Combined Antitumor Therapy Research Articles

Nanoformulation-based sequential combination cancer therapy.

Although combining two or more treatments is regarded as an indispensable approach for effectively treating cancer, the traditional cocktail-based combination therapies are seriously limited by coordination issues that fail to account for differences in the pharmacokinetics and action sites of each drug. The careful manipulation of dosing regimens, such as by the sequential application of combination treatments, may satisfy the temporal and spatial needs of each drug and achieve successful combination antitumor therapy. Nanotechnology-based carriers might be the best tools for sequential combination therapy, as they can be loaded with multiple cargos and may provide targeted and sustained delivery to target tumor cells. Single nanoformulations capable of sequentially releasing drugs have shown synergistic anticancer activity, such as by sensitizing tumor cells through cascaded drug delivery or remodeling the tumor vasculature and microenvironment to enhance the tumor distribution of nanotherapeutics. This review highlights the use of nanotechnology-based multistage drug delivery for cancer treatment, focusing on the ability of such formulations to enhance antitumor efficacy by applying sequential treatment and modulating dosing regimens, which are challenges currently being faced in the clinic.

Tumor-triggered drug release from calcium carbonate-encapsulated gold nanostars for near-infrared photodynamic/photothermal combination antitumor therapy

Different stimulus including pH, light and temperature have been used for controlled drug release to prevent drug inactivation and minimize side-effects. Herein a novel nano-platform (GNS@CaCO3/ICG) consisting of calcium carbonate-encapsulated gold nanostars loaded with ICG was established to couple the photothermal properties of gold nanostars (GNSs) and the photodynamic properties of indocyanine green (ICG) in the photodynamic/photothermal combination therapy (PDT/PTT). In this study, the calcium carbonate worked not only a drug keeper to entrap ICG on the surface of GNSs in the form of a stable aggregate which was protected from blood clearance, but also as the a pH-responder to achieve highly effective tumor-triggered drug release locally. The application of GNS@CaCO3/ICG for in vitro and in vivo therapy achieved the combined antitumor effects upon the NIR irradiation, which was superior to the single PDT or PTT. Meanwhile, the distinct pH-triggered drug release performance of GNS@CaCO3/ICG implemented the tumor-targeted NIR fluorescence imaging. In addition, we monitored the bio-distribution and excretion pathway of GNS@CaCO3/ICG based on the NIR fluorescence from ICG and two-photon fluorescence and photoacoustic signal from GNSs, and the results proved that GNS@CaCO3/ICG had a great ability for tumor-specific and tumor-triggered drug release. We therefore conclude that the GNS@CaCO3/ICG holds great promise for clinical applications in anti-tumor therapy with tumor imaging or drug tracing.

Multifunctional polycationic photosensitizer conjugates with rich hydroxyl groups for versatile water-soluble photodynamic therapy nanoplatforms.

Photodynamic therapy (PDT) has already shown immense potential in antitumor fields due to its low systemic toxicity and negligible drug resistance. However, the clinical application of current photosensitizers is still restricted by the low singlet oxygen yield or insolubility. Herein, series of star-like hydroxyl-rich polycations (Pc-PGEA/Pc) with flanking phthalocyanine (Pc) were proposed for effective water-soluble photosensitizers. The designed Pc-PGEA/Pc polymers consist of one Pc core and four ethanolamine and Pc-difunctionalized poly(glycidyl methacrylate) arms. The strong π-π stacking and hydrophobicity of introduced Pc units drive the amphipathic Pc-PGEA/Pc polymers to self-assemble into well-defined cationic nanoparticles. Such Pc-PGEA/Pc nanoparticles present impressive photodynamic therapy effects under moderate irradiation and remarkable photoacoustic imaging (PAI) ability. These kinds of nanoparticles also exhibit good performance as gene vectors. The PAI ability given by the proper wavelength absorbance of Pc units provides one promising method for PAI-guided combined antitumor therapy. The present work would contribute valuable information for the development of new strategies of visible antitumor therapy.

