The advantages of rare disease biobanking: A localised source of genetic knowledge to benefit the South African rare disease community and related stakeholders worldwide

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Polyunsaturated fatty acid status in treated isovaleric acidemia patients

BACKGROUND/OBJECTIVES

Nutritional deficiencies are frequently observed when treating patients with inborn errors of metabolism due to an unbalanced diet. Thus far, patients with isovaleric acidemia (IVA) who adhere to a restricted protein diet have not been investigated in this respect. We hypothesize that these patients may have a polyunsaturated fatty acid (PUFA) deficiency, leading to potential clinical complications.

SUBJECTS/METHODS

We examined the nutritional status by reporting on potential deficiencies in PUFAs in treated IVA patients. A general clinical chemistry work-up as well as gas chromatography flame ionization detector analysis was performed to determine PUFAs in the plasma of 10 IVA patients.

RESULTS

The general clinical chemistry tests did not indicate severe hematological abnormalities or nutritional insufficiencies. We identified a significant reduction in plasma PUFA levels, especially in omega-3 (all acids, P<0.001) and omega-6 (in particular 20:3n-6 P<0.0001 and 20:4n-6 P=0.0005) fatty acids. In addition, an elevation in omega-9 fatty acids, with the exception of 20:3n-9 and C22:1n-9, was not suggestive of complete essential fatty acid deficiency but rather indicative of isolated and/or combined omega-3 and omega-6 fatty acid depletion.

CONCLUSIONS

This study emphasizes the potential nutritional insufficiencies that may occur because of therapeutic intervention in IVA.

Addition of zoledronic acid to neoadjuvant chemotherapy does not enhance tumor response in patients with HER2-negative stage II/III breast cancer: the NEOZOTAC trial (BOOG 2010-01)

BACKGROUND

The role of zoledronic acid (ZA) when added to the neoadjuvant treatment of breast cancer (BC) in enhancing the clinical and pathological response of tumors is unclear. The effect of ZA on the antitumor effect of neoadjuvant chemotherapy has not prospectively been studied before.

PATIENTS AND METHODS

NEOZOTAC is a national, multicenter, randomized study comparing the efficacy of TAC (docetaxel, adriamycin and cyclophosphamide i.v.) followed by granulocyte colony-stimulating factor on day 2 with or without ZA 4 mg i.v. q 3 weeks inpatients withstage II/III, HER2-negative BC. We present data on the pathological complete response (pCR in breast and axilla), on clinical response using MRI, and toxicity. Post hoc subgroup analyses were undertaken to address the predictive value of menopausal status.

RESULTS

Addition of ZA to chemotherapy did not improve pCR rates (13.2% for TAC+ZA versus 13.3% for TAC). Postmenopausal women (N = 96) had a numerical benefit from ZA treatment (pCR 14.0% for TAC+ZA versus 8.7% for TAC, P = 0.42). Clinical objective response did not differ between treatment arms (72.9% versus 73.7%). There was no difference in grade III/IV toxicity between treatment arms.

CONCLUSIONS

Addition of ZA to neoadjuvant chemotherapy did not improve pathological or clinical response to chemotherapy. Further investigations are warranted in postmenopausal women with BC, since this subgroup might benefit from ZA treatment.

Abstract P3-06-05: HER2/HR positive early breast cancer patients have nowadays the highest disease-free survival: Results from the south-east of the Netherlands

Background

Adjuvant systemic therapy choices in early breast cancer largely depend on human epidermal growth factor receptor 2 (HER2) and hormone receptor (HR) status. Overexpression of HER2 has been shown to be associated with a worse outcome (Slamon et al, Science, 1987). With this cohort study, we aimed to assess the outcome of early breast cancer patients per subtype based on HER2 and HR status in daily practice treated in a time period of routine use of anti-HER2 treatment.

Patients and methods

Patients diagnosed with early breast cancer during the years 2005-2007 in five participating hospitals in the South-East part of the Netherlands were included. Patients with primary metastatic breast cancer were excluded. Information regarding disease characteristics and treatment was collected. Patients were categorized in 4 subtypes based on the HER2 and HR status of the primary tumor: HER2 positive (+)/HR positive (+), HER2 negative (-)/HR+, HER2+/HR-, and triple negative (TN) (i.e. HER2- and HR-). Disease-free survival (DFS) was estimated using the Kaplan-Meier method. Cox proportional hazards model was used to determine the prognostic impact of breast cancer subtype, adjusted for possible confounders.

Results

A total of 2579 patients were included with a median follow-up of 52.6 months.

