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Acute Toxicity Profile and Compliance to Accelerated Radiotherapy Plus Carbogen and Nicotinamide for Clinical Stage T2–4 Laryngeal Cancer: Results of a Phase III Randomized Trial. Int J Radiat Oncol Biol Phys 2012; 82:532-8. [DOI: 10.1016/j.ijrobp.2010.11.045] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2010] [Revised: 10/01/2010] [Accepted: 11/14/2010] [Indexed: 11/21/2022]
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Antinociceptive and anti-inflammatory activities of nicotinamide and its isomers in different experimental models. Pharmacol Biochem Behav 2011; 99:782-8. [DOI: 10.1016/j.pbb.2011.07.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2011] [Revised: 06/30/2011] [Accepted: 07/04/2011] [Indexed: 12/31/2022]
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Gottschalk A, Raabe A, Hommel M, Rempf C, Freitag M, Standl T. Influence of the Hemoglobin Solution HBOC-201 on Tissue Oxygenation in the Rat R1H-Tumor. ACTA ACUST UNITED AC 2009; 33:379-89. [PMID: 16317957 DOI: 10.1080/10731190500289750] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
BACKGROUND HBOC-201 is an ultra purified bovine hemoglobin solution. It has already been used in clinical phase II/III trials for emergency treatments. Animal experiments have shown that HBOC-201 is highly effective in tissue oxygenation. The study was performed in order to assess the potential of low dose HBOC-201 to improve tumor oxygenation. METHODS 30 rats with a subcutaneously growing rhabdomyosarcoma R1H tumor were randomly assigned either to be ventilated with carbogen (n = 10), or to receive an IV injection of 0.3 g/kg HBOC-201 (n = 10) or a combination of 0.3 g/kg HBOC-201 and carbogen breathing (n = 10). Under general anesthesia the effects of the respective treatment on the tissue oxygen tension (tpO2) of the tumor were determined using a flexible stationary probe at baseline (b) and 15 and 60 min after application of the respective medication. RESULTS HBOC-201 alone failed to improve tumor tpO2 (b: 1.3 +/- 1.2mmHg; 15min: 1.4 +/- 1 mmHg; 60min: 1 +/- 1 mmHg). In combination with carbogen the mean tpO2 of the tumor raised in comparison to baseline values (b: 3.1 +/- 4.6 mmHg; mmHg; 15min: 8.5 +/- 11*mmHg; 60min: 4.8 +/- 5mmHg; *p < 0.05 vs. b), but this effect was less pronounced than the increase in tpO2 by carbogen alone (b: 3.4 +/- 3.4mmHg; 15min: 9 +/- 10* mmHg; 60 min: 13 +/- 19* mmHg; *p < 0.05 vs. b). CONCLUSION The application of low dose hemoglobin solution HBOC-201 does not result in improvement of tissue oxygenation in the rat rhabdomyosarcoma R1H.
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Khandelwal A, Bahadduri PM, Chang C, Polli JE, Swaan PW, Ekins S. Computational models to assign biopharmaceutics drug disposition classification from molecular structure. Pharm Res 2007; 24:2249-62. [PMID: 17846869 DOI: 10.1007/s11095-007-9435-9] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2007] [Accepted: 08/08/2007] [Indexed: 01/16/2023]
Abstract
PURPOSE We applied in silico methods to automatically classify drugs according to the Biopharmaceutics Drug Disposition Classification System (BDDCS). MATERIALS AND METHODS Models were developed using machine learning methods including recursive partitioning (RP), random forest (RF) and support vector machine (SVM) algorithms with ChemDraw, clogP, polar surface area, VolSurf and MolConnZ descriptors. The dataset consisted of 165 training and 56 test set molecules. RESULTS RF model 3, RP model 1, and SVM model 1 can correctly predict 73.1, 63.6 and 78.6% test compounds in classes 1, 2 and 3, respectively. Both RP and SVM models can be used for class 4 prediction. The inclusion of consensus analysis resulted in improved test set predictions for class 2 and 4 drugs. CONCLUSIONS The models can be used to predict BDDCS class for new compounds from molecular structure using readily available molecular descriptors and software, representing an area where in silico approaches could aid the pharmaceutical industry in speeding drugs to the patient and reducing costs. This could have significant applications in drug discovery to identify molecules that may have future developability issues.
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Affiliation(s)
- Akash Khandelwal
- Department of Pharmaceutical Sciences, University of Maryland, 20 Penn Street, Baltimore, Maryland 21201, USA
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Pisarev MA, Dagrosa MA, Juvenal GJ. Boron neutron capture therapy in cancer: past, present and future. ACTA ACUST UNITED AC 2007; 51:852-6. [PMID: 17891250 DOI: 10.1590/s0004-27302007000500024] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2006] [Accepted: 12/11/2006] [Indexed: 11/22/2022]
Abstract
Undifferentiated thyroid cancer (UTC) is a very aggressive tumor with no effective treatment, since it lacks iodine uptake and does not respond to radio or chemotherapy. The prognosis of these patients is bad, due to the rapid growth of the tumor and the early development of metastasis. Boron neutron capture therapy (BNCT) is based on the selective uptake of certain boron non-radioactive compounds by a tumor, and the subsequent irradiation of the area with an appropriate neutron beam. 10B is then activated to 11B, which will immediately decay releasing alpha particles and 7Li, of high linear energy transfer (LET) and limited reach. Clinical trials are being performed in patients with glioblastoma multiforme and melanoma. We have explored its possible application to UTC. Our results demonstrated that a cell line of human UTC has a selective uptake of borophenylalanine (BPA) both in vitro and after transplantation to nude mice. Treatment of mice by BNCT led to a complete control of growth and cure of 100% of the animals. Moreover dogs with spontaneous UTC also have a selective uptake of BPA. At the present we are studying the biodistribution of BPA in patients with UTC before its application in humans.
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Affiliation(s)
- Mario A Pisarev
- Division of Nuclear Biochemistry, Department of Radiobiology, National Atomic Energy Commission, Buenos Aires, Argentina.
