Investigation on adaptations of broiler chickens to high dietary free amino acid levels in nitrogen utilisation and plasma amino acid concentrations.

1. A reduction in crude protein (CP) in feed for broiler chickens necessitates elevated free amino acid (AA) levels to meet the requirement of each AA. This study investigated adaptations following a change to diets with increasing free AA concentrations and possible reasons for the limitation caused by the inclusion of more free AA.2. Male Ross 308 broiler hatchlings received a starter diet (164 g CP/kg containing 80 g/kg soy protein isolate (SPI)) until d 7. From d 7-22, birds received a diet almost identical to the starter diet or two other diets, where 50% or 100% of digestible AA in SPI were substituted with a free AA mixture. Birds were allocated to metabolism units located in the same barn to determine performance (n = 7 units) and blood traits (n = 14 birds). Total excreta collection was performed on d 7-8, 8-9, 9-10, 11-12, 14-15 and 21-22. Blood samples were collected on d 7, 8, 9, 11, 14 and 21.3. Average daily weight gain (ADG) and average daily feed intake (ADFI) was unaffected at 50% AA substitution but decreased at 100% AA substitution on d 7-22 (p ≤ 0.001). The 100% substitution led to a decline in ADG and ADFI consistently on all days (p ≤ 0.037) except on d 11-12. A 50% AA substitution resulted in lower ADFI on d 7-8 and 14-15 (p ≤ 0.032). Nitrogen utilisation efficiency (NUE) was on a level of ~ 0.74 and was only affected by treatment up to d 11-12 (p ≤ 0.008). Concentrations of 10, 9, 8, 10 and 4 plasma free AA were affected on d 8, 9, 11, 14 and 21, respectively (p ≤ 0.037).4. Following a change to diets containing high levels of free AA, NUE and free AA concentrations in the circulation became more balanced within 3 to 7 d. The results suggested that peptide-bound and free AA did not cause different NUE, particularly 3 and 7 d after the diet change.

Amino acid digestibility and metabolizable energy of soybean meal of different origins in cecectomized laying hens.

This study investigated the variation in amino acid (AA) digestibility and MEn of 18 samples of solvent-extracted soybean meal (SBM; 6 European, 7 Brazilian, 2 Argentinian, 2 North American, 1 Indian) in cecectomized laying hens. The experimental diets contained either 300 g/kg of cornstarch or one of the SBM samples. Pelleted diets were fed to 10 hens in two 5 × 10 row-column designs so that 5 replicates were obtained from each diet during 5 periods. A regression approach and the difference method were used to determine AA digestibility and MEn, respectively. The variation in the digestibility of SBM differed among AA with ranges in digestibility of 6 to 12%-units for most AA. Among the first-limiting AA, the digestibility was 87 to 93%, 63 to 86%, 85 to 92%, 79 to 89%, and 84 to 95% for Met, Cys, Lys, Thr, and Val, respectively. The range of MEn for the SBM samples was 7.5 to 10.5 MJ/kg DM. Indicators of SBM quality (including trypsin inhibitor activity, KOH solubility, urease activity, and in vitro N solubility) and analyzed SBM constituents were significantly correlated (P ≤ 0.05) with AA digestibility or MEn only in a few cases. No differences were observed in AA digestibility and MEn between countries of origins, except low digestibility of some AA and MEn for the 2 Argentinian SBM samples. These results suggest that the precision of feed formulation benefits from considering the variations in AA digestibility and MEn. Often used indicators for SBM quality and analyzed constituents were not suitable to explain variations in AA digestibility and MEn, suggesting that AA digestibility and MEn are determined by other factors.

Research Note: Influence of monocalcium phosphate and phytase in the diet on phytate degradation in cecectomized laying hens.