18P - TKI pazopanib impaires immunostimulatory properties of monocytes: Implication for monocyte-derived DC-based anti-cancer vaccine preparation

We manufacture fully personalized monocyte-derived dendritic cell-based vaccines that are evaluated in investigator-initiated clinical trial „Combined antitumor therapy with ex vivo manipulated dendritic cells producing interleukin-12 in children, adolescents and young adults with progressive, recurrent of primarily metastatic high-risk tumours”. Immunobiological part of quality control (QC) of DC batches revealed variability in immunostimulatory properties. We analyzed DC parametres within the context of patients medical history and explore the effect of anti-cancer compound on monocyte functional properties.

Abstract B143: Fc gamma receptor IV mediated depletionof tumor infiltrating regulatory T cells by anti-CTLA4 antibody is promoted byTLR1/2 agonist and hence its efficacy in anti-tumor combination therapy

Abstract Immune checkpoint blockade therapy has been effective but still a significant number of cancer patients either do not respond or become resistant to these therapies. We hypothesized that activating innate immune pathway along with adaptive immune pathway will have a better tumor reduction and survival outcome from immunotherapy treatment. Therefore, we injected TLR1/2 ligand intratumorally in combination with intraperitoneal injection of anti-CTLA4 antibody in a mouse model of melanoma. We show that this combination treatment enhanced anti-tumor immune responses both qualitatively and quantitatively, which is dependent on both CD4 and CD8 T cells. Interestingly, Our results further suggested that increased depletion of regulatory T cells in tumor microenvironment could be one of the mechanisms of enhanced efficacy of combination therapy and this efficacy is dependent upon Fcγ receptor IV expression. This study shows modulation of Fcγ receptor IV expression by a TLR ligand on macrophages to be important in efficacy of anti-CTLA4 antibody in a combination therapy and this mechanism could be harnessed to modulate the final outcome of other antibody-based immunomodulatory therapies. Citation Format: Naveen Sharma, James P. Allison. Fc gamma receptor IV mediated depletionof tumor infiltrating regulatory T cells by anti-CTLA4 antibody is promoted byTLR1/2 agonist and hence its efficacy in anti-tumor combination therapy [abstract]. In: Proceedings of the Second CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; 2016 Sept 25-28; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(11 Suppl):Abstract nr B143.

Activation of autophagic flux by epigallocatechin gallate mitigates TRAIL-induced tumor cell apoptosis via down-regulation of death receptors.

Epigallocatechin gallate (EGCG) is a major polyphenol in green tea. Recent studies have reported that EGCG can inhibit TRAIL-induced apoptosis and activate autophagic flux in cancer cells. However, the mechanism behind these processes is unclear. The present study found that EGCG prevents tumor cell death by antagonizing the TRAIL pathway and activating autophagy flux. Our results indicate that EGCG dose-dependently inhibits TRAIL-induced apoptosis and decreases the binding of death receptor 4 and 5 (DR4 and 5) to TRAIL. In addition, EGCG activates autophagy flux, which is involved in the inhibition of TRAIL cell death. We confirmed that the protective effect of EGCG can be reversed using genetic and pharmacological tools through re-sensitization to TRAIL. The inhibition of autophagy flux affects not only the re-sensitization of tumor cells to TRAIL, but also the restoration of death receptor proteins. This study demonstrates that EGCG inhibits TRAIL-induced apoptosis through the manipulation of autophagic flux and subsequent decrease in number of death receptors. On the basis of these results, we suggest further consideration of the use of autophagy activators such as EGCG in combination anti-tumor therapy with TRAIL.

Polyethylenimine mediated magnetic nanoparticles for combined intracellular imaging, siRNA delivery and anti-tumor therapy

PEI–magnetic γ-Fe2O3nanoparticles (MNPs) were modified with fluorescent FITC for intracellular imaging and were also used for survivin siRNA delivery. The results suggested that the fabricated PEI–MNPs are a promising nanovehicle for efficient anti-tumor therapy.

Interleukin-15: New kid on the block for antitumor combination therapy

Interleukin (IL)-15 is one of the most promising molecules to be used in antitumor immune therapy, as it is able to stimulate the main killer cells of both the innate and adaptive immune system. Although this cytokine can be used as a stand-alone immunotherapeutic agent, IL-15 will probably be most efficient in combination with other strategies to overcome high tumor burden, immune suppression of the tumor microenvironment and/or the short half-life of IL-15. In this review, we will discuss the combination strategies with IL-15 that have been tested to date in different animal tumor models, which include chemotherapy, other immunostimulatory cytokines, targeted therapy, adoptive cell transfer and gene therapy. In addition, we give an overview of IL-15 combination therapies that are currently tested in clinical studies to treat patients with hematological or advanced solid tumors.