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Aalders MCG, Triesscheijn M, Ruevekamp M, de Bruin M, Baas P, Faber DJ, Stewart FA. Doppler optical coherence tomography to monitor the effect of photodynamic therapy on tissue morphology and perfusion. JOURNAL OF BIOMEDICAL OPTICS 2006; 11:044011. [PMID: 16965168 DOI: 10.1117/1.2337302] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
We investigated the feasibility of using optical coherence tomography (OCT) for noninvasive real-time visualization of the vascular effects of photodynamic therapy (PDT) in normal and tumor tissue in mice. Perfusion control measurements were initially performed after administrating vaso-active drugs or clamping of the subcutaneous tumors. Subsequent measurements were made on tumor-bearing mice before and after PDT using the photosensitizer meta-tetrahydroxyphenylchlorin (mTHPC). Tumors were illuminated using either a short drug light interval (D-L, 3 h), when mTHPC is primarily located in the tumor vasculature or a long D-L interval (48 h), when the drug is distributed throughout the whole tumor. OCT enabled visualization of the different layers of tumor, and overlying skin with a maximal penetration of < or =0.5-1 mm. PDT with a short D-L interval resulted in a significant decrease of perfusion in the tumor periphery, to 20% of pre-treatment values at 160 min, whereas perfusion in the skin initially increased by 10% (at 25 min) and subsequently decreased to 60% of pre-treatment values (at 200 min). PDT with a long D-L interval did not induce significant changes in perfusion. The concept of using noninvasive OCT measurements for monitoring early, treatment-related changes in morphology and perfusion may have applications in evaluating effects of anti-angiogenic or antivascular (cancer) therapy.
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Affiliation(s)
- Maurice C G Aalders
- University of Amsterdam, Academic Medical Center, Laser Center, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands.
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Rojas A, Stratford MRL, Bentzen SM, Denekamp J. Is sensitization with nicotinamide and carbogen dependent on nicotinamide concentration at the time of irradiation? Int J Radiat Biol 2004; 80:499-506. [PMID: 15360088 DOI: 10.1080/09553000410001724199] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
PURPOSE To determine whether tumour radiosensitization and the therapeutic benefit of administering carbogen with nicotinamide depend upon irradiating at the time of peak drug concentration. MATERIALS AND METHODS Local tumour control of CaNT tumours in CBA mice and acute skin reactions in albino WHT mice were assessed after treatment with 10 X-ray fractions in air, carbogen alone or combined with 0.1, 0.2 or 0.5 mg g(-1) nicotinamide, injected 15, 30 or 60 min before irradiation. Plasma and tumour drug pharmacokinetics were performed. RESULTS Nicotinamide was rapidly taken up into tumours; a six- and threefold higher concentration was obtained with 0.5 mg g(-1) compared with 0.1 and 0.2 mg g(-1), respectively. Tumour, but not skin, radiosensitization increased as the dose of nicotinamide increased (p = 0.03), but at each dose level there was no significant difference in radiosensitivity when irradiations were done at or after the time of peak concentration. An almost eightfold increase in plasma levels increased tumour enhancement ratios from 1.74 to 1.92 (p < 0.0001). In tumours all schedules gave significant enhancement relative to carbogen alone (p < or = 0.04). CONCLUSIONS Tumour and skin radiosensitivity was independent of time of nicotinamide administration. Higher drug concentrations were not mirrored by proportionally higher enhancement ratios. Lower plasma levels than previously suggested significantly enhanced tumour radiosensitivity relative to carbogen alone. The clinical implications of these findings are discussed.
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Affiliation(s)
- A Rojas
- Translational Research Unit of Oncology and Radiobiology, Department of Radiation Sciences, Umeå University, Umeå, Sweden.
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Horsman MR, Overgaard J. Preclinical studies on how to deal with patient intolerance to nicotinamide and carbogen. Radiother Oncol 2004; 70:301-9. [PMID: 15064017 DOI: 10.1016/j.radonc.2004.01.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2003] [Revised: 01/15/2004] [Accepted: 01/27/2004] [Indexed: 10/26/2022]
Abstract
BACKGROUND AND PURPOSE Accelerated radiation carbogen nicotinamide (ARCON) therapy is generally well tolerated, but some patients experience intolerance to nicotinamide and carbogen (95% O(2)+5% CO(2)). This study investigated the effect of reducing both the nicotinamide dose and carbogen CO(2) content on radiation response. MATERIALS AND METHODS A C3H mouse mammary carcinoma grown in the right rear foot of female CDF1 was used and treated when at 200 mm(3). Nicotinamide was intraperitoneally injected 20 min prior to irradiation. Carbogen (CO(2) content of either 2 or 5%, balance O(2)) breathing was started 5 min before, and continued during, additional treatments. Radiation was given locally to tissues of restrained non-anaesthetised mice either as a single or fractionated (10 fractions in 12 days) schedule. The endpoints were local tumour control at 90 days, development of moist desquamation 11-23 days after treatment of normal foot skin, or tumour oxygenation measured with the Eppendorf electrode. RESULTS The TCD50 values in this tumour following single or fractionated radiation treatment were 52 and 71Gy, respectively. Carbogen (5% CO(2) content) breathing with every radiation treatment in the fractionated schedule significantly (Chi-squared test; P<0.05) enhanced radiation response (ER 1.25). Significant enhancements were also seen with nicotinamide given either as 10x120 mg/kg (ER 1.25), 6x120 mg/kg (ER 1.11) or 10x90 mg/kg (ER 1.18), although the 6x120 schedule was significantly less effective than 10x120. Combining nicotinamide with carbogen resulted in ERs of 1.39-1.44, and these were independent of the nicotinamide treatments. There was also no significant difference in the enhancement of tumour radiation response or improved tumour oxygenation status if the CO(2) content of the gas breathing was varied from 0% (i.e. 100% O(2)) to 2 or 5% (balance O(2)), although a CO(2) content of 2% did give a smaller enhancement of radiation-induced normal skin damage than 5%. CONCLUSIONS Both the nicotinamide dose, but not the frequency, and carbogen CO(2) content may be reduced in patients experience intolerance without any significant loss of sensitisation.