This study investigated the effects of phytase and monocalcium phosphate supplementation on the dephosphorylation of phytic acid [myo-inositol 1,2,3,4,5,6-hexakis (dihydrogen phosphate); InsP6] in cecectomized laying hens using total excreta collection. Four corn-soybean meal-rapeseed meal-based diets were mixed with or without 6 g of monocalcium phosphate/kg, with or without supplementation of 1,500 FTU phytase/kg, and had the same calcium concentration at 39 g/kg of feed. Each diet was tested in 5 replicates using a row-column design with 10 cecectomized laying hens in 2 periods. The hens received 120 g/d of feed while being housed individually in metabolism units, and total excreta were collected for a period of 4 d. The monocalcium phosphate × phytase interaction was not significant for InsP6 degradation (P = 0.054). Phytase increased InsP6 disappearance from 13% to 83% (P < 0.001), whereas monocalcium phosphate had no effect. Concentrations of most of the lower inositol phosphate isomers in excreta were higher when monocalcium phosphate was added to the diets. The concentration of Ins(1,2,5,6)P4 in excreta was the highest among the studied partially dephosphorylated inositol phosphates with phytase supplementation and was higher than in diets without phytase supplementation (P < 0.001). Supplementation with phytase increased myo-inositol concentration in excreta (P = 0.002), whereas monocalcium phosphate had no effect. Phosphorus utilization ranged from 4% to 18% and was not significantly affected by the treatments. These results suggest that phytase supplementation markedly increased InsP6 degradation in laying hens. The cecectomized laying hen assay may be suitable for studying the effects of phytase supplementation on phytate dephosphorylation under dietary conditions when performance and phosphorus excretion are unlikely to be affected.

Meta-analysis-based estimates of efficiency of calcium utilisation by ruminants.

The most abundant mineral in the body of animals is Ca, which has crucial importance for the regulation of various processes. The maintenance of Ca balance has become more challenging, especially in lactating ruminants, owing to the increased milk yields and thus Ca requirement. To determine the Ca requirement, factors such as Ca secretion via milk or Ca deposition in body tissues and conception products are summed up to the net Ca requirement. Nevertheless, dietary Ca cannot be completely utilised by the animal to cover the net Ca requirement, therefore a value for the efficiency of Ca utilisation is applied, which is the maximum proportion of Ca from the feed that the animal can use for covering the net requirement. However, current estimates for the efficiency of Ca utilisation are inconsistent. Therefore, the objective of the present meta-analysis was to estimate the efficiency of Ca utilisation for ruminants, considering the Ca supply of the animal. A data set of 223 observations was compiled from 37 studies, including data on cattle and small ruminants. Standardised Ca digestibility was calculated from data on Ca intake and faecal Ca excretion, corrected for faecal endogenous losses. Furthermore, a data subset on only lactating ruminants was created. For this subset, Ca excretion via faeces and urine and standardised Ca digestibility were related to the Ca supply of the animal. An exponential function was fitted to standardised digestibility data in response to Ca concentration in the diet and Ca supply, revealing that standardised Ca digestibility decreased with increasing dietary Ca concentration and Ca supply. The median for standardised Ca digestibility was 40%, with a remarkable variation between 9% and 88%. In response to Ca supply, faecal Ca excretion increased in a strong linear manner (slope = 0.76, R2 = 0.96). Excretion of Ca via urine was very low even when Ca supply was very high. To conclude, Ca digestibility is a suitable indicator for the efficiency of Ca utilisation, since excessive Ca is almost completely excreted in faeces; however, Ca digestibility has to be determined at a Ca supply level below the requirement of the animal. To date, only very limited number of data have been reported for such supply conditions. Comparative studies using various Ca sources are suggested for future studies but should be conducted using a marginal Ca supply level.

Prececal amino acid digestibility and phytate degradation in broiler chickens when using different oilseed meals, phytase and protease supplements in the feed.