Median 5-year DFS rate was highest for the HER2+/HR+ subtype (comprising of 13% of all patients) with 78%, compared to 68% for the HER2+/HR- subtype (5% of all patients), 75% for the HER2-/HR+ subtype (70% of all patients) and 64% for the TN subtype (12% of all patients).

In multivariate analysis, subtype was confirmed to be an independent prognostic factor. Compared to the HER2+/HR+ subtype, the HER2+/HR- subtype was associated with a worse DFS (HR 2.05, 95% CI 1.21-3.46, P = 0.008) and the HER2-/HR+ was associated with a similar DFS (HR 1.09, 95% CI 0.79-1.52, P = 0.6). Furthermore, classical clinicopathological parameters were all confirmed to be of independent prognostic relevance, as well as the use of adjuvant systemic therapy. At the meeting, we will show the results according to the type of adjuvant systemic treatment used.

Conclusion

In this cohort, we noted that 13% of patients had HER2+/HR+ early breast cancer. These had the highest 5-year disease-free survival of all subtypes, significantly better than the HER2+/HR- subgroup. This may indicate a differential prognostic impact of HER2 according to HR status, with HR+ having a positive prognostic impact, irrespective of the presence of HER2 overexpression.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P3-06-05.

Abstract P3-13-11: Unexpected large treatment and outcome variations in metastatic breast cancer: Results of a hormone receptor positive cohort study in the Netherlands

Introduction

Treatment of patients with metastatic breast cancer (MBC) generally has a palliative intent. The systemic treatment approach is based on hormone receptor (HR) and human epidermal growth factor receptor 2 (HER2) status. However, with a variety of available agents and major changes in adjuvant breast cancer treatment, treatment decisions in MBC are complex. The objective of this study was to present treatment patterns of HR positive metastatic breast cancer patients, categorized by HER2 status.

Patients and methods

All patients diagnosed with HR positive MBC between 2007 and 2009 (irrespective of date of primary diagnosis) in eight participating hospitals in the South-East part of the Netherlands were included and all medical charts were reviewed. Patient and tumor characteristics as well as treatments and outcomes were collected. Survival was estimated using the Kaplan-Meier method.

Results

A total of 611 patients had HR positive MBC; 529 of these (86.6%) had a negative HER2 status. Median survival after diagnosis of distant metastases was 22.1 months for the HR+/HER2-subtype and 32.9 months for the HR+/HER2+ subtype.

In the HR+/HER2- subgroup 7% of patients did not receive any palliative systemic treatment and in the HR+/HER2+ subgroup 8.5% of patients did not receive any palliative systemic treatment.

In the HR+/HER2- subgroup, first given palliative systemic treatment was chemotherapy in 22% and endocrine therapy in 71% of patients. Of the patients starting with chemotherapy, 15% had bone metastases only, 37% had visceral metastases and 39% had multiple metastatic sites compared to 49%, 20% and 25% respectively for those starting with endocrine treatment. Of the patients starting with chemotherapy, 38% had progressive disease during or after this line of treatment and 62% had either response or stable disease.

In the HR+/HER2+ subgroup, 59.8% of patients received chemotherapy as first palliative systemic treatment (in two thirds of these patients targeted therapy was added to the chemotherapy) and 31.7% received endocrine therapy with or without trastuzumab. Of the patients starting with chemotherapy (+/- targeted therapy) 20% had bone metastases only, 39% visceral metastases and 37% had multiple metastatic sites versus respectively 23%, 31% and 35% for the patients starting with endocrine therapy. Of the patients starting with chemotherapy (+/- targeted therapy), 17% had progressive disease during or after this line of treatment and 83% had either response or stable disease.

Conclusion

A considerable proportion of HR+ MBC patients received chemotherapy as first given treatment despite HR positive status and presence of bone metastases only or limited visceral metastases, which is more than expected based on current treatment guidelines. Daily-practice monitoring of MBC, as we have reported here, may improve future treatment decision-making.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P3-13-11.

Inhibition of N-acetylglutamate synthase by various monocarboxylic and dicarboxylic short-chain coenzyme A esters and the production of alternative glutamate esters

