FOLFIRINOX after first-line gemcitabine-based chemotherapy in advanced pancreatic cancer: a retrospective comparison with FOLFOX and FOLFIRI schedules.

BACKGROUND: Pancreatic adenocarcinoma is the fourth leading cause of cancer-related death. In cases with metastasis, the combination of 5-fluorouracil, irinotecan, and oxaliplatin (FOLFIRINOX) or gemcitabine-based chemotherapy regimens are considered the standard of care. However, the optimal sequence of these regimens is unclear. METHODS: This retrospective study initially evaluated 186 patients with locally advanced/metastatic pancreatic cancer at three Italian institutions between February 2013 and October 2019. All patients had progressed after receiving gemcitabine-based first-line chemotherapy and were subsequently offered second-line FOLFIRINOX, FOLFOX-6, or FOLFIRI treatment. This study evaluated progression-free survival (PFS), overall survival from the start of second-line treatment (OS2), overall survival from the start of first-line treatment (OS1), and safety outcomes. RESULTS: A total of 77 patients received ⩾4 cycles of second-line chemotherapy and were considered eligible: 15 patients received FOLFIRINOX, 32 patients received FOLFOX-6, and 30 patients received FOLFIRI. The FOLFIRINOX group had median PFS of 26.29 weeks and median OS2 of 47.86 weeks, while the FOLFIRI group had median PFS of 10.57 weeks and median OS2 of 25.00 weeks (p = 0.038). No significant differences were observed between the FOLFIRINOX and FOLFOX-6 groups in terms of PFS (26.29 weeks versus 23.07 weeks) or OS2 (47.86 weeks versus 42.00 weeks). The most common grade 3-4 toxicities were anemia, neutropenia, and thrombocytopenia, which occurred more frequently in the FOLFIRINOX and FOLFOX-6 groups. CONCLUSION: Relative to the FOLFIRI regimen, the FOLFIRINOX regimen had a favorable toxicity profile and better survival outcomes. No significant differences were observed relative to the FOLFOX-6 regimen.

Combining Immune Checkpoint Inhibitors with Anti-Angiogenic Agents.

Immunotherapy has recently emerged as a novel strategy for treating different types of solid tumors, with promising results. However, still a large fraction of patients do not primarily respond to such approaches, and even responders sooner or later develop resistance. Moreover, immunotherapy is a promising strategy for certain malignancies but not for others, with this discrepancy having been attributed to a more immunogenic microenvironment of some tumors. As abnormal and augmented tumor vessels often occur in cancerogenesis, anti-angiogenic drugs have already demonstrated their effectiveness both in preclinical and in clinical settings. By targeting abnormal formation of tumor vessels, anti-angiogenetic agents potentially result in an enhanced infiltration of immune effector cells. Moreover, crosstalks downstream of the immune checkpoint axis and vascular endothelial growth factor receptor (VEGFR) signaling may result in synergistic effects of combined treatment in tumor cells. In this review, we will describe and discuss the biological rationale of a combined therapy, underlying the modification in tumor microenvironment as well as in tumor cells after exposure to checkpoint inhibitors and anti-angiogenic drugs. Moreover, we will highlight this strategy as a possible way for overcoming drug resistance. By first discussing potential prognostic and predictive factors for combined treatment, we will then turn to clinical settings, focusing on clinical trials where this strategy is currently being investigated.

Mechanisms of resistance to mTOR inhibitors.

In several tumors the PI3K/AKT/mTOR pathway is frequently disrupted, an event that results in uncontrolled cell proliferation and tumor growth. Through the years, several compounds have been developed to inhibit the pathway at different steps: the mammalian target of rapamycin (mTOR) seemed to be the most qualified target. However, this kinase has such a key role in cell survival that mechanisms of resistance are rapidly developed. Nevertheless, clinical results obtained with mTOR inhibitors in breast cancer, renal cell carcinoma, neuroendocrine tumors and mantle cell lymphoma push oncologists to actively further develop these drugs, maybe by better selecting the population to which they are offered, through the research of predictive factors of responsiveness. In this review, we aim to describe mechanisms of resistance to mTOR inhibitors, from preclinical and clinical perspectives.

