Glomerular filtration rate estimation for carboplatin dosing in patients with gynaecological cancers

Background

Carboplatin remains integral for treatment of gynaecological malignancies and dosing is based on glomerular filtration rate (GFR). Measurement via radiotracer decay [nuclear medicine GFR (nmGFR)] is ideal. However, this may be unavailable. Therefore GFR is often estimated using formulae that have not been validated in patients with cancer and/or specifically for gynaecological malignancies, leading to debate over optimal estimation. Suboptimal GFR estimation may affect efficacy or toxicity.

Methods

We surveyed several UK National Health Service Trusts to assess carboplatin dosing practise. We then explored single-centre accuracy, bias and precision of various formulae for GFR estimation, relative to nmGFR, before validating our findings in an external cohort.

Results

Across 18 Trusts, there was considerable heterogeneity in GFR estimation, including the formulae used [Cockcroft–Gault (CG) versus Wright], weight adjustment and area under the curve (AUC; 5 versus 6). We analysed 274 and 192 patients in two centres. Overall, CamGFR v2 (a novel formula for GFR estimation developed at Cambridge University Hospitals NHS Foundation Trust) excelled, showing the highest accuracy and precision. This translated into accuracy of hypothetical carboplatin dosing; nmGFR-derived carboplatin dose fell within 20% of the Cam GFR v2-derived dose in 86.5% and 87% of patients across the cohorts. Among the CG formula and its derivatives, using adjusted body weight in those with body mass index ≥25 kg/m² [CG-adjusted body weight (CG-AdBW)] was optimal. The Wright and unadjusted CG estimators performed most poorly.

Conclusions

When compared with nmGFR assessment, accuracy, bias and precision varied widely between GFR estimators, with the newly developed Cam GFR v2 and CG-AdBW performing best. In general, weight (or body surface area)-adjusted formulae excelled, while the unadjusted CG and Wright formulae or the use of AUC6 (versus nmGFR AUC5) produced risk of significant overdose. Thus, individual centres should validate their GFR estimation methods. In the absence of validation, CG-AdBW or CamGFR v2 is likely to perform well while unadjusted CG/Wright formulae or AUC6 dosing should be avoided.

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Despite therapeutic advances, carboplatin is still used repeatedly for treatment of gynaecological cancers.

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Between centres, there is heterogenous use of GFR estimation methods for carboplatin dosing.

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The novel CamGFR v2 and CG-AdBW are the most accurate estimators.

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The Wright formula, unadjusted CG and the use of AUC6 with estimated GFR should all be avoided.

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If internal validation unavailable, centres should use CamGFR v2 or CG-AdBW for GFR estimation.

Safe administration of chemotherapy in mast cell activation syndrome

INTRODUCTION

Mast Cell Activation Syndrome (MCAS) is an immunogenic disorder typically presenting with episodic multi-organ symptoms, caused by the inappropriate and aberrant release of mast cell mediators. Symptoms may be severe, including anaphylaxis and often occur in response to specific triggers which include many drugs and potentially chemotherapeutic agents. The administration of adjuvant chemotherapy and radiotherapy in endometrial cancer significantly reduces the risk of reoccurrence in patients with high risk disease. Currently there is no evidence or case reports to guide the safe administration of chemotherapy in MCAS patients.

CASE REPORT

We present the case of a 59-year-old lady with stage 3 A grade 2 endometroid endometrial cancer who underwent successful surgical management. She then received 4 cycles of adjuvant chemotherapy in the form of carboplatin and paclitaxel. This case describes a staged approach to chemotherapy administration and the utilisation of a carboplatin desensitization regimen to reduce the risk of immediate and delayed hypersensitivity sequalae.Management & outcome: Utilising an enhanced pre-medication strategy and a staged approach to chemotherapy administration, she was able to complete adjuvant treatment without any serious complications. At the date of censoring (May 2020) she has not shown any evidence of disease re-occurrence.Discussion & conclusion: Administering chemotherapy to patients with any mast cell disorder remains challenging. We hope that this case may provide the framework for safer chemotherapy administration for any patients at high risk of serious hypersensitivity sequalae in endometrial cancer and beyond.

