Phase I/II and phase II studies of targeted gene delivery in vivo: intravenous Rexin-G for chemotherapy-resistant sarcoma and osteosarcoma

Overcoming drug resistance with specific nano scales to targeted therapy: Focused on metastatic cancers

Metastatic cancer, which accounts for the majority of cancer fatalities, is a difficult illness to treat. Currently used cancer treatments include radiation therapy, chemotherapy, surgery, and targeted treatment (immune, gene, and hormonal). The disadvantages of these treatments include a high risk of tumor recurrence and surgical complications that may result in permanent deformities. On the other hand, most chemotherapy drugs are small molecules, which usually have unfavorable side effects, low absorption, poor selectivity, and multi-drug resistance. Anticancer drugs can be delivered precisely to the cancer spot by encapsulating them to reduce side effects. Stimuli-responsive nanocarriers can be used for drug release at cancer sites and provide target-specific delivery. As previously stated, metastasis is the primary cause of cancer-related mortality. We have evaluated the usage of nano-medications in the treatment of some metastatic tumors.

Viral Vectors in Gene Replacement Therapy

Throughout the years, several hundred million people with rare genetic disorders have been receiving only symptom management therapy. However, research and development efforts worldwide have led to the development of long-lasting, highly efficient, and safe gene therapy for a wide range of hereditary diseases. Improved viral vectors are now able to evade the preexisting immunity and more efficiently target and transduce therapeutically relevant cells, ensuring genome maintenance and expression of transgenes at the relevant levels. Hematological, ophthalmological, neurodegenerative, and metabolic therapeutic areas have witnessed successful treatment of hemophilia and muscular dystrophy, restoration of immune system in children with immunodeficiencies, and restoration of vision. This review focuses on three leading vector platforms of the past two decades: adeno-associated viruses (AAVs), adenoviruses (AdVs), and lentiviruses (LVs). Special attention is given to successful preclinical and clinical studies that have led to the approval of gene therapies: six AAV-based (Glybera® for lipoprotein lipase deficiency, Luxturna® for retinal dystrophy, Zolgensma® for spinal muscular atrophy, Upstaza® for AADC, Roctavian® for hemophilia A, and Hemgenix® for hemophilia B) and three LV-based (Libmeldy® for infantile metachromatic leukodystrophy, Zynteglo® for β-thalassemia, and Skysona® for ALD). The review also discusses the problems that arise in the development of gene therapy treatments, which, nevertheless, do not overshadow the successes of already developed gene therapies and the hope these treatments give to long-suffering patients and their families.

A systematic review of recent phase-II trials in refractory or recurrent osteosarcoma: Can we inform future trial design?

BACKGROUND/OBJECTIVE

To analyze changes in recurrent/refractory osteosarcoma phase II trials over time to inform future trials in this population with poor prognosis.

METHODS

A systematic review of trials registered on trial registries between 01/01/2017-14/02/2022. Comparison of 98 trials identified between 2003 and 2016. Publication search/analysis for both periods, last update on 01/12/2022.

RESULTS

Between 2017 and 2022, 71 phase-II trials met our selection criteria (19 osteosarcoma-specific trials, 14 solid tumor trials with and 38 trials without an osteosarcoma-specific stratum). The trial number increased over time: 13.9 versus 7 trials/year (p = 0.06). Monotherapy remained the predominant treatment (62% vs. 62%, p = 1). Targeted therapies were increasingly evaluated (66% vs. 41%, P = 0.001). Heterogeneity persisted in the trial characteristics. The inclusion criteria were measurable disease (75%), evaluable disease (14%), and surgical remission (11%). 82% of the trials included pediatric or adolescent patients. Biomarker-driven trials accounted for 25% of the total trials. The survival endpoint use (rather than response) slightly increased (40% versus 31%), but the study H1/H0 hypotheses remained heterogeneous. Single-arm designs predominated over multiarm trials (n = 7). Available efficacy data on 1361 osteosarcoma patients in 58 trials remained disappointing, even though 21% of these trials were considered positive, predominantly those evaluating multi-targeted kinase inhibitors.

CONCLUSION

Despite observed changes in trial design and an increased number of trials investigating new therapies, high heterogeneity remained with respect to patient selection, study design, primary endpoints, and statistical hypotheses in recently registered phase II trials for osteosarcoma. Continued optimization of trial design informed by a deeper biological understanding should strengthen the development of new therapies.

Molecular characterization of cancer-intrinsic immune evasion genes indicates prognosis and tumour microenvironment infiltration in osteosarcoma

Cancer-intrinsic immune evasion (IE) to cells is a critical factor in tumour growth and progression, yet the molecular characterization of IE genes (IEGs) in osteosarcoma remains underexplored. In this study, 85 osteosarcoma patients were comprehensively analyzed based on 182 IEGs, leading to the identification of two IE clusters linked to distinct biological processes and clinical outcomes. In addition, two IE clusters demonstrated diverse immune cell infiltration patterns, with IEGcluster A displaying increased levels compared to IEGcluster B. Moreover, an IE score was identified as an independent prognostic factor and nomogram may serve as a practical tool for the individual prognostic evaluation of patients with osteosarcoma. Finally, GBP1, a potential biomarker with high expression in osteosarcoma was identified. The findings of this study highlight the presence of two IE clusters, each associated with differing patient outcomes and immune infiltration properties. The IE score may serve to assess individual patient IE characteristics, enhance comprehension of immune features, and guide more efficacious treatment approaches.

Nanomedicine in cancer therapy

Cancer remains a highly lethal disease in the world. Currently, either conventional cancer therapies or modern immunotherapies are non-tumor-targeted therapeutic approaches that cannot accurately distinguish malignant cells from healthy ones, giving rise to multiple undesired side effects. Recent advances in nanotechnology, accompanied by our growing understanding of cancer biology and nano-bio interactions, have led to the development of a series of nanocarriers, which aim to improve the therapeutic efficacy while reducing off-target toxicity of the encapsulated anticancer agents through tumor tissue-, cell-, or organelle-specific targeting. However, the vast majority of nanocarriers do not possess hierarchical targeting capability, and their therapeutic indices are often compromised by either poor tumor accumulation, inefficient cellular internalization, or inaccurate subcellular localization. This Review outlines current and prospective strategies in the design of tumor tissue-, cell-, and organelle-targeted cancer nanomedicines, and highlights the latest progress in hierarchical targeting technologies that can dynamically integrate these three different stages of static tumor targeting to maximize therapeutic outcomes. Finally, we briefly discuss the current challenges and future opportunities for the clinical translation of cancer nanomedicines.

