Current molecular imaging of spinal tumors in clinical practice

Energy metabolism measurements in spinal cord tumors, as well as in osseous spinal tumors/metastasis in vivo, are rarely performed only with molecular imaging (MI) by positron emission tomography (PET). This imaging modality developed from a small number of basic clinical science investigations followed by subsequent work that influenced and enhanced the research of others. Apart from precise anatomical localization by coregistration of morphological imaging and quantification, the most intriguing advantage of this imaging is the opportunity to investigate the time course (dynamics) of disease-specific molecular events in the intact organism. Most importantly, MI represents one of the key technologies in translational molecular neuroscience research, helping to develop experimental protocols that may later be applied to human patients. PET may help monitor a patient at the vertebral level after surgery and during adjuvant treatment for recurrent or progressive disease. Common clinical indications for MI of primary or secondary CNS spinal tumors are: (i) tumor diagnosis, (ii) identification of the metabolically active tumor compartments (differentiation of viable tumor tissue from necrosis) and (iii) prediction of treatment response by measurement of tumor perfusion or ischemia. While spinal PET has been used under specific circumstances, a question remains as to whether the magnitude of biochemical alterations observed by MI in CNS tumors in general (specifically spinal tumors) can reveal any prognostic value with respect to survival. MI may be able to better identify early disease and to differentiate benign from malignant lesions than more traditional methods. Moreover, an adequate identification of treatment effectiveness may influence patient management. MI probes could be developed to image the function of targets without disturbing them or as treatment to modify the target's function. MI therefore closes the gap between in vitro and in vivo integrative biology of disease. At the spinal level, MI may help to detect progression or recurrence of metastatic disease after surgical treatment. In cases of nonsurgical treatments such as chemo-, hormone- or radiotherapy, it may better assess biological efficiency than conventional imaging modalities coupled with blood tumor markers. In fact, PET provides a unique possibility to correlate topography and specific metabolic activity, but it requires additional clinical and experimental experience and research to find new indications for primary or secondary spinal tumors.     

Targeted therapies in pancreatic cancer: Promises and failures

Pancreatic ductal adenocarcinoma (PDAC) is an incidence rate nearly equal to its mortality rate. The poor prognosis of the disease can be explained by the absence of effective biomarkers for screening and early detection, together with the aggressive behavior and resistance to the currently available chemotherapy. The therapeutic failure can also be attributed to the inter-/intratumor genetic heterogeneity and the abundance of tumor stroma that occupies the majority of the tumor mass. Gemcitabine is used in the treatment of PDAC; however, the response rate is less than 12%. A recent phase III trial revealed that the combination of oxaliplatin, irinotecan, fluorouracil, and leucovorin could be an option for the treatment of metastatic PDAC patients with good performance status, although these approaches can result in high toxicity level. Further investigations are required to develop innovative anticancer agents that either improve gemcitabine activity, within novel combinatorial approaches or acts with a better efficacy than gemcitabine. The aim of the current review is to give an overview of preclinical and clinical studies targeting key dysregulated signaling pathways in PDAC.     

Application of genetically-engineered anti-CEA antibodies for potential immunotherapy of colorectal cancer.

Hitherto anti-CEA monoclonal antibodies (MAbs), normally of mouse origin, have been used primarily for clinical diagnosis of colorectal cancer, either as a tumor marker in serum to monitor tumor recurrence, or latterly as a means to localize in vivo CEA-bearing tumors, and metastases in patients. In vivo diagnosis using mouse anti-CEA MAbs has so far had limited clinical utility because the antibodies elicit a strong anti-mouse immunoglobulin immune response on repeated administration in man. This problem has been addressed by the development of various strategies for "humanization" of mouse anti-CEA MAbs by genetic manipulation of immunoglobulin genes. Such humanized, engineered antibodies markedly attenuate the antigenic response directed against the MAb, such that safe, repeated administration to patients has become feasible. Such humanized anti-CEA antibodies can thus be radioactively-labelled and applied for in vivo monitoring and detection of recurrent malignant disease, or used for therapeutic strategies which similarly take advantage of the ability of the antibodies to target cytotoxic agents selectively to tumor cells. The application of these novel procedures for manipulating MAb structure presents entirely new opportunities for diagnosis and treatment of human colorectal cancer.     