Response to sunitinib (Sutent) in chemotherapy refractory clear cell ovarian cancer

•Case describes a response to sunitinib in clear cell ovarian cancer.•Discussion of unique molecular characteristics of clear cell ovarian cancers•Practical points regarding dosing and toxicity when using sunitinib discussed.

Abstract P2-08-08: Circulating tumor cells count-based nomograms to predict survival of metastatic breast cancer patients: Results from the European pooled analysis

Background: The European Pooled Analysis of CTC (EPAC) in metastatic breast cancer, based on 1,944 individual data from patients with various tumor types and clinical settings (Bidard et al, Lancet Oncol 2014), has established CTC count (CellSearch) at baseline and during therapy as a level of evidence 1 independent prognostic biomarker and demonstrated its superiority over serum blood markers. As part of the study pre-planned objectives, we sought to establish nomograms allowing accurate individual survival predictions.

Methods: Using individual data from 17 centers, we built simplified multivariate prognostic models taking into account the independent prognostic clinico-pathological (CP) characteristics including CTC count, dichotomized using the 5CTC/7.5ml threshold, at baseline and at 3-5 weeks after the start of a new treatment regimen, and derived nomograms for progression-free survival (PFS) and overall survival (OS) prediction at baseline and after 3-5 weeks of treatment. We report here the internal validation of these nomograms. Discrimination of the models was assessed using the c-index estimated by a jackknife procedure and the calibration was visually assessed through 10-fold crossvalidated calibration plots at 1,2,3 years for OS and 1,2 years for PFS.

Results: Multivariate models at baseline for PFS and OS were fitted on 1501 and 568 individual patient data with CTC count at baseline and CTC count at baseline and after 3-5 weeks, respectively. Models include tumor subtype, the number of previous chemotherapy lines (0/1/≥2), PS, age (<=50/>50-65/>65 years), metastasis-free intervals (0/>0-3/>3 years), metastatic sites (liver and CNS) and CTC count at baseline and eventually at 3-5 weeks of treatment. The C-index increased from 0.722 to 0.755 (increase in C-index:0.033, 95% CI [0.019;0.045]) when adding baseline CTC to the CP only model for OS (n=1501). For those patients with CTC values at 3-5 weeks (n=568), there was an additional increase in the C-index when adding CTC at 3-5 weeks to a model with already CP and baseline CTC from 0.731 to 0.743 (increase in C-index 0.013, 95% CI [-0.004;0.025]). The model with CP and baseline CTC counts showed a good calibration for OS at 1,2,3 years and the model with CP, baseline CTC and CTC count at 3-5 weeks a moderately good calibration. Similar results were obtained for PFS.

Conclusion: From the largest database with individual CTC data, we were able to build PFS and OS survival nomograms, with satisfactory discrimination and calibration. Our planned next step is to validate the nomogram in an additional cohort.

Citation Format: Bidard F-C, Peeters D, Fehm T, Nole F, Gisbert-Criado R, Mavroudis D, Grisanti S, Generali D, Garcia-Saenz JA, Stebbing J, Caldas C, Gazzaniga P, Manso L, Zamarchi R, Fernandez de Lascoiti A, de Mattos-Arruda L, Ignatiadis M, van Laere SJ, Meier-Stiegen F, Sandri M-T, Vidal-Martinez J, Politaki E, Consoli F, Bottini A, Diaz-Rubio E, Krell J, Dawson S-J, Raimondi C, Rutten A, Janni W, Munzone E, Carañana V, Agelaki S, Almici C, Dirix L, Solomayer E, Zorzino L, Reis-Filho JS, Squifflet P, Pantel K, Beije N, Sleijfers S, Pierga J-Y, Michiels S. Circulating tumor cells count-based nomograms to predict survival of metastatic breast cancer patients: Results from the European pooled analysis. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P2-08-08.

