Derk Jan De Groot

Proteasome inhibitor MG132 sensitizes HPV-positive human cervical cancer cells to rhTRAIL-induced apoptosis.

In cervical carcinogenesis, the p53 tumor suppressor pathway is disrupted by HPV (human papilloma virus) E6 oncogene expression. E6 targets p53 for rapid proteasome‐mediated degradation. We therefore investigated whether proteasome inhibition by MG132 could restore wild‐type p53 levels and sensitize HPV‐positive cervical cancer cell lines to apoptotic stimuli such as rhTRAIL (recombinant human TNF‐related apoptosis inducing ligand). In a panel of cervical cancer cell lines, CaSki was highly, HeLa intermediate and SiHa not sensitive to rhTRAIL‐induced apoptosis. MG132 strongly sensitized HeLa and SiHa to rhTRAIL‐induced apoptosis in a caspase‐dependent and time‐dependent manner. MG132 massively induced TRAIL receptor DR4 and DR5 membrane expression in HeLa, whereas in SiHa only DR5 membrane expression was upregulated from almost undetectable to high levels. Antagonistic DR4 antibody partially inhibited apoptosis induction by rhTRAIL and MG132 in HeLa but had no effect on apoptosis in SiHa. Inhibition of E6‐mediated p53 proteasomal degradation by MG132 resulted in elevated levels of active p53 as demonstrated by p53 small interfering RNA (siRNA) sensitive p21 upregulation. Although p53 siRNA partially inhibited MG132‐induced DR5 upregulation in HeLa and SiHa, no effect on rhTRAIL‐induced apoptosis was observed. MG132 plus rhTRAIL enhanced caspase 8 and caspase 3 activation and concomitant cleavage of X‐linked inhibitor of apoptosis (XIAP), particularly in HeLa. In addition, caspase 9 activation was only observed in HeLa. Downregulation of XIAP using siRNA in combination with rhTRAIL induced high levels of apoptosis in HeLa, whereas MG132 had to be added to the combination of XIAP siRNA plus rhTRAIL to induce apoptosis in SiHa. In conclusion, proteasome inhibition sensitized HPV‐positive cervical cancer cell lines to rhTRAIL independent of p53. Our results indicate that not only DR4 and DR5 upregulation but also XIAP inactivation contribute to rhTRAIL sensitization by MG132 in cervical cancer cell lines. Combining proteasome inhibitors with rhTRAIL may be therapeutically useful in cervical cancer treatment.

Theranostics Using Antibodies and Antibody-Related Therapeutics

In theranostics, radiolabeled compounds are used to determine a treatment strategy by combining therapeutics and diagnostics in the same agent. Monoclonal antibodies (mAbs) and antibody-related therapeutics represent a rapidly expanding group of cancer medicines. Theranostic approaches using these drugs in oncology are particularly interesting because antibodies are designed against specific targets on the tumor cell membrane and immune cells as well as targets in the tumor microenvironment. In addition, these drugs are relatively easy to radiolabel. Noninvasive molecular imaging techniques, such as SPECT and PET, provide information on the whole-body distribution of radiolabeled mAbs and antibody-related therapeutics. Molecular antibody imaging can potentially elucidate drug target expression, tracer uptake in the tumor, tumor saturation, and heterogeneity for these parameters within the tumor. These data can support drug development and may aid in patient stratification and monitoring of the treatment response. Selecting a radionuclide for theranostic purposes generally starts by matching the serum half-life of the mAb or antibody-related therapeutic and the physical half-life of the radionuclide. Furthermore, PET imaging allows better quantification than the SPECT technique. This information has increased interest in theranostics using PET radionuclides with a relatively long physical half-life, such as 89Zr. In this review, we provide an overview of ongoing research on mAbs and antibody-related theranostics in preclinical and clinical oncologic settings. We identified 24 antibodies or antibody-related therapeutics labeled with PET radionuclides for theranostic purposes in patients. For this approach to become integrated in standard care, further standardization with respect to the procedures involved is required.

