Gene-expression-based T-Cell-to-Stroma Enrichment (TSE) score predicts response to immune checkpoint inhibitors in urothelial cancer

Immune checkpoint inhibitors (ICI) improve overall survival in patients with metastatic urothelial cancer (mUC), but therapeutic success at the individual patient level varies significantly. Here we identify predictive markers of response, based on whole-genome DNA (n = 70) and RNA-sequencing (n = 41) of fresh metastatic biopsy samples, collected prior to treatment with pembrolizumab. We find that PD-L1 combined positivity score does not, whereas tumor mutational burden and APOBEC mutagenesis modestly predict response. In contrast, T cell-to-stroma enrichment (TSE) score, computed from gene expression signature data to capture the relative abundance of T cells and stromal cells, predicts response to immunotherapy with high accuracy. Patients with a positive and negative TSE score show progression free survival rates at 6 months of 67 and 0%, respectively. The abundance of T cells and stromal cells, as reflected by the TSE score is confirmed by immunofluorescence in tumor tissue, and its good performance in two independent ICI-treated cohorts of patients with mUC (IMvigor210) and muscle-invasive UC (ABACUS) validate the predictive power of the TSE score. In conclusion, the TSE score represents a clinically applicable metric that potentially supports the prospective selection of patients with mUC for ICI treatment.

Low dose cisplatin weekly versus high dose cisplatin every three weeks in primary chemoradiotherapy in head and neck cancer patients with low skeletal muscle mass: The CISLOW-study protocol

Chemoradiotherapy with cisplatin in a triweekly regimen of 100 mg/m2 body surface area, is used to treat locally advanced head and neck squamous cell carcinoma (HNSCC) with curative intent. Cisplatin dose limiting toxicity (CDLT) occurs often and impedes obtaining the planned cumulative cisplatin dose. A cumulative cisplatin dose of 200 mg/m2 or more is warranted for better survival and locoregional control. Patients with a low skeletal muscle mass (SMM) have a three-fold higher risk of developing CDLT than patients with a normal SMM. SMM can be assessed through measurements on routinely performed diagnostic head and neck CT- or MRI-scans. A weekly regimen of 40 mg/m2 body surface area cisplatin is proposed as a less toxic schedule, which possibly decreases the risk of developing CDLT and enables reaching a higher cumulative cisplatin dose. The aim of this multicenter randomized clinical trial (NL76533.041.21, registered in the Netherlands Trial Register) is to identify whether a regimen of weekly cisplatin increases compliance to the planned chemotherapy scheme in HNSCC patients with low SMM. The primary outcome is the difference in compliance rate, defined as absence of CDLT, between low SMM patients receiving either the weekly or triweekly regimen. Secondary outcomes consist of toxicities, the cumulative cisplatin dose, time to recurrence, incidence of recurrence at two years of follow-up, location of recurrence, 2-year overall, disease free and disease specific survival, quality of life, patient's experiences, and cost-effectiveness.

Early dose escalation of LAVA-1207, a novel bispecific gamma-delta T-cell engager (Gammabody), in patients with metastatic castration-resistant prostate cancer (mCRPC)

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Background: LAVA-1207 is a humanized bispecific antibody of 78 kDa comprised of two single domain antibody (VHH) fragments linked to a silenced fragment crystallizable immunoglobulin region. As shown pre-clinically, LAVA-1207 binds with high affinity to the Vδ2 chain of Vγ9Vδ2-T cells, a potent immune effector cell population, and to prostate specific membrane antigen (PSMA) expressed by prostate cancer cells to trigger robust (pM range EC50) Vγ9Vδ2-T cell mediated lysis of prostate cancer cells, whereas normal cells are relatively spared. Based on earlier clinical experience with systemic activation of Vγ9Vδ2-T cells through aminobisphosphonates and in vivo studies in non-human primates with cross-reactive surrogate bispecific γδ-T cell engagers, a low risk for cytokine release syndrome (CRS) is expected in the clinic. Methods: This is an open label, 3+3 design, phase 1/2a study in patients with therapy refractory metastatic castration resistant prostate cancer (NCT05369000; EudraCT Number: 2021-001789-39) to determine the safety of LAVA-1207 and its recommended Phase 2a dose (RP2D) and schedule. Secondary objectives include evaluation of PK, PD, immunogenicity, and preliminary antitumor activity. LAVA-1207 is administered IV every two weeks with an infusion duration of 2 hours for the first dose, 1 hour for the second dose, and 30 minutes for all subsequent doses. Results: As of September 23, 2022, a dose level of 40 µg (starting dose was 1.5 µg based on MABEL approach) has been reached without dose limiting toxicities (DLTs). A total of 16 patients have been treated with LAVA-1207 with treatment duration ranging from 1 to 25+ weeks. Treatment emergent AEs (TEAEs) that were suspected to be related were all grade 1-2, and included nausea (n=3), AST increase (n=2), fatigue (n=2), and infusion related reaction (n=2). Severity of TEAEs did not increase with escalating doses and no patient discontinued treatment due to an AE. PK data indicate increasing drug exposure in correlation with increasing doses of LAVA-1207. PD data show a consistent early reduction in Vγ9Vδ2-T cell frequencies at 2hrs after the first dose, which could be indicative of Vγ9Vδ2-T cell redistribution after treatment, often accompanied by an increase in Vγ9Vδ2-T cell activation markers. Vγ9Vδ2-T cell numbers are restored in the subsequent 3 to 5 days to at least pre-dose levels. Additionally, receptor occupancy of Vγ9Vδ2-T cells was detectable up to 5 days after first dosing. To date, stable disease at 8 weeks has been observed in 3 out of 8 evaluable patients. Conclusions: LAVA-1207 has been well tolerated early in dose escalation; further clinical activity including PSA results, response assessment, and pharmacodynamic data will clarify determination of an optimal biological active dose. Clinical trial information: NCT05369000 .