Myocardial MiR-30 downregulation triggered by doxorubicin drives alterations in β-adrenergic signaling and enhances apoptosis

The use of anthracyclines such as doxorubicin (DOX) has improved outcome in cancer patients, yet associated risks of cardiomyopathy have limited their clinical application. DOX-associated cardiotoxicity is frequently irreversible and typically progresses to heart failure (HF) but our understanding of molecular mechanisms underlying this and essential for development of cardioprotective strategies remains largely obscure. As microRNAs (miRNAs) have been shown to play potent regulatory roles in both cardiovascular disease and cancer, we investigated miRNA changes in DOX-induced HF and the alteration of cellular processes downstream. Myocardial miRNA profiling was performed after DOX-induced injury, either via acute application to isolated cardiomyocytes or via chronic exposure in vivo, and compared with miRNA profiles from remodeled hearts following myocardial infarction. The miR-30 family was downregulated in all three models. We describe here that miR-30 act regulating the β-adrenergic pathway, where preferential β1- and β2-adrenoceptor (β1AR and β2AR) direct inhibition is combined with Giα-2 targeting for fine-tuning. Importantly, we show that miR-30 also target the pro-apoptotic gene BNIP3L/NIX. In aggregate, we demonstrate that high miR-30 levels are protective against DOX toxicity and correlate this in turn with lower reactive oxygen species generation. In addition, we identify GATA-6 as a mediator of DOX-associated reductions in miR-30 expression. In conclusion, we describe that DOX causes acute and sustained miR-30 downregulation in cardiomyocytes via GATA-6. miR-30 overexpression protects cardiac cells from DOX-induced apoptosis, and its maintenance represents a potential cardioprotective and anti-tumorigenic strategy for anthracyclines.

Abstract PD6-5: Pooled analysis of circulating tumor cells in metastatic breast cancer: Findings from 1944 individual patients data

Background: Clinical validity of CTCs (CellSearch®) in metastatic breast cancer (MBC) patients has previously been assessed in studies with limited statistical power. We aimed to pool all European studies to obtain high-level evidence on the prognostic value of CTCs, to investigate their effects across different clinico-pathological characteristics and therapies and to further validate the MD Anderson/Institut Curie/Fox Chase CTC-based prognostic nomogram established in first-line treated MBC patients (Giordano et al, Clin Cancer Res 2013).

Material and methods: Methods were predefined in a written protocol. In December 2012, we searched for eligible studies that accrued patients in 2003-2012. We contacted all European laboratories using CellSearch®. We used likelihood ratio tests (LR) in Cox regression models stratified by study to assess the independent prognostic value of CTC when added to a clinicopathological (CP) model for progression-free (PFS) and overall survival (OS). Landmark analyses were used to assess the prognostic effect of early changes in CTC. The CTC-based nomogram (http://cancernomograms.com/CTCOnline.html) score was retrieved for every patient; we calculated C-indices, drew calibration plots and Kaplan-Meier curves according to quintiles of the nomogram score.

Results: We collected individual data of 1944 MBC patients, from 20 different studies (some unpublished), from 17 centers in 7 European countries. We observed 1507 PFS events and 929 deaths. Baseline CTC count was significantly associated with several patient characteristics, such as performance status (PS, p<10-4), synchronous metastasis (p<10- 2) tumor subtype (p<10-4), liver & bone metastases (p<10-4), CEA & CA15-3 levels (p<10-4). The CP model for OS included PS, MBC subtypes, number of previous lines of treatment, patient's age, metastasis-free interval, metastatic sites (p<0.01 for all). In a multivariate analysis containing the CP model parameters and CTC count at baseline, elevated CTC count (≥5) was a significant independent predictor of OS (n = 1444, HR = 2.7, 95%CI [2.2-3.2], LR p<10-4). Baseline serum markers added either no or marginal effect to the CP plus baseline CTC model for OS. In contrast, early changes in CTC status at week 3-5 significantly added prognostic information for OS to the model with CP factors and baseline CTC+ (n = 569, HR = 1.8 [2.2-3.2], LR p<0.001). In the population of interest (MBC treated by first line chemotherapy, n = 402 patients, 176 deaths), the CTC-based nomogram exhibited a good C-index for OS (0.69), was well calibrated and showed clear separation of the survival curves. Additional results, including subgroup analyses by tumor subtype and treatments will be presented at the meeting.

Conclusions: This pooled analysis is the largest study ever reported on CTC in MBC, with a previously unreached statistical power. It provides a clear level-of-evidence 1 on the independent prognostic value of CTCs before and during treatment in MBC. Also, the CTC-based prognostic nomogram is independently validated.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr PD6-5.

'Being there' for women with metastatic breast cancer: a pan-European patient survey

BACKGROUND

Understanding their experiences of diagnosis is integral to improving the quality of care for women living with advanced/metastatic breast cancer.