Chemotherapy of breast cancer: focus on paclitaxel

Paclitaxel is among the most effective agents in the treatment of breast cancer. Both as a single agent and in combinations, paclitaxel is effective as first-line therapy and as a salvage therapy in patients with locally advanced or metastatic disease. Paclitaxel also demonstrated efficacy in patients who received prior anthracyclin therapy and those with anthracyclin-resistant disease. In the adjuvant setting, data from randomized study have supported the sequential use of paclitaxel after therapy with doxorubicin / cyclophosphamide for patients with node-positive disease. The drug may be used in combination with other chemotherapeutical agents and immune stymulatory agents. Therapy on weekly and every-three-week schedules has been effective.     

IMD-0354 Targets Breast Cancer Stem Cells: A Novel Approach for an Adjuvant to Chemotherapy to Prevent Multidrug Resistance in a Murine Model

Although early detection of breast cancer improved in recent years, prognosis of patients with late stage breast cancer remains poor, mostly due to development of multidrug resistance (MDR) followed by tumor recurrence. Cancer stem cells (CSCs), with higher drug efflux capability and other stem cell-like properties, are concentrated in a side population (SP) of cells, which were proposed to be responsible for MDR and tumor repopulation that cause patients to succumb to breast cancer. Therefore, targeting of CSCs as an adjuvant to chemotherapy should be able to provide a more effective treatment of this disease. Here, we used IMD-0354, an inhibitor of NF-κB, identified for targeting CSCs, in a combination therapy with doxorubicin encapsulated in targeted nanoparticles. IMD-0354 did target CSCs, evidenced by a decrease in the SP, demonstrated by the inhibition of the following: dye/drug efflux, reduction in ABC transporters as well as in colony formation in soft agar and low attachment plates. Decrease of stem-like gene expression of Oct4, Nanog and Sox2, and apoptosis resistance related to the Survivin gene also was observed after treatment with this compound. In addition, IMD-0354 targeted non-CSCs as indicated by reducing viability and increasing apoptosis. Targeted drug delivery, achieved with a legumain inhibitor, proved to enhance drug delivery under hypoxia, a hallmark of the tumor microenvironment, but not under normoxia. Together, this allowed a safe, non-toxic delivery of both anticancer agents to the tumor microenvironment of mice bearing syngeneic metastatic breast cancer. Targeting both bulk tumor cells with a chemotherapeutic agent and CSCs with IMD-0354 should be able to reduce MDR. This could eventually result in decreasing tumor recurrences and/or improve the outcome of metastatic disease.     

Therapeutic efficacy of melanoma-reactive TIL injected in stage III melanoma patients

Adoptive therapy for cancer using tumor-infiltrating lymphocytes (TIL) has mainly been investigated in cancer patients with advanced stage disease. The limited clinical success has not been encouraging, although this might be explained by poor TIL specificity and/or high tumor burden. To re-evaluate the effectiveness of adoptive therapy, we analyzed the capacity of tumor-reactive TIL injection in preventing the further development of disease in stage III melanoma patients after complete tumor resection. A phase II/III randomized trial was performed on 88 melanoma patients, who received autologous TIL plus interleukin-2 (IL-2) or IL-2 only. The duration of relapse-free survival was analyzed, taking into account the immunological specificity of injected TIL and the number of metastatic lymph nodes removed before treatment. Kaplan-Meyer analysis revealed that the injection of tumor-reactive TIL was statistically correlated with prolonged relapse-free survival in patients with only one metastatic lymph node. Therefore, improved clinical outcome could be obtained after adoptive therapy by selecting appropriate groups of patients and monitoring the specificity of the injected TIL populations.     

Clinical breast cancer, new developments in selection and endocrine treatment of patients.