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Affiliation(s)
- Michael R Horsman
- Department of Experimental Clinical Oncology, Aarhus University Hospital, Nørrebrogade 44, Bldg 5, DK-8000 Aarhus C, Denmark
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Abstract
Two mechanisms of radiotherapy resistance which are of major importance in various tumour types are tumour-cell repopulation and hypoxia. ARCON (accelerated radiotherapy with carbogen and nicotinamide) is a new therapeutic strategy that combines radiation treatment modifications, with the aim of counteracting these resistance mechanisms. To limit clonogenic repopulation during therapy, the overall duration of the radiotherapy is reduced, generally by delivering several fractions per day. This accelerated radiotherapy is combined with inhalation of hyperoxic gas to decrease diffusion-limited hypoxia, and nicotinamide, a vasoactive agent, to decrease perfusion-limited hypoxia. Preclinical studies have been done to test the enhancing effects of these three components of ARCON, individually and in combination, in several experimentally induced tumours and normal tissues. In a mouse mammary carcinoma, the tumour-control rate obtained with ARCON was the same as that with conventional treatment, but with a radiation dose almost 50% lower. Phase 1 and 2 clinical trials have shown the feasibility and tolerability of ARCON, and have produced promising results in terms of tumour control. In particular in cancers of the head and neck and bladder, the local tumour-control rates are higher than in other studies, and phase 3 trials for these tumour types are underway. In conjunction with these trials, hypoxia markers detectable by immunohistochemistry are being tested for their potential use in predictive assays to select patients for ARCON and other hypoxia-modifying therapies.
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Affiliation(s)
- Johannes H A M Kaanders
- Department of Radiation Ocology of the University Medical Centre Nijmegen, Nijmegen, Netherlands.
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Bussink J, Stratford MRL, van der Kogel AJ, Folkes LK, Kaanders JHAM. Pharmacology and toxicity of nicotinamide combined with domperidone during fractionated radiotherapy. Radiother Oncol 2002; 63:285-91. [PMID: 12142092 DOI: 10.1016/s0167-8140(02)00072-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
BACKGROUND AND PURPOSE Treatment of head and neck tumors by the ARCON regimen has yielded high local control rates. As a result of this treatment intensification there was some increase in mainly acute toxicity of radiotherapy, but nicotinamide by itself has specific side effects such as nausea and vomiting. Due to these side effects and with the initial dose of 80 mg/kg, 31% of the patients discontinued nicotinamide intake. The aim of the study was to investigate the effect of a dose reduction to 60 mg/kg, and the addition of domperidone on the side effects of nicotinamide and its pharmacokinetic profile. PATIENTS AND METHODS In 22 patients blood plasma nicotinamide levels were determined after intake of 60 mg/kg nicotinamide. A next group of 87 patients received 60 mg/kg nicotinamide in combination with domperidone. In ten of these patients blood plasma nicotinamide levels were also determined. A full pharmacokinetic profile was constructed over the first 24 h after intake of the first drug dose. Furthermore, daily plasma levels at 1 h after nicotinamide intake was determined in the first and last weeks of radiotherapy. All patients were treated according to the ARCON schedule. RESULTS AND DISCUSSION The mean maximum plasma nicotinamide concentration was 793 nmol/ml without domperidone and 776 nmol/ml with domperidone. The median time at which the maximum concentration occurred was not significantly different for 60 mg/kg nicotinamide without or with domperidone (0.46 versus 0.54 h). The side effects were drastically reduced if nicotinamide was accompanied by domperidone. The percentage of patients that stopped nicotinamide intake was reduced from 32% without domperidone to 14% with domperidone. No correlation was found between the plasma peak concentrations of nicotinamide and the severity of side effects. CONCLUSION The currently used dose of 60 mg/kg nicotinamide results in a 30% reduction in peak plasma concentrations compared with 80 mg/kg nicotinamide. If nicotinamide was given in combination with domperidone, 86% of the patients continued the nicotinamide medication until the end of the treatment period.
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Affiliation(s)
- Johan Bussink
- Department of Radiation Oncology, University Medical Center Nijmegen, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
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Bernier J, Denekamp J, Rojas A, Trovò M, Horiot JC, Hamers H, Antognoni P, Dahl O, Richaud P, Kaanders J, van Glabbeke M, Piérart M. ARCON: accelerated radiotherapy with carbogen and nicotinamide in non small cell lung cancer: a phase I/II study by the EORTC. Radiother Oncol 1999; 52:149-56. [PMID: 10577700 DOI: 10.1016/s0167-8140(99)00106-1] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
BACKGROUND Non small cell lung cancers (NSCLC) are rapidly proliferating tumours, which are characterized by the presence of extensive hypoxic components, especially in patients with advanced loco-regional disease. Previous studies suggest a deleterious impact of acute (perfusion-limited) hypoxia on the outcome of radiotherapy for these tumours. AIM This pilot study was aimed at determining the feasibility and tumour response rates that can be achieved with an ARCON regime in patients with locally advanced, staged IIIA or B, NSCLC tumours. METHODS The phase I/II study included three steps: accelerated fractionation (AF) combined with carbogen (ten analysable patients), AF together with the daily administration of nicotinamide (n = 11 ) and AF with both carbon and nicotinamide (n = 14). Radiotherapy was based on a large daily dose per fraction (2.75 Gy up to 55 Gy in 4 weeks). Nicotinamide was administered at a dose of 6 g per patient per treatment day and carbogen was inhaled for 5 min before and during radiotherapy. RESULTS The incidence of grade 3 + acute toxicity during the irradiation did not exceed 10%, neither in the lung parenchyma nor in the mediastinum. No significant difference was found in loco-regional, radio-induced toxicity among the three study steps. Although a similar fraction of patients showed grade 2 or 3 emesis in all the steps, of the 25 patients entered in the two Nicotinamide containing steps 10 (40%) developed grade 2 or greater reactions which significantly detracted from their quality of life. There was no significant difference in tumour clearance rate among the three steps. The percentage of objective responses at 2 months was 60, 54 and 57% in steps 1, 2 and 3, respectively. CONCLUSION The feasibility of this ARCON protocol, using 2.75 Gy doses per fraction over 4 weeks, is good as regards radiotherapy-related side effects but it appears necessary in future to reduce the dose of Nicotinamide to reduce the incidence of nausea and vomiting. There was no significant difference in time to progression among the three study steps.