Phase I-II study using DeltaRex-G, a tumor-targeted retrovector encoding a cyclin G1 inhibitor for metastatic carcinoma of breast

Background: Metastatic breast cancer is associated with a poor prognosis and therefore, innovative therapies are urgently needed. Here, we report on the results of a Phase I-II study using DeltaRex-G for chemotherapy resistant metastatic carcinoma of breast. Patients and Methods: Endpoints: Dose limiting toxicity; Antitumor activity. Eligibility: ≥18 years of age, pathologic diagnosis of breast carcinoma, adequate hematologic and organ function. Treatment: Dose escalation of DeltaRex-G 1-4 x 1011cfu intravenously thrice weekly x 4 weeks with 2-week rest period. Treatment cycles repeated if there is ≤ Grade 1 toxicity until disease progression or unacceptable toxicity. Safety: NCI CTCAE v3 for adverse events reporting, vector related testing. Efficacy: RECIST v1.0, International PET criteria and Choi criteria for response, progression free and overall survival. Results: Twenty patients received escalating doses of DeltaRex-G from 1 × 1011 cfu to 4 × 1011 cfu thrice weekly for 4 weeks with a 2-week rest period. Safety: ≥ Grade 3 treatment-related adverse event: pruritic rash (n = 1), no dose limiting toxicity, no replication-competent retrovirus, nor vector-neutralizing antibodies detected. No vector DNA integration was observed in peripheral blood lymphocytes evaluated. Efficacy: by RECIST v1.0: 13 stable disease, 4 progressive disease; tumor control rate 76%; by PET and Choi Criteria: 3 partial responses, 11 stable disease, 3 progressive disease; tumor control rate 82%. Combined median progression free survival by RECIST v1.0, 3.0 months; combined median overall survival, 20 months; 1-year overall survival rate 83% for Dose Level IV. Biopsy of residual tumor in a participant showed abundant CD8+ killer T-cells and CD45+ macrophages suggesting an innate immune response. Two patients with pure bone metastases had >12-month progression free survival and overall survival and are alive 12 years from the start of DeltaRex-G therapy. These patients further received DeltaRex-G + DeltaVax for 6 months. Conclusion: Taken together, these data indicate that 1) DeltaRex-G has a distinctively high level of safety and exhibits anti-cancer activity, 2) PET/Choi provide a higher level of sensitivity in detecting early signs of tumor response to DeltaRex-G, 3) DeltaRex-G induced 12- year survival in 2 patients with pure bone metastases who subsequently received DeltaVax immunotherapy, and 4) DeltaRex-G may prove to be a biochemical and/or immune modulator when combined with other cancer therapy/immunotherapy.

Nanobiotechnological approaches in osteosarcoma therapy: Versatile (nano)platforms for theranostic applications

Constructive achievements in the field of nanobiotechnology and their translation into clinical course have led to increasing attention towards evaluation of their use for treatment of diseases, especially cancer. Osteosarcoma (OS) is one of the primary bone malignancies that affects both males and females in childhood and adolescence. Like other types of cancers, genetic and epigenetic mutations account for OS progression and several conventional therapies including chemotherapy and surgery are employed. However, survival rate of OS patients remains low and new therapies in this field are limited. The purpose of the current review is to provide a summary of nanostructures used in OS treatment. Drug and gene delivery by nanoplatforms have resulted in an accumulation of therapeutic agents for tumor cell suppression. Furthermore, co-delivery of genes and drugs by nanostructures are utilized in OS suppression to boost immunotherapy. Since tumor cells have distinct features such as acidic pH, stimuli-responsive nanoparticles have been developed to appropriately target OS. Besides, nanoplatforms can be used for biosensing and providing phototherapy to suppress OS. Furthermore, surface modification of nanoparticles with ligands can increase their specificity and selectivity towards OS cells. Clinical translation of current findings suggests that nanoplatforms have been effective in retarding tumor growth and improving survival of OS patients.

Emerging Nanotherapeutic Approaches to Overcome Drug Resistance in Cancers with Update on Clinical Trials

A key issue with modern cancer treatments is the emergence of resistance to conventional chemotherapy and molecularly targeted medicines. Cancer nanotherapeutics were created in order to overcome the inherent limitations of traditional chemotherapeutics. Over the last few decades, cancer nanotherapeutics provided unparalleled opportunities to understand and overcome drug resistance through clinical assessment of rationally designed nanoparticulate delivery systems. In this context, various design strategies such as passive targeting, active targeting, nano-drug, and multimodal nano-drug combination therapy provided effective cancer treatment. Even though cancer nanotherapy has made great technological progress, tumor biology complexity and heterogeneity and a lack of comprehensive knowledge of nano-bio interactions remain important roadblocks to future clinical translation and commercialization. The current developments and advancements in cancer nanotherapeutics employing a wide variety of nanomaterial-based platforms to overcome cancer treatment resistance are discussed in this article. There is also a review of various nanotherapeutics-based approaches to cancer therapy, including targeting strategies for the tumor microenvironment and its components, advanced delivery systems for specific targeting of cancer stem cells (CSC), as well as exosomes for delivery strategies, and an update on clinical trials. Finally, challenges and the future perspective of the cancer nanotherapeutics to reverse cancer drug resistance are discussed.

Viral vector-based gene therapies in the clinic

Gene therapies are currently one of the most investigated therapeutic modalities in both the preclinical and clinical settings and have shown promise in treating a diverse spectrum of diseases. Gene therapies aim at introducing a gene material in target cells and represent a promising approach to cure diseases that were thought to be incurable by conventional modalities. In many cases, a gene therapy requires a vector to deliver gene therapeutics into target cells; viral vectors are among the most widely studied vectors owing to their distinguished advantages such as outstanding transduction efficiency. With decades of development, viral vector-based gene therapies have achieved promising clinical outcomes with many products approved for treating a range of diseases including cancer, infectious diseases and monogenic diseases. In addition, a number of active clinical trials are underway to further expand their therapeutic potential. In this review, we highlight the diversity of viral vectors, review approved products, and discuss the current clinical landscape of in vivo viral vector-based gene therapies. We have reviewed 13 approved products and their clinical applications. We have also analyzed more than 200 active trials based on various viral vectors and discussed their respective therapeutic applications. Moreover, we provide a critical analysis of the major translational challenges for in vivo viral vector-based gene therapies and discuss possible strategies to address the same.

Tumor protein p53 mutation in archived tumor samples from a 12-year survivor of stage 4 pancreatic ductal adenocarcinoma may predict long-term survival with DeltaRex-G: A case report and literature review

DeltaRex-G is a replication-incompetent amphotropic murine leukemia virus-based retroviral vector that displays a collagen-matrix-targeting decapeptide on its surface envelope protein, gp70, and encodes a cytocidal ‘dominant negative’, i.e. a truncated construct of the executive cyclin G1 (CCNG1) oncogene. DeltaRex-G inhibits the CCNG1 function of promoting cell competence and survival through the commanding CCNG1/cyclin-dependent kinase (CDK)/Myc/mouse double minute 2 homolog (Mdm2)/p53 axis. In 2009, DeltaRex-G was granted Fast Track designation from the US Food and Drug Administration for the treatment of pancreatic cancer. In 2019, the results of a phase 1/2 study that used DeltaRex-G as monotherapy for stage 4 chemotherapy-resistant pancreatic ductal adenocarcinoma (PDAC) were published. A unique participant of the aforementioned phase 1/2 study is now an 84-year-old Caucasian woman with chemoresistant PDAC who was treated with DeltaRex-G, 3x10¹¹ colony forming units (cfu)/dose, 3 times/week for 4 weeks with a 2-week rest period, for 1.5 years. During the treatment period, the patient's tumors in the liver, lymph node and peritoneum exhibited progressive decreases in size, which were accompanied by a reduction and normalization of serum carbohydrate antigen 19-9 levels, and the patient achieved complete remission after 8 months of DeltaRex-G therapy with minimal side effects (grade 2 fatigue). Henceforth, the patient has been in remission for 12 years with no evidence of disease, no late therapy-related adverse events, and no further cancer therapy following DeltaRex-G treatment. The present study reports a mutation of tumor protein p53 (TP53) (G199V) found retrospectively in the patient's archived tumor samples. TP53 is a well-characterized tumor suppressor gene, and a critical regulatory component of the executive CCNG1/CDK/Myc/Mdm2/p53 axis, which regulates proliferative cell competence, DNA fidelity and survival. Studies are underway to determine whether TP53 mutations in pancreatic cancer can help identify a subset of patients with advanced metastatic cancer with an otherwise poor prognosis who would respond favorably to DeltaRex-G, which would broaden the treatment options for patients with otherwise lethal PDAC.

