Gunhild von Amsberg

Second Line Chemotherapy for Advanced and Metastatic Urothelial Carcinoma: Vinflunine and Beyond—A Comprehensive Review of the Current Literature

PURPOSE We comprehensively reviewed current efforts and advances in the field of chemotherapeutic and biologically targeted treatment options after the failure of cisplatin based, first line regimens for urothelial carcinoma. MATERIALS AND METHODS We searched MEDLINE®, Central®, and meeting abstracts of ASCO (American Society of Clinical Oncology) and ESMO (European Society for Medical Oncology) to identify original articles, reviews and retrospective analyses on second line treatment of urothelial carcinoma. Articles were included in analysis if they described prospective phase II/III studies or larger high quality retrospective studies of second line treatment of urothelial carcinoma. RESULTS Although considered a chemosensitive disease, most patients with advanced or metastatic urothelial carcinoma relapse after cisplatin based first line treatment. Today none of the commonly used drugs, ie paclitaxel, carboplatin and/or gemcitabine, are approved by the FDA (Food and Drug Administration) for second line systemic treatment. In Europe vinflunine plus best supportive care is the only option approved by the EMA (European Medicines Agency) with moderate clinical efficacy. Responses to combined chemotherapy approaches are often better but associated with remarkable toxicity. In patients who respond well to first line treatment and, thus, are considered cisplatin sensitive readministration of a platinum based combination regimen may be an option. To date targeted therapies do not have a role in second line treatment of urothelial cancer. Immunotherapeutic strategies to target the PD-1/PD-L1 axis are emerging. In a recent phase I trial evaluating the PD-L1 targeted monoclonal antibody MPDL3280A a promising 43% response rate with good tolerability was achieved, which led to an immediate breakthrough therapy designation by the FDA. Combining chemotherapy with targeted agents, eg weekly paclitaxel and pazopanib, also shows promising activity in this prognostically poor treatment situation. CONCLUSIONS Response rates and survival are poor after second line chemotherapy for advanced or metastatic urothelial carcinoma. To improve outcomes of salvage treatment novel biologically targeted drugs as monotherapy or as part of a combination with conventional cytostatics are urgently needed.

The marine triterpene glycoside frondoside A exhibits activity in vitro and in vivo in prostate cancer.

Despite recent advances in the treatment of metastatic castration‐resistant prostate cancer (CRPC), outcome of patients remains poor due to the development of drug resistance. Thus, new drugs are urgently needed. We investigated efficacy, toxicity and mechanism of action of marine triterpene glycoside frondoside A (FrA) using CRPC cell lines in vitro and in vivo. FrA revealed high efficacy in human prostate cancer cells, while non‐malignant cells were less sensitive. Remarkably, proliferation and colony formation of cells resistant to enzalutamide and abiraterone (due to the androgen receptor splice variant AR‐V7) were also significantly inhibited by FrA. The marine compound caused cell type specific cell cycle arrest and induction of caspase‐dependent or ‐independent apoptosis. Up‐regulation or induction of several pro‐apoptotic proteins (Bax, Bad, PTEN), cleavage of PARP and caspase‐3 and down‐regulation of anti‐apoptotic proteins (survivin and Bcl‐2) were detected in treated cells. Global proteome analysis revealed regulation of proteins involved in formation of metastases, tumor cell invasion, and apoptosis, like keratin 81, CrkII, IL‐1β and cathepsin B. Inhibition of pro‐survival autophagy was observed following FrA exposure. In vivo, FrA inhibited tumor growth of PC‐3 and DU145 cells with a notable reduction of lung metastasis, as well as circulating tumor cells in the peripheral blood. Increased lymphocyte counts of treated animals might indicate an immune modulating effect of FrA. In conclusion, our results suggest that FrA is a promising new drug for the treatment of mCRPC. Induction of apoptosis, inhibition of pro‐survival autophagy, and immune modulatory effects are suspected modes of actions.

