CD25high Effector Regulatory T Cells Hamper Responses to PD-1 Blockade in Triple-Negative Breast Cancer

Regulatory T cells (Treg) impede effective antitumor immunity. However, the role of Tregs in the clinical outcomes of patients with triple-negative breast cancer (TNBC) remains controversial. Here, we found that an immunosuppressive TNBC microenvironment is marked by an imbalance between effector αβCD8+ T cells and Tregs harboring hallmarks of highly suppressive effector Tregs (eTreg). Intratumoral eTregs strongly expressed PD-1 and persisted in patients with TNBC resistant to PD-1 blockade. Importantly, CD25 was the most selective surface marker of eTregs in primary TNBC and metastases compared with other candidate targets for eTreg depletion currently being evaluated in trials for patients with advanced TNBC. In a syngeneic TNBC model, the use of Fc-optimized, IL2 sparing, anti-CD25 antibodies synergized with PD-1 blockade to promote systemic antitumor immunity and durable tumor growth control by increasing effector αβCD8+ T-cell/Treg ratios in tumors and in the periphery. Together, this study provides the rationale for the clinical translation of anti-CD25 therapy to improve PD-1 blockade responses in patients with TNBC.

SIGNIFICANCE

An imbalance between effector CD8+ T cells and CD25high effector Tregs marks immunosuppressive microenvironments in αPD-1-resistant TNBC and can be reversed through effector Treg depletion to increase αPD-1 efficacy.

Abstract 710: Preclinical development of ALD2510, a Next-Gen Fc-enhanced, TREG-selective and IL-2-sparing anti-CD25 antibody for the treatment of solid tumors

Within the tumor microenvironment (TME), TREGS have been associated with worse prognosis and/or resistance to checkpoint inhibitor (CPI) therapy in various cancer diseases, making these cells a promising target for the development of new immunotherapies. Here, we present recent preclinical development data about ALD2510, a next-gen low-fucose IL-2/TCONV-sparing anti-CD25 antibody designed for the selective depletion of CD25high TREGS and the boost of host anti-tumor immunity. Ultra-humanization of parental anti-CD25 antibody was achieved through phage display and, in parallel, all putative liability sequences were replaced for maximizing developability while minimizing off-target and immunogenicity risks. ALD2510 sequences were re-formatted and used for further CHO cell line development, using the GlymaxX™ technology which boosts Fc effector functions. Early tox ALD2510 material was produced following 10L fed-batch USP/DSP and analytical characterization, including a 6-month early stability study. Preliminary safety and pharmacokinetic/pharmacodynamic (PKPD) profile of ALD2510 were then determined through a non-GLP MTD/DRF study in cynomolgus monkey. ALD2510 demonstrated excellent potency (TREG depletion, ADCC, ADCP), manufacturability and stability together with very low immunogenicity potential. CHO productivity reached ~4g/L in 10L fed-batch bioreactor and characterization revealed excellent purity and activity in line with its low fucose content, together with very low levels of process- or cell-related impurities. This material showed a good behavior during the 6-month stability study and was therefore administered in cynomolgus monkeys during a non-GLP exploratory MTD/DRF study. Increasing doses of ALD2510 (from 0.3 to 100mg/kg) were given to four animals during MTD and same animals received three additional doses at 100mg/kg during DRF. Very good tolerability and safety were reported in animals. ALD2510 half-life and exposure were found consistent with that of humanized IgG1 in cynomolgus. Strong TREG depletion was monitored in the blood in all animals with, importantly, no drop was observed in CD4+ or CD8+ T-cells, confirming ALD2510 capacity to selectively target TREGS while sparing TCONV. Overall, ALD2510 demonstrated excellent potency, manufacturability and stability during the 1st phase of preclinical development. Very good tolerability and safety profile together with satisfying PKPD data were reported during exploratory MTD/DRF study in cynomolgus monkeys. Noteworthy, strong TREG depletion was confirmed while CD4+ or CD8+ T-cells were not impacted, confirming ALD2510 selectivity for TREGS while sparing TCONV. This makes ALD2510 a promising candidate for the treatment of solid tumors, in particular those where the presence of TREGS in the TME is associated with worse prognosis and/or resistance to CPI.