Hyperammonemia is a frequent finding in various organic acidemias. One possible mechanism involves the inhibition of the enzyme N-acetylglutamate synthase (NAGS), by short-chain acyl-CoAs which accumulate due to defective catabolism of amino acids and/or fatty acids in the cell. The aim of this study was to investigate the effect of various acyl-CoAs on the activity of NAGS in conjunction with the formation of glutamate esters. NAGS activity was measured in vitro using a sensitive enzyme assay with ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) product analysis. Propionyl-CoA and butyryl-CoA proved to be the most powerful inhibitors of N-acetylglutamate (NAG) formation. Branched-chain amino acid related CoAs (isovaleryl-CoA, 3-methylcrotonyl-CoA, isobutyryl-CoA) showed less pronounced inhibition of NAGS whereas the dicarboxylic short-chain acyl-CoAs (methylmalonyl-CoA, succinyl-CoA, glutaryl-CoA) had the least inhibitory effect. Subsequent work showed that the most powerful inhibitors also proved to be the best substrates in the formation of N-acylglutamates. Furthermore, we identified N-isovalerylglutamate, N-3-methylcrotonylglutamate and N-isobutyrylglutamate (the latter two in trace amounts), in the urines of patients with different organic acidemias. Collectively, these findings explain one of the contributing factors to secondary hyperammonemia, which lead to the reduced in vivo flux through the urea cycle in organic acidemias and result in the inadequate elimination of ammonia.

Clinical variability of isovaleric acidemia in a genetically homogeneous population

Isovaleric acidemia (IVA) is one of the most common organic acidemias found in South Africa. Since 1983, a significant number of IVA cases have been identified in approximately 20,000 Caucasian patients screened for metabolic defects. IVA is caused by an autosomal recessive deficiency of isovaleryl-CoA dehydrogenase (IVD) resulting in the accumulation of isovaleryl-CoA and its metabolites. In total, 10 IVA patients and three carriers were available for phenotypic and genotypic investigation in this study. All patients were found to be homozygous for a single c.367 G > A (p.G123R) mutation. The amino acid substitution of a glycine to arginine resulted in a markedly reduced steady-state level of the IVD protein, which explains the nearly complete lack of IVD enzyme activity as assessed in fibroblast homogenates. Despite the genetic homogeneity of this South African IVA group, the clinical presentation varied widely, ranging from severe mental handicap and multiple episodes of metabolic derangement to an asymptomatic state. The variation may be due to poor dietary intervention, delayed diagnosis or even epigenetic and polygenetic factors of unknown origin.

ALG6-CDG in South Africa: Genotype-Phenotype Description of Five Novel Patients

ALG6-CDG (formerly named CDG-Ic) (phenotype OMIM 603147, genotype OMIM 604566), is caused by defective endoplasmic reticulum α-1,3-glucosyltransferase (E.C 2.4.1.267) in the N-glycan assembly pathway (Grünewald et al. 2000). It is the second most frequent N-glycosylation disorder after PMM2-CDG; some 37 patients have been reported with 21 different ALG6 gene mutations (Haeuptle & Hennet 2009; Al-Owain 2010). We report on the clinical and biochemical findings of five novel Caucasian South African patients. The first patient had a severe neuro-gastrointestinal presentation. He was compound heterozygous for the known c.998C>T (p.A333V) mutation and the novel c.1338dupA (p.V447SfsX44) mutation. Four more patients, presenting with classical neurological involvement were identified and were compound heterozygous for the known c.257 + 5G>A splice mutation and the c.680G>A (p.G227E) missense mutation. The patients belong to a semi-isolated Caucasian community that may have originated from European pioneers who colonized South Africa in the seventeenth/eighteenth centuries.

P3-16-13: Cardiac Safety of Non-Pegylated Liposomal Doxorubicin and Docetaxel as 1st Line Treatment in Metastatic HER2 Negative Breast Cancer (Myotax Study)

Background: Doxorubicin (DOX) is an effective, but cardiotoxic agent in metastatic breast cancer (BC). Incidence of heart failure (HF) is 2–4% and increases considerably with cumulative doses over 450–550 mg/m2. In Myocet® DOX is encapsulated in liposomes. It is delivered predominantly to areas with increased capillary permeability such as tumors and reduces cardiac exposure. We conducted an open non-comparative study to assess cardiac safety of Myocet® combined with docetaxel.

Materials and methods: Females with locally advanced or metastatic HER2 negative BC. 6 cycles of Myocet® 60 mg/m2 and docetaxel 75 mg/m2 q3w as 1st line therapy. Left ventricular ejection fraction (LVEF) and disease status were assessed after cycle 2,4 and 6. Primary endpoint: signs and symptoms of HF (NYHA III-IV) or LVEF &lt;50% and decrease ≥5% (with symptoms) or ≥10% (without symptoms). Results: 68 patients (pats) were included. Mean (sd;range) age 56,3 y (10,2;32-79), mean disease duration 5,5 y (5,1 y;1 mo-19 y), 31 pats had anthracyclines (AN) in the past. 49 pats completed all 6 cycles. Mean LVEF (%) over time are presented in table 1.

Post-myocardial infarction rehabilitation

No abstract available.