Systemic treatment of vulvar cancer

Squamous cell carcinoma of the vulva is a rare disease, accounting for approximately 5% of cancers of the female genital tract. Standard therapy for early-stage vulvar cancer mainly comprises of surgery of the vulva and groins. In locally advanced or metastatic vulvar cancer, neoadjuvant or definitive chemoradiation is often considered as an alternative treatment option. Given its rarity, the level of evidence for different treatment modalities is poor and few clinical trials have been performed on this disease. Therefore indication criteria for systemic treatment in advanced stage vulvar cancer vary widely among countries and institutions. This review focuses on the different systemic treatment options for patients with locally advanced, recurrent or metastatic vulvar cancer, and highlights the need for an international multicenter approach to identify the most effective therapeutic options.

Guanidine alkaloids from the marine sponge Monanchora pulchra show cytotoxic properties and prevent EGF-induced neoplastic transformation in vitro

Guanidine alkaloids from sponges Monanchora spp. represent diverse bioactive compounds, however, the mechanisms underlying bioactivity are very poorly understood. Here, we report results of studies on cytotoxic action, the ability to inhibit EGF-induced neoplastic transformation, and the effects on MAPK/AP-1 signaling of eight rare guanidine alkaloids, recently isolated from the marine sponge Monanchora pulchra, namely: monanchocidin A (1), monanchocidin B (2), monanchomycalin C (3), ptilomycalin A (4), monanchomycalin B (5), normonanchocidin D (6), urupocidin A (7), and pulchranin A (8). All of the compounds induced cell cycle arrest (apart from 8) and programmed death of cancer cells. Ptilomycalin A-like compounds 1–6 activated JNK1/2 and ERK1/2, following AP-1 activation and caused p53-independent programmed cell death. Compound 7 induced p53-independent cell death without activation of AP-1 or caspase-3/7, and the observed JNK1/2 activation did not contribute to the cytotoxic effect of the compound. Alkaloid 8 induced JNK1/2 (but not ERK1/2) activation leading to p53-independent cell death and strong suppression of AP-1 activity. Alkaloids 1–4, 7, and 8 were able to inhibit the EGF-induced neoplastic transformation of JB6 P+ Cl41 cells. Our results suggest that investigated guanidine marine alkaloids hold potential to eliminate human cancer cells and prevent cancer cell formation and spreading.

A non-randomized, prospective, clinical study on the impact of circulating tumor cells on outcomes of urothelial carcinoma of the bladder patients treated with radical cystectomy with or without adjuvant chemotherapy.

To investigate outcomes of urothelial carcinoma of the bladder (UCB) patients treated with radical cystectomy (RC) according to the presence of circulating tumor cells (CTC) and the administration of adjuvant chemotherapy (AC). We prospectively enrolled 226 UCB patients treated with RC without neoadjuvant chemotherapy at our institution between 2007 and 2013. Blood samples were obtained from all patients preoperatively and analyzed for CTC using the CellSearch® system. Platinum‐based AC was administered in 50 patients (27.0%). Cox regression models evaluated the association of CTC with disease recurrence, cancer‐specific and overall mortality according to AC administration. 185 patients were available for analyses. CTC were present in 41 patients (22.2%). Patients with presence of CTC received AC more frequently, compared to patients without CTC (p = 0.027). At a median follow‐up of 31 months, the presence of CTC was associated with disease recurrence, cancer‐specific and overall mortality (p‐values < 0.001) in patients without AC administration. In patients who received AC, there was no difference in either endpoint between patients with or without presence of CTC. In multivariable analysis of patients without AC administration, the presence of CTC was an independent predictor for disease recurrence (HR: 4.9; p < 0.001), cancer‐specific (HR: 4.2; p = 0.003) and overall mortality (HR: 4.2; p = 0.001). The CTC status may be implemented in decision‐making regarding AC administration in UCB patients following RC. CTC measurement should be implemented in future UCB studies on systemic chemotherapy to validate our findings.