Systematic Review of Recurrent Osteosarcoma Systemic Therapy

Osteosarcoma is the most frequent primary bone cancer, mainly affecting those of young ages. Although surgery combined with cytotoxic chemotherapy has significantly increased the chances of cure, recurrent and refractory disease still impose a tough therapeutic challenge. We performed a systematic literature review of the available clinical evidence, regarding treatment of recurrent and/or refractory osteosarcoma over the last two decades. Among the 72 eligible studies, there were 56 prospective clinical trials, primarily multicentric, single arm, phase I or II and non-randomized. Evaluated treatment strategies included cytotoxic chemotherapy, tyrosine kinase and mTOR inhibitors and other targeted agents, as well as immunotherapy and combinatorial approaches. Unfortunately, most treatments have failed to induce objective responses, albeit some of them may sustain disease control. No driver mutations have been recognized, to serve as effective treatment targets, and predictive biomarkers of potential treatment effectiveness are lacking. Hopefully, ongoing and future clinical and preclinical research will unlock the underlying biologic mechanisms of recurrent and refractory osteosarcoma, expanding the therapeutic choices available to pre-treated osteosarcoma patients.

Systematic review of phase-I/II trials enrolling refractory and recurrent Ewing sarcoma: Actual knowledge and future directions to optimize the research

BACKGROUND

Optimal Phase-II design to evaluate new therapies in refractory/relapsed Ewing sarcomas (ES) remains imperfectly defined.

OBJECTIVES

Recurrent/refractory ES phase-I/II trials analysis to improve trials design.

METHODS

Comprehensive review of therapeutic trials registered on five databases (who.int/trialsearch, clinicaltrials.gov, clinicaltrialsregister.eu, e-cancer.fr, and umin.ac.jp) and/or published in PubMed/ASCO/ESMO websites, between 2005 and 2018, using the criterion: (Ewing sarcoma OR bone sarcoma OR sarcoma) AND (Phase-I or Phase-II).

RESULTS

The 146 trials identified (77 phase-I/II, 67 phase-II, and 2 phase-II/III) tested targeted (34%), chemo- (23%), immune therapies (19%), or combined therapies (24%). Twenty-three trials were ES specific and 48 had a specific ES stratum. Usually multicentric (88%), few trials were international (30%). Inclusion criteria cover the recurrent ES age range for only 12% of trials and allowed only accrual of measurable diseases (RECIST criteria). Single-arm design was the most frequent (88%) testing mainly single drugs (61%), only 5% were randomized. Primary efficacy outcome was response rate (RR=CR+PR; Complete+Partial response) (n = 116/146; 79%), rarely progression-free or overall survival (16% PFS and 3% OS). H0 and H1 hypotheses were variable (3%-25% and 20%-50%, respectively). The 62 published trials enrolled 827 ES patients. RR was poor (10%; 15 CR=1.7%, 68 PR=8.3%). Stable disease was the best response for 186 patients (25%). Median PFS/OS was of 1.9 (range 1.3-14.7) and 7.6 months (5-30), respectively. Eleven (18%) published trials were considered positive, with median RR/PFS/OS of 15% (7%-30%), 4.5 (1.3-10), and 16.6 months (6.9-30), respectively.

CONCLUSION

This review supports the need to develop the international randomized phase-II trials across all age ranges with PFS as primary endpoint.

Design strategies and evolving role of biomaterial assisted treatment of osteosarcoma

Osteosarcoma is the most commonly diagnosed form of bone cancer. It is characterized by a high risk of developing lung metastasis as the disease progresses. Standard treatment includes combination of surgical intervention, chemotherapy and radiotherapy. However, the non-specificity of potent chemotherapeutic agents often leads to major side effects. In this review, we discuss the role of various classes of biomaterials, including both organic as well as inorganic in realizing the local and systemic delivery of therapeutic agents like drugs, radioisotopes and even gene silencing agents to treat osteosarcoma. Biomaterial assisted unconventional therapies such as targeted therapy, nanotherapy, magnetic hyperthermia, gene therapy, photothermal and photodynamic therapies are also being explored. A wide variety of biomaterials including lipids, carbon-based materials, polymers, silica, bioactive glass, hydroxyapatite and metals are designed as delivery systems with the desired loading efficiency, release profile, and on-demand delivery. Among others, liposomal carriers have attracted a great deal of attention due to their capability to encapsulate both hydrophobic and hydrophilic drugs. Polymeric systems have high drug loading efficiency and stability and can even be tailored to achieve desired size and physiochemical properties. Carbon-based systems can also be seen as an upcoming class of therapeutics with great potential in treating different types of cancer. Inorganic materials like silica nanoparticles have high drug payload owing to their mesoporous structure. On the other hand, ceramic materials like bioactive glass and hydroxyapatite not only act as excellent delivery vectors but also participate in osteo-regeneration activity. These multifunctional biomaterials are also being investigated for their theranostic abilities to monitor cancer ablation. This review systematically discusses the vast landscape of biomaterials along with their challenges and respective opportunities for osteosarcoma therapy.

Bupivacaine and Lidocaine Induce Apoptosis in Osteosarcoma Tumor Cells

BACKGROUND

Osteosarcoma is the most common type of bone cancer in adolescents. There have been no significant improvements in outcomes since chemotherapy was first introduced. Bupivacaine and lidocaine have been shown to be toxic to certain malignancies. This study evaluates the effect of these medications on two osteosarcoma cell lines.

QUESTIONS/PURPOSES

(1) Does incubation of osteosarcoma cells with bupivacaine or lidocaine result in cell death? (2) Does this result from an apoptotic mechanism? (3) Is a specific apoptotic pathway implicated?

METHODS

Two cell lines were chosen to account for the inherent heterogeneity of osteosarcoma. UMR-108 is a transplantable cell line that has been used in multiple studies as a primary tumor. MNNG/HOS has a high metastatic rate in vivo. Both cell lines were exposed bupivacaine (0.27, 0.54, 1.08, 2.16, 4.33 and 8.66 mM) and lidocaine (0.66, 1.33, 5.33, 10.66, 21.32 and 42.64 mM) for 24 hours, 48 hours, and 72 hours. These concentrations were determined by preliminary experiments that found the median effective dose was 1.4 mM for bupivacaine and 7.0 mM for lidocaine in both cell lines. Microculture tetrazolium and colony formation assay determined whether cell death occurred. Apoptosis induction was evaluated by phase-contrast micrographs, flow cytometry, DNA fragmentation and reactive oxygen species (ROS). The underlying pathways were analyzed by protein electrophoresis and Western blot. All testing was performed in triplicate and compared with pH-adjusted controls. Quantitative results were analyzed without blinding.