Tumour Microenvironment and Immune Evasion in EGFR Addicted NSCLC: Hurdles and Possibilities.

In the last few years, the treatment strategy in Non-Small Cell Lung Cancer (NSCLC) patients has been heavily modified by the introduction of the immune-checkpoint inhibitors. Anti-programmed cell death 1/programmed cell death ligand 1 (PD-1/PD-L1) therapy has improved both progression-free and the overall survival in almost all subgroups of patients, with or without PDL1 expression, with different degrees of responses. However, there are patients that are not benefitting from this treatment. A defined group of immune-checkpoint inhibitors non-responder tumours carry EGFR (epidermal growth factor receptor) mutations: nowadays, anti-PD-1/PD-L1 clinical trials often do not involve this type of patient and the use of immune-checkpoint inhibitors are under evaluation in this setting. Our review aims to elucidate the mechanisms underlying this resistance: we focused on evaluating the role of the tumour microenvironment, including infiltrating cells, cytokines, secreted factors, and angiogenesis, and its interaction with the tumour tissue. Finally, we analysed the possible role of immunotherapy in EGFR mutated tumours.

The Molecular Effects of Ionizing Radiations on Brain Cells: Radiation Necrosis vs. Tumor Recurrence.

The central nervous system (CNS) is generally resistant to the effects of radiation, but higher doses, such as those related to radiation therapy, can cause both acute and long-term brain damage. The most important results is a decline in cognitive function that follows, in most cases, cerebral radionecrosis. The essence of radio-induced brain damage is multifactorial, being linked to total administered dose, dose per fraction, tumor volume, duration of irradiation and dependent on complex interactions between multiple brain cell types. Cognitive impairment has been described following brain radiotherapy, but the mechanisms leading to this adverse event remain mostly unknown. In the event of a brain tumor, on follow-up radiological imaging often cannot clearly distinguish between recurrence and necrosis, while, especially in patients that underwent radiation therapy (RT) post-surgery, positron emission tomography (PET) functional imaging, is able to differentiate tumors from reactive phenomena. More recently, efforts have been done to combine both morphological and functional data in a single exam and acquisition thanks to the co-registration of PET/MRI. The future of PET imaging to differentiate between radionecrosis and tumor recurrence could be represented by a third-generation PET tracer already used to reveal the spatial extent of brain inflammation. The aim of the following review is to analyze the effect of ionizing radiations on CNS with specific regard to effect of radiotherapy, focusing the attention on the mechanism underling the radionecrosis and the brain damage, and show the role of nuclear medicine techniques to distinguish necrosis from recurrence and to early detect of cognitive decline after treatment.

Delayed response to maintenance therapy after first-line chemotherapy in metastatic intrahepatic cholangiocarcinoma: a case report.

BACKGROUND: Intrahepatic cholangiocarcinoma is an aggressive tumor originating in the epithelium of the bile duct, often associated with distant dissemination. The prognosis is poor and treatment is challenging due to low response rate to standard chemotherapy and lack of targeted therapies. CASE PRESENTATION: Here we report the case of a 74-year-old white woman affected by intrahepatic cholangiocarcinoma with metastatic involvement of spleen, lung, peritoneum, and intra-abdominal lymph nodes. As first-line chemotherapy, she was given cisplatin-gemcitabine chemotherapy. The treatment was well tolerated with the exception of grade 1 constipation and a single episode of grade 4 thrombocytopenia occurring after the fourth course. After the first three courses of chemotherapy a computed tomography scan evaluation demonstrated no change; her CA19-9 levels were slightly decreased. However, after the sixth course of chemotherapy a computed tomography scan revealed a dimensional enlargement of the lung metastases; her CA19-9 levels increased. She was then treated with gemcitabine alone. After 2 months of gemcitabine monotherapy a significant regression of lung and spleen metastases, as well a CA19-9 level reduction, occurred. Eight months after the start of gemcitabine monotherapy no signs of progression were reported. CONCLUSIONS: Treatment of metastatic intrahepatic cholangiocarcinoma with gemcitabine as maintenance therapy after first-line chemotherapy could be continued until clear evidence of disease progression since delayed responses are possible.