Breast cancer is the most common malignant tumor among women, comprising an estimated 24% of all cancer cases and 18% of all cancer deaths. At least half of the patients with primary breast cancer will ultimately die by metastatic disease. The tumor characteristics, the natural course of the disease and the response to therapy vary strongly. A number of recently detected cell biological parameters such as oncogenes/suppressor genes, growth factors and secretory proteins are more or less important prognostic factors, because they influence the characteristics and behavior of a tumor with respect to metastatic pattern, extent of cellular differentiation, growth rate and response to treatment. However, there is no clear consensus how best to identify patients at high or low risk. In our experience c-myc amplification and pS2 protein are strong prognosticators for relapse rate, while in advanced disease (apart from a negative estrogen/progesterone receptor/pS2 status) amplification of HER2/neu is a good prognosticator for failure to endocrine therapy. In the diagnosis of breast cancer, in vivo imaging of tumors by labeled hormones or other factors also forms a new development which might have implications for treatment too. With respect to treatment both endocrine and chemotherapy can cure a minority of patients with micrometastases, but in patients with advanced disease only a prolongation of (progression-free) survival can be reached. Response rates decrease with increasing tumor load. In the past decade a number of interesting new endocrine agents has been developed such as new (pure) (anti)steroidal agents, vitamins, aromatase inhibitors, analogs of peptide hormones, prolactin inhibitors and growth factor antagonists. However, less is known on the (potential) interaction between hormones, chemotherapeutic agents, retinoids, cytokins, growth factor antagonists and irradiation. Rapid detection of new powerful combination therapies are needed to improve treatment results during the nineties.     

The potential role of thioredoxin 1 and CD30 systems as multiple pathway targets and biomarkers in tumor therapy

Our progress in understanding pathological disease mechanisms has led to the identification of biomarkers that have had a considerable impact on clinical practice. It is hoped that the move from generalized to stratified approaches, with the grouping of patients into clinical/therapeutic subgroups according to specific biomarkers, will lead to increasingly more effective clinical treatments in the near future. This success depends on the identification of biomarkers that reflect disease evolution and can be used to predict disease state and therapy response, or represent themselves a target for treatment. Biomarkers can be identified by studying relationships between serum, tissue, or tumor microenvironment parameters and clinical or therapeutic parameters at onset and during the progression of the disease, using systems biology. Given that multiple pathways, such as those responsible for redox and immune regulation, are deregulated or altered in tumors, the future of tumor therapy could lie in the simultaneous targeting of these pathways using extracellular and intracellular targets and biomarkers. With this aim in mind, we evaluated the role of thioredoxin 1, a key redox regulator, and CD30, a cell membrane receptor, in immune regulation. Our results lead us to suggest that the combined use of these biomarkers provides more detailed information concerning the multiple pathways affected in disease and hence the possibility of more effective treatment.     

The Treatment with Interleukin 17 Inhibitors and Immune-Mediated Inflammatory Diseases

IL-17 inhibitors (IL-17i) are medicines used to treat dermatological and rheumatic diseases They belong to a class of medicines called biological disease-modifying anti-rheumatic drugs (bDMARDs). This class of drugs has had a major impact on the therapy of autoimmune diseases, being much safer and more effective than treatment with small molecules. At the same time, they have highly beneficial effects on skin and joint changes, and their efficacy has been extensively monitored and demonstrated in numerous clinical trials. More and more such drugs are still being discovered today to ensure the best possible treatment of these patients, but more frequently and relatively constantly three agents are used. Two of them (Secukinumab and Ixekizumab) inhibit IL-17A directly, and the third, Brodamulab, inhibits the IL-17A receptor. Although they are extremely effective in the treatment of these diseases, sometimes their administration has been associated with paradoxical effects, i.e., there is an exacerbation of the inflammatory process. Tough, clinical trials of IL-17i have described cases of exacerbation or even onset of inflammatory bowel disease (IBD), such as Crohn’s disease and ulcerative colitis, after administration of these drugs in patients previously diagnosed with psoriasis (PS), psoriatic arthritis (PsA), or ankylosing spondylitis (AS). The pathophysiological mechanism of action is not well understood at present. One explanation would be that this hyperreactive inflammatory process would be triggered by Interferon 1 derived from dendritic plasma cells. Even though there are many reports in the recent literature about the role of IL17i in the onset of IBD, conclusions of studies do not converge. Some of them show an increased incidence of IBD in patients treated with IL17i, while some others affirm their safety of them. In the near future we will surely have more data emerging from ongoing meta-analyses regarding safety of use IL17i in patients who are at risk of developing IBD. Clinical and paraclinical evaluation (inflammatory intestinal markers) are carefully advised before recommending treatment with IL-17i and after initiation of treatment, and prospective surveillance by clinical and biomarkers of patients treated with IL-17i is absolutely essential to capture the onset of IBD.     