AXL BLOCKADE BY BGB324 INHIBITS BCR-ABL TYROSINE KINASE INHIBITOR-SENSITIVE AND -RESISTANT CHRONIC MYELOID LEUKEMIA

Purpose: BCR-ABL kinase inhibitors are employed successfully for chronic myeloid leukemia (CML) treatment. However, resistant disease and persistence of BCR-ABL1–independent leukemia stem and progenitor cells (LSPC) remain clinical challenges. The receptor tyrosine kinase Axl can mediate survival and therapy resistance of different cancer cells. We investigated the therapeutic potential of Axl inhibition in CML. Experimental Design: We used primary cells from patients with CML and TKI-sensitive and -resistant BCR-ABL1+ CML cell lines and a novel ponatinib-resistant cell line KCL-22 PonR. We analyzed the effects of genetic and pharmacologic Axl blockade by the small-molecule Axl inhibitor BGB324 in vitro and in vivo. In BCR-ABL1–unmutated cells, we also investigated BGB324 in combination with imatinib. Results: We demonstrate overexpression of Axl receptor tyrosine kinase in primary cells of patients with CML compared with healthy individuals and a further increase of Axl expression in BCR-ABL TKI-resistant patients. We show that Axl blockage decreased growth of BCR-ABL TKI-sensitive CML cells including CD34+ cells and exerts additive effects with imatinib via inhibition of Stat5 activation. BGB324 also inhibits BCR-ABL TKI-resistant cells, including T315I-mutated and ponatinib-resistant primary cells. BGB324 exerted therapeutic effects in BCR-ABL1 T315I-mutated and ponatinib-resistant preclinical mouse models. Notably, BGB324 does not inhibit BCR-ABL1 and consequently inhibits CML independent of BCR-ABL1 mutational status. Conclusions: Our data show that Axl inhibition has therapeutic potential in BCR-ABL TKI-sensitive as well as -resistant CML and support the need for clinical trials. Clin Cancer Res; 23(9); 2289–300. ©2016 AACR.

Anti‐migratory activity of marine alkaloid monanchocidin A – proteomics‐based discovery and confirmation

Monanchocidin A (MonA) is a novel marine alkaloid with promising anti‐cancer properties. We recently demonstrated its high efficacy in human urogenital cancers including germ cell tumors. Here, we applied a global proteome screening approach to investigate molecular targets and biological processes affected by MonA in the human cisplatin‐resistant germ cell cancer cell line NCCIT‐R. Bioinformatical analysis of the proteomics data predicted an effect of MonA on cancer cell migration. Thus, proteins known to be involved in cancer cell migration and invasion were chosen for further validation. The protein alterations identified by proteomics resulted from both, regulation of the total protein expression and post‐transcriptional modifications. Among others, regulation of an isoform of vimentin, up‐regulation of multiple apolipoprotein E isoforms, and inhibition of hypusination of eukaryotic translation initiation factor 5A‐1 were found upon treatment with MonA. Further functional analyses were performed and revealed decreased cell migration and colony formation of cancer cells treated with MonA at non‐cytotoxic and non‐antiproliferative concentrations. This work provides further insights into the molecular mechanisms behind MonA bioactivity. Furthermore, our research is exemplary for the ability of proteomics to predict drug targets and mode of action of natural anti‐cancer agents.

In Situ Detection and Quantification of AR-V7, AR-FL, PSA, and KRAS Point Mutations in Circulating Tumor Cells

