reduce bone formation and has cytostatic antitumor efficacy. These results document that conjugation of an antimetabolite with bisphosphonates offers flexibility in creating potent bone-targeting drugs with cytostatic, bone protection properties that show limited nephrotoxicity. This unique class of drugs may offer distinct advantages in the setting of targeted adjuvant therapy and chemoprevention of bone diseases. © 2016 American Society for Bone and Mineral Research.