Vascular disrupting agents

It has been well established that a functioning vascular supply is essential for solid tumor growth and metastases. In the absence of a viable vascular network, tumors are unable to grow beyond a few millimeters and therefore remain dormant. Initiation of angiogenesis allows for continued tumor growth and progression. Targeting tumor vasculature, either by inhibiting growth of new tumor blood vessels (antiangiogenic agents) or by destroying the already present tumor vessels (vascular disrupting agents; VDA), is an area of extensive research in the development of new antitumor agents. These two groups differ in their direct physiological target, the type or extent of disease that is likely to be susceptible, and the treatment schedule. VDAs target the established tumor blood vessels, resulting in tumor ischemia and necrosis. These agents show more immediate effects compared to antiangiogenic agents and may have more efficacy against advanced bulky disease. VDAs can be divided into two groups--ligand-bound and small molecule agents. Both VDA groups have demonstrated antitumor effects and tumor core necrosis, but consistently leave a thin rim of viable tumor cells at the periphery of the tumor. More evidence suggests VDAs will have their greatest effect in combination with conventional chemotherapy or other modes of treatment that attack this outer rim of cells.     

Comparative efficacy of several potential treatments for copper mobilization in copper-overloaded rats

d-Penicillamine (DPA) is effective in the treatment of Wilson’s disease, whereas zinc salts are also used as a therapy for this disorder of copper transport. Recently, it has been shown that the copper chelators 1,4,7,11-tetraazaundecane tetrahydrochloride (TAUD) and tetraethylenepentamine pentahydrochloride (TETREN) could be useful for copper mobilization in rats. Because these agents could be potential clinical alternatives to DPA for patients with Wilson’s disease who are intolerant to this drug, we examined whether oral administration of TAUD and TETREN could be effective in mobilizing copper in experimental copper-overloaded rats. The efficacy of a combined administration of zinc and DPA, TAUD, or TETREN was also assessed. Rats were copper loaded with 0.125% copper acetate in water for 12 wk. After this period, DPA, TAUD, and TETREN were administered by gavage at 0.67 mmol/kg/d for 5 d, and zinc was given at 2.5 mg Zn/kg/d. Twelve weeks of copper loading resulted in a 32-fold increase in total hepatic copper. TETREN was the most effective chelator in increasing the urinary excretion of copper. However, it did not reduce significantly the hepatic copper levels. In turn, combined administration of zinc and chelating agents significantly reduced the amount of copper found in the feces. Although TAUD and TETREN showed a similar or higher efficacy to DPA in mobilizing copper, concurrent treatment of chelating agents and zinc salts should be discarded according to the current results.     