The purpose of this study was to investigate the effects of phytase and protease supplementation on prececal (pc) amino acid (AA) digestibility, phytate (InsP6) degradation, and MEn concentration in diets using 3 oilseed meals as main protein sources in broiler chicken feed. The broiler chicken diets, which lacked mineral phosphorus, contained either soybean meal (SBM), SBM and rapeseed meal (SBM/RSM), or SBM and sunflower meal (SBM/SFM) as main protein sources. Diets were not supplemented with enzymes or supplemented with 1,500 or 3,000 FTU phytase/kg, or with 1,600 mg protease/kg. For diets containing SBM as the main protein source, the effects of phytase supplementation with and without monocalcium phosphate were also investigated. Data were obtained during 2 subsequent runs from days 14 to 22 and from days 23 to 31. Each diet was tested using 8 replicates with 4 replicates per run. For pc AA digestibility, no significant interactions were observed between main protein sources, enzyme supplementation, or addition of monocalcium phosphate except for Cys. Supplementation of 1,500 FTU phytase/kg increased pc digestibility of all AA. No differences in pc AA digestibility were observed between 1,500 and 3,000 FTU phytase/kg supplementation treatments. Prececal disappearance of InsP6 and pc P digestibility were greater in the high phytase supplementation treatment. Protease supplementation increased pc digestibility of all AA except for Cys when SBM/RSM was the main protein source. Supplementation of protease and 3,000 FTU phytase/kg increased MEn concentrations. The effect of phytase on pc AA digestibility was fully expressed at a lower supplementation level than needed for a maximized pc InsP6 disappearance and MEn concentration.

The relevance of glycine and serine in poultry nutrition: a review.

1. Dietary glycine equivalents (Glyequi) for glycine and serine represent the first-limiting non-essential amino acid in poultry diets. Targeted adjustment of essential amino acids and Glyequi in diets can considerably decrease crude protein (CP) in poultry diets below the limit of CP reduction when only essential amino acids are adjusted. 2. The level to which CP can be reduced in diets adequate in Glyequi depends on the objective; which includes reducing dietary CP without affecting performance and increasing nitrogen utilisation efficiency. Dietary CP can be reduced to ~15-16% in diets for up to 21 d old broiler chicken without affecting growth performance compared to responses to diets with currently common CP concentrations by considering Glyequi in the diet formulation. Dietary CP can be further reduced to maximise nitrogen utilisation efficiency; however, this leads to reduced growth performance. 3. The dietary Glyequi requirement of poultry varies depending on other dietary constituents. In broiler chickens up to 21 days of age, the dietary Glyequi requirement is estimated to be between 11 and 20 g/kg. This estimate is influenced by the concentrations of Cys and the endogenous Glyequi precursors, threonine and choline. Urinary nitrogen excretion seems to be a major determinant of the response to dietary Glyequi, because it is needed for uric acid formation. 4. The variable requirement for dietary Glyequi means that its static recommendation in poultry diets would lead to high safety margins in Glyequi supply or the risk of Glyequi deficiency. Variable recommendations for dietary Glyequi concentrations would help to supply birds based on their specific requirements and could reduce nitrogen emissions originating from poultry farming.

Effects of protease and phytase supplements on small intestinal microbiota and amino acid digestibility in broiler chickens.

The objective of this study was to determine the effects of protease origin and dosage on the prececal (pc) amino acid (AA) digestibility and the influence on composition of the microbial community in the small intestine. In addition, the effects of phytase supplementation were investigated. A total of 8 dietary treatments were included. The basal diet contained mainly corn and soybean meal. Three protease products were added to the basal diet, each at the level recommended by the supplier and at an 8-fold level. Phytase was supplemented in another dietary treatment. Each dietary treatment was allocated to 8 replicates of 15 birds each. The experimental diets were offered from day 15 to 21 for ad libitum consumption. The effect of protease supplementation on the pc AA digestibility depended on the protease product type and the amount supplemented. The pc AA digestibility was significantly increased by 1 protease product when supplemented at high level and when phytase was supplemented. In all the other treatments, protease supplementation had no significant influence or it decreased pc AA digestibility, when compared with the treatment with no enzymes added. In general, Firmicutes was the most abundant phylum among the ileal microbiota across all the treatments. Significant effects on microbiota composition were observed at the genus level for some but not all protease treatments and phytase supplementation. The genera Streptococcus, Lactobacillus, and uncultured Clostridiaceae were responsible for these differences. Furthermore, microbial networks established for each diet showed either high or low number of intergeneric interactions, but without a consistent enzyme effect. We conclude that enzyme supplementation effects were evident in the terminal small intestine microbiota composition, and to a lesser extent, in pc AA digestibility. However, the changes in microbiota composition and pc AA digestibility could not be correlated, indicating absence of a causal relationship.