The SGK1 Kinase Inhibitor SI113 Sensitizes Theranostic Effects of the 64CuCl2 in Human Glioblastoma Multiforme Cells.

BACKGROUND/AIMS: The importance of copper in the metabolism of cancer cells has been widely studied in the last 20 years and a clear-cut association between copper levels and cancer deregulation has been established. Copper-64, emitting positrons and ß-radiations, is indicated for the labeling of a large number of molecules suitable for radionuclide imaging as well as radionuclide therapy. Glioblastoma multiforme (GBM) is the CNS tumor with the worse prognosis, characterized by high number of recurrences and strong resistance to chemo-radio therapy, strongly affecting patients survival. We have recently discovered and studied the small molecule SI113, as inhibitor of SGK1, a serine/threonine protein kinase, that affects several neoplastic phenotypes and signaling cascades. The SI113-dependent SGK1 inhibition induces cell death, blocks proliferation, perturbs cell cycle progression and restores chemo-radio sensibility by modulating SGK1-related substrates. In the present paper we aim to characterize the combined effects of 64CuCl2 and SI113 on human GBM cell lines with variable p53 expression. METHODS: Cell viability, cell death and stress/authopagic related pathways were then analyzed by FACS and WB-based assays, after exposure to SI113 and/or 64CuCl2. RESULTS: We demonstrate here, that i) 64CuCl2 is able to induce a time and dose dependent modulation of cell viability (with different IC50 values) in highly malignant gliomas and that the co-treatment with SI113 leads to ii) additive/synergistic effects in terms of cell death; iii) enhancement of the effects of ionizing radiations, probably by a TRC1 modulation; iv) modulation of the autophagic response. CONCLUSIONS: Evidence reported here underlines the therapeutic potential of the combined treatment with SI113 and 64CuCl2 in GBM cells.

SGK1 affects RAN/RANBP1/RANGAP1 via SP1 to play a critical role in pre-miRNA nuclear export: a new route of epigenomic regulation.

The serum- and glucocorticoid-regulated kinase (SGK1) controls cell transformation and tumor progression. SGK1 affects mitotic stability by regulating the expression of RANBP1/RAN. Here, we demonstrate that SGK1 fluctuations indirectly modify the maturation of pre-miRNAs, by modulating the equilibrium of the RAN/RANBP1/RANGAP1 axis, the main regulator of nucleo-cytoplasmic transport. The levels of pre-miRNAs and mature miRNAs were assessed by qRT-PCR, in total extracts and after differential nuclear/cytoplasmic extraction. RANBP1 expression is the limiting step in the regulation of SGK1-SP1 dependent nuclear export. These results were validated in unrelated tumor models and primary human fibroblasts and corroborated in tumor-engrafted nude mice. The levels of pri-miRNAs, DROSHA, DICER and the compartmental distribution of XPO5 were documented. Experiments using RANGTP conformational antibodies confirmed that SGK1, through RANBP1, decreases the level of the GTP-bound state of RAN. This novel mechanism may play a role in the epigenomic regulation of cell physiology and fate.

SGK1, the New Player in the Game of Resistance: Chemo-Radio Molecular Target and Strategy for Inhibition.

The serum- and glucocorticoid-regulated kinase (SGK) family consists of three members, SGK1, SGK2 and SGK3, all displaying serine/threonine kinase activity and sharing structural and functional similarities with the AKT family of kinases. SGK1 was originally described as a key enzyme in the hormonal regulation of several ion channels and pumps. Over time, growing and impressive evidence has been accumulated, linking SGK1 to the cell survival, de-differentiation, cell cycle control, regulation of caspases, response to chemical, mechanical and oxidative injury in cancer models as well as to the control of mitotic stability. Much evidence shows that SGK1 is over-expressed in a variety of epithelial tumors. More recently, many contributions to the published literature demonstrate that SGK1 can mediate chemo-and radio-resistance during the treatment of various human tumors, both in vitro and in vivo. SGK1 appears therefore as a dirty player in the stress response to chemical and radio-agents, responsible of a selective advantage that favors the uncontrolled tumor progression and the selection of the most aggressive clones. The purpose of this review is the analysis of the literature describing SGK1 as central node of the cell resistance, and a summary of the possible strategies in the pharmacological targeting of SGK1.