METHODS

A survey, initiated in March 2011, was conducted in two stages. First, the views of 47 breast cancer-related patient groups in eight European countries were sought on standards of breast cancer care and unmet needs of patients. Findings were used to develop a patient-centric survey to capture personal experiences of advanced breast cancer to determine insights into the 'trade-off' between extending overall survival and side effects associated with its treatment. The second online survey was open to women with locally advanced or metastatic breast cancer, or their carers, and responders were recruited through local patient groups. Data were collected via anonymous local language questionnaires.

RESULTS

The online stage II survey received a total of 230 responses from 17 European countries: 94% of respondents had locally advanced or metastatic breast cancer and 6% were adult carers. Although the overall experience of care was generally good/excellent (77%), gaps were still perceived in terms of treatment choice and information provision. Treatment choice for patients was felt to be lacking by 32% of responders. In addition, 68% of those who responded would have liked more information about future medical treatments and research, with 57% wishing to receive this information from their oncologist. Two-thirds (66%) of women with advanced breast cancer, or their carers, believed life-extending treatment to be important so that they can spend more time with family and friends, and 67% said that the treatment was worthwhile, despite potential associated side effects.

CONCLUSION

These findings show a continuing need to provide women with advanced breast cancer with better information and emphasise the importance that these patients often place on prolonging survival.

The efficacy of tacrolimus and sirolimus in heavily pre-treated unresectable thymic malignancies

BACKGROUND

Thymomas and thymic carcinomas, although uncommon, constitute a significant proportion of anterior mediastinal tumours. Systemic chemotherapy is the mainstay of treatment for inoperable or recurrent disease, but immunosuppressive therapy may provide an alternative treatment strategy.

PATIENTS AND METHODS

We present a series of 18 patients diagnosed with unresectable thymic tumours, of which eight received immunosuppressive therapy following relapse after chemotherapy.

RESULTS

Eight individuals were treated with primary immunotherapy after a median of 3.5 lines of chemotherapy (range 2-6 lines), of which 3 had confirmed myasthenia gravis (MG). After 3 months, 2 patients achieved a radiological partial response and 4 had stable disease. The median time to progression measured 6.8 months (CI 1.4-19.3 months). Two of the 4 patients who progressed on tacrolimus and prednisolone received sirolimus. One of these patients has stable disease (SD) at 21 months, and the other has SD at 3 months.

CONCLUSIONS

Although previous case reports have related tacrolimus therapy with tumour shrinkage in patients with MG-associated invasive thymomas, these data are the first to demonstrate the efficacy of such immunosuppressive agents in a larger cohort of heavily pre-treated patients with thymic tumours. Our experience adds to the limited anecdotal evidence in the literature, and suggests that immunosuppressive agents represent a valuable additional treatment for thymic tumours.

Abstract C88: A novel multiplex RNA in situ hybridization (ISH)-based method for circulating tumor cell detection with demonstrated clinical utility for metastatic breast cancer

Purpose: Sensitive and specific detection of circulating tumor cells (CTCs) in a blood sample is required for realizing the full potential of CTCs as prognostic and predictive factors. Current approaches of CTC detection are largely ineffective, and are dependent on the presence of differential epithelial protein markers or upon crude morphological characteristics like cell size differences between CTCs and blood cells. These combined approaches do not detect all relevant CTCs due to their significant heterogeneity. The objectives of this study are to develop and characterize a novel RNA in situ hybridization (ISH)-based CTC detection system called CTCscope, and to demonstrate its potential clinical utility in metastatic breast cancer patients.

Experimental Design: Cultured cells of different cancer cell lines were spiked into whole blood, which was used as a model system for CTCscope development. A novel ultrasensitive fluorescent RNA-ISH method was used to detect mRNA transcripts of a multitude of tumor markers at single-cell resolution. To demonstrate feasibility of CTC detection in patient blood, duplicate blood samples were collected from 45 metastatic breast cancer patients with informed consent for CTC analysis by the newly developed CTCscope system and the CellSearch system. Association of CTCs with tumor marker CA15–3 and progression-free survival (PFS) was assessed.