PEG-pHPMAm-based polymeric micelles loaded with doxorubicin-prodrugs in combination antitumor therapy with oncolytic vaccinia viruses

An enzymatically activatable prodrug of doxorubicin was covalently coupled, using click-chemistry, to the hydrophobic core of poly(ethylene glycol)-b-poly[N-(2-hydroxypropyl)-methacrylamide-lactate] micelles. The release and cytotoxic activity of the prodrug was evaluated in vitro in A549 non-small-cell lung cancer cells after adding β-glucuronidase, an enzyme which is present intracellularly in lysosomes and extracellularly in necrotic areas of tumor lesions. The prodrug-containing micelles alone and in combination with standard and β-glucuronidase-producing oncolytic vaccinia viruses were also evaluated in vivo, in mice bearing A549 xenograft tumors. When combined with the oncolytic viruses, the micelles completely blocked tumor growth. Moreover, a significantly better antitumor efficacy as compared to virus treatment alone was observed when β-glucuronidase virus treated tumor-bearing mice received the prodrug-containing micelles. These findings show that combining tumor-targeted drug delivery systems with oncolytic vaccinia viruses holds potential for improving anticancer therapy.

Nano-engineering of 5-fluorouracil-loaded magnetoliposomes for combined hyperthermia and chemotherapy against colon cancer

The present investigation aimed to develop magnetoliposome nanoparticles loaded with 5-fluorouracil by following a reproducible thin film hydration technique. The physicochemical characterization (including electron microscopy analysis, dynamic light scattering, infrared spectrometry, X-ray diffractometry, electrophoresis, and surface thermodynamics) suggested that superparamagnetic magnetite nuclei were successfully embedded into a multilamellar lipid vesicle. Magnetic responsiveness of these nanocomposites was quantitatively analyzed by determining the hysteresis cycle and qualitatively confirmed by microscopic visualizations. A high frequency alternating electromagnetic field was further used to define their heating properties. The absence of cytotoxicity in human colon fibroblast CCD-18 and in human colon carcinoma T-84 cell lines and excellent hemocompatibility of these core/shell particles were demonstrated. Additionally, 5-fluorouracil incorporation was investigated by two procedures: (i) entrapment into the nanoparticulate matrix and (ii) surface deposition onto already formed magnetoliposome particles. The former method reported greater drug loading values and a sustained release profile. Interestingly, 5-fluorouracil release was also triggered by the heating properties of the nanoparticles (hyperthermia-triggered drug release). Hence, we put forward that magnetoliposome particles hold important properties, that is, magnetically targeted delivery, hyperthermia inducing capability, high 5-fluorouracil loading capability, and hyperthermia-triggered burst drug release, suggestive of their potential for a combined antitumor therapy against colon cancer.

Synthesis of a Biodegradable Magnetic Nanomedicine Based on the Antitumor Molecule Tegafur

The introduction of magnetic nanocarriers in chemotherapy aims to enhance the anticancer activity of antitumor molecules whereas keeping their toxicity to a very minimum. Magnetite/poly(hexylcyanoacrylate) (core/shell) nanoplatforms were synthesized by an emulsion/polymerization procedure. An exhaustive physicochemical characterization (including infrared spectrometry, electrophoresis, and thermodynamic analysis) suggested that the magnetite nuclei were embedded into a polymeric nanomatrix. The very good magnetic responsiveness of such core/shell nanoparticles was defined by the hysteresis cycle. To improve the intravenous delivery of tegafur to cancer, we investigated its incorporation into the nanoplatform. Compared to surface adsorption, drug entrapment into the polymeric shell yielded higher tegafur loading values, and a much slower release profile. A high frequency alternating magnetic gradient was used to elucidate the heating characteristics of the nanoparticles: a stable maximum temperature of 46 °C was successfully achieved within 32 min. Thus, we put forward that such kind of multifunctional nanomedicine hold very important characteristics (i.e., high drug loading, little burst release, hyperthermia, and magnetically targeted tegafur delivery), suggestive of its potential for combined antitumor therapy against cancer.