Human Pythiosis: Emergence of Fungal-Like Organism

Pythiosis is an emerging infectious disease caused by the aquatic oomycete Pythium insidiosum, a fungal-like organism. It is believed that P. insidiosum’s zoospores, its infected form, play major role in pathogenesis. Vascular and ocular infections are the most common clinical manifestation in humans. It is difficult to establish the diagnosis given its relatively rarity and difficulty to distinguish P. insidiosum from other molds. Delay in diagnosis and treatment has been associated with poor outcomes. High index of suspicion is the key, particularly in thalassemia patients with arterial insufficiency and patients with fungal keratitis/endophthalmitis without improvement on antifungal therapy. Tissue culture and zoospore induction remain gold standard for diagnosis; however, DNA-based method should be performed simultaneously. The combination of radical surgery, antifungal agents, and immunotherapy has been recommended. It was previously believed that surgery with negative surgical margins was the essential to survive in vascular pythiosis; however, it was recently found that patients could have residual disease despite documented negative surgical margins as infected clot may be dislodged to proximal arterial sites prior to surgery. Serum β-d-glucan (BG) has been used to monitor disease response after treatment initiation in vascular pythiosis. A significant decrease in BG levels within 2 weeks after surgery is indicative of the absence of residual infection. Unfortunately, monitoring tools for ocular pythiosis are not yet available. Itraconazole plus terbinafine have generally been used in P. insidiosum-infected patients; however, antibacterial agents, including azithromycin and linezolid, have also been used with favorable outcomes in ocular disease. Recently, azithromycin or clarithromycin plus doxycyclin were used in two relapsed vascular pythiosis patients with good outcomes.

     

Unmet needs in rheumatoid arthritis

Until the pathophysiology/etiology of rheumatoid arthritis (RA) is better understood, treatment strategies must focus on disease management. Early diagnosis and treatment with disease-modifying antirheumatic drugs (DMARDs) are necessary to reduce early joint damage, functional loss, and mortality. Several clinical trials have now clearly shown that administering appropriate DMARDs early yields better therapeutic outcomes. However, RA is a heterogeneous disease in which responses to treatment vary considerably for any given patient. Thus, choosing which patients receive combination DMARDs, and which combinations, remains one of our major challenges in treating RA patients. In many well controlled clinical trials methotrexate and other DMARDs, including the tumor necrosis factor-alpha inhibitors, have shown considerable efficacy in controlling the inflammatory process, but many patients continue to have active disease. Optimizing clinical response requires the use of a full spectrum of clinical agents with different therapeutic targets. Newer therapies, such as rituximab, that specifically target B cells have emerged as viable treatment options for patients with RA.     

Progesterone antagonists and progesterone receptor modulators in the treatment of breast cancer

Progesterone antagonists (PAs) (antiprogestins) or progesterone receptor modulators (PRMs) form an interesting category of new hormonal agents in the treatment of breast cancer. In vitro, antiproliferative effects of different PAs are mainly observed in estrogen-stimulated growth of PR-positive tumor cell lines. Both progestin agonist/antagonist actions on mammary tumor cells are dependent on the type of cell line, culture medium and concentrations of the PAs used, and type of biologic response measured. In various experimental animal tumor models, different PAs showed a greater antitumor activity than tamoxifen or high-dose progestins. Most interestingly, combination treatment of different PAs (mifepristone, ORG 31710, onapristone) or PRMs with different antiestrogens (tamoxifen, droloxifen, ICI 164384) or with an aromatase inhibitor (atemestane) showed greater antitumor efficacy than treatment with each single type of drug alone. These additive antiproliferative effects were demonstrated in various experimental in vitro and in vivo models. In some studies, these effects were accompanied by additive effects on several cell biologic parameters. In pretreated postmenopausal patients with metastatic breast cancer, objective responses have been observed in 10-12%, and stable disease in 42-46% of the patients; in previously untreated patients objective response rates of 11 and 56% have been reported. The clinical development of onapristone was stopped because of liver toxicity. At the present time, apart from development of new pure potent PAs, clinical investigation of combined therapy of PAs with antiestrogens are urgently needed.     

miR-141 and miR-200a act on ovarian tumorigenesis by controlling oxidative stress response

Although there is evidence that redox regulation has an essential role in malignancies, its impact on tumor prognosis remains unclear. Here we show crosstalk between oxidative stress and the miR-200 family of microRNAs that affects tumorigenesis and chemosensitivity. miR-141 and miR-200a target p38α and modulate the oxidative stress response. Enhanced expression of these microRNAs mimics p38α deficiency and increases tumor growth in mouse models, but it also improves the response to chemotherapeutic agents. High-grade human ovarian adenocarcinomas that accumulate miR-200a have low concentrations of p38α and an associated oxidative stress signature. The miR200a-dependent stress signature correlates with improved survival of patients in response to treatment. Therefore, the role of miR-200a in stress could be a predictive marker for clinical outcome in ovarian cancer. In addition, although oxidative stress promotes tumor growth, it also sensitizes tumors to treatment, which could account for the limited success of antioxidants in clinical trials.     