RESULTS

Both medications caused cell death in a dose- and time-dependent manner. Exposure to bupivacaine for 24 hours reduced viability of UMR-108 cells by 6 ± 0.75% (95% CI 2.9 to 9.11; p = 0.01) at 1.08 mM and 89.67 ± 1.5% (95% CI 82.2 to 95.5; p < 0.001) at 2.16 mM. Under the same conditions, MNNG/HOS viability was decreased in a similar fashion. After 24 hours, the viability of UMR-108 and MNNG/HOS cells exposed to 5.33 mM of lidocaine decreased by 25.33 ± 8.3% (95% CI 2.1 to 48.49; p = 0.03) and 39.33 ± 3.19% (95% CI 30.46 to 48.21; p < 0.001), respectively, and by 90.67 ± 0.66% (95% CI 88.82 to 92.52; p < 0.001) and 81.6 ± 0.47% (95% CI 79.69 to 82.31; p < 0.001) at 10.66 mM, respectively. After 72 hours, the viability of both cell lines was further reduced. Cell death was consistent with apoptosis based on cell morphology, total number of apoptotic cells and DNA fragmentation. The percentage increase of apoptotic UMR-108 and MNNG/HOS cells confirmed by Annexin-V positivity compared with controls was 21.3 ± 2.82 (95% CI 16.25 to 26.48; p < 0.001) and 21.23 ± 3.23% (95% CI 12.2 to 30.2; p = 0.003) for bupivacaine at 1.08 mM and 25.15 ± 4.38 (95% CI 12.9 to 37.3; p = 0.004) and 9.11 ± 1.74 (95% CI 4.35 to 13.87; p = 0.006) for lidocaine at 5.33 mM. The intrinsic apoptotic pathway was involved as the expression of Bcl-2 and survivin were down-regulated, and Bax, cleaved caspase-3 and cleaved poly (ADP-ribose) polymerase-1 were increased. ROS production increased in the UMR-108 cells but was decreased in the MNNG/HOS cells.

CONCLUSION

These findings provide a basis for evaluating these medications in the in vivo setting. Studies should be performed in small animals to determine if clinically relevant doses have a similar effect in vivo. In humans, biopsies could be performed with standard doses of these medications to see if there is a difference in biopsy tract contamination on definitive resection.

CLINICAL RELEVANCE

Bupivacaine and lidocaine could potentially be used for their ability to induce and enhance apoptosis in local osteosarcoma treatment. Outcome data when these medications are used routinely during osteosarcoma treatment can be evaluated compared with controls. Further small animal studies should be performed to determine if injection into the tumor, isolated limb perfusion, or other modalities of treatment are viable.

Current Treatment Considerations for Osteosarcoma Metastatic at Presentation

Approximately one-fourth of osteosarcoma patients have metastases at presentation. The best treatment options for these patients include chemotherapy, surgery, and radiotherapy; however, the optimal scheme has not yet been defined. Standard chemotherapy for osteosarcoma metastatic at presentation is based on high-dose methotrexate, doxorubicin, and cisplatin (the MAP regimen), with the possible addition of ifosfamide. Surgical treatment continues to be fundamental; complete surgical resection of all sites of disease (primary and metastatic) remains essential for survival. In patients whose tumors do not respond to neoadjuvant chemotherapy, early surgical resection of the primary tumor with limb-salvage surgery or amputation and multiple metastasectomies, if feasible, after the completion of adjuvant chemotherapy is a reasonable option, as the reduction of the tumor volume could probably increase the effect of chemotherapy. Advanced radiotherapy techniques, such as carbon ion radiotherapy and stereotactic radiosurgery, and molecular targeted chemo-therapy with drugs such as pazopanib or apatinib have improved the dismal prognosis, especially for patients who are medically inoperable or who refuse surgery. Given that the presence of metastatic disease at diagnosis of a patient with osteosarcoma is a poor prognostic factor, a multidisciplinary approach by surgeons, medical oncologists, and radiotherapists is important. [Orthopedics. 2020;43(5):e345-e358.].

Controlled anti-cancer drug release through advanced nano-drug delivery systems: Static and dynamic targeting strategies

Advances in nanomedicine, including early cancer detection, targeted drug delivery, and personalized approaches to cancer treatment are on the rise. For example, targeted drug delivery systems can improve intracellular delivery because of their multifunctionality. Novel endogenous-based and exogenous-based stimulus-responsive drug delivery systems have been proposed to prevent the cancer progression with proper drug delivery. To control effective dose loading and sustained release, targeted permeability and individual variability can now be described in more-complex ways, such as by combining internal and external stimuli. Despite these advances in release control, certain challenges remain and are identified in this research, which emphasizes the control of drug release and applications of nanoparticle-based drug delivery systems. Using a multiscale and multidisciplinary approach, this study investigates and analyzes drug delivery and release strategies in the nanoparticle-based treatment of cancer, both mathematically and clinically.

Recent advances of drug delivery nanocarriers in osteosarcoma treatment

Osteosarcoma is the most common primary malignant bone tumor mainly occurred in children and adolescence, and chemotherapy is limited for the side effects and development of drug resistance. Advances in nanotechnology and knowledge of cancer biology have led to significant improvements in developing tumor-targeted drug delivery nanocarriers, and some have even entered clinically application. Delivery of chemotherapeutic agents by functionalized smart nanocarriers could protect the drugs from rapid clearance, prolong the circulating time, and increase the drug concentration at tumor sites, thus enhancing the therapeutic efficacy and reducing side effects. Various drug delivery nanocarriers have been designed and tested for osteosarcoma treatment, but most of them are still at experimental stage, and more further studies are needed before clinical application. In this present review, we briefly describe the types of commonly used nanocarriers in osteosarcoma treatment, and discuss the strategies for osteosarcoma-targeted delivery and controlled release of drugs. The application of nanoparticles in the management of metastatic osteosarcoma is also briefly discussed. The purpose of this article is to present an overview of recent progress of nanoscale drug delivery platforms in osteosarcoma, and inspire new ideas to develop more effective therapeutic options.

A Phase I-II Study Using Rexin-G Tumor-Targeted Retrovector Encoding a Dominant-Negative Cyclin G1 Inhibitor for Advanced Pancreatic Cancer

Rexin-G is a replication-incompetent retroviral vector displaying a cryptic SIG-binding peptide for targeting abnormal Signature (SIG) proteins in tumors and encoding a dominant-negative human cyclin G1 construct. Herein we report on the safety and antitumor activity of escalating doses of Rexin-G in gemcitabine-refractory pancreatic adenocarcinoma, with one 10-year survivor. For the safety analysis (n = 20), treatment-related grade 1 adverse events included fatigue (n = 6), chills (n = 2), and headache (n = 1), with no organ damage and no DLT. No patient tested positive for vector-neutralizing antibodies, antibodies to gp70, replication-competent retrovirus (RCR), or vector integration into genomic DNA of peripheral blood lymphocytes (PBLs). For the efficacy analysis (n = 15), one patient achieved a complete response (CR), two patients had a partial response (PR), and 12 had stable disease (SD). Median progression-free survival (PFS) was 2.7, 4.0, and 5.6 months at doses 0–I, II, and III, respectively. Median overall survival (OS) and 1-year OS rate at dose 0–I were 4.3 months and 0%, and at dose II–III they were 9.2 months and 33.3%. To date, one patient is still alive with no evidence of cancer 10 years after the start of Rexin-G treatment. Taken together, these data suggest that Rexin-G, the first targeted gene delivery system, is uniquely safe and exhibits significant antitumor activity, for which the FDA granted fast-track designation.