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Affiliation(s)
- J Bernier
- Cantonal Departrlent of Radiation Oncology, San Giovanni Hospital, Bellinzona, Switzerland
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Bernier J, Stratford MR, Denekamp J, Dennis MF, Bieri S, Hagen F, Kocagöncü O, Bolla M, Rojas A. Pharmacokinetics of nicotinamide in cancer patients treated with accelerated radiotherapy: the experience of the Co-operative Group of Radiotherapy of the European Organization for Research and Treatment of Cancer. Radiother Oncol 1998; 48:123-33. [PMID: 9783883 DOI: 10.1016/s0167-8140(98)00048-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND The EORTC has initiated studies to combine nicotinamide with carbogen in accelerated fractionation schedules (ARCON), since for some tumour types, acute and chronic hypoxia as well as treatment protraction may prejudice the outcome of radiotherapy. The tolerable dose of nicotinamide and the optimal interval for administration need to be ascertained. AIM Full pharmacokinetic profiles of nicotinamide concentrations in plasma were analyzed repeatedly in 15 patients to determine the inter- and intra-patient variability in peak plasma concentrations and the optimum times for administering nicotinamide as a radiosensitizer. METHODS Nicotinamide (Nicobion) was administered in tablet form to patients with advanced head and neck and non-small cell lung carcinomas. A standard 6 g dose was given regardless of body weight after an overnight fast and at least 30 min before breakfast. In 15 patients, blood samples were taken prior to and 1, 2, 4, 6, 8, 12 and 24 h after administration of the drug. This full profile was determined on two to four occasions for the head and neck cancer patients and on two occasions for the lung cancer patients. For each profile, the maximum concentration of nicotinamide (Cmax), time to peak plasma concentration (Tmax), elimination half-lives (t1/2) and area under the curve (AUC) were determined. Compliance was recorded and nausea and vomiting were graded on a 0-3 scale. Complete profiles of the five major metabolites were also obtained. RESULTS In the 48 complete sets of blood samples, peak plasma concentrations ranged from 787 to 2312 nmol/ml with a median value of 1166 nmol/ml. The peak plasma concentration was achieved at 1 h in only 54% of the pharmacokinetic profiles, but at this time 92% of the profiles had already exceeded the target concentration of 700 nmol/ml, the level required in the mouse for tumour radiosensitization. The median t1/2 for all 15 cases was 9.3 h, with minimum and maximum values of 4.2 and 26.8 h. The highest concentrations of nicotinamide metabolites were found to be the N-oxide, 2-pyridone and 1-methylnicotinamide. The toxicity (nausea and vomiting) was scored and found not to be correlated with any of the pharmacokinetic parameters. CONCLUSIONS The plasma concentrations considered necessary to radiosensitize can easily be exceeded with a dose of 6 g taken as 12 x 500 mg in tablet form; 700 nmol/ml was achieved in all patients and apparently would have been achieved in most even with a considerable reduction in dose. An adequate time between administration and radiotherapy appeared to be 1 h with this drug formulation for 92% of the profiles.
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Affiliation(s)
- J Bernier
- Cantonal Department of Radiation Oncology, San Giovanni Hospital, Bellinzona, Switzerland
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Lartigau E, Lusinchi A, Weeger P, Wibault P, Luboinski B, Eschwege F, Guichard M. Variations in tumour oxygen tension (pO2) during accelerated radiotherapy of head and neck carcinoma. Eur J Cancer 1998; 34:856-61. [PMID: 9797698 DOI: 10.1016/s0959-8049(97)10172-1] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The study was performed to assess the effect of accelerated radiotherapy on oxygenation of primary tumours and metastatic nodes in patients with advanced head and neck tumours. In 14 patients with head and neck tumour, oxygen tension (pO2) was evaluated in normal tissues and tumours (primary tumour or metastatic neck node) before (0 Gy) and after 2 weeks (32 Gy) of accelerated radiotherapy (70 Gy in 3.5 weeks, with three daily fractions). Radiotherapy was combined with carbogen breathing in 5 patients. pO2 was measured using a polarographic technique. For pooled normal tissues, median pO2 was 38 mmHg before treatment and 46 mmHg after 2 weeks. For tumours, very low values (< 2 mmHg) represented 20% of the recorded values before treatment and 10% after 2 weeks. The relative increase in tumour oxygenation was more pronounced for primary tumours (median pO2 12 mmHg before treatment versus 26 mmHg after 2 weeks, P < 0.05) than for metastatic nodes (respectively, 20 and 27 mmHg P = 0.1). For the 5 patients who breathed carbogen during accelerated radiotherapy, the median pO2 was 44 mmHg at 2 weeks, compared with 13.5 mmHg before treatment (P = 0.05). Very low pO2 values, corresponding to tumour hypoxia, were found in the tumours (primary and metastatic neck nodes) prior to accelerated treatment. During the first 2 weeks of accelerated treatment, an increase in median pO2 was found in nine of the 14 tumours, together with a decrease in the frequency of very low values.
