Eric Kampmann

Hallmarks of hyperthermia in driving the future of clinical hyperthermia as targeted therapy: translation into clinical application

Abstract Regional hyperthermia is described as a targeted therapy and the definitions of six hallmarks of hyperthermia are proposed, representing the pleiotropic effect of this therapeutic modality to counteract tumour growth and progression. We recommend the considerations of these hallmarks in the design of clinical trials involving regional hyperthermia as targeted therapy. Randomised clinical studies using loco-regional hyperthermia as an adjuvant to radiotherapy or to chemotherapy for locally advanced tumours demonstrate the benefit of the combination compared to either of the standard treatments alone for tumour response, disease control, and patient survival outcome. These impressive results were obtained from proof-of-concept trials for superficial or deep-seated malignancies in unselected patients. None of these trials was designed as tailored approaches for the treatment of specified targets or to select potentially more sensitive subpopulations of patients using eligibility criteria. Based upon clinical examples of targeted chemotherapy, some guidelines are described for the successful development of targeted therapeutic combinations. We also retrospectively analyse the stepwise process of generating an ongoing new clinical trial using hyperthermia as targeted therapy to evade DNA repair in combination with a DNA damaging anticancer agent to implement this new vision.

Overexpression of heat shock protein 27 (HSP27) increases gemcitabine sensitivity in pancreatic cancer cells through S-phase arrest and apoptosis

We previously established a role for HSP27 as a predictive marker for therapeutic response towards gemcitabine in pancreatic cancer. Here, we investigate the underlying mechanisms of HSP27‐mediated gemcitabine sensitivity. Utilizing a pancreatic cancer cell model with stable HSP27 overexpression, cell cycle arrest and apoptosis induction were analysed by flow cytometry, nuclear staining, immunoblotting and mitochondrial staining. Drug sensitivity studies were performed by proliferation assays. Hyperthermia was simulated using mild heat shock at 41.8°C. Upon gemcitabine treatment, HSP27‐overexpressing cells displayed an early S‐phase arrest subsequently followed by a strongly increased sub‐G1 fraction. Apoptosis was characterized by PARP‐, CASPASE 3‐, CASPASE 8‐, CASPASE 9‐ and BIM‐ activation along with a mitochondrial membrane potential loss. It was reversible through chemical caspase inhibition. Importantly, gemcitabine sensitivity and PARP cleavage were also elicited by heat shock‐induced HSP27 overexpression, although to a smaller extent, in a panel of pancreatic cancer cell lines. Finally, HSP27‐overexpressing pancreatic cancer cells displayed an increased sensitivity also towards death receptor‐targeting agents, suggesting another pro‐apoptotic role of HSP27 along the extrinsic apoptosis pathway. Taken together, in contrast to the well‐established anti‐apoptotic properties of HSP27 in cancer, our study reveals novel pro‐apoptotic functions of HSP27—mediated through both the intrinsic and the extrinsic apoptotic pathways—at least in pancreatic cancer cells. HSP27 could represent a predictive marker of therapeutic response towards specific drug classes in pancreatic cancer and provides a novel molecular rationale for current clinical trials applying the combination of gemcitabine with regional hyperthermia in pancreatic cancer patients.

Loss of p16(INK4a) is associated with reduced patient survival in soft tissue tumours, and indicates a senescence barrier

Aims p16(INK4a) is an important factor in carcinogenesis, and its expression is linked to oncogene-induced senescence. Very recently it was shown that upregulation and downregulation of p16 indicates a senescence barrier in the serrated route of colorectal cancer. However, in soft tissue sarcoma (STS), the senescence mechanism is still not understood. In this study, we analysed a well characterised cohort of STS for p16(INK4a) expression and correlated the results with clinicopathological parameters including survival. Methods Tissue microarrays (TMA) of 183 soft tissue and bone tumours were analysed immunohistochemically. Furthermore, mRNA expression of p16(INK4a) was evaluated in four sarcoma cell lines, and a demethylation test was performed by treatment with 5-aza-2′-deoxycytide. Results On protein level, expression of p16(INK4a) was observed in undifferentiated pleomorphic sarcoma (UPS) in 69.1%, leiomyosarcoma in 85.7%, synovial sarcoma in 77.8%, liposarcoma in 88.9%, angiosarcoma in 60.9% and MPNST in 22.2%. Loss of p16(INK4a) was observed in high grade sarcomas and showed a significant correlation with reduced patient survival (p=0.032). On DNA level, one out of four sarcoma cell lines exhibited a methylated p16(INK4a) promoter analysed by methylation-specific PCR. p16(INK4a) mRNA and protein expression was restored after demethylation using 5-aza-2′-deoxycytide. Conclusions Upregulation of p16(INK4a) might be associated with the induction of senescence and indicates a senescence barrier. Downregulation of p16(INK4a) is found in malignant progression, and is significantly correlated with reduced patient survival. Downregulation of p16(INK4a) may be explained by DNA-hypermethylation in sarcoma cells.