Functional genomic mRNA profiling of a large cancer data base demonstrates mesothelin overexpression in a broad range of tumor types

The membrane bound glycoprotein mesothelin (MSLN) is a highly specific tumor marker, which is currently exploited as target for drugs. There are only limited data available on MSLN expression by human tumors. Therefore we determined overexpression of MSLN across different tumor types with Functional Genomic mRNA (FGM) profiling of a large cancer database. Results were compared with data in articles reporting immunohistochemical (IHC) MSLN tumor expression. FGM profiling is a technique that allows prediction of biologically relevant overexpression of proteins from a robust data set of mRNA microarrays. This technique was used in a database comprising 19,746 tumors to identify for 41 tumor types the percentage of samples with an overexpression of MSLN compared to a normal background. A literature search was performed to compare the FGM profiling data with studies reporting IHC MSLN tumor expression. FGM profiling showed MSLN overexpression in gastrointestinal (12–36%) and gynecological tumors (20–66%), non-small cell lung cancer (21%) and synovial sarcomas (30%). The overexpression found in thyroid cancers (5%) and renal cell cancers (10%) was not yet reported with IHC analyses. We observed that MSLN amplification rate within esophageal cancer depends on the histotype (31% for adenocarcinomas versus 3% for squamous-cell carcinomas). Subset analysis in breast cancer showed MSLN amplification rates of 28% in triple-negative breast cancer (TNBC) and 33% in basal-like breast cancer. Further subtype analysis of TNBCs showed the highest amplification rate (42%) in the basal-like 1 subtype and the lowest amplification rate (9%) in the luminal androgen receptor subtype.

Rapid granulomatosis with polyangiitis induced by immune checkpoint inhibition

SIR, there is a rise in the use of immune-potentiating drugs in oncology. The immune checkpoint modulators ipilimumab [an anti-cytotoxic T-lymphocyte-associated protein 4 (CTLA4) antibody], and nivolumab and pembrolizumab [anti-programmed cell death 1 (PD1) antibodies] have demonstrated survival benefit in metastatic melanoma. Potential drawbacks of anti-CTLA4 and anti-PD1 are their immune-potentiating side effects. CTLA4, a key negative regulator of T cell activation, binds to CD80/ CD86 on the surface of antigen-presenting cells (APCs). This interaction dampens the costimulatory second signal of T cell activation mediated via interaction between CD80/CD86 on APCs and CD28 on T cells. Thus, by blocking the action of CTLA4, ipilimumab promotes stimulation and potentiation of T cell activation. Also, PD1 belongs to the CD28/CTLA4 family of negative regulators of T cell activation, which serves to protect against autoimmune diseases [1]. However, cancer cells can co-opt the PD1 pathway to escape immune surveillance. Therefore, blockade of either the CTLA4 or the PD1 pathway has become an attractive target in cancer therapy.’ We treated a 56-year-old woman with metastatic melanoma successfully with four courses of 3 mg/kg ipilimumab. During ipilimumab treatment she reported mild arthralgias. Unfortunately, 6 months later she had progressive melanoma, and treatment with 850 mg/m dacarbazine every 3 weeks was initiated. The disease progressed further after two courses and dacarbazine was discontinued. At that time, pembrolizumab became available in the setting of a Named Patient Program. She was included after giving informed consent. One week after her first infusion of 2 mg/kg pembrolizumab, she had high-grade fever without signs of infection. She developed purpura on her feet and arthritis in her hands, elbows and ankles. A chest X-ray revealed stable pulmonary nodular lesions (Fig. 1A) and her urine sediment was normal. She was diagnosed as having serum sickness based on the presence of arthritis, high-grade fever and cutaneous vasculitis and was treated with 40 mg prednisone once daily. Under this regimen she developed progressive dyspnoea, and a repeated chest X-ray 1 week later showed diffuse infiltrates (Fig. 1B). Complement C3 FIG. 1 Progression and resolution of bilateral pulmonary lesions

Data-Driven Prioritization and Review of Targets for Molecular-Based Theranostic Approaches in Pancreatic Cancer

Molecularly targeted therapeutic and imaging strategies directed at aberrant signaling pathways in pancreatic tumor cells may improve the poor outcome of pancreatic ductal adenocarcinoma (PDA). Therefore, relevant molecular targets need to be identified. Methods: We collected publicly available expression profiles of patient-derived normal pancreatic tissue (n = 77) and PDA samples (n = 103). Functional genomic messenger RNA profiling was applied to predict target upregulation on the protein level. We prioritized these targets based on current status of preclinical therapeutic and imaging evaluation in PDA. Results: We identified 213 significantly upregulated proteins in PDA compared with normal pancreatic tissue. We prioritized mucin-1, mesothelin, γ-glutamyltransferase 5, and cathepsin-E as the most interesting targets, because studies already demonstrated their potential for both therapeutic and imaging strategies in literature. Conclusion: This study can assist clinicians and drug developers in deciding which theranostic targets should be taken for further clinical evaluation in PDA.