Magnolol, a natural compound, induces apoptosis of SGC-7901 human gastric adenocarcinoma cells via the mitochondrial and PI3K/Akt signaling pathways

Gastric cancer is the fourth most commonly diagnosed cancer with the second highest mortality rate worldwide. Surgery, chemotherapy and radiation therapy are generally used for the treatment of stomach cancer but only limited clinical response is shown by these therapies and still no effectual therapy for advanced gastric adenocarcinoma patients is available. Therefore, there is a need to identify other therapeutic agents against this life-threatening disease. Plants are considered as one of the most important sources for the development of anticancer drugs. Magnolol, a natural compound possesses anticancer properties. However, effects of Magnolol on human gastric cancer remain unexplored. The effects of Magnolol on the viability of SGC-7901 cells were determined by the MTT assay. Apoptosis, mitochondrial membrane potential and cell cycle were evaluated by flow cytometry. Protein expression of Bcl-2, Bax, caspase-3 and PI3K/Akt was analysed by Western blotting. Magnolol induced morphological changes in SGC-7901 cells and its cytotoxic effects were linked with DNA damage, apoptosis and S-phase arrest in a dose-dependent manner. Magnolol triggered the mitochondrial-mediated apoptosis pathway as shown by an increased ratio of Bax/Bcl-2, dissipation of mitochondrial membrane potential (ΔΨm), and sequential activation of caspase-3 and inhibition of PI3K/Akt. Additionally, Magnolol induced autophagy in SGC-7901 cells at high concentration but was not involved in cell death. Magnolol-induced apoptosis of SGC-7901 cells involves mitochondria and PI3K/Akt-dependent pathways. These findings provide evidence that Magnolol is a promising natural compound for the treatment of gastric cancer and may represent a candidate for in vivo studies of monotherapies or combination antitumor therapies.

Multifunctional antitumor magnetite/chitosan-l-glutamic acid (core/shell) nanocomposites

The development of anticancer drug delivery systems based on biodegradable nanoparticles has been intended to maximize the localization of chemotherapy agents within tumor interstitium, along with negligible drug distribution into healthy tissues. Interestingly, passive and active drug targeting strategies to cancer have led to improved nanomedicines with great tumor specificity and efficient chemotherapy effect. One of the most promising areas in the formulation of such nanoplatforms is the engineering of magnetically responsive nanoparticles. In this way, we have followed a chemical modification method for the synthesis of magnetite/chitosan-l-glutamic acid (core/shell) nanostructures. These magnetic nanocomposites (average size ≈340 nm) exhibited multifunctional properties based on its capability to load the antitumor drug doxorubicin (along with an adequate sustained release) and its potential for hyperthermia applications. Compared to drug surface adsorption, doxorubicin entrapment into the nanocomposites matrix yielded a higher drug loading and a slower drug release profile. Heating characteristics of the magnetic nanocomposites were investigated in a high-frequency alternating magnetic gradient: a stable maximum temperature of 46 °C was successfully achieved within 40 min. To our knowledge, this is the first time that such kind of stimuli-sensitive nanoformulation with very important properties (i.e., magnetic targeting capabilities, hyperthermia, high drug loading, and little burst drug release) has been formulated for combined antitumor therapy against cancer.

Abstract 5144: Oligonucleotide-based inhibition of the pro-angiogenic activity of Hepatoma-derived growth factor related protein 3 in neuroblastoma