Citation Format: Jemila Houacine, Riad Abes, Anne Marie-Cardine, Aude Le Roy, Bettina Serbin, Lucie Robert, Jérôme Giustiniani, Anne-Sophie Chrétien, Stéphane Fattori, Laurent Gorvel, Armand Bensussan, Daniel Olive, Arnaud Foussat. Preclinical development of ALD2510, a Next-Gen Fc-enhanced, TREG-selective and IL-2-sparing anti-CD25 antibody for the treatment of solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 710.

Immune biology of NSCLC revealed by single-cell technologies: implications for the development of biomarkers in patients treated with immunotherapy

First-line immunotherapy in non-small-cell lung cancer largely improved patients' survival. PD-L1 testing is required before immune checkpoint inhibitor initiation. However, this biomarker fails to accurately predict patients' response. On the other hand, immunotherapy exposes patients to immune-related toxicity, the mechanisms of which are still unclear. Hence, there is an unmet need to develop clinically approved predictive biomarkers to better select patients who will benefit the most from immune checkpoint inhibitors and improve risk management. Single-cell technologies provide unprecedented insight into the tumor and its microenvironment, leading to the discovery of immune cells involved in immune checkpoint inhibitor response or toxicity. In this review, we will underscore the potential of the single-cell approach to identify candidate biomarkers improving non-small-cell lung cancer patients' care.

High-throughput mass cytometry staining for deep phenotyping of human natural killer cells

This protocol details the step-by-step procedure for in-depth immune phenotyping of peripheral blood natural killer (NK) cells from clinical samples by mass cytometry. The protocol consists of three main steps: PBMC incubation with a mix of metal-conjugated antibodies for extracellular phenotyping followed by fixation, permeabilization and incubation with a mix of metal-conjugated antibodies for staining of intracellular proteins, and sample acquisition on a mass cytometer. High-dimensional analysis enables the visualization of NK cell subsets and their phenotypical characteristics. For complete details on the use and execution of this protocol, please refer to Chretien et al. (2021).

Therapeutic targeting of tumor-infiltrating regulatory T cells in breast cancer

Regulatory T cells (Treg) are an immunosuppressive subtype of CD4+ T cells essential for maintaining self-tolerance in physiological settings. Tregs also abundantly infiltrate inflamed tumor tissues, impeding the host's antitumor immune response and contributing to tumor growth and metastasis. In breast cancers, subsets of Tregs express highly immunosuppressive effector phenotypes that favor tumorigenesis, progression, and resistance to immune-checkpoint inhibitor therapies. Tregs share phenotypic features with cytotoxic lymphocytes, rendering them difficult to inhibit without compromising productive anti-tumor immunity. In addition, systemic targeting of Tregs causes serious autoimmune adverse events (SAAE) in cancer patients. Hence, the identification of candidate targets or methodologies allowing the specific elimination of tumor antigen-specific Tregs, including tumor-infiltrating Tregs, is a prerequisite for developing efficient and safe combinatorial immunotherapeutic strategies in breast cancers. To date, numerous preclinical studies have demonstrated that specific targeting of breast tumor-infiltrating Tregs restores a competent antitumor immune response and improves responses to immune-checkpoint inhibitors such as PD-1/PD-L1 blockade. Herein, we discuss major candidate molecules for Treg-targeted therapeutic strategies in breast cancers, detailing the pros and cons of various approaches including monoclonal antibody (mAb)-mediated depletion, homeostasis destabilization, and functional blockade.

4He dose- and track-averaged linear energy transfer: Monte Carlo algorithms and experimental verification

Objective. In the present hadrontherapy scenario, there is a growing interest in exploring the capabilities of different ion species other than protons and carbons. The possibility of using different ions paves the way for new radiotherapy approaches, such as the multi-ions treatment, where radiation could vary according to target volume, shape, depth and histologic characteristics of the tumor. For these reasons, in this paper, the study and understanding of biological-relevant quantities was extended for the case of 4He ion. Approach. Geant4 Monte Carlo based algorithms for dose- and track-averaged LET (Linear Energy Transfer) calculations, were validated for 4He ions and for the case of a mixed field characterised by the presence of secondary ions from both target and projectile fragmentation. The simulated dose and track averaged LETs were compared with the corresponding dose and frequency mean values of the lineal energy, y D ¯ and y ¯ F , derived from experimental microdosimetric spectra. Two microdosimetric experimental campaigns were carried out at the Italian eye proton therapy facility of the Laboratori Nazionali del Sud of Istituto Nazionale di Fisica Nucleare (INFN-LNS, Catania, I) using two different microdosimeters: the MicroPlus probe and the nano-TEPC (Tissue Equivalent Proportional Counter). Main results. A good agreement of L ¯ d Total and L ¯ t Total with y ¯ D and y ¯ T experimentally measured with both microdosimetric detectors MicroPlus and nano-TEPC in two configurations: full energy and modulated 4He ion beam, was found. Significance. The results of this study certify the use of a very effective tool for the precise calculation of LET, given by a Monte Carlo approach which has the advantage of allowing detailed simulation and tracking of nuclear interactions, even in complex clinical scenarios.