Variability of amino acid digestibility of lupin and pea grains in caecectomised laying hens.

1. The objective of this study was to investigate the variations in amino acid (AA) digestibility of lupin and pea grains in caecectomised laying hens. The relationship between AA digestibility and chemical constituents of the grains was determined. 2. Twelve variants of lupins and peas were each added to a basal diet at a concentration of 300 g/kg, at the expense of maize starch. The lupin and pea variants were separately investigated in two subsequent trials. Each trial consisted of two 7 × 7 Latin squares, each comprising the basal diet and six diets with lupins or peas. 3. Fourteen caecectomised laying hens (LSL-classic) were individually housed in metabolism cages and 120 g/d of experimental diets were provided for eight days. During the last four days, excreta were collected quantitatively and feed intake was recorded. A regression approach was used to determine the AA digestibility of the lupin and pea variants. 4. Amino acid digestibility of the lupins and peas was high, although significant differences in AA digestibility among the lupins and peas were detected. The digestibility of lysine was in the range of 0.87-0.91 and 0.87-0.93 for lupins and peas, respectively. The digestibility of methionine in lupins and peas varied between 0.80-0.88 and 0.72-0.90. Variations in AA digestibility in peas were more pronounced than in lupins. 5. Significant correlations between chemical constituents of lupins, such as alkaloids, and AA digestibility were detected in some cases, without a consistent pattern. In peas, tannin concentration and the insoluble protein fraction were negatively correlated with digestibility of some AAs, but only when one colour flower variant was considered. Trypsin inhibitor activity in peas was negatively correlated with AA digestibility, particularly for the white flower variants.

Effect of particle size distribution of maize and soybean meal on the precaecal amino acid digestibility in broiler chickens.

1. Herein, it was investigated whether different particle size distributions of feed ingredients achieved by grinding through a 2- or 3-mm grid would have an effect on precaecal (pc) amino acid (AA) digestibility. Maize and soybean meal were used as the test ingredients. 2. Maize and soybean meal was ground with grid sizes of 2 or 3 mm. Nine diets were prepared. The basal diet contained 500 g/kg of maize starch. The other experimental diets contained maize or soybean meal samples at concentrations of 250 and 500, and 150 and 300 g/kg, respectively, instead of maize starch. Each diet was tested using 6 replicate groups of 10 birds each. The regression approach was applied to calculate the pc AA digestibility of the test ingredients. 3. The reduction of the grid size from 3 to 2 mm reduced the average particle size of both maize and soybean meal, mainly by reducing the proportion of coarse particles. Reducing the grid size significantly (P < 0.050) increased the pc digestibility of all AA in the soybean meal. In maize, reducing the grid size decreased the pc digestibility of all AA numerically, but not significantly (P > 0.050). The mean numerical differences in pc AA digestibility between the grid sizes were 0.045 and 0.055 in maize and soybean meal, respectively. 4. Future studies investigating the pc AA digestibility should specify the particle size distribution and should investigate the test ingredients ground similarly for practical applications.

Prececal amino acid digestibility of soybean cake in fast- and slow-growing broiler chickens.

The objective of the present study was to determine whether there are differences in prececal amino acid digestibility between commonly used slow- and fast-growing broiler strains when the regression approach is applied. ISA J-275 and Ross 308 were selected as common representatives of slow- and fast-growing broiler strains, respectively. The experimental diets with soybean cake at levels of 0, 100, and 200 g/kg were offered for ad libitum consumption between 22 and 29 d post-hatch. Titanium dioxide was used as an indigestible marker. Each treatment was tested with six pens comprising 10 birds each. Digesta samples were collected on a pen basis from the distal two-thirds of the intestine section between Meckel's diverticulum and 2 cm anterior to the ileocecal-colonic junction. The prececal amino acid digestibility of soybean cake was calculated by linear regression simultaneously for both strains. There was no significant interaction between broiler strain and inclusion level of soybean cake with respect to the prececal CP and amino acid digestibility of complete diets; there was a significant strain effect for 5 out of the 16 measured amino acids. The prececal CP and amino acid digestibility of soybean cake did not differ significantly between strains and was numerically almost identical. The results of the present study provide evidence of the transferability between broiler strains of prececal amino acid digestibility data, determined using the regression approach, thus improving the accuracy of diet formulation without drawbacks.