Abstract Hepatoma-derived growth factor related protein 3 (HDGFRP3) belongs to the HDGF polypeptide family. Expression of HDGF is a prognostic factor for NSCLC, pancreatic and gastrointestinal tumors, and silencing of HDGF suppressed cell proliferation, migration and invasion of squamous lung cancer cells. Here we investigated the expression of HDGFRP3 in various tumor cell lines by quantitative PCR and western blot analysis. HDGFRP3 is highly expressed and secreted from neuroblastoma (NB) cell lines. The presence of high levels of HDGFRP3 was confirmed in two animal models of human NB. Since HDGFRP3 shares a conserved Pro-Trp-Trp-Pro motif (PWWP) domain with its family members, we assessed whether it could promote proliferation, migration and angiogenesis in analogy to HDGF. Recombinant HDGFRP3 inhibited migration of endothelial cells in a modified Boyden chamber experiment, while cell survival was not affected. Nevertheless, the protein promoted angiogenesis in vitro, as assessed through vascular sprouting and tubulogenesis assays. Starting from the structural insight of the PWWP domain, an oligonucleotide-based inhibitor was designed and tested to block the pro-angiogenic effect of HDGFRP3. A single stranded DNA inhibited the pro-angiogenic properties of HDGFRP3 in vitro. After modifications to improve its serum stability, the cytotoxicity of the designed oligonucleotide-based molecule (BN210) was tested by an MTT cell viability assay on various NB cell lines. BN210 slightly reduced NB cells proliferation. To determine if BN210 could be used both as single anti-angiogenic agent and in combination with chemotherapy in vivo, orthotopic NB tumor-bearing mice were randomly divided in different groups of treatment: 1 mg/kg of vincristine (VCR), once a week for 4 weeks; 7-21 mg/kg of BN210, either i.p. (5 days/week) or i.v (every 2 days). Other mice were treated with a combination of VCR and BN210. NB-bearing mice treated with BN210 alone showed a partial increase in life span, compared to control mice. However, mice treated with the combination of VCR plus BN210 had statistically significant increased life span, compared to both the control and the single treatment groups, with long term survivors obtained with the combined schedule when BN210 was injected i.v. Thus, the oligonucleotide-based inhibition of the pro-angiogenic activity of HDGFRP3 can be considered as a novel strategy for combined anti-tumor therapy in NB. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 5144. doi:10.1158/1538-7445.AM2011-5144

Abstract 576: Hydrogen peroxide and iron released from nitroprusside cooperate to induce melanoma cell death: role of the p53 genotype

Abstract BACKGROUND. We recently reported that sodium nitroprusside or nitroferricyanide (III) (SNP), an iron nitrosyl complex clinically used as a powerful vasodilator, promotes melanoma cell apoptosis independently of the status of the p53 tumor suppressor gene. This occurred with intact SNP but was delayed when using its light-exhausted form (lex-SNP) devoid of nitric oxide (NO) (1). OBJECTIVES. Since extracellular NO and hydrogen peroxide (H2O2) are increased after SNP treatment (2), to define antitumor effects of H2O2 plus NO or iron, we used sub-toxic exogenous H2O2 singly or together with either: a) SNP; b) lex-SNP; c) potassium ferricyanide or d) ferric ammonium sulphate, against genetically-matched human C8161 melanoma harboring wild type (wt) or mutant p53, since the latter contributes to drug resistance. METHODS. Cell survival was assayed by crystal violet staining or by determining percentage of calcein AM retention and lack of propidium iodide uptake. DNA damage was assessed by laser scanning cytometry and PARP fragmentation was measured by immune blotting. RESULTS. While each treatment alone showed low efficacy, a synergistic cytotoxicity was demonstrated only between either intact or lex-SNP + H2O2. Shorter treatments of these combinations were preferentially cytotoxic against wt p53 melanoma compared to their mutant p53 matched counterparts, in crystal violet survival assays. However, longer treatments with [SNP + H2O2] induced apoptosis-associated PARP cleavage irrespective of cellular p53 genotype. All these changes were antagonized by anti-oxidant N-acetyl cysteine (NAC) or metal chelator o-phenanthroline, suggesting that metal-dependent redox changes are important in this anti-tumor activity. CONCLUSIONS. When using alternative iron sources like those provided by potassium ferricyanide, ferric ammonium sulphate or sodium nitroferricyanide (III) (SNP), we show for the first time that in vitro anti-tumor combination therapy with sub-toxic H2O2 is achieved only with iron made available by SNP, since H2O2 did not synergize with iron provided by potassium ferricyanide or ferric ammonium sulphate. Lex-SNP devoid of NO (1) also potentiated the effect of H2O2, implying that the cooperative effect of [SNP + H2O2] is independent of its NO-donating ability. REFERENCES (1) Gomez-Sarosi LA, Strasberg-Rieber M, Rieber M. ERK activation increases nitroprusside induced apoptosis in human melanoma cells irrespective of p53 status: role of superoxide dismutases. Cancer Biol Ther 2009; 8:1173-82. (2) Rabkin SW and Kong JY. Nitroprusside induces cardiomyocyte death: interaction with hydrogen peroxide. Am J Physiol Heart Circ Physiol 2000; 279:H3089-H3100. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 576.