Nanomedicine in cancer stem cell therapy: from fringe to forefront

Nanomedicine is the spin-off of modern medicine and nanotechnology and aims to prevent and treat diseases using nanoscale materials such as biocompatible nanoparticles and nanorobots. Targeted cellular and tissue-specific clinical applications with maximal therapeutic effects and insignificant side effects could be achieved by the pursuit of nanotechnology in medicine and healthcare regimen. The majority of conventional cancer therapies eliminate the cells of the tumor but not the cancer stem cells (CSCs). Conversely, the use of nanotechnology in CSC-based therapies is an emerging field of biomedical sciences. This article summarizes the recent trends and application of nanomedicine especially in CSC therapy along with its limitations.

Cell cycle checkpoint control: The cyclin G1/Mdm2/p53 axis emerges as a strategic target for broad-spectrum cancer gene therapy - A review of molecular mechanisms for oncologists

Basic research in genetics, biochemistry and cell biology has identified the executive enzymes and protein kinase activities that regulate the cell division cycle of all eukaryotic organisms, thereby elucidating the importance of site-specific protein phosphorylation events that govern cell cycle progression. Research in cancer genomics and virology has provided meaningful links to mammalian checkpoint control elements with the characterization of growth-promoting proto-oncogenes encoding c-Myc, Mdm2, cyclins A, D1 and G1, and opposing tumor suppressor proteins, such as p53, pRb, p16^INK4A and p21^WAF1, which are commonly dysregulated in cancer. While progress has been made in identifying numerous enzymes and molecular interactions associated with cell cycle checkpoint control, the marked complexity, particularly the functional redundancy, of these cell cycle control enzymes in mammalian systems, presents a major challenge in discerning an optimal locus for therapeutic intervention in the clinical management of cancer. Recent advances in genetic engineering, functional genomics and clinical oncology converged in identifying cyclin G1 (CCNG1 gene) as a pivotal component of a commanding cyclin G1/Mdm2/p53 axis and a strategic locus for re-establishing cell cycle control by means of therapeutic gene transfer. The purpose of the present study is to provide a focused review of cycle checkpoint control as a practicum for clinical oncologists with an interest in applied molecular medicine. The aim is to present a unifying model that: i) clarifies the function of cyclin G1 in establishing proliferative competence, overriding p53 checkpoints and advancing cell cycle progression; ii) is supported by studies of inhibitory microRNAs linking CCNG1 expression to the mechanisms of carcinogenesis and viral subversion; and iii) provides a mechanistic basis for understanding the broad-spectrum anticancer activity and single-agent efficacy observed with dominant-negative cyclin G1, whose cytocidal mechanism of action triggers programmed cell death. Clinically, the utility of companion diagnostics for cyclin G1 pathways is anticipated in the staging, prognosis and treatment of cancers, including the potential for rational combinatorial therapies.

Oral administration of edelfosine encapsulated lipid nanoparticles causes regression of lung metastases in pre-clinical models of osteosarcoma

Osteosarcoma (OS) is the most frequent paediatric bone cancer, responsible for 9% of all cancer-related deaths in children. In this paper, a new strategy based on delivering edelfosine (ET) in lipid nanoparticles (LN) was explored in order to target the primary tumour and eliminate metastases. The in vitro and in vivo efficacy of the free drug, drug loaded into lipid nanoparticles (ET-LN) and doxorubicin (DOX) against osteosarcoma (OS) cells was analysed. ET and ET-LN decreased the growth of OS cells in vitro in a time- and dose-dependent manner. Interestingly, the uptake of ET and ET-LN was lower when OS cells were pre-treated with DOX. In vivo studies revealed that ET and ET-LN slowed down the primary tumour growth in two OS models. However, the combination of both drugs showed no additional anti-tumour effect. Importantly, ET-LN successfully prevented the metastatic spread of OS cells from the primary tumour to the lungs. On the whole, ET-LN are a promising candidate for OS chemotherapy.

Magnetic field-guided cell delivery with nanoparticle-loaded human corneal endothelial cells

To improve the delivery and integration of cell therapy using magnetic cell guidance for replacement of corneal endothelium, here we assess magnetic nanoparticles' (MNPs') effects on human corneal endothelial cells (HCECs) in vitro. Biocompatible, 50 nm superparamagnetic nanoparticles endocytosed by cultured HCECs induced no short- or long-term change in viability or identity. Assessment of guidance of the magnetic HCECs in the presence of different magnet shapes and field strengths showed a 2.4-fold increase in delivered cell density compared to gravity alone. After cell delivery, HCECs formed a functional monolayer, with no difference in tight junction formation between MNP-loaded and control HCECs. These data suggest that nanoparticle-mediated magnetic cell delivery may increase the efficiency of cell delivery without compromising HCEC survival, identity or function. Future studies may assess the safety and efficacy of this therapeutic modality in vivo. From the clinical editor: The authors show in this article that magnetic force facilitates the delivery of human corneal endothelial cells loaded by superparamagnetic nanoparticles to cornea, without changing their morphology, identity or functional properties. This novel idea can potentially have vast impact in the treatment of corneal endothelial dystrophies by providing self-endothelial cells after ex-vivo expansion.

Trial watch: DNA vaccines for cancer therapy

The foundation of modern vaccinology dates back to the 1790s, when the English physician Edward Jenner uncovered the tremendous medical potential of prophylactic vaccination. Jenner’s work ignited a wave of nationwide vaccination campaigns abating the incidence of multiple life-threatening infectious diseases and culminating with the eradication of natural smallpox virus, which was definitively certified by the WHO in 1980. The possibility of using vaccines against cancer was first proposed at the end of the 19th century by Paul Ehrlich and William Coley. However, it was not until the 1990s that such a hypothesis began to be intensively investigated, following the realization that the immune system is not completely unresponsive to tumors and that neoplastic cells express immunogenic tumor-associated antigens (TAAs). Nowadays, anticancer vaccines are rapidly moving from the bench to the bedside, and a few prophylactic and therapeutic preparations have already been approved by FDA for use in humans. In this setting, one interesting approach is constituted by DNA vaccines, i.e., TAA-encoding circularized DNA constructs, often of bacterial origin, that are delivered to patients as such or by means of specific vectors, including (but not limited to) liposomal preparations, nanoparticles, bacteria and viruses. The administration of DNA vaccines is most often performed via the intramuscular or subcutaneous route and is expected to cause (1) the endogenous synthesis of the TAA by myocytes and/or resident antigen-presenting cells; (2) the presentation of TAA-derived peptides on the cell surface, in association with MHC class I molecules; and (3) the activation of potentially therapeutic tumor-specific immune responses. In this Trial Watch, we will summarize the results of recent clinical trials that have evaluated/are evaluating DNA vaccines as therapeutic interventions against cancer.