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Affiliation(s)
- E Lartigau
- Department of Radiotherapy, Institut Gustave Roussy, Villejuif, France
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Horsman MR, Siemann DW, Chaplin DJ, Overgaard J. Nicotinamide as a radiosensitizer in tumours and normal tissues: the importance of drug dose and timing. Radiother Oncol 1997; 45:167-74. [PMID: 9424008 DOI: 10.1016/s0167-8140(97)00127-8] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND AND PURPOSE Nicotinamide is a radiation sensitizer currently undergoing clinical testing. This was an experimental study to determine the importance of drug dose and time interval between drug administration and irradiation for radiosensitization. MATERIALS AND METHODS Nicotinamide (50-500 mg/kg) was injected intraperitoneally into CDFI or C3H mice and drug plasma pharmacokinetics were determined by HPLC. Radiosensitization was measured in tumours and normal tissues after local irradiation. The tumours were a C3H mammary carcinoma, the KHT sarcoma and the SCCVII carcinoma. Tumour response was assessed using either growth delay (C3H) or clonogenic survival (KHT/SCCVII). Normal tissue toxicities evaluated included early responding skin (development of moist desquamation of the foot) and late responding bladder (reservoir function estimated by cystometry) and lung (ventilation rate measured by plethysmography). RESULTS All nicotinamide peak plasma concentrations were seen within 30 min after injection. Irradiating tumours at peak times resulted in enhancement ratios (ERs) of 1.27 (C3H), 1.75 (KHT) and 1.45 (SCCVII) with high nicotinamide doses and 1.27 (C3H), 1.28 (KHT) and 1.36 (SCCVII) after giving clinically relevant doses (100-200 mg/kg). Lower ERs were observed when the time interval between drug injection and irradiation was increased beyond the peak time. Irradiating normal tissues at peak times after injecting 100-200 mg/kg nicotinamide gave ERs of 1.20 (skin), 0.90 (bladder) and 1.02 (lung). CONCLUSIONS Clinically achievable doses of nicotinamide will enhance tumour radiation damage while having minimal effects in normal tissues, but for the best tumour effect radiation should be given at the time of peak plasma drug concentrations.
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Affiliation(s)
- M R Horsman
- Department of Experimental Clinical Oncology, Danish Cancer Society, Aarhus University Hospital, Aarhus C
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Saunders MI, Hoskin PJ, Pigott K, Powell ME, Goodchild K, Dische S, Denekamp J, Stratford MR, Dennis MF, Rojas AM. Accelerated radiotherapy, carbogen and nicotinamide (ARCON) in locally advanced head and neck cancer: a feasibility study. Radiother Oncol 1997; 45:159-66. [PMID: 9424007 DOI: 10.1016/s0167-8140(97)00151-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND AND PURPOSE ARCON (Accelerated Radiotherapy, CarbOgen, Nicotinamide) achieves a large therapeutic gain in rodents. A phase I/II study was therefore undertaken to determine its feasibility in patients with locally advanced head and neck cancer. MATERIALS AND METHODS The accelerated regime CHART was used in 35 patients given carbogen and/or nicotinamide with 11 small volume fractions. Eight patients received carbogen, 12 received nicotinamide and 15 were treated with ARCON. Treatment compliance, side-effects and acute mucositis were monitored in all cases. RESULTS All patients underwent CHART as intended. In the 23 patients receiving carbogen, two failed to complete treatment. Compliance with nicotinamide was much lower. Out of 25 patients, only 52% received 10-11 doses of the 80 mg/kg/day of the drug. The most common side-effect was nausea and vomiting, which responded to standard anti-emetics in almost half of the patients. Historical comparisons with the CHART head and neck trials indicate that there was no increase in the severity of acute mucositis in any of these patients. Although the observation period is not sufficiently long to be definitive (median 20 months) there is no evidence of an increase in late normal tissue reactions. CONCLUSIONS ARCON using CHART as the radiotherapy protocol is feasible in patients with advanced head and neck cancer. However, we are concerned about the low compliance rate in our patients, which is far lower than that reported elsewhere. The implications are discussed together with identifying strategies for increasing compliance.
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Affiliation(s)
- M I Saunders
- Marie Curie Research Wing, Mount Vernon Hospital, Northwood, Middlesex, UK
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Kaanders JH, Stratford MR, Liefers J, Dennis MF, van der Kogel AJ, van Daal WA, Rojas A. Administration of nicotinamide during a five- to seven-week course of radiotherapy: pharmacokinetics, tolerance, and compliance. Radiother Oncol 1997; 43:67-73. [PMID: 9165139 DOI: 10.1016/s0167-8140(96)01896-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
BACKGROUND AND PURPOSE Nicotinamide was administered daily as a liquid formulation to head and neck cancer patients receiving a 5- to 7-week course of radiotherapy. The pharmacokinetics, compliance, and tolerance of this drug formulation were studied. MATERIALS AND METHODS Blood samples were drawn and nicotinamide levels determined in 40 head and neck cancer patients. On the first treatment day serial samples were obtained followed by daily samples at the time of irradiation during the first and last full weeks of the treatment. Side-effects of nicotinamide were monitored. RESULTS In all patients peak concentrations greater than 700 nmol/ml could be obtained 0.25-3 h (mean 0.83 +/- 0.73 h) after drug intake. During the first week of treatment plasma levels at the time of irradiation were adequate in 82% of the samples. This decreased to 59% in the last week of treatment which can be partly attributed to reduced compliance. The most important side-effect of nicotinamide was nausea with or without vomiting occurring in 65% of the patients. Severe side-effects were associated with high plasma concentrations over subsequent days. Tolerance improved after a 25% reduction of dose in six of seven patients but plasma levels at the time of irradiation fell below 700 nmol/ml in four out of six of these patients. CONCLUSIONS Peak plasma concentrations above the 700 nmol/ml level were obtained in all patients but these concentrations could not be reproduced during the entire course of the treatment in a significant portion of the subjects. Side-effects of nicotinamide are associated with plasma concentrations and tolerance can be improved by a moderate reduction of dose.