Results: CTCscope detected mRNA transcripts of 8 epithelial tumor markers and 3 epithelial-mesenchymal-transition (EMT) markers, and resulted in increased sensitivity for CTC detection. CTCscope was used to detect CTCs without enrichment, and did not result in false positives from detection of apoptotic or dead cells. In patient blood samples, CTCs detected by CellSearch but not CTCscope were positively correlated with CA15–3 levels. CTCs detected by either CTCscope or CellSearch predicted PFS, but only CTCs detected by CTCscope remained significantly associated with PFS (hazard ratio 2.01, 95% CI 1.14–3.92, p=0.038) after adjusting for CA15–3 levels.

Conclusions: The CTCscope assay may offer unique advantages over existing CTC detection approaches. By enumerating and characterizing only viable CTCs, CTCscope may provide additional prognostic and predictive information.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr C88.

[Daily ailments among healthy, middle-aged adults--situation report and explanatory approaches]

BACKGROUND

Physical performance steadily declines with increasing age even among healthy adults.

METHODS

A sport scientific screening-battery was used to determine the relationship between physical performance--that is endurance, strength, coordination, flexibility--and typical daily ailments as measured by a questionnaire among 222 healthy, middle-aged women and men. Cardiopulmonary performance was estimated by a 2-km walking test.

RESULTS

Cardiopulmonary performance declined significantly as a result of increasing age and increasing body-mass index. 44% of men and 29% of women reached substandard values when compared to norm tables. Daily ailments such as "Problems while climbing stairs" or "Breathing difficulty" showed a strong correlation to the estimated cardiopulmonary performance. In contrast, they were less influenced by strength or flexibility. The subjects were oblivious of the relationship between the decreased performance of the cardiovascular system and daily ailments.

CONCLUSION

Performing a simple screening-battery may be a good chance to promote the participation of middle-aged and non-athletic people in an adequate and health oriented sports program.

Re-evaluating the efficacy of axillary ultrasound in the detection of nodal metastasis and its impact on clinical practice

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Background: Recent reports have indicated a lack of overall survival benefit for axillary node dissection versus sentinel lymph node biopsy in early breast cancer. To study this further, we wished to assess the accuracy and effectiveness of ultrasound guided fine needle aspiration (FNA) cytology in detecting lymph node involvement in breast cancer patients, in order to refine and evaluate our current clinical pathways as newly diagnosed invasive breast cancer patients routinely undergo pre-surgical axillary ultrasound.

Methods: An FNA was taken from nodes of consecutive patients, which appeared abnormal on ultrasonography based on size, morphology, fatty hilum and cortical thickness measurements. Ultrasound and FNA cytological findings were correlated with histology following axillary node dissection. Of 260 cases, 123 (47.3%) had metastatic nodal involvement. Of these cases, only 66 (53.7%) were reported as positive on US findings.

Results: The overall positive predictive value (PPV) of ultrasound for detecting metastatic nodal involvement measured 0.82, and the negative predictive value (NPV) was 0.60. The sensitivity was 0.54, specificity measured 0.85 and the accuracy was 0.68. The ultrasound morphological nodal features with the greatest correlation with malignancy were absence of a fatty hilum (p=0.003) and an increased cortical thickness (p=0.03). Cases with a metastatic nodal burden density of a least 20% were also more likely to be detected as abnormal on axillary ultrasound. (p=0.009).

Conclusions: Axillary ultrasound has a low NPV and negative sonographic results do not exclude node metastases with sufficient sensitivity in most cases, to justify its routine clinical use.

[Table: see text]

The cost of a QALY

BACKGROUND

Current regulation of drug approvals has caused considerable controversy as entrusted to the National Institute of Clinical Excellence, and has led to a lack of availability of modern medicines on the basis of calculations made of 'value'.

AIM

We have examined the assessment tool used by National Institute of Clinical Excellence (NICE) to establish the cost of drugs in order to assess whether it is a reasonable and objective evaluation methodology.

DESIGN

A review of the methods of analysis.

METHODS

An objective assessment of the value of the Quality Adjusted Life Year (QALY).

RESULTS

We conclude that current methods used by NICE to assess drug costs are arbitrary, subjective and fail to reflect the true costs for patients, which are grossly overestimated.

CONCLUSION

NICE needs to look again at the evaluation methods for calculating drug costs, and change their methodology from a subjective to an objective measure of true cost.