SI113, a SGK1 inhibitor, potentiates the effects of radiotherapy, modulates the response to oxidative stress and induces cytotoxic autophagy in human glioblastoma multiforme cells.

Glioblastoma multiforme (GBM) is the most aggressive CNS tumor and is characterized by a very high frequency of clinical relapse after therapy and thus by a dismal prognosis, which strongly compromises patients survival. We have recently identified the small molecule SI113, as a potent and selective inhibitor of SGK1, a serine/threonine protein kinase, that modulates several oncogenic signaling cascades. The SI113-dependent SGK1 inhibition induces cell death, blocks proliferation and perturbs cell cycle progression by modulating SGK1-related substrates. SI113 is also able to strongly and consistently block, in vitro and in vivo, growth and survival of human hepatocellular-carcinomas, either used as a single agent or in combination with ionizing radiations. In the present paper we aim to study the effect of SI113 on human GBM cell lines with variable p53 expression. Cell viability, cell death, caspase activation and cell cycle progression were then analyzed by FACS and WB-based assays, after exposure to SI113, with or without oxidative stress and ionizing radiations. Moreover, autophagy and related reticulum stress response were evaluated. We show here, that i) SGK1 is over-expressed in highly malignant gliomas and that the treatment with SI113 leads to ii) significant increase in caspase-mediated apoptotic cell death in GBM cell lines but not in normal fibroblasts; iii)enhancement of the effects of ionizing radiations; iv) modulation of the response to oxidative reticulum stress; v) induction of cytotoxic autophagy. Evidence reported here underlines the therapeutic potential of SI113 in GBM, suggesting a new therapeutic strategy either alone or in combination with radiotherapy.

Preclinical model in HCC: the SGK1 kinase inhibitor SI113 blocks tumor progression in vitro and in vivo and synergizes with radiotherapy.

The SGK1 kinase is pivotal in signal transduction pathways operating in cell transformation and tumor progression. Here, we characterize in depth a novel potent and selective pyrazolo[3,4-d]pyrimidine-based SGK1 inhibitor. This compound, named SI113, active in vitro in the sub-micromolar range, inhibits SGK1-dependent signaling in cell lines in a dose- and time-dependent manner. We recently showed that SI113 slows down tumor growth and induces cell death in colon carcinoma cells, when used in monotherapy or in combination with paclitaxel. We now demonstrate for the first time that SI113 inhibits tumour growth in hepatocarcinoma models in vitro and in vivo. SI113-dependent tumor inhibition is dose- and time-dependent. In vitro and in vivo SI113-dependent SGK1 inhibition determined a dramatic increase in apoptosis/necrosis, inhibited cell proliferation and altered the cell cycle profile of treated cells. Proteome-wide biochemical studies confirmed that SI113 down-regulates the abundance of proteins downstream of SGK1 with established roles in neoplastic transformation, e.g. MDM2, NDRG1 and RAN network members. Consistent with knock-down and over-expressing cellular models for SGK1, SI113 potentiated and synergized with radiotherapy in tumor killing. No short-term toxicity was observed in treated animals during in vivo SI113 administration. These data show that direct SGK1 inhibition can be effective in hepatic cancer therapy, either alone or in combination with radiotherapy.

In silico identification and biological evaluation of novel selective serum/glucocorticoid-inducible kinase 1 inhibitors based on the pyrazolo-pyrimidine scaffold.

The serum/glucocorticoid-inducible kinase 1 (Sgk1) has demonstrated antiapoptotic function and the capability to regulate cell survival, proliferation, and differentiation. A pivotal role of Sgk1 in carcinogenesis and in resistance to anticancer therapy has been suggested. With the aim of identifying new Sgk1 modulators, 322 pyrazolo-pyrimidine derivatives have been virtually screened with respect to a crystallographic model of Sgk1. The top five ranked compounds have been evaluated demonstrating Sgk1 inhibition in vitro and selectivity compared to RAC-alpha serine/threonine-protein kinase (Akt1).