Results of an international phosphorus digestibility ring test with broiler chickens.

The objective of this ring test was to investigate the prececal phosphorus (P) digestibility of soybean meal (SBM) in broiler chickens using the trial protocol proposed by the World's Poultry Science Association. It was hypothesized that prececal P digestibility of SBM determined in the collaborating stations is similar. Three diets with different inclusion levels of SBM were mixed in a feed mill specialized in experimental diets and transported to 17 collaborating stations. Broiler chicks were raised on commercial starter diets according to station-specific management routine. Then they were fed the experimental diets for a minimum of 5 d before content of the posterior half of the ileum was collected. A minimum of 6 experimental replicates per diet was used in each station. All diets and digesta samples were analyzed in the same laboratory. Diet, station, and their interaction significantly affected (P < 0.05) the prececal digestibility values of P and calcium of the diets. The prececal P digestibility of SBM was determined by linear regression and varied among stations from 19 to 51%, with significant differences among stations. In a subset of 4 stations, the prececal disappearance of myo-inositol 1,2,3,4,5,6-hexakis (dihydrogen phosphate)-P; InsP6-P) also was studied. The prececal InsP6-P disappearance correlated well with the prececal P digestibility. We hypothesized that factors influencing InsP6 hydrolysis were main contributors to the variation in prececal P digestibility among stations. These factors were probably related to the feeding and housing conditions (floor pens or cages) of the birds in the pre-experimental phase. Therefore, we suggest that the World's Poultry Science Association protocol for the determination of digestible P be should extended to the standardization of the pre-experimental period. We also suggest that comparisons of P digestibility measurements among studies are made only with great caution until the protocol is more refined.

Variability in amino acid digestibility of triticale grain from diverse genotypes as studied in cecectomized laying hens.

Triticale, an anthropogenic hybrid grain, is increasing in importance as a feed grain for laying hens. However, our limited knowledge of its nutritional qualities and their impact on hen performance prevents optimization of its use. The present study investigated the digestibility of amino acids ( AA: ) in triticale grain in laying hens, and additionally examined relationships between AA digestibility and chemical and physical characteristics of the grain. Twenty genotypes of triticale were grown under standardized agronomic and environmental conditions and were characterized according to their physical properties (thousand-seed weight, test weight, falling number, extract viscoelasticity), chemical composition (proximate nutrients, non-starch polysaccharides, AA, minerals, inositol phosphates) and gross energy concentration. Additionally, the in vitro solubility of nitrogen was determined. The animal trial comprised 4 Latin Squares (6 × 6) distributed among 2 subsequent runs. Twelve cecectomized LSL-Classic hens were individually housed in metabolism cages and either fed a basal diet containing 500 g/kg cornstarch or one of 20 triticale diets, each replacing the cornstarch with one triticale genotype, for 8 d. During the last 4 d, feed intake was recorded and excreta were collected quantitatively. Amino acid digestibility of the triticale genotypes was calculated by linear regression. The digestibility of all AA differed significantly between the 20 genotypes, including Lys (digestibility range 68 to 80%), Met (77 to 86%), Thr (68 to 78%) and Trp (74 to 83%). However, AA digestibility only correlated with characteristics of the grain in few cases, without a consistent pattern among AA. Equations to predict AA digestibility based on the grain's physical and chemical characteristics were calculated by multiple linear regression. The explanatory power (adjusted R2;) of these prediction equations was below 0.7 for most AA and thus not sufficiently precise to be suitable for practical application. In conclusion, AA digestibility of triticale grain is high overall in laying hens but varies significantly between crop genotypes. This variation could not be well explained by physical and chemical characteristics of the grain.

Effect of glycine supplementation in low protein diets with amino acids from soy protein isolate or free amino acids on broiler growth and nitrogen utilisation.