Comprehensive analysis of published studies involving systemic treatment for chondrosarcoma of bone between 2000 and 2013

BACKGROUND

The majority of patients with chondrosarcoma of bone have an excellent overall survival after local therapy. However, in case of unresectable locally advanced or metastatic disease the outcome is poor and limited treatment options exist. Therefore we conducted a survey of clinical phase I or II trials and retrospective studies that described systemic therapy for chondrosarcoma patients.

MATERIALS AND METHODS

Using PubMed, clinicaltrials.gov, the Cochrane controlled trial register and American Society of Clinical Oncology (ASCO) abstracts a literature survey was conducted. From the identified items, data were collected by a systematic analysis. We limited our search to semi-recent studies published between 2000 and 2013 to include modern drugs, imaging techniques and disease evaluations.

RESULTS

A total of 31 studies were found which met the criteria: 9 phase I trials, 11 phase II and 8 retrospective studies. In these studies 855 chondrosarcoma patients were reported. The tested drugs were mostly non-cytotoxic, either alone or in combination with another non-cytotoxic agent or chemotherapy. Currently two phase I trials, one phase IB/II trial and three phase II trials are enrolling chondrosarcoma patients.

CONCLUSION

Because chondrosarcoma of bone is an orphan disease it is difficult to conduct clinical trials. The meagre outcome data for locally advanced or metastatic patients indicate that new treatment options are needed. For the phase I trials it is difficult to draw conclusions because of the low numbers of chondrosarcoma patients enrolled, and at different dose levels. Some phase II trials show promising results which support further research. Retrospective studies are encouraged as they could add to the limited data available. Efforts to increase the number of studies for this orphan disease are urgently needed.

Trial Watch: DNA vaccines for cancer therapy

During the past 2 decades, the possibility that preparations capable of eliciting tumor-specific immune responses would mediate robust therapeutic effects in cancer patients has received renovated interest. In this context, several approaches to vaccinate cancer patients against their own malignancies have been conceived, including the administration of DNA constructs coding for one or more tumor-associated antigens (TAAs). Such DNA-based vaccines conceptually differ from other types of gene therapy in that they are not devised to directly kill cancer cells or sensitize them to the cytotoxic activity of a drug, but rather to elicit a tumor-specific immune response. In spite of an intense wave of preclinical development, the introduction of this immunotherapeutic paradigm into the clinical practice is facing difficulties. Indeed, while most DNA-based anticancer vaccines are well tolerated by cancer patients, they often fail to generate therapeutically relevant clinical responses. In this Trial Watch, we discuss the latest advances on the use of DNA-based vaccines in cancer therapy, discussing the literature that has been produced around this topic during the last 13 months as well as clinical studies that have been launched in the same time frame to assess the actual therapeutic potential of this intervention.

Cancer nanotechnology: the impact of passive and active targeting in the era of modern cancer biology

Cancer nanotherapeutics are progressing at a steady rate; research and development in the field has experienced an exponential growth since early 2000's. The path to the commercialization of oncology drugs is long and carries significant risk; however, there is considerable excitement that nanoparticle technologies may contribute to the success of cancer drug development. The pace at which pharmaceutical companies have formed partnerships to use proprietary nanoparticle technologies has considerably accelerated. It is now recognized that by enhancing the efficacy and/or tolerability of new drug candidates, nanotechnology can meaningfully contribute to create differentiated products and improve clinical outcome. This review describes the lessons learned since the commercialization of the first-generation nanomedicines including DOXIL® and Abraxane®. It explores our current understanding of targeted and non-targeted nanoparticles that are under various stages of development, including BIND-014 and MM-398. It highlights the opportunities and challenges faced by nanomedicines in contemporary oncology, where personalized medicine is increasingly the mainstay of cancer therapy. We revisit the fundamental concepts of enhanced permeability and retention effect (EPR) and explore the mechanisms proposed to enhance preferential "retention" in the tumor, whether using active targeting of nanoparticles, binding of drugs to their tumoral targets or the presence of tumor associated macrophages. The overall objective of this review is to enhance our understanding in the design and development of therapeutic nanoparticles for treatment of cancers.

Evolution of clinical trial design in early drug development: systematic review of expansion cohort use in single-agent phase I cancer trials

PURPOSE

To evaluate the use and objectives of expansion cohorts in phase I cancer trials and to explore trial characteristics associated with their use.

METHODS

We performed a systematic review of MEDLINE and EMBASE, limiting studies to single-agent phase I trials recruiting adults and published after 2006. Eligibility assessment and data extraction were performed by two reviewers. Data were assessed descriptively, and associations were tested by univariable and multivariable logistic regression.

RESULTS

We identified 611 unique phase I cancer trials, of which 149 (24%) included an expansion cohort. The trials were significantly more likely to use an expansion cohort if they were published more recently, were multicenter, or evaluated a noncytotoxic agent. Objectives of the expansion cohort were reported in 74% of trials. In these trials, safety (80%), efficacy (45%), pharmacokinetics (28%), pharmacodynamics (23%), and patient enrichment (14%) were cited as objectives. Among expansion cohorts with safety objectives, the recommended phase II dose was modified in 13% and new toxicities were described in 54% of trials. Among trials aimed at assessing efficacy, only 11% demonstrated antitumor activity assessed by response criteria that was not previously observed during dose escalation.

CONCLUSION

The utilization of expansion cohorts has increased with time. Safety and efficacy are common objectives, but 26% fail to report explicit aims. Expansion cohorts may provide useful supplementary data for phase I trials, particularly with regard to toxicity and definition of recommended dose for phase II studies.

Ligand-targeted particulate nanomedicines undergoing clinical evaluation: current status

Since the introduction of Doxil® on the market nearly 20years ago, a number of nanomedicines have become part of treatment regimens in the clinic. With the exception of antibody-drug conjugates, these nanomedicines are all devoid of targeting ligands and rely solely on their physicochemical properties and the (patho)physiological processes in the body for their biodistribution and targeting capability. At the same time, many preclinical studies have reported on nanomedicines exposing targeting ligands, or ligand-targeted nanomedicines, yet none of these have been approved at this moment. In the present review, we provide a concise overview of 13 ligand-targeted particulate nanomedicines (ligand-targeted PNMs) that have progressed into clinical trials. The progress of each ligand-targeted PNM is discussed based on available (pre)clinical data. Main conclusions of these analyses are that (a) ligand-targeted PNMs have proven to be safe and efficacious in preclinical models; (b) the vast majority of ligand-targeted PNMs is generated for the treatment of cancer; (c) contribution of targeting ligands to the PNM efficacy is not unambiguously proven; and (d) targeting ligands do not cause localization of the PNM within the target tissue, but rather provide benefits in terms of target cell internalization and target tissue retention once the PNM has arrived at the target site. Increased understanding of the in vivo fate and interactions of the ligand-targeted PNMs with proteins and cells in the human body is mandatory to rationally advance the clinical translation of ligand-targeted PNMs. Future perspectives for ligand-targeted PNM approaches include the delivery of drugs that are unable or inefficient in passing cellular membranes, treatment of drug resistant tumors, targeting of the tumor blood supply, the generation of targeted vaccines and nanomedicines that are able to cross the blood-brain barrier.