BACKGROUND Liquid biopsies can be used in castration-resistant prostate cancer (CRPC) to detect androgen receptor splice variant 7 (AR-V7), a splicing product of the androgen receptor. Patients with AR-V7-positive circulating tumor cells (CTCs) have greater benefit of taxane chemotherapy compared with novel hormonal therapies, indicating a treatment-selection biomarker. Likewise, in those with pancreatic cancer (PaCa), KRAS mutations act as prognostic biomarkers. Thus, there is an urgent need for technology investigating the expression and mutation status of CTCs. Here, we report an approach that adds AR-V7 or KRAS status to CTC enumeration, compatible with multiple CTC-isolation platforms. METHODS We studied 3 independent CTC-isolation devices (CellCollector, Parsortix, CellSearch) for the evaluation of AR-V7 or KRAS status of CTCs with in situ padlock probe technology. Padlock probes allow highly specific detection and visualization of transcripts on a cellular level. We applied padlock probes for detecting AR-V7, androgen receptor full length (AR-FL), and prostate-specific antigen (PSA) in CRPC and KRAS wild-type (wt) and mutant (mut) transcripts in PaCa in CTCs from 46 patients. RESULTS In situ analysis showed that 71% (22 of 31) of CRPC patients had detectable AR-V7 expression ranging from low to high expression [1-76 rolling circle products (RCPs)/CTC]. In PaCa patients, 40% (6 of 15) had KRAS mut expressing CTCs with 1 to 8 RCPs/CTC. In situ padlock probe analysis revealed CTCs with no detectable cytokeratin expression but positivity for AR-V7 or KRAS mut transcripts. CONCLUSIONS Padlock probe technology enables quantification of AR-V7, AR-FL, PSA, and KRAS mut/wt transcripts in CTCs. The technology is easily applicable in routine laboratories and compatible with multiple CTC-isolation devices.

Marine compound rhizochalinin shows high in vitro and in vivo efficacy in castration resistant prostate cancer.

Development of drug resistance is an inevitable phenomenon in castration-resistant prostate cancer (CRPC) cells requiring novel therapeutic approaches. In this study, efficacy and toxicity of Rhizochalinin (Rhiz) – a novel sphingolipid-like marine compound – was evaluated in prostate cancer models, resistant to currently approved standard therapies. In vitro activity and mechanism of action of Rhiz were examined in the human prostate cancer cell lines PC-3, DU145, LNCaP, 22Rv1, and VCaP. Rhiz significantly reduced cell viability at low micromolar concentrations showing most pronounced effects in enzalutamide and abiraterone resistant AR-V7 positive cells. Caspase-dependent apoptosis, inhibition of pro-survival autophagy, downregulation of AR-V7, PSA and IGF-1 expression as well as inhibition of voltage-gated potassium channels were identified as mechanisms of action. Remarkably, Rhiz re-sensitized AR-V7 positive cells to enzalutamide and increased efficacy of taxanes. In vivo activity and toxicity were evaluated in PC-3 and 22Rv1 NOD SCID mouse xenograft models using i.p. administration. Rhiz significantly reduced growth of PC-3 and 22Rv1 tumor xenografts by 27.0% (p = 0.0156) and 46.8% (p = 0.047) compared with controls with an increased fraction of tumor cells showing apoptosis secondary to Rhiz exposure. In line with the in vitro data, Rhiz was most active in AR-V7 positive xenografts in vivo. In animals, no severe side effects were observed. In conclusion, Rhiz is a promising novel marine-derived compound characterized by a unique combination of anticancer properties. Its further clinical development is of high impact for patients suffering from drug resistant prostate cancer especially those harboring AR-V7 mediated resistance to enzalutamide and abiraterone.

Pretrichodermamides D–F from a Marine Algicolous Fungus Penicillium sp. KMM 4672

Three new epidithiodiketopiperazines pretrichodermamides D–F (1–3), together with the known N-methylpretrichodermamide B (4) and pretrichodermamide С (5), were isolated from the lipophilic extract of the marine algae-derived fungus Penicillium sp. KMM 4672. The structures of compounds 1–5 were determined based on spectroscopic methods. The absolute configuration of pretrichodermamide D (1) was established by a combination of modified Mosher′s method, NOESY data, and biogenetic considerations. N-Methylpretrichodermamide B (5) showed strong cytotoxicity against 22Rv1 human prostate cancer cells resistant to androgen receptor targeted therapies.