Here, it was investigated whether substitution of amino acids (AA) from soy protein isolate with free AA in low crude protein diets influences the growth performance and N utilisation in broilers, and whether interactions with dietary glycine equivalent (Glyequi) concentration exist. Birds were distributed in two 2 × 2 factorial arrangements of 48 floor pens containing 10 birds each, plus 48 metabolism cages containing two birds each. Experimental feed was provided for ad libitum consumption from d 7 to 22. Diets contained either a soy protein isolate at 79 g/kg or a mix of free AA, which supplied the same amount of 18 proteinogenic AA. A mix of free glycine and l-serine was used to obtain low and high (12.0 and 20.5 g/kg dry matter) levels of dietary Glyequi. Substitution of soy protein isolate with free AA reduced the average daily gain and feed efficiency, mainly due to reduced feed intake. Efficiency of N accretion was not influenced by the AA source or Glyequi concentration on d 21, possibly due to the lower AA digestibility of soy protein isolate and higher urinary excretion of nitrogenous substances in the treatments with the AA mix. The average daily weight gain of the treatments with high Glyequi concentration was higher for both AA sources. This increase was due to higher average daily feed intake by broilers in the treatments with soy protein isolate and due to the increased feed efficiency in the treatments with the AA mix. Broilers exhibited different growth responses to dietary Glyequi between the AA sources; however, these responses could not be attributed to the different utilisation of Glyequi for uric acid synthesis.

Meta-analysis of the influence of dietary glycine and serine, with consideration of methionine and cysteine, on growth and feed conversion of broilers.

The existing literature is inconsistent with respect to optimal dietary concentrations of glycine (Gly) and serine (Ser) in broiler feed. Therefore, we conducted a meta-analysis to investigate the response of broilers to dietary levels of Gly using a full quadratic model based on mixed model methodology. Response was measured as ADG (g/d), ADFI (g/d), and G:F (g/g). In addition, the influence of other dietary constituents was evaluated. This meta-analysis was based on a data set comprising a total of 9,626 broilers in 10 peer-reviewed papers that investigated the response of broilers to different dietary concentrations of Gly, achieved by addition of free Gly. The fitted quadratic model, with either Gly+Ser or the calculated glycine equivalent (Glyequi) of both amino acids as the independent variable, revealed that all model terms were significant (P ≤ 0.05), and hence proved a curvilinear relationship between these independent variables and response traits. The R(2) value and root MS error confirmed a strong relationship between observed and predicted traits. A comparison of the influence of Gly+Ser and Glyequi on response traits revealed that both approaches produced similar results. Because Glyequi should meet the physiological values of a diet better than Gly+Ser, models with 2 independent variables were conducted using Glyequi. The second independent variables were methionine (Met):TSAA ratio and the concentrations of cysteine (Cys) and CP. In models with one or 2 independent variables, the impact of dietary Gly on ADFI was low. By contrast, G:F was markedly influenced by dietary Gly; this effect intensified at lower Met:TSAA ratios and higher Cys and CP levels. ADG was also a function of Glyequi and the second independent variables. For ADG, an optimal Met:TSAA ratio of 0.655 and Cys concentration of 0.302% was calculated. Following the nonlinear nature of relationship, generally applicable replacement values could not be calculated. However, it was concluded that consideration of dietary Cys can diminish the requirement for Glyequi, and therefore, enable a reduction in the CP of broiler diets without limiting growth performance.

A quantitative study of the interactive effects of glycine and serine with threonine and choline on growth performance in broilers.