The current status of novel PET radio-pharmaceuticals in radiotherapy treatment planning of glioma.

Malignant glioma is a primary tumor of the central nervous system, representing a major cause of mortality in a young, productive subset of population. The management of this neoplasm requires aggressive treatments, including radiotherapy. Accurate imaging plays a central role in treatment planning process with curative intent based on radiation therapy. In order to maximize the radiation dose to the tumor and to minimize the damage to the normal surrounding tissue, a reliable identification of viable tumor margins is indeed required. The use of PET in the treatment planning process has become more promising over the years, although many important questions must be addressed. The aim of this article is to critically review the evidence supporting PET in radiotherapy planning, with special emphasis on the role of novel radiopharmaceuticals, comparing its sensitivity and specificity with respect to 18F-FDG and other anatomic imaging modalities.

Sphingosine analog fingolimod (FTY720) increases radiation sensitivity of human breast cancer cells in vitro.

Radiotherapy is one of the most effective therapeutic strategies for breast cancer patients, although its efficacy may be reduced by intrinsic radiation resistance of cancer cells. Recent investigations demonstrate a link between cancer cell radio-resistance and activation of sphingosine kinase (SphK1), which plays a key role in the balance of lipid signaling molecules. Sphingosine kinase (SphK1) activity can alter the sphingosine-1-phosphate (S1P)/ceramide ratio leading to an imbalance in the sphingolipid rheostat. Fingolimod (FTY720) is a novel sphingosine analog and a potent immunosuppressive drug that acts as a SphK1 antagonist, inhibits the growth, and induces apoptosis in different human cancer cell lines. We sought to investigate the in vitro radiosensitizing effects of FTY720 on the MDA-MB-361 breast cancer cell line and to assess the effects elicited by radiation and FTY720 combined treatments. We found that FTY720 significantly increased anti-proliferative and pro-apoptotic effects induced by a single dose of ionizing radiation while causing autophagosome accumulation. At the molecular level, FTY720 significantly potentiated radiation effects on perturbation of signaling pathways involved in regulation of cell cycle and apoptosis, such as PI3K/AKT and MAPK. In conclusion, our data highlight a potent radiosensitizing effect of FTY720 on breast cancer cells and provide the basis of novel therapeutic strategies for breast cancer treatment.

Repeat stereotactic radiosurgery in the management of brain metastases from NSCLC: A case report and review of the literature.

The aims of radiotherapeutic treatment of brain metastases include maintaining neurocognitive function and improvement of survival. Based on these premises, we present a case report in which the role of repeat stereotactic radiosurgery (SRS) was investigated in a patient with a recurrent brain metastasis from non-small cell lung cancer in the same area as previously treated with radiosurgery. A 40-year-old male caucasian patient was diagnosed with brain metastasis from non-small cell lung cancer (NSCLC) and underwent SRS. The patient developed a recurrence of the disease and a second SRS on the same area was performed. After 8 months, tumor restaging demonstrated a lesion compatible with a recurrence and the patient underwent surgery. Histological diagnosis following surgery revealed only the occurrence of radionecrosis. Radiotherapy was well-tolerated and no grade 3/4 neurological toxicity occurred. To date, no consensus exists on the efficacy of retreatment with SRS. Despite the limited number of studies in this field, in the present case report, we outline the outcomes of this unconventional approach.

Synergistic antitumor activity of ZD6474, an inhibitor of vascular endothelial growth factor receptor and epidermal growth factor receptor signaling, with gemcitabine and ionizing radiation against pancreatic cancer.