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Affiliation(s)
- J H Kaanders
- Institute of Radiotherapy, University of Nijmegen, The Netherlands
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17
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Abstract
BACKGROUND AND PURPOSE Solid tumours contain hypoxic cells which are resistant to radiotherapy. This study compares the efficacy of several strategies to counteract diffusion-limited hypoxia, or intermittent hypoxia in a fractionated regimen of 1 to 6 x 2 Gy. MATERIALS AND METHODS Nicotinamide (250 mg/kg), perflubron emulsion (Oxygent) (4 ml/kg), tirapazamine (SR4233) (0.10 mmol/kg) and carbogen breathing, administered alone or in combination, were investigated on two tumour cell lines: EMT6 (a rodent mammary carcinoma) and HRT18 (a human rectal adenocarcinoma) using a clonogenic assay. The radiosensitizing effect of the agents was assessed after 1 and 6 x 2 Gy for drugs used alone, and 1, 2, 4, 6 x 2 Gy for drugs used in combination. RESULTS At the end of the fractionated radiation regimen, the combination of nicotinamide + carbogen induced the greatest radiosensitization for EMT6 tumours, while greatest radiosensitization of HRT18 was obtained with nicotinamide + carbogen + tirapazamine. CONCLUSION The efficacy of the strategies for overcoming hypoxia using a fractionated regimen depends on the tumour cell line. These differences could be linked to differences in the initial percentages of acute and chronic hypoxic cells, and to changes in the two types of hypoxia during treatment.
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Affiliation(s)
- S Stern
- Laboratoire de Radiobiologie Cellulaire, Institut Gustave Roussy, Villejuif, France
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18
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Wood PJ, Sansom JM, Stratford IJ, Adams GE, Szabo C, Thiemermann C, Vane JR. Changes in energy metabolism and X-ray sensitivity in murine tumours by the nitric oxide donor SIN-1. THE BRITISH JOURNAL OF CANCER. SUPPLEMENT 1996; 27:S177-80. [PMID: 8763875 PMCID: PMC2149982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The effect of the nitric oxide (NO) donor SIN-1 on energy metabolism was examined in three murine transplantable tumours in vivo using 31P MRS. SIN-1 at 2 mg kg-1 i.v. reduced Pi/total by 40-50% in SCCVII/Ha and KHT tumours within 5 min of injection, returning to control levels by 20 min. However, this dose of SIN-1 did not consistently alter Pi/total in RIF-1 tumours. Reduction in Pi/total in SCCVII/Ha tumours 10 min after 5 mg kg-1 i.v. SIN-1 was similar to that for 2 mg kg-1. SIN-1 at 10 mg kg-1 had no effect on Pi/total at 10 min after injection, but increased this ratio 2-fold over control at 60 min, at which time no effect of the lower doses of SIN-1 were observed. SIN-1 effects on SCCVII/Ha tumour response to X-rays were also examined, using an in vivo/in vitro clonogenic assay 24 h after treatment. SIN-1 at 0.5-2 mg kg-1 i.v. given immediately before irradiation increased tumour cell killing 2-4-fold over that for 15 Gy X-rays alone, while higher SIN-1 doses were ineffective. The results indicate that NO donors can alter tumour energy metabolism and X-ray response in a manner consistent with increased oxygenation. However, these responses are dependent upon dose, timing and tumour type.
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Affiliation(s)
- P J Wood
- MRC Radiobiology Unit, Chilton, Didcot, Oxon, UK
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19
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Rojas A, Vojnovic B, Johns H, Joiner MC, Martindale C, Fowler JF, Denekamp J. Radiosensitisation in normal tissues with oxygen, carbogen or nicotinamide: therapeutic gain comparisons for fractionated x-ray schedules. Radiother Oncol 1996; 39:53-64. [PMID: 8735494 DOI: 10.1016/0167-8140(95)01678-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
METHODS Radiosensitisation with oxygen, carbogen or nicotinamide alone and oxygen or carbogen combined with nicotinamide was compared in early and late responding normal tissues in rodents. X-ray treatments were delivered as single doses or fractionated schedules of 2 fractions in 1 day, 2, 12 and 36 fractions in an overall time of 12 days and 10 fractions in 5 or 12 days. Acute skin reactions, survival of intestinal crypts, breathing rate, reduction in the packed red-cell volume and clearance of 51Cr-EDTA were used as assays of epidermal, gut, lung and renal damage. RESULTS Relative to air-breathing mice, carbogen or oxygen produced a small, and not always significant, increase in sensitivity (enhancement ratios < or = 1.15) in gut, lung and kidneys; however, in skin a dose enhancement of 1.2-1.3 was observed. The effect of nicotinamide in air, carbogen or oxygen was studied only in lung and gut. The drug produced variable but generally significant increases in radiosensitisation ( < or = 1.26) in all three gases. Relative to treatments in air, enhancement ratios for nicotinamide alone were usually slightly higher than those observed when either carbogen or oxygen were administered without the drug. With all three modifiers (i.e. oxygen, carbogen, nicotinamide alone or for the drug-gas combinations) there was no significant change in the enhancement ratios observed as the number of radiation dose fractions was varied. CONCLUSIONS Comparisons with fractionated X-ray studies done previously in rodent tumours indicate that a therapeutic benefit, relative to lung, gut and renal damage, would be observed with oxygen or carbogen alone but not with nicotinamide alone. The greatest gain would be achieved with the combination of carbogen and nicotinamide, with which a benefit was observed even relative to epidermal damage. These results indicate that some decrease in normal tissue tolerance could be observed when using these modifiers in clinical radiotherapy and, although small, the appropriate dose reductions should be considered; caution should be exercised especially when carbogen and nicotinamide are used in conjunction with the more radical accelerated schedules.