857 Selective Treg depletion in solid tumors with ALD2510, a novel humanized CD25-specific, IL-2 sparing monoclonal antibody

Background

Regulatory T cells (Tregs) inhibit immune responses in solid cancers using cell-cell contacts and anti-inflammatory cytokine release. Also, due to high and constitutive levels of IL2Ralpha chain (CD25) expression, Tumor infiltrating (TIL)-Tregs cells preferably consume local Interleukin-2 (IL2), thus depriving conventional T cells from IL2-induced activation and proliferation. Therefore, the selective depletion of TIL-Tregs using therapeutic antibodies targeting CD25 represents a promising strategy to unleash tumor-specific immune responses in solid cancers.

Methods

CD25 expression was evaluated by flow and mass cytometry on T -cell subsets from tumor biopsies collected in patients with various solid cancers (Breast, Endometrial and Cervix). ALD2510 potency was demonstrated in vitro and in vivo in human CD25 Knock-In huGEMM (huCD25-KI) MC38-bearing mice and in CD34+ humanized NSG mice grafted with human cancer cell lines (MDA-MB-231 and HT29).

Results

In tumor biopsies, CD25 is highly and homogeneously expressed by TIL-Tregs, while being much less expressed by only a fraction of conventional CD4+ T cells and barely expressed by TIL-CD8+ cells. This confirms CD25 as the most selective marker to target TIL-Tregs in cancer patients.In vitro, ALD2510 shows potent ADCC and ADCP as well as strong Treg depletion capacity. Importantly, CD8+ and CD4+ conventional T cells are not impacted by ALD2510 even after activation confirming ALD2510 ability to selectively deplete Tregs. Accordingly, ALD2510 neither blocks IL-2 binding to CD25 nor inhibits IL-2 induced proliferation of activated T cells. In CD34+-humanized mice, ALD2510 efficiently depletes human Tregs but spares conventional T cells. Also, in the MC38 model in huCD25-KI mice, ALD2510 shows a strong anti-tumor activity as a single agent with 60% overall tumor growth inhibition together with massive Treg depletion 7 days after a single administration. In addition, combination of ALD2510 with anti-PD1 leads to complete tumor regression and strong activation of conventional T cells. Importantly, Basiliximab, a CD25-specific IL-2 blocking antibody, although efficient at depleting Treg cells, did not impact tumor growth, thus demonstrating that the IL-2 sparing feature of ALD2510 is critical to elicit anti-tumour response in vivo.

Conclusions

This preclinical data package supports CD25 as a potent and selective Treg marker allowing Tregs depletion while sparing conventional T cells. In this context, ALD2510, a novel humanized CD25-specific and IL-2 sparing antibody presents all the required attributes for selective and efficient TIL-Tregs depletion, making it a promising drug candidate to treat a broad range of solid tumor patients.

Ethics Approval

The studies involving human material were approved by the ethical committee “Comité de Protection des Personnes Sud Méditerranée » under approval numbers 1362 and 1048. All participants gave informed consent before taking part.

Endometrial Carcinoma: Immune Microenvironment and Emerging Treatments in Immuno-Oncology