Polyaminohydroxamic Acids and Polyaminobenzamides as Isoform Selective Histone Deacetylase Inhibitors

A series of polyaminohydroxamic acids (PAHAs) and polyaminobenzamides (PABAs) were synthesized and evaluated as isoform-selective histone deacetylase (HDAC) inhibitors. These analogues contain a polyamine chain to increase affinity for chromatin and facilitate cellular import. Seven PAHAs inhibited HDAC >50% (1 microM), and two PABAs inhibited HDAC >50% (5 microM). Compound 17 increased acetylated alpha-tubulin in HCT116 colon tumor cells 253-fold but only modestly increased p21 (waf1) and acetylated histones 3 and 4, suggesting that 17 selectively inhibits HDAC 6. PABA 22 alone minimally increased p21 (waf1) and acetylated histones 3 and 4 but caused dose-dependent increases in p21 (waf1) in combination with 0.1 microM 5-azadeoxycytidine. Finally, 22 appeared to be a substrate for the polyamine transport system. None of these compounds were cytotoxic at 100 microM. PAHAs and PABAs exhibit strikingly different cellular effects from SAHA and have the potential for use in combination antitumor therapies with reduced toxicity.

S179D prolactin sensitizes human prostate cancer cells such that physiological concentrations of 1, 25 dihydroxy vitamin D3 result in growth inhibition and cell death

S179D Prolactin (PRL) is a molecular mimic of naturally phosphorylated human PRL which has been shown to inhibit the growth of human prostate cancer cells both in vitro and when grown as tumors in nude mice. In the current study, we have investigated the potential interplay between S179D PRL and 1,25 dihydroxy vitamin D3 (1,25D) in the inhibition of prostate cancer cell growth by incubating cells under circumstances where each hormone alone has no effect. Incubation of DU145 or PC3 cells in 100 pM 1,25D or 10 nM S179D PRL for 3 days showed no effect of each alone on expression of the vitamin D receptor (VDR), or the cell cycle regulatory protein p21, or on cell number. Incubation in both together increased expression of the VDR and p21 two to threefold. This co-operative effect was reproduced when activation of the p21 promoter was analyzed using a p21-luciferase (p21-luc) construct. Elimination of the VDR response element from p21-luc eliminated response to the hormone combination, showing that the effect on p21 was through the VDR. Most importantly, S179D PRL sensitized the cells to 1,25D such that there was a concentration-related reduction in cell number versus controls between 40 and 160 pM. At least part of this effect was via the induction of cell death. These results suggest that combined anti-tumor therapy may be very efficacious and that the dose of 1,25D required may be below the range that results in hypercalcemia.

Possible Risk of Invasive Pulmonary Aspergillosis with Marijuana Use during Chemotherapy for Small Cell Lung Cancer

Bacterial and fungal contaminants have been identified in marijuana samples and thus are a potential risk factor in the immunocompromised patient using it as an antiemetic. We describe the development of an invasive pulmonary aspergillosis in a patient using illicitly obtained marijuana as an antiemetic during combination antitumor therapy for small cell lung cancer. Although this patient had multiple risk factors implicated in the development of invasive pulmonary aspergillosis, the infectious potential of inhaled marijuana must be recognized. Further study of this potential health risk in needed.

Synergistic Combination Therapy of 5-Fluorouracil, Vitamin A, and Cobalt-60 Radiation for Head and Neck Tumors—Antitumor Combination Therapy With Vitamin A

Using cultured transformed fibroblasts, an antitumor agent, 5-fluorouracil (5-FU), was found to be potentiated in its inhibitory action on RNA formation by vitamin A. 5-FU in combination with vitamin A enhanced more effectively the cellular sensitivity to irradiation than when 5-FU was used alone. So we have applied a triple combination of 5-FU, vitamin A, and cobalt-60 radiation (FAR therapy) to clinical treatment of head and neck tumors since 1972. The treatment of 192 patients with cancer of the larynx, 60 patients with hypopharyngeal and cervical esophageal cancer, and 23 patients with epipharyngeal cancer with FAR therapy during 6 years from 1972 to 1977 resulted in highly effective synergism, and the improved points of this therapy were considered.