PURPOSE: Standard treatments have modest effect against pancreatic cancer, and current research focuses on agents targeting molecular pathways involved in tumor growth and angiogenesis. This study investigated the interactions between ZD6474, an inhibitor of tyrosine kinase activities of vascular endothelial growth factor receptor-2 and epidermal growth factor receptor (EGFR), gemcitabine, and ionizing radiation in human pancreatic cancer cells and analyzed the molecular mechanisms underlying this combination. EXPERIMENTAL DESIGN: ZD6474, ionizing radiation, and gemcitabine, alone or in combination, were given in vitro to MIA PaCa-2, PANC-1, and Capan-1 cells and in vivo to MIA PaCa-2 tumor xenografts. The effects of treatments were studied by the evaluation of cytotoxicity, apoptosis, cell cycle, EGFR and Akt phosphorylation, modulation of gene expression of enzymes related to gemcitabine activity (deoxycytidine kinase and ribonucleotide reductase), as well as vascular endothelial growth factor immunohistochemistry and microvessel count. RESULTS: In vitro, ZD6474 dose dependently inhibited cell growth, induced apoptosis, and synergistically enhanced the cytotoxic activity of gemcitabine and ionizing radiation. Moreover, ZD6474 inhibited phosphorylation of EGFR and Akt and triggered cell apoptosis. PCR analysis showed that ZD6474 increased the ratio between gene expression of deoxycytidine kinase and ribonucleotide reductase. In vivo, ZD6474 showed significant antitumor activity alone and in combination with radiotherapy and gemcitabine, and the combination of all three modalities enhanced MIA PaCA-2 tumor growth inhibition compared with gemcitabine alone. CONCLUSIONS: ZD6474 decreases EGFR and Akt phosphorylation, enhances apoptosis, favorably modulates gene expression in cancer cells, and acts synergistically with gemcitabine and radiotherapy to inhibit tumor growth. These findings support the investigation of this combination in the clinical setting.

ZD6474, an inhibitor of VEGFR and EGFR tyrosine kinase activity in combination with radiotherapy.

Radiation enhances both epithelial growth factor receptor (EGFR) and vascular endothelial growth factor (VEGF) expression, which are a part of key pathways for tumor progression. Some tumors may not respond well to EGFR inhibitors alone or may develop resistance to EGFR inhibitors. Therefore, drug therapy targeted to VEGF receptors and EGFRs, when combined with radiotherapy (RT), may improve tumor control and provide wider applicability. This article focuses on ZD6474, an inhibitor of EGFR and VEGF receptor signaling in combination with RT. We discuss preclinical and clinical studies with RT and inhibitors of VEGF or EGFR signaling first. We then address issues associated with ZD6474 pharmacokinetic dosing, and scheduling when combined with RT. We also discuss ZD6474 in the context of anti-EGFR therapy resistance. Dual inhibition of EGFR and VEGF receptor signaling pathways shows promise in enhancing RT efficacy.

Cooperative antitumor effect of multitargeted kinase inhibitor ZD6474 and ionizing radiation in glioblastoma.

PURPOSE: Glioblastoma multiforme is an aggressive disease in which vascular endothelial growth factor (VEGF) and the EGF receptor (EGFR) are implicated in tumor growth, relapse, and resistance to radiotherapy and chemotherapy. The VEGF receptors VEGFR-1 (flt-1) and VEGFR-2 (KDR), typically present on endothelial cells, have also been identified in human glioblastoma tissues and cell lines. In addition, EGFR is dysregulated in the majority of human glioblastomas and EGFR overexpression correlates with shorter survival. We have investigated the antitumor and antiangiogenic effect of ZD6474, an inhibitor of both VEGFR and EGFR signaling as a single agent and in combination with ionizing radiation. EXPERIMENTAL DESIGN: We have used ZD6474 and/or ionizing radiation in human glioblastoma cell lines D54 and U251 in vitro and in nude mice bearing established xenografts. The effects of treatment on tumor blood vessels and protein expression were evaluated by Western blot and immunohistochemistry. RESULTS: As single agents, ionizing radiation and ZD6474 caused a dose-dependent inhibition of soft agar growth in D54 and U251 cell lines, whereas a cooperative effect was obtained in combination. Treatment of mice bearing D54 xenografts with either ZD6474 or radiotherapy alone caused tumor growth inhibition that was reversible upon treatment cessation. A cooperative and long-lasting inhibition of tumor growth was obtained with ZD6474 in combination with concomitant radiotherapy. The antiproliferative effect was accompanied by inhibition of VEGF protein expression and inhibition of angiogenesis as measured by vessel counting. CONCLUSION: This study shows the antitumor activity of ZD6474 in combination with ionizing radiation in glioblastoma both in vitro and in vivo, and provides a scientific rationale to evaluate ZD6474 alone or in combination with radiotherapy in patients affected by this disease.