Endometrial cancer (EC) can easily be cured when diagnosed at an early stage. However, advanced and metastatic EC is a common disease, affecting more than 15,000 patients per year in the United Sates. Only limited treatment options were available until recently, with a taxane–platinum combination as the gold standard in first-line setting and no efficient second-line chemotherapy or hormone therapy. EC can be split into four molecular subtypes, including hypermutated cases with POLE mutations and 25–30% harboring a microsatellite instability (MSI) phenotype with mismatch repair deficiency (dMMR). These tumors display a high load of frameshift mutations, leading to increased expression of neoantigens that can be targeted by the immune system, including (but not limited) to T-cell response. Recent data have demonstrated this impact of programmed death 1 and programmed death ligand 1 (PD-1/PD-L1) inhibitors on chemo-resistant metastatic EC. The uncontrolled KEYNOTE-158 and GARNET trials have shown high response rates with pembrolizumab and dostarlimab in chemoresistant MSI-high tumors. Most responders experiment long responses that last more than one year. Similar, encouraging results were obtained for MMR proficient (MMRp) cases treated with a combination of pembrolizumab and the angiogenesis inhibitor lenvatinib. Approvals have, thus, been obtained or are underway for EC with immune checkpoint inhibitors (ICI) used as monotherapy, and in combination with antiangiogenic agents. Combinations with other targeted therapies are under evaluation and randomized studies are ongoing to explore the impact of ICI-chemotherapy triplets in first-line setting. We summarize in this review the current knowledge of the immune environment of EC, both for MMRd and MMRp tumors. We also detail the main clinical data regarding PD-1/PD-L1 inhibitors and discuss the next steps of development for immunotherapy, including various ICI-based combinations planned to limit resistance to immunotherapy.

Quantification of Immune Variables from Liquid Biopsy in Breast Cancer Patients Links Vδ2+ γδ T Cell Alterations with Lymph Node Invasion

The rationale for therapeutic targeting of Vδ2+ γδ T cells in breast cancer is strongly supported by in vitro and murine preclinical investigations, characterizing them as potent breast tumor cell killers and source of Th1-related cytokines, backing cytotoxic αβ T cells. Nonetheless, insights regarding Vδ2+ γδ T cell phenotypic alterations in human breast cancers are still lacking. This paucity of information is partly due to the challenging scarcity of these cells in surgical specimens. αβ T cell phenotypic alterations occurring in the tumor bed are detectable in the periphery and correlate with adverse clinical outcomes. Thus, we sought to determine through an exploratory study whether Vδ2+ γδ T cells phenotypic changes can be detected within breast cancer patients' peripheral blood, along with association with tumor progression. By using mass cytometry, we quantified 130 immune variables from untreated breast cancer patients' peripheral blood. Supervised analyses and dimensionality reduction algorithms evidenced circulating Vδ2+ γδ T cell phenotypic alterations already established at diagnosis. Foremost, terminally differentiated Vδ2+ γδ T cells displaying phenotypes of exhausted senescent T cells associated with lymph node involvement. Thereby, our results support Vδ2+ γδ T cells implication in breast cancer pathogenesis and progression, besides shedding light on liquid biopsies to monitor surrogate markers of tumor-infiltrating Vδ2+ γδ T cell antitumor activity.

Search for Event Rate Modulation in XENON100 Electronic Recoil Data

We have searched for periodic variations of the electronic recoil event rate in the (2-6) keV energy range recorded between February 2011 and March 2012 with the XENON100 detector, adding up to 224.6 live days in total. Following a detailed study to establish the stability of the detector and its background contributions during this run, we performed an unbinned profile likelihood analysis to identify any periodicity up to 500 days. We find a global significance of less than 1σ for all periods, suggesting no statistically significant modulation in the data. While the local significance for an annual modulation is 2.8σ, the analysis of a multiple-scatter control sample and the phase of the modulation disfavor a dark matter interpretation. The DAMA/LIBRA annual modulation interpreted as a dark matter signature with axial-vector coupling of weakly interacting massive particles to electrons is excluded at 4.8σ.

Management of ischemic diabetic foot

Diabetic foot pathology represent the more disabling complication of diabetes. More the 1 million of diabetes patients undergo a lower limb amputation per year; 85% of these amputation are preceded by un ulcer that can be avoided by a prevention program. Critical limb ischemia (CLI), the only independent cause of major amputation in diabetic population, can be correctly treated when an early diagnosis is made. Both endoluminal and surgical revascularization procedures can be applied in diabetes with high rate of success when performed by skilled operator. Infection of diabetic foot, in particular in patients suffering from peripheral artery disease (PVD), may rapidly evolves in severe local or systemic infection putting the patient at high risk of major amputation or death. Together with an early diagnosis of infection and ischemia it is mandatory to apply a correct medical and surgical treatment protocol with the aim to control infection and to improve blood perfusion to the foot. In case of infection surgical procedure should be applied first while revascularization procedure will follow soonest. Antibiotic therapy should be chosen considering different local biological pattern and different type of infection. Reconstructive surgery, the last step in treatment of any diabetic foot lesion, must obtain a functional residual foot or a stump that will allow the patient to go back walking soonest with residual good walking capacity.