Targeted therapies for bone sarcomas

Bone sarcomas include a very large number of tumour subtypes, which originate form bone and more particularly from mesenchymal stem cell lineage. Osteosarcoma, Ewing's sarcoma and chondrosarcoma, the three main bone sarcoma entities develop in a favourable microenvironment composed by bone cells, blood vessels, immune cells, based on the 'seed and soil theory'. Current therapy associates surgery and chemotherapy, however, bone sarcomas remain diseases with high morbidity and mortality especially in children and adolescents. In the past decade, various new therapeutic approaches emerged and target the tumour niche or/and directly the tumour cells by acting on signalling/metabolic pathways involved in cell proliferation, apoptosis or drug resistance. The present review gives a brief overview from basic to clinical assessment of the main targeted therapies of bone sarcoma cells.

Library screening and receptor-directed targeting of gammaretroviral vectors

Gene- and cell-based therapies hold great potential for the advancement of the personalized medicine movement. Gene therapy vectors have made dramatic leaps forward since their inception. Retroviral-based vectors were the first to gain clinical attention and still offer the best hope for the long-term correction of many disorders. The fear of nonspecific transduction makes targeting a necessary feature for most clinical applications. However, this remains a difficult feature to optimize, with specificity often coming at the expense of efficiency. The aim of this article is to discuss the various methods employed to retarget retroviral entry. Our focus will lie on the modification of gammaretroviral envelope proteins with an in-depth discussion of the creation and screening of envelope libraries.

The Current and Future Therapies for Human Osteosarcoma

Osteosarcoma (OS) is the most common non-hematologic malignant tumor of bone in adults and children. As sarcomas are more common in adolescents and young adults than most other forms of cancer, there are a significant number of years of life lost secondary to these malignancies. OS is associated with a poor prognosis secondary to a high grade at presentation, resistance to chemotherapy and a propensity to metastasize to the lungs. Current OS management involves both chemotherapy and surgery. The incorporation of cytotoxic chemotherapy into therapeutic regimens escalated cure rates from <20% to current levels of 65-75%. Furthermore, limb-salvage surgery is now offered to the majority of OS patients. Despite advances in chemotherapy and surgical techniques over the past three decades, there has been stagnation in patient survival outcome improvement, especially in patients with metastatic OS. Thus, there is a critical need to identify novel and directed therapy for OS. Several Phase I trials for sarcoma therapies currently ongoing or recently completed have shown objective responses in OS. Novel drug delivery mechanisms are currently under phase II and III clinical trials. Furthermore, there is an abundance of preclinical research which holds great promise in the development of future OS-directed therapeutics. Our continuously improving knowledge of the molecular and cell-signaling pathways involved in OS will translate into more effective therapies for OS and ultimately improved patient survival. The present review will provide an overview of current therapies, ongoing clinical trials and therapeutic targets under investigation for OS.

Bone sarcomas: from biology to targeted therapies

Primary malignant bone tumours, osteosarcomas, and Ewing sarcomas are rare diseases which occur mainly in adolescents and young adults. With the current therapies, some patients remain very difficult to treat, such as tumour with poor histological response to preoperative CT (or large initial tumour volume for Ewing sarcomas not operated), patients with multiple metastases at or those who relapsed. In order to develop new therapies against these rare tumours, we need to unveil the key driving factors and molecular abnormalities behind the malignant characteristics and to broaden our understanding of the phenomena sustaining the metastatic phenotype and treatment resistance in these tumours. In this paper, starting with the biology of these tumours, we will discuss potential therapeutic targets aimed at increasing local tumour control, limiting metastatic spread, and finally improving patient survival.

Systemic therapy for advanced soft tissue sarcomas: highlighting novel therapies and treatment approaches

Soft tissue sarcomas (STS) are a rare, heterogeneous group of solid tumors in need of improved therapeutic options. First-line chemotherapy is considered the current standard of care for patients with advanced, symptomatic STS, but the median survival is only 8 to 12 months. Efforts to increase response rates by using combination or dose-dense regimens have largely failed to improve patient outcomes. However, increasing evidence supports the use of specific treatments for certain histological subtypes of STS, and novel therapies, including tyrosine kinase and mammalian target of rapamycin inhibitors, are currently under active investigation. In addition, novel treatment approaches (such as maintenance therapy) designed to prolong the duration of response to chemotherapy and delay disease progression are being explored. This article provides an overview of current systemic therapies for patients with advanced STS and discusses ongoing efforts designed to improve patient outcomes through the use of novel therapeutic agents and treatment strategies.

Comprehensive analysis of published phase I/II clinical trials between 1990-2010 in osteosarcoma and Ewing sarcoma confirms limited outcomes and need for translational investment

Background

High grade primary bone sarcomas are rare cancers that affect mostly children and young adults. Osteosarcoma and Ewing sarcoma are the most common histological subtypes in this age group, with current multimodality treatment strategies achieving 55-70% overall survival. As there remains an urgent need to develop new therapeutic interventions, we have reviewed published phase I/II trials that have been reported for osteosarcoma and Ewing sarcoma in the last twenty years.

Results

We conducted a literature search for clinical trials between 1990 and 2010, either for trials enrolling bone sarcoma patients as part of a general sarcoma indication or trials specifically in osteosarcoma and Ewing sarcoma. We identified 42 clinical trials that fulfilled our search criteria for general sarcoma that enrolled these patient groups, and eight and twenty specific trials for Ewing and osteosarcoma patients, respectively. For the phase I trials which enrolled different tumour types our results were incomplete, because the sarcoma patients were not mentioned in the PubMed abstract. A total of 3,736 sarcoma patients were included in these trials over this period, 1,114 for osteosarcoma and 1,263 for Ewing sarcoma. As a proportion of the worldwide disease burden over this period, these numbers reflect a very small percentage of the potential patient recruitment, approximately 0.6% for Ewing sarcoma and 0.2% for osteosarcoma. However, these data show an increase in recent activity overall and suggest there is still much room for improvement in the current trial development structures.

Conclusion

Lack of resources and commercial investment will inevitably limit opportunity to develop sufficiently rapid improvements in clinical outcomes. International collaboration exists in many well founded co-operative groups for phase III trials, but progress may be more effective if there were also more investment of molecular and translational research into disease focused phase I/II clinical trials. Examples of new models for early translational and early phase trial collaboration include the European based EuroBoNeT network, the Sarcoma Alliance for Research through Collaboration network (SARC) and the new European collaborative translational trial network, EuroSarc.