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Affiliation(s)
- A Rojas
- Gray Laboratory Cancer Research Trust, Mount Vernon Hospital, Northwood, Middlesex, UK
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20
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Rojas A, Hirst VK, Calvert AS, Johns H. Carbogen and nicotinamide as radiosensitizers in a murine mammary carcinoma using conventional and accelerated radiotherapy. Int J Radiat Oncol Biol Phys 1996; 34:357-65. [PMID: 8567336 DOI: 10.1016/0360-3016(95)02087-x] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
PURPOSE To compare the radiosensitivity of mouse tumors treated in air with conventional and accelerated radiotherapy with that of tumors treated in carbogen alone or carbogen combined with nicotinamide. METHODS AND MATERIALS CaNT mammary tumors were irradiated with either 30 x-ray fractions in 6 weeks or 40 fractions in 26 days in air, carbogen alone, or carbogen combined with 120 mg/kg of nicotinamide (NAM), the latter given intraperitonealy 30 min before each fraction. The response to treatment was assessed using local control, weight loss, and metastasis-free survival. RESULTS Both carbogen and carbogen plus nicotinamide significantly increased tumor radiosensitivity; enhancement ratios (ERs) in the 6-week regimen were similar to those seen in the accelerated schedule. The majority of the effect was achieved by carbogen alone but the addition of NAM further enhanced tumor radiosensitization (ERs of 1.5 and 1.4 for carbogen in the conventional and accelerated schedule, respectively, were significantly lower than ERs of 1.7 and 1.6 obtained with carbogen plus nicotinamide; p < or = 0.005). Treatment protraction significantly increased radioresistance, especially when tumors were treated under air. An extra 1.5 Gy per day was required in air to counterbalance proliferation; in carbogen alone and carbogen plus nicotinamide a dose loss of 0.9 and 0.6 Gy per day was observed, respectively. Compared with treatments in air alone delivered in 6 weeks, acceleration of treatment combined with carbogen and nicotinamide gave the greatest increase in tumor radiosensitization (ER = 1.9). No toxic side effects and no detrimental changes in body weight were encountered when the sensitizers were administered 30 times (one fraction per day) or 40 times (two fractions per day). In both regimens, the incidence of metastases in mice treated with carbogen or carbogen plus nicotinamide was similar to that seen in animals treated in air. There was, however, a nonsignificant trend of a higher proportion of mice with metastasis in the accelerated schedule compared with the 6-week schedule. CONCLUSIONS In both conventional and accelerated experimental radiotherapy, carbogen alone or combined with a small clinically relevant dose of NAM were well tolerated, achieved large and significant increases in radiosensitization, and did not affect the incidence of metastases. The sparing of damage, resulting from extending the overall treatment time, was less when the sensitizers were administered than when irradiations were performed in air. The study suggests that clinical radiotherapy regimens, which aim to reduce hypoxic and/or tumor clonogen proliferation, would benefit from the use of carbogen, especially if the gas is combined with nicotinamide and treatment acceleration.
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Affiliation(s)
- A Rojas
- Gray Laboratory, Mount Vernon Hospital, Northwood, Middlesex, UK
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21
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Stratford MR, Dennis MF, Hoskin PJ, Saunders MI, Hodgkiss RJ, Rojas A. Nicotinamide pharmacokinetics in normal volunteers and patients undergoing palliative radiotherapy. Acta Oncol 1996; 35:213-9. [PMID: 8639318 DOI: 10.3109/02841869609098504] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The influence of nicotinamide formulation on absorption characteristics and incidence of adverse side-effects has been studied in normal volunteers and in patients undergoing radiotherapy. Escalating single or repeated oral doses of nicotinamide were administered in tablet or liquid form under fasting or non-fasting conditions. Drug absorption was slowed both by the presence of food in the stomach and by the administration of nicotinamide in tablet form compared with when it was dissolved in orange juice. Peak concentrations were generally slightly higher following the liquid preparation, but the incidence of adverse side-effects (chiefly nausea) was increased. A single dose of 9 g (88-97 mg/kg) nicotinamide in tablet form was well tolerated in two fasting normal volunteers, and in patients, doses of up to 133 mg/kg as tablets were tolerated twice/week for three weeks. Daily administration of 80 mg/kg nicotinamide was tolerated when given as tablets, but not in a liquid formulation. Neither the peak concentration nor the area under the concentration/time curve (AUC) of nicotinamide, nor the main metabolites of nicotinamide appeared to correlate with the incidence of toxicity.
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Affiliation(s)
- M R Stratford
- Gray Laboratory Cancer Research Trust, Mount Vernon Hospital, Northwood, Middlesex, England
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22
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Abstract
Pharmacokinetic analyses were performed on blood samples of 12 patients undergoing treatment with nicotinamide, hyperthermia and radiation therapy for a variety of recurrent/metastatic cancers. Escalating oral doses of 3, 4, 5, 6 and 10 g of nicotinamide showed a linear relationship between maximum recorded plasma concentrations and the dose in grams (correlation coefficient, r = 0.91). Maximum plasma levels were observed by 30 min in most patients ingesting up to 6 g of nicotinamide. In marked contrast, five out of six patients ingesting 10 g of nicotinamide demonstrated increasing plasma levels at least up to 3 h post-ingestion. Doses up to 6 g were well tolerated and resulted in average maximum recorded plasma levels (mean +/- 1 SEM) of 156.4 +/- 33.6 micrograms/ml. Doses of 10 g were generally not well tolerated, but a high plasma level was maintained on average for at least 4 h. Plasma concentrations of the above order have been previously associated with maximal enhancement of radiation damage in mouse tumor models. This suggests that radiosensitization can be expected to occur in human tumors following oral administration of a safe and well tolerated dose of 6 g. However, at higher doses (i.e., 10 g), the pharmacokinetics, and perhaps radiosensitization, may differ markedly.