Circulating mutant DNA to assess tumor dynamics

The measurement of circulating nucleic acids has transformed the management of chronic viral infections such as HIV. The development of analogous markers for individuals with cancer could similarly enhance the management of their disease. DNA containing somatic mutations is highly tumor specific and thus, in theory, can provide optimum markers. However, the number of circulating mutant gene fragments is small compared to the number of normal circulating DNA fragments, making it difficult to detect and quantify them with the sensitivity required for meaningful clinical use. In this study, we applied a highly sensitive approach to quantify circulating tumor DNA (ctDNA) in 162 plasma samples from 18 subjects undergoing multimodality therapy for colorectal cancer. We found that ctDNA measurements could be used to reliably monitor tumor dynamics in subjects with cancer who were undergoing surgery or chemotherapy. We suggest that this personalized genetic approach could be generally applied to individuals with other types of cancer.     

Adjuvant immunotherapy for solid tumors: from promise to clinical application

Although surgery remains the mainstay for the treatment of most solid tumors, investigators are seeking complementary therapies to eradicate microscopic disease, which causes tumor relapse even after an apparently complete surgical excision. Although adjuvant chemotherapy has achieved some significant results, the control of minimal residual disease is still a challenge for clinicians. Among novel therapeutic approaches, immunotherapy holds promise. This anticancer strategy aims at triggering a highly specific endogenous killing machine against tumor cells. Recent progress in tumor immunology has improved our understanding of host-immune system interactions. In particular, new technologies have fostered the identification of potentially immunogenic tumor antigens that can be used as suitable targets for immune effector cells. After observing immunotherapy-mediated clinical responses in patients with metastatic disease, investigators have started evaluating this anticancer modality in the adjuvant setting. Here, we review the immunological strategies so far explored in humans and report worldwide results following the clinical application of adjuvant immunotherapy for solid tumors.     

The relationship between aromatase in primary breast tumors and response to treatment with aromatase inhibitors in advanced disease

Aromatase inhibitors are proving to be more effective than tamoxifen for postmenopausal patients with breast cancer. Estrogen concentrations in the breast are similar in both premenopausal and postmenopausal women, and several fold higher than circulating levels in postmenopausal women. In order to investigate the importance of intratumoral aromatase in stimulating the proliferation of the tumor, we used immunocytochemistry to determine the extent of aromatase expression in relationship to the response of the patient to aromatase inhibitor treatment. The relationship between positive staining for aromatase in the primary tumor and response to treatment with an aromatase inhibitor was investigated in a retrospective study of 102 patients with advanced breast cancer. Immunohistochemical staining using a monoclonal antibody against aromatase was performed on paraffin embedded tumor tissue. Response was evaluated using UICC criteria. Nine out of 13 patients with objective response to treatment stained positive and 49 of 89 patients with stable or progressive disease stained positive. No significant relationship between positive staining and objective response to treatment could be found. When patients with 'clinical benefit' (i.e. objective response plus prolonged stable disease of at least 6 months) were considered, also no relationship could be found. Further analysis of subgroups with positive hormone receptors, treatment with newer generation aromatase inhibitors, single metastatic site, non-visceral metastases and previous treatment only with tamoxifen did not show any relationship. Tumor aromatase expression did not correlate with response of patients with advanced breast cancer to aromatase inhibitor treatment. Most patients had relapsed from other treatments before receiving an aromatase inhibitor. It seems likely that many of these patients had tumors that may have progressed to hormone independence at this stage of the disease. Research in patients who have received treatment with aromatase inhibitors in earlier stages of disease (first line and adjuvant treatment) may provide further information on the relationship between tumor aromatase, steroid receptors and response to inhibitor treatment.