A short perspective on gene therapy: Clinical experience on gene therapy of gliomablastoma multiforme

More than two decades have passed since the first gene therapy clinical trial was conducted. During this time, we have gained much knowledge regarding gene therapy in general, but also learned to understand the fear that persists in society. We have experienced drawbacks and successes. More than 1700 clinical trials have been conducted where gene therapy is used as a means for therapy. In the very first trial, patients with advanced melanoma were treated with tumor infiltrating lymphocytes genetically modified ex-vivo to express tumor necrosis factor. Around the same time the first gene therapy trial was conducted, the ethical aspects of performing gene therapy on humans was intensively discussed. What are the risks involved with gene therapy? Can we control the technology? What is ethically acceptable and what are the indications gene therapy can be used for? Initially, gene therapy was thought to be implemented mainly for the treatment of monogenetic diseases, such as adenosine deaminase deficiency. However, other therapeutic areas have become of interest and currently cancer is the most studied therapeutic area for gene therapy based medicines. In this review I will be giving a short introduction into gene therapy and will direct the discussion to where we should go from here. Furthermore, I will focus on the use of the Herpes simplex virus-thymidine kinase for gene therapy of malignant gliomas and highlight the efficacy of gene therapy for the treatment of malignant gliomas, but other strategies will also be mentioned.

Systematic therapy for unresectable or metastatic soft-tissue sarcomas: past, present, and future

Unresectable or metastatic disease occurs in 40% to 60% of soft-tissue sarcoma (STS) patients and portends a poor prognosis. For decades, doxorubicin has formed the backbone of systemic treatment, with response rates of approximately 26%. Patients progressing following first-line therapy were left with few proven options. No other cytotoxic chemotherapy agent or combination has demonstrated superiority to doxorubicin. Advances in targeted therapy of STS have been hindered by STS heterogeneity and poorly understood disease biology. Despite challenges, progress has been made in specific STS subtypes. Here, we highlight the challenges, progress, and lessons learned from STS trials published in the last 20 to 25 years.

Review of therapeutic strategies for osteosarcoma, chondrosarcoma, and Ewing's sarcoma

The most prevalent forms of bone cancer are osteosarcoma, chondrosarcoma, and Ewing’s sarcoma. Although chemotherapy and radiotherapy have replaced traditional surgical treatments, survival rates have undergone only marginal improvements. Current knowledge of the molecular pathways involved in each type of cancer has led to better approaches in cancer treatment. A number of cell signaling molecules are involved in tumorigenesis, and specific targets have been identified based on these signal transducers. This review highlights some of the important cellular pathways and potential therapeutic targets, tumor site-specific irradiation techniques, and novel drug delivery systems used to administer these drugs.

Phase 1 clinical trials for sarcomas: the cutting edge

PURPOSE OF REVIEW

Few standard second-line treatment options exist for advanced sarcoma patients. Some of these patients are offered early-phase clinical trials involving targeted or nontargeted agents. This review outlines recent phase 1 trials involving sarcoma patients, explores current challenges and highlights future opportunities in sarcoma developmental therapeutics.

RECENT FINDINGS

New molecularly targeted phase 1 studies have demonstrated efficacy in sarcomas. For instance, insulin-like growth factor-1 receptor (IGF1R) antibodies have produced single agent activity in Ewing's sarcoma. Other promising novel agents include an agonist for the apoptosis ligand 2/tumor necrosis factor-related apoptosis-inducing ligand (Apo2L/TRAIL) for chondrosarcoma, small molecule inhibitor crizotinib for anaplastic lymphoma kinase (ALK)-rearranged inflammatory myofibroblastic tumor, cedarinib for alveolar soft part sarcoma, and rexin-G, a tumor targeted retrovector for osteosarcoma. In addition, different combinations of chemotherapy in combination with newer agents such as trabectedin exhibited efficacy in advanced soft tissue sarcoma.

SUMMARY

Patients with refractory sarcoma demonstrate benefit from treatment with targeted drugs even in the setting of phase 1 trials. Sarcomas that have a defined translocation and those that express specific activated kinases are particularly promising tumors for targeted therapy. The primary challenge is identifying the biomarkers predictive of response or resistance, matching them with specific patient histology, resulting in successful translation of biology into clinical benefit.

Current advances in retroviral gene therapy

There have been major changes since the incidents of leukemia development in X-SCID patients after the treatments using retroviral gene therapy. Due to the risk of oncogenesis caused by retroviral insertional activation of host genes, most of the efforts focused on the lentiviral therapies. However, a relative clonal dominance was detected in a patient with β-thalassemia Major, two years after the subject received genetically modified hematopoietic stem cells using lentiviral vectors. This disappointing result of the recent clinical trial using lentiviral vector tells us that the current and most advanced vector systems does not have enough safety. In this review, various safety features that have been tried for the retroviral gene therapy are introduced and the possible new ways of improvements are discussed. Additional feature of chromatin insulators, co-transduction of a suicidal gene under the control of an inducible promoter, conditional expression of the transgene only in appropriate target cells, targeted transduction, cell type-specific expression, targeted local administration, splitting of the viral genome, and site specific insertion of retroviral vector are discussed here.

Gammaretroviral vectors: biology, technology and application

Retroviruses are evolutionary optimized gene carriers that have naturally adapted to their hosts to efficiently deliver their nucleic acids into the target cell chromatin, thereby overcoming natural cellular barriers. Here we will review—starting with a deeper look into retroviral biology—how Murine Leukemia Virus (MLV), a simple gammaretrovirus, can be converted into an efficient vehicle of genetic therapeutics. Furthermore, we will describe how more rational vector backbones can be designed and how these so-called self-inactivating vectors can be pseudotyped and produced. Finally, we will provide an overview on existing clinical trials and how biosafety can be improved.

Targeted therapies in bone sarcomas: current approach and future directions

INTRODUCTION

Bone sarcomas are rare malignancies and once advanced, there is limited response to current chemotherapeutic regimens. Targeted therapies could have substantial impact on these diseases.

AREAS COVERED

Specific molecular targets of bone sarcomas are reviewed along with the various targeted therapies that have potential to change the outcome of these chemotherapy resistant diseases.

EXPERT OPINION

There are promising pathways identified that targeted inhibitors could provide better treatment options for metastatic bone sarcomas. There is a strong need for continued Phase II and III clinical trials investigating these molecularly targeted therapies.

Expression of platelet-derived growth factor-alpha receptor in human osteosarcoma is not a predictor of outcome

AIMS

The aims of this study were to examine the prognostic relevance of platelet-derived growth factor-α receptor (PDGFRA) expression in human osteosarcomas and to evaluate the mutation status of exon 12 and exon 18 of the PDGFRA gene.

METHODS

PDGFRA expression was examined in 100 human osteosarcomas by immunohistochemistry using paraffin embedded tumour tissues, and capillary sequencing of genomic DNA was performed to search for mutations in exons 12 and 18 of the PDGFRA gene.

RESULTS

Ninety-six osteosarcomas showed PDGFRA expression ranging from 4% to 90% (mean 40%, median 37.5%, SD 27.11%). Furthermore, DNA sequence of exon 12 and exon 18 of the PDGFRA gene were not altered in 40 tumours with high PDGFRA expression. Overall and disease-free survival analysis did not reveal any differences between osteosarcoma patients with high PDGFRA expression and patients with low PDGFRA expression.

CONCLUSIONS

The protein expression is not linked to mutations in exon 12 or exon 18 of PDGFRA gene. Therefore, treatment modalities based on the suppression of PDGFRA tyrosine kinase activity may need further investigation. PDGFRA expression is not a prognostic marker for osteosarcoma patients.