Differences in the optimal dietary concentrations of Gly (glycine) and Ser (serine) in broiler diets may be due to levels of endogenous Gly precursors that differ in literature. Therefore, we measured the extent of the interactive effects between equivalents of Gly and Ser (Glyequi) and the endogenous Gly precursors choline and Thr (threonine) on growth performance. A fractional central composite design included concentrations of 15-25 g/kg DM, 0.6-2.0 g/kg DM, and 6.4-10.4 g/kg DM for Glyequi, choline, and Thr, respectively, in 5 levels each. The various concentrations were achieved by adding Gly, choline chloride, and l-Thr to a basal mix. Except for 20 replicates of the central diet, all treatments were tested with 5 replicates, each with 10 birds. Food was provided for ad libitum consumption throughout the experiment. The data were evaluated using artificial neural networks. Digestibility was studied for selected diets using separate birds. Since average daily feed intake (ADFI) varied between replicates, the intake of prececal digestible Glyequi, choline, and prececal digestible Thr were more adequate independent variables than the dietary concentration of each amino acid. From d 1 to d 7, no treatment effects on G:F and average daily gain (ADG) were detected; subsequent results refer to the period from d 7 to d 21. Increasing prececal digestible Thr intake considerably decreased the need for prececal digestible Glyequi to achieve certain levels of G:F and ADG. The extent of this effect cannot be explained only by the endogenous metabolism of Thr to Gly. Since essential amino acids were present above the recommended levels, Thr probably limited performance, and excessive intake of other essential amino acids prompted a Gly-dissipating process. Choline exerted a considerable effect on the required intake of prececal digestible Glyequi and prececal digestible Thr to achieve certain levels of G:F and ADG. The results of this study partly explain the previously reported variations in response to dietary Thr, Gly, and Ser.

Activity of thalidomide in patients with platinum-refractory germ-cell tumours.

The aim of this study was assess the activity of thalidomide in patients with progressive relapsed or platinum-refractory germ-cell tumours (GCT). Between April 2002 and January 2003, 15 patients with inoperable progressive GCT were treated with escalated daily doses of 200-600 mg thalidomide. All patients had failed first-line and salvage chemotherapy with a median of 6 (range 4-12) cisplatin-based treatment cycles, 13/15 (87%) patients had received high-dose chemotherapy (HDCT) and 8/15 (53%) patients were considered platinum-refractory or absolute refractory; 8/15 (53%) patients had previously received other palliative chemotherapy regimens. No patient achieved a complete remission (CR) or partial remission (PR). However, 5/15 (33%) patients achieved serological PR and 1 additional patient had stable disease for 3 months. The median duration of remissions was 3 months (range 2-12 months) including 2 patients with a progression-free survival of 9 and 12 months. Responses occurred mainly in patients with a low tumour burden, slow disease progression and alpha-foetoprotein (AFP) elevations. Responses to thalidomide were independent from platinum-sensitivity. Toxicity was mild, with lethargy and constipation in the majority of patients. Skin rash grade II developed in 2 patients and peripheral neurotoxicity grade II/III developed in 4 patients. One responding patient died suddenly from an unknown cause. It is concluded that thalidomide shows single-agent activity in patients with heavily pre-treated GCT, AFP elevations and slowly progressive disease.

A randomised trial of high-dose chemotherapy in the salvage treatment of patients failing first-line platinum chemotherapy for advanced germ cell tumours.

BACKGROUND: Incomplete remission or relapse from first-line chemotherapy has poor prognosis in male germ cell tumour patients. This phase III randomised trial compares conventional salvage to high-dose-intensification chemotherapy. PATIENTS AND METHODS: Between February 1994 and September 2001, 280 patients from 43 institutions in 11 countries, were randomly assigned to receive either four cycles of cisplatin, ifosfamide and etoposide (or vinblastine) (arm A), or three such cycles followed by high-dose carboplatin, etoposide and cyclophosphamide (CarboPEC) with haematopoietic stem cell support (arm B). RESULTS: Similar complete and partial response rates were observed in both treatment arms (56%; 95% CI 50% to 62%). There were 3% and 7% toxic deaths in arms A and B, respectively. No significant improvements with CarboPEC were observed in either 3-year event-free survival (35% versus 42%, P=0.16) or overall survival (53%; 95% CI 46% to 59%). Complete responders with CarboPEC had a significant improvement in disease-free survival (55% versus 75% at 3 years, P <0.04). CONCLUSIONS: The single cycle of high-dose salvage chemotherapy after three cycles of standard dose chemotherapy had no effect on treatment outcomes. These results suggest that data from uncontrolled studies should not be used to justify routine use of a toxic and expensive treatment without confirmation in a randomised trial.

Second-line high-dose chemotherapy in patients with mediastinal and retroperitoneal primary non-seminomatous germ cell tumors: the EBMT experience.