The role of steroid receptor coactivator-3 (SRC-3) in human malignant disease

BACKGROUND

The p160 steroid receptor coactivator (SRC) family is critical to the transcriptional activation function of nuclear hormone receptors. A key member of this family is SRC-3, initially found to be amplified and expressed in breast cancer it has subsequent been shown to be expressed in malignant disease arising from a wide range of other organs. An understanding of the potential role of SRC-3 in the pathogenesis and its possible prognostic role in a broad range of tumours will improve our general understanding of carcinogenesis as well as potentially leading to a new prognostic marker as well as new therapeutic targets.

METHODS

Relevant papers were identified by searching the PubMed and MEDLINE databases for article published until 28th February 2009. Only articles published in English were considered. The search terms included "SRC-3", "AIB1" in association with the following terms: "human", "cancer" and "malignant disease". The search focused on malignant disease arising outside of the mammary gland. Full articles were obtained and references were checked for additional material when appropriate.

RESULTS

SRC-3 is amplified and expressed in a wide spectrum of human malignant diseases and appears to be a potential prognostic marker in a number of different tumours.

CONCLUSION

SRC-3 appears to be implicated in the possible risk of developing prostate and ovarian cancer. Its presence appears to be a marker of aggressive disease. Further research is required to determine its predictive and prognostic utility given the relative paucity of studies for each specific malignant disease.

What is the evidence for rechallenging with anthracyclines or taxanes in metastatic breast cancer? A review of the data

1072

Background: Anthracyclines and taxanes are widely used in the adjuvant setting for high risk, early stage breast cancer. This raises the issue of what is the optimal therapy for those patients who relapse, and what the potential role, if any, there is for rechallenge with these agents. The current evidence base for rechallenging with anthracyclines/anthracediones and taxanes in metastatic breast cancer (MBC) is examined in this study. Methods: Medline/Pubmed database searches were performed upto October 2008 to identify studies in which patients (pts) were rechallenged with anthracyclines/anthracediones or taxanes in MBC. Results: The efficacy data, as well as the safety data relating to neurotoxicity and cardiotoxicity from these studies, are summarized in the Table. Twenty-seven studies were identified (20=anthracycline/anthracedione, 7= taxane) of which only two were prospective studies. Both were small (n= 74 & 51) and related to anthracycline rechallenging. Conclusions: Evidence exists to support rechallenging with anthracyclines and taxanes. However, there are few prospective data on reexposure to taxanes and no data comparing anthracyclines versus taxanes following adjuvant exposure to both agents, supporting the need for clinical trials in this area. Such trials should ideally incorporate a cross-over design at treatment failure, which would shed light on the optimal sequence in which these agents should be administered.

[Table: see text]

No significant financial relationships to disclose.

Using a side effect to therapeutic advantage: the darkening of red eyebrow tattoo pigment following Q-switched laser treatment

BACKGROUND

Q-switched lasers are commonly used to achieve tattoo removal, utilizing the principle of selective photothermolysis. However, certain tattoo pigments may darken following laser pulsing.

OBJECTIVE

To determine whether this side effect can be used to therapeutic advantage in a woman who previously had her eyebrows enhanced with a dark tattoo that spontaneously changed to a reddish hue over time.

METHOD

The woman's eyebrows were pulsed with the Q-switched Nd:YAG laser at both 532 nm and 1064 nm.

RESULTS

The test areas pulsed with the 1064 nm laser revealed partial clearing. However, 532 nm Q-switched Nd:YAG pulses produced darkening of tattoo pigment both at the test sites and in the subsequent treatment.

CONCLUSION

Q-switched lasers can produce darkening of red tattoo pigment. In some cases this side effect can be used to therapeutic advantage.

Comparison of an immunohistochemical and immunofluorescence procedure to detect antibody to pancreatic islet cells

Antibody to the islet cells of the pancreas is detected in the serum of many patients with recent onset, insulin-dependent diabetes. Islet cell antibodies have been detected using the procedure of indirect immunofluorescence. We have adopted an immunohistochemical procedure using glucose oxidase to the histochemical identification of islet cell antibody. This procedure was found to be more sensitive than the immunofluorescence procedure, and, in addition, it was much easier to determine when a positive reaction was present. Thus, the glucose-oxidase immunohistochemical procedure for detecting antibodies to islet cells is preferable in comparison with indirect immunofluorescence.