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Affiliation(s)
- J Dragovic
- Department of Radiation Oncology, Henry Ford Hospital, Detroit, MI 48202, USA
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23
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Hoskin PJ, Stratford MR, Saunders MI, Hall DW, Dennis MF, Rojas A. Administration of nicotinamide during chart: pharmacokinetics, dose escalation, and clinical toxicity. Int J Radiat Oncol Biol Phys 1995; 32:1111-9. [PMID: 7607932 DOI: 10.1016/0360-3016(95)00022-q] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
PURPOSE To determine nicotinamide pharmacokinetics in patients undergoing accelerated radiotherapy with the CHART regimen (continuous, hyperfractionated, accelerated radiotherapy) and given nicotinamide on a daily basis. The aim was to establish the pharmacokinetic profiles and their reproducibility during repeated administration, the maximum tolerated dose with fractionated radiotherapy, whether such a dose achieves sufficiently high plasma levels for radiosensitization, the optimal time interval between nicotinamide and irradiation, and toxic side effects. METHODS AND MATERIALS Nicotinamide plasma concentrations were determined using high performance liquid chromatography in 11 patients with advanced carcinomas of the head and neck and rectum being treated with CHART (36 fractions in 12 days). Kinetic profiles on the first day of radiotherapy and residual 24-h values were obtained in 10 patients; in four of these, full profiles were repeated two or three times during the course of treatment. In one other, a single sample per day was taken four times over the 12-day period. Doses of 80, 90, or 100 mg/kg/day were given 90 min prior to the second radiotherapy fraction on each day. RESULTS A dose of 80 mg/kg/day was well tolerated by all the patients. However, an increase of 10-25% in dose led to significant drug accumulation and major clinical toxicity, and none of the patients in the dose-escalation arm completed the planned regimen. Large interpatient variations in absolute peak concentrations were seen from 0.4 to 1.4 mumol/ml (mean 0.9 +/- 0.3; standard deviation (SD)). Of the five samples with the lowest peak levels, four were obtained from one patient. The time taken to peak concentration was also very variable from 0.8 to 4 h (mean 2.1 +/- 1.3 h; SD). In 70% of the samples, absolute plasma levels > or = 0.7 mumol/ml were reached within 1-2 h after administration and maintained for up to 6 h (mean 2.8 +/- 1.8 h; SD). There was a small but nonsignificant increase in the half-life of nicotinamide when the dose was increased from 80 to 90 or 100 mg/kg (7.1 h and 8.6 h, respectively). CONCLUSIONS In an accelerated regimen such as CHART, 80 mg/kg/day of oral nicotinamide is feasible and clinically tolerated, giving no or few side effects, and a 2-h interval between its oral administration and radiotherapy should achieve effective plasma levels in most patients.
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Affiliation(s)
- P J Hoskin
- CRC Tumour Biology and Radiation Therapy Group, Mount Vernon Hospital, Northwood, Middlesex, UK
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24
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Honess DJ, Bleehen NM. Perfusion changes in the RIF-1 tumour and normal tissues after carbogen and nicotinamide, individually and combined. Br J Cancer 1995; 71:1175-80. [PMID: 7779707 PMCID: PMC2033837 DOI: 10.1038/bjc.1995.229] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The strategy of combining carbogen breathing and nicotinamide to overcome chronic and acute hypoxia respectively is being evaluated clinically. The effects of both agents individually and in combination on relative perfusion of 400-700 mm3 RIF-1 tumours and normal tissues were measured by 86Rb extraction. Carbogen breathing alone for 6 min increased relative tumour perfusion by 50-70% compared with control at flow rates of 50 to 200 ml min-1, but the effect was lost at 300 ml min-1. All flow rates also produced similar increases in relative perfusion of lung, of between 36% and 58%, and smaller increases in skin, of between 20% and 34%. The minimum breathing time at 150 ml min-1 to produce a significant increase in relative tumour perfusion was 4.5 min, and the effect was maintained up to 9 min. Nicotinamide alone at 1000 mg kg-1 60 min before assay did not alter relative tumour perfusion. Comparing the combination of nicotinamide with 6 min carbogen breathing at 150 ml min-1 with carbogen breathing alone showed no difference in relative tumour perfusion; increases were of 36% and 42% respectively. Nicotinamide-induced alterations in microcirculation associated with reduction of acute hypoxia have therefore not been detected by 86Rb extraction. The perfusion-enhancing effect of carbogen in this tumour is probably an important component of its radiosensitising ability, in addition to its known ability to increase the oxygen-carrying capacity of the blood, and should be taken into consideration in clinical studies.
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25
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Horsman MR. Nicotinamide and other benzamide analogs as agents for overcoming hypoxic cell radiation resistance in tumours. A review. Acta Oncol 1995; 34:571-87. [PMID: 7546822 DOI: 10.3109/02841869509094031] [Citation(s) in RCA: 104] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Oxygen deficient hypoxic cells, which are resistant to sparsely ionising radiation, have now been identified in most animal and some human solid tumours and will influence the response of those tumours to radiation treatment. This hypoxia can be either chronic, arising from an oxygen diffusion limitation, or acute, resulting from transient stoppages in microregional blood flow. Although clinical attempts to overcome hypoxia have met with some success, the results have been far from satisfactory, and efforts are still being made to find better methods. Extensive experimental studies, especially in the last decade, have shown that nicotinamide and structurally related analogs can effectively sensitise murine tumours to both single and fractionated radiation treatments and that they do so in preference to the effects seen in mouse normal tissues. The earliest studies suggested that this enhancement of radiation damage was the result of an inhibition of the repair mechanisms, as was well documented in vitro. However, recent studies in mouse tumours have shown that the primary mode of action actually involves a reduction in tumour hypoxia. More specifically, these drugs prevent transient cessations in blood flow, thus inhibiting the development of acute hypoxia. This novel discovery led to the suggestion that the potential role of these agents as radiosensitizers would be when combined with treatments that overcame chronic hypoxia. The first attempt to demonstrate this combined nicotinamide with hyperthermia and found that the enhancement of radiation damage by both agents together was greater than that seen with each agent alone. Similar results were later seen for nicotinamide combined with a perfluorochemical emulsion, carbogen breathing, and pentoxifylline, and in all these studies the effects in tumours were always greater than those seen in appropriate normal tissues. Of all the analogs, it is nicotinamide itself which has been the most extensively studied as a radiosensitizer in vivo and the one that shows the greatest effect in animal tumours. It is also an agent that has been well established clinically for the treatment of a variety of disorders, with daily doses of up to 6 g being considered reasonably safe and associated with a low incidence of side effects. This human dose is equivalent to 100-200 mg/kg in mice and such doses will maximally sensitize murine tumours to radiation. These findings have now resulted in phase I/II clinical trials of nicotinamide, in combination with carbogen breathing, as a potential radiosensitizing treatment.
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Affiliation(s)
- M R Horsman
- Danish Cancer Society, Department of Experimental Clinical Oncology, Aarhus
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