Hyperthermia adds to trabectedin effectiveness and thermal enhancement is associated with BRCA2 degradation and impairment of DNA homologous recombination repair

The tetrahydroisoquinoline trabectedin is a marine compound with approved activity against human soft‐tissue sarcoma. It exerts antiproliferative activity mainly by specific binding to the DNA and inducing DNA double‐strand breaks (DSB). As homologous recombination repair (HRR)‐deficient tumors are more susceptible to trabectedin, hyperthermia‐mediated on‐demand induction of HRR deficiency represents a novel and promising strategy to boost trabectedin treatment. For the first time, we demonstrate enhancement of trabectedin effectiveness in human sarcoma cell lines by heat and characterize cellular events and molecular mechanisms related to heat‐induced effects. Hyperthermic temperatures (41.8 or 43°C) enhanced significantly trabectedin‐related clonogenic cell death and G2/M cell cycle arrest followed by cell type‐dependent induction of apoptosis or senescence. Heat combination increased accumulation of γH2AX foci as key marker of DSBs. Expression of BRCA2 protein, an integral protein of the HRR machinery, was significantly decreased by heat. Consequently, recruitment of downstream RAD51 to γH2AX‐positive repair foci was almost abolished indicating relevant impairment of HRR by heat. Accordingly, enhancement of trabectedin effectiveness was significantly augmented in BRCA2‐proficient cells by hyperthermia and alleviated in BRCA2 knockout or siRNA‐transfected BRCA2 knockdown cells. In peripheral blood mononuclear cells isolated from sarcoma patients, increased numbers of nuclear γH2AX foci were detected after systemic treatment with trabectedin and hyperthermia of the tumor region. The findings establish BRCA2 degradation by heat as a key factor for a novel treatment strategy that allows targeted chemosensitization to trabectedin and other DNA damaging antitumor drugs by on‐demand induction of HRR deficiency.

Tyrosine kinases in soft tissue tumors

The development of therapeutic agents that specifically target the molecular alterations critical for tumorigenesis has a tremendous impact on the management of cancer patients. The successful treatment of advanced gastrointestinal stromal tumors (GIST) with receptor tyrosine kinase (RTK) inhibitors has raised the hope that other malignancies could also benefit from a similar treatment. Tyrosine kinase receptors are promising targets for personalized medicine and new drugs are currently in phase 2 and phase 3 clinical trials. We analyzed a large cohort of soft tissue sarcomas for different tyrosine kinase receptors and correlated the results with clinicopathological parameters. A total of 275 soft tissue sarcomas from the Ludwig-Maximilians University (LMU) were revisited and catagorized according to the current World Health Organization (WHO) classification system. Different entities showed distinct survival curves in 10-year long-term survival. Furthermore, different subtypes of sarcomas showed distinct expression profiles at the protein level. The expression of vascular endothelial growth factor (VEGF) receptors is associated with tumor progression. Due to the fact that not all patients respond to RTK inhibitor therapy, protein signatures should be evaluated before targeting therapy to give a rationale for a viable personalized therapy.

Neoadjuvant or adjuvant sirolimus for malignant metastatic or locally advanced perivascular epithelioid cell tumors: two case reports.

Perivascular epithelioid cell tumors (PEComas) are very rare mesenchymal tumors, characterized by the presence of perivascular epithelioid cells. Despite their often benign nature, malignant variants with a locally aggressive growth pattern and even distant metastases are known. We describe two cases of malignant PEComas. The first patient had an extensive peritoneal spread and a history of multiple resections, and received the mechanistic target of rapamycin inhibitor sirolimus in a postoperative setting as maintenance therapy. The second patient presented with locally advanced disease in the iliac fossa and was treated with sirolimus in a neoadjuvant setting and achieved complete remission. Both patients have been under treatment for 18 and 52 months, respectively, and are currently in complete remission. These two cases indicate that mechanistic target of rapamycin inhibition for malignant PEComas could be a safe and successful treatment strategy in a neoadjuvant setting with an acceptable toxicity profile.

Tyrosinkinasen in Weichgewebstumoren

The development of therapeutic agents that specifically target the molecular alterations critical for tumorigenesis has a tremendous impact on the management of cancer patients. The successful treatment of advanced gastrointestinal stromal tumors (GIST) with receptor tyrosine kinase (RTK) inhibitors has raised the hope that other malignancies could also benefit from a similar treatment. Tyrosine kinase receptors are promising targets for personalized medicine and new drugs are currently in phase 2 and phase 3 clinical trials. We analyzed a large cohort of soft tissue sarcomas for different tyrosine kinase receptors and correlated the results with clinicopathological parameters. A total of 275 soft tissue sarcomas from the Ludwig-Maximilians University (LMU) were revisited and catagorized according to the current World Health Organization (WHO) classification system. Different entities showed distinct survival curves in 10-year long-term survival. Furthermore, different subtypes of sarcomas showed distinct expression profiles at the protein level. The expression of vascular endothelial growth factor (VEGF) receptors is associated with tumor progression. Due to the fact that not all patients respond to RTK inhibitor therapy, protein signatures should be evaluated before targeting therapy to give a rationale for a viable personalized therapy.

Sinnvolle Ergänzungen zur Chemo- und Strahlentherapie

ZusammenfassungDie Hyperthermie hat in Form der Oberflächenhyperthermie und der regionalen Tiefenhyperthermie Einzug in internationale Leitlinien zur Therapie des Weichteilsarkoms und des Mammakarzinoms gehalten. Auch beim Zervixkarzinom gibt es erfolgversprechende Ergebnisse. Nach den Leitlinien der European Society of Hyperthermic Oncology (ESHO) wird sie stets im Rahmen einer Kombinationstherapie gemeinsam mit Chemo- und/oder Strahlentherapie angewandt, jedoch nie alleine. Die Hyperthermie ist insgesamt eine nebenwirkungsarme und sichere Therapieform, die jedoch nur in spezialisierten und nach den aktuellen Leitlinien handelnden Zentren mit der entsprechenden Erfahrung und Geräteausstattung angeboten werden sollte.