Limits on spin-dependent WIMP-nucleon cross sections from 225 live days of XENON100 data

We present new experimental constraints on the elastic, spin-dependent WIMP-nucleon cross section using recent data from the XENON100 experiment, operated in the Laboratori Nazionali del Gran Sasso in Italy. An analysis of 224.6 live days×34 kg of exposure acquired during 2011 and 2012 revealed no excess signal due to axial-vector WIMP interactions with 129Xe and 131Xe nuclei. This leads to the most stringent upper limits on WIMP-neutron cross sections for WIMP masses above 6 GeV/c², with a minimum cross section of 3.5×10(-40) cm² at a WIMP mass of 45 GeV/c², at 90% confidence level.

Dark matter results from 225 live days of XENON100 data

We report on a search for particle dark matter with the XENON100 experiment, operated at the Laboratori Nazionali del Gran Sasso for 13 months during 2011 and 2012. XENON100 features an ultralow electromagnetic background of (5.3 ± 0.6) × 10(-3) events/(keV(ee) × kg × day) in the energy region of interest. A blind analysis of 224.6 live days × 34 kg exposure has yielded no evidence for dark matter interactions. The two candidate events observed in the predefined nuclear recoil energy range of 6.6-30.5 keV(nr) are consistent with the background expectation of (1.0 ± 0.2) events. A profile likelihood analysis using a 6.6-43.3 keV(nr) energy range sets the most stringent limit on the spin-independent elastic weakly interacting massive particle-nucleon scattering cross section for weakly interacting massive particle masses above 8 GeV/c(2), with a minimum of 2 × 10(-45) cm(2) at 55 GeV/c(2) and 90% confidence level.

Dark matter results from 100 live days of XENON100 data

We present results from the direct search for dark matter with the XENON100 detector, installed underground at the Laboratori Nazionali del Gran Sasso of INFN, Italy. XENON100 is a two-phase time-projection chamber with a 62 kg liquid xenon target. Interaction vertex reconstruction in three dimensions with millimeter precision allows the selection of only the innermost 48 kg as the ultralow background fiducial target. In 100.9 live days of data, acquired between January and June 2010, no evidence for dark matter is found. Three candidate events were observed in the signal region with an expected background of (1.8 ± 0.6) events. This leads to the most stringent limit on dark matter interactions today, excluding spin-independent elastic weakly interacting massive particle (WIMP) nucleon scattering cross sections above 7.0 × 10(-45) cm(2) for a WIMP mass of 50 GeV/c(2) at 90% confidence level.

First dark matter results from the XENON100 experiment

The XENON100 experiment, in operation at the Laboratori Nazionali del Gran Sasso in Italy, is designed to search for dark matter weakly interacting massive particles (WIMPs) scattering off 62 kg of liquid xenon in an ultralow background dual-phase time projection chamber. In this Letter, we present first dark matter results from the analysis of 11.17 live days of nonblind data, acquired in October and November 2009. In the selected fiducial target of 40 kg, and within the predefined signal region, we observe no events and hence exclude spin-independent WIMP-nucleon elastic scattering cross sections above 3.4 × 10⁻⁴⁴  cm² for 55  GeV/c² WIMPs at 90% confidence level. Below 20  GeV/c², this result constrains the interpretation of the CoGeNT and DAMA signals as being due to spin-independent, elastic, light mass WIMP interactions.

Neck lesions mimicking thyroid pathology

INTRODUCTION

Nodular lesions within the neck may origin from several structures. A misdiagnosed origin may expose the surgeon to inappropriate procedures. These lesions are paradoxically frequent in high specialised centre for endocrine surgery.

PATIENTS AND METHODS

In the year 2006, three patients were first admitted to our department with a diagnosis of thyroid nodule (1) or lymphatic metastases of thyroid carcinoma (2). The first patient had ultrasound (US) and Tc-99-m scan orienting for thyroid nodule. The two other patients, presented with lateral neck lesion in ipsilateral sincronous and previous diagnosis of papillary thyroid carcinoma, respectively, with US and computed tomography scan confirmed lesion but with a FNA cytology negative for tumoural cells.