BACKGROUND: Results of second-line chemotherapy in patients with extragonadal non-seminomatous germ cell tumor (NSGCT) appear inferior to results in testicular NSGCT. Patients with retroperitoneal NSGCT achieve a comparable long-term survival rate of 30%, but the salvage rates of patients with mediastinal primary are less than 10%. We conducted a retrospective analysis on patients with mediastinal and retroperitoneal NSGCT treated with second-line high-dose chemotherapy (HDCT) registered with the European Group for Blood and Marrow Transplantation (EBMT). PATIENTS AND METHODS: Between 1987 and 1999, 59 registered patients with retroperitoneal (n=37) and mediastinal (n=22) primary NSGCT, median age 28 years (range 18-60), were treated with second-line HDCT. All had received cisplatin-containing chemotherapy as first-line treatment. RESULTS: Toxic death occurred in three cases (5%). With a median follow-up of 58 months (range 14-114), 18/59 patients (30%) continue to be disease-free. Of three patients who had a disease recurrence after HDCT, one patient achieved a disease-free status with further chemotherapy and surgery. In total, 19 patients (32%) are currently disease-free. Sixteen of 37 patients (43%) with retroperitoneal NSGCT, and three of 22 patients (14%) with mediastinal NSGCT are currently alive and disease-free. CONCLUSIONS: Second-line HDCT might represent a possible option for patients with retroperitoneal primary NSGCT. New salvage strategies are needed for patients with mediastinal NSGCT.

Residual tumor resection after high-dose chemotherapy in patients with relapsed or refractory germ cell cancer.

PURPOSE: To assess the role of residual tumor resection performed after high-dose chemotherapy (HDCT) in patients with relapsed or refractory germ cell tumors (GCT). PATIENTS AND METHODS: Between July 1987 and October 1999, postchemotherapy resections of residual tumors were performed in 57 patients who had been treated with HDCT for relapsed or refractory GCT and who had achieved a partial remission to this treatment. RESULTS: Complete resections of residual masses were achieved in 52 (91%) of 57 patients who were rendered disease free; in five (9%) of 57 patients, the resections were incomplete. Resection of a single site was performed in 39 (68%) of 57 patients, and the remaining 18 (32%) of 57 patients required interventions at two or more residual tumor sites. Necrosis was found in 22 (38%) of 57 patients, mature teratoma with or without necrosis was found in nine (16%) of 57 patients, and viable cancer with or without additional necrosis or mature teratoma was found in 26 (46%) of 57 patients. Viable cancer consisted either of residual germ cell or undifferentiated cancer in 22 (85%) of 26 patients, with additional non-GCT histologies in the remaining four patients. Patients with viable cancer had a significantly inferior outcome after surgery compared with patients with necrosis and/or mature teratoma even if all cancer was completely resected. Pulmonary lesions with a diameter of more than 2 cm were the only predictive variable for viable cancer in univariate analysis. CONCLUSION: Resections of all residual tumors should be attempted in patients with relapsed or refractory GCT and partial remissions after HDCT.

The role of high-dose chemotherapy in relapsed germ cell tumors.

Overall, patients with relapsed or progressive germ cell tumors after cisplatin-based chemotherapy have a low chance of cure. Using conventional-dose chemotherapy (CDCT) as salvage treatment, only 15-30% of the patients will become long-term survivors. It is well known that the majority of these patients will ultimately die of their disease. Therefore, improvement of the standard treatment is clearly desirable. In the last years, high-dose chemotherapy (HDCT) has been established as an effective salvage modality. A matched-pair analysis showed an advantage for HDCT compared with CDCT with an improvement in event-free and overall survival. Furthermore, due to increasing clinical experience in the management of side-effects, the use of peripheral blood progenitor cells and the availability of hematopoietic growth factors, HDCT has become relatively safe. Therefore, HDCT should be administered in patients with first relapse and unfavorable prognostic factors, and as second or subsequent salvage treatment followed by complete resections of tumor residuals. Patients with relapse or progressive disease after HDCT who do not qualify for desperation surgery could be salvaged with palliative chemotherapy combinations using gemcitabine, oxaliplatin and paclitaxel. This report reviews the current treatment strategies and recent developments with respect to HDCT given as salvage treatment and discusses the role of prognostic factors in the management of such situations.