Antitumor activity of ZD6126, a novel vascular-targeting agent, is enhanced when combined with ZD1839, an epidermal growth factor receptor tyrosine kinase inhibitor, and potentiates the effects of radiation in a human non-small cell lung cancer xenograft model.

OBJECTIVE: Targeting the tumor vasculature may offer an alternative or complementary therapeutic approach to targeting growth factor signaling in lung cancer. The aim of these studies was to evaluate the antitumor effects in vivo of the combination of ZD6126, a tumor-selective vascular-targeting agent; ZD1839 (gefitinib, Iressa), an epidermal growth factor receptor tyrosine kinase inhibitor; and ionizing radiation in the treatment of non-small cell lung cancer xenograft model. METHODS: Athymic nude mice with established flank A549 human non-small cell lung cancer xenograft model xenografts were treated with fractionated radiation therapy, ZD6126, ZD1839, or combinations of each treatment. ZD6126 (150 mg/kg) was given i.p. the day after each course of radiation. Animals treated with ZD1839 received 100 mg/kg per dose per animal, 5 or 7 days/wk for 2 weeks. Immunohistochemistry was done to evaluate the effects on tumor growth using an anti-Ki67 monoclonal antibody. Effects on tumor-induced vascularization were quantified using an anti-factor VIII-related antigen monoclonal antibody. RESULTS: ZD6126 attenuated the growth of human A549 flank xenografts compared with untreated animals. Marked antitumor effects were observed when animals were treated with a combination of ZD6126 and fractionated radiation therapy with protracted tumor regression. ZD6126 + ZD1839 resulted in a greater tumor growth delay than either agent alone. Similar additive effects were seen with ZD1839 + fractionated radiation. Finally, the addition of ZD6126 to ZD1839 and radiation therapy seemed to further improve tumor growth control, with a significant tumor growth delay compared with animals treated with single agent or with double combinations. Immunohistochemistry showed that ZD1839 induced a marked reduction in A549 tumor cell proliferation. Both ZD1839 and ZD6126 treatment substantially reduced tumor-induced angiogenesis. ZD6126 caused marked vessel destruction through loss of endothelial cells and thrombosis, substantially increasing the level of necrosis seen when combined with radiation therapy. The combination of radiation therapy, ZD6126, and ZD1839 induced the greatest effects on tumor growth and angiogenesis. CONCLUSION: This first report shows that a selective vascular-targeting agent (ZD6126) + an anti-epidermal growth factor receptor agent (ZD1839) and radiation have additive in vivo effects in a human cancer model. Targeting the tumor vasculature offers an excellent strategy to enhance radiation cytotoxicity. Polytargeted therapy with agents that interfere with both growth factor and angiogenic signaling warrants further investigation.

Targeted therapies and radiation for the treatment of head and neck cancer: are we making progress?

Targeting specific biological pathways in tumor development has been heralded as a promising approach to the treatment of cancer. Familiar to most investigators are the studies done with epidermal growth factor receptor (EGFR) antagonists, but newer agents currently under development also target angiogenic or cell cycle pathways. EGFR activation stimulates many important signaling pathways associated with cancer development and progression, and importantly, resistance to radiation. Because EGFR overexpression portends for a worse outcome in patients with advanced head and neck cancer (HNC), selective targeting of this signaling pathway has gained attention. The agents selected for initial studies include monoclonal antibodies and tyrosine kinase inhibitors against EGFR. Encouraging laboratory findings in different xenografts resulted in rapid translation into the clinic. Results from initial clinical trials show rather surprisingly that only a minority of patients benefited from EGFR inhibition as monotherapy or in combination with chemotherapy. Current challenges for investigators are to determine (1). who will benefit from targeted agents and which agents are most appropriate to combine with radiation and/or chemotherapy, (2). how to sequence these agents with radiation and/or cytotoxic compounds, (3). reliable markers for patient selection and verification of effective blockade of signaling in vivo, and (4). mechanisms behind intrinsic or acquired resistance to targeted agents to facilitate rational development of multiple targeted therapy. Well-integrated laboratory-clinical research programs are needed to address these issues.