RESULTS

All three patients underwent surgical exploration. In the first two cases, a whitish tender nodule (4 and 4.5cm), cleavable from surrounding structures, was removed with final histology of Schwannoma and Paraganglioma, respectively. Both patients experienced Bernard Horner Syndrome. In the last patients, a firm grey nodule of 5cm strictly adherent to muscular planes was removed with diagnosis of Castleman's Disease.

CONCLUSIONS

Nodular neck lesions mimicking a thyroid pathology (thyroid nodules or metastatic lymph nodes) are rare but can represent a tough challenge for surgeons who might fall into incorrect surgical approaches, resulting in high morbidity. Pre-operative work-up would help the surgeon to obtain the correct diagnosis, thus, to follow the better surgical approach. Nevertheless, a careful approach would be used for that neurogenic tumour amenable of resection without jeopardising nervous structures.

Gas chromatography-mass spectrometry measurement of 6beta-OH-cortisol/cortisol ratio in human urine: a specific marker of enzymatic induction

The urinary 6beta-OH-cortisol/cortisol ratio is a specific, non-invasive marker for evaluating inductive or inhibitory effects on cytochrome P450 3A activity. We propose a new quantitative gas chromatography-mass spectrometry with isotope dilution (GC-ID-MS) method for the simultaneous determination of urinary free cortisol (UFC) and 6beta-OH-cortisol (6beta-OHC). The method utilizes the following: (a) addition of internal standard (2H2 cortisol) to 1 ml of urine; (b) loading on to an Extrelut column and elution with dichloromethane; (c) derivatization to dimethoxime tri-(trimethyl-silyl)ether (MOX-TMS); (d) separation and identification by GC-ID-MS. The detection limit for cortisol was 22 pg injected (signal-to-noise ratio 10:1) and for 6beta-OH-cortisol 123 pg injected (signal-to-noise ratio 10:1). The intra-assay and the inter-assay imprecision were 4.69% and 7.4% for 6beta-OHC and 2.44% and 3.53% for cortisol, respectively. We used this method to analyze 57 morning urine samples of healthy volunteers and patients under different conditions. We found that chronic alcoholics had a significantly higher ratio of 6beta-OHC/UFC compared to controls (p<0.0001), whereas adults undergoing methadone therapy and patients with acute alcohol intoxication exhibited a significantly lower urinary 6beta-OHC/UFC ratio (p<0.05 and p<0.01, respectively). The proposed method allows a rapid and accurate assessment of the 6beta-OHC/UFC ratio.

[Sentinel lymph nodes in skin melanoma]

BACKGROUND

Early node dissection offers increased survival in patients with node metastases only. The study of sentinel node (SN) using blue dye and radiolocalization permits to identify patients who could undergo lymphadenectomy.

METHODS

At Department of Surgery of Macerata General Hospital 22 patients with melanoma of trunk or limbs at I and II stage were submitted to SN biopsy.

RESULTS

SN was identified in all cases by combined approach. Dynamic lymphoscintigraphy permitted identification of SL when it was not the node nearest the tumor. Nodal metastases were found in 2 cases (9.1%) and the patients underwent regional lymphadenectomy. In 1 patient the SN was the only node with metastases. Both patients had high thickness melanomas. The measurement of radioactive exposition for operating room personnel and pathologist demonstrated that the technique is safe and without risks.

CONCLUSIONS

Biopsy of SN is effective for identification of occult nodal metastases from cutaneous melanoma. Combined technique allows to localize SN in 100% of cases. There is not radio-exposition for operators.

[The value of fine-needle biopsy under ultrasonic control in the diagnosis of kidney tumors]

127 fine-needle aspiration biopsies obtained under ultrasonographic control from circumscribed kidney lesions of 102 patients (with histologically examined lesions) were selected from a total of 867 fine-needle aspiration biopsies performed in the years between 1978 and 1986. The result of the cytological examination was compared with the histological diagnosis of the lesion. A correct diagnosis of the nature of the lesion (concerning dignity) was achieved in 90.2% of the cases under optimal circumstances. No mistakenly positive diagnosis was made. A total of 88% of the histologically malignant tumors or 80.2% of the kidney cancers were correctly diagnosed already on the basis of the cytological examination. The fine-needle aspiration can be repeated when the obtained material is insufficient: A kidney cancer was diagnosed in this way 13 times among 22 patients. The cytological examination permitted a more precise tumor-type differentiation in the large majority of cases. These results demonstrate the value of this diagnostic tool that carries only an irrelevant risk.