Phase 1 Study of Chemoradiotherapy Combined with Nivolumab ± Ipilimumab for the Curative Treatment of Muscle-invasive Bladder Cancer

BACKGROUND

Muscle-invasive bladder cancer (MIBC) has a poor prognosis. Chemoradiotherapy (CRT) in selected patients has comparable results to radical cystectomy. Results of neoadjuvant immune checkpoint inhibitors (ICIs) before radical cystectomy are promising. We hypothesize that ICI concurrent to CRT (iCRT) is safe and may improve treatment outcomes.

OBJECTIVE

To determine the safety of iCRT for MIBC.

DESIGN, SETTING, AND PARTICIPANTS

This multicenter, phase 1b, open-label, dose-escalation study determined the safety of CRT with three ICI regimens in patients with nonmetastatic (T2-4aN0-1) MIBC. Twenty-six patients received mitomycin C/capecitabine and 20 × 2.75 Gy to the bladder. Tolerability was evaluated in a cohort of up to ten patients. If two or fewer out of the first six patients or three or fewer of ten patients experienced dose-limiting toxicity (DLT), accrual continued in the next cohort.

INTERVENTION

Patients received nivolumab 480 mg (NIVO480), nivolumab 3 mg/kg and ipilimumab 1 mg/kg (NIVO3 + IPI1), or nivolumab 1 mg/kg and ipilimumab 3 mg/kg (IPI3 + NIVO1).

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The primary endpoint was safety. Secondary objectives were response rate, disease-free survival, metastatic-free survival (MFS), and overall survival (OS).

RESULTS AND LIMITATIONS

In the NIVO480 cohort, no patients experienced DLT. The NIVO3 + IPI1 2 patients experienced DLT, thrombocytopenia (grade 4), and asystole (grade 5). IPI3 + NIVO1 was discontinued after three out of six patients experienced DLT. Clinically significant adverse events (AEs) of grade ≥3 occurred in zero, three, and five patients in the NIVO480, NIVO3 + IPI1, and IPI3 + NIVO1 groups, respectively. The most common AEs were immune related and gastrointestinal. MFS and OS were 90% at 2 yr for NIVO480 and 90% at 1 yr for NIVO3 + IPI1. Limitations include the absence of a centralized pathology and radiology review, and a lack of biomarker analysis.

CONCLUSIONS

In this dose-finding study of iCRT, the regimens of nivolumab monotherapy and nivolumab 3 mg/kg with ipilimumab 1 mg/kg have acceptable toxicity.

PATIENT SUMMARY

We tested the safety of a new bladder-sparing treatment modality for muscle-invasive bladder cancer patients, combining immune checkpoint inhibitors simultaneously with chemoradiotherapy. We report that two regimens, nivolumab monotherapy and nivolumab 3 mg/kg with ipilimumab 1 mg/kg, are safe and can be used in phase 3 trials.

Safety and tolerability of MEDI0562, an OX40 agonist monoclonal antibody, in combination with durvalumab or tremelimumab in adult patients with advanced solid tumors

PURPOSE

Combination therapies targeting immunological checkpoints have shown promise in treating multiple tumor types. We report safety and tolerability of MEDI0562, a humanized IgG1K OX40 monoclonal antibody, in combination with durvalumab (anti-PD-L1), or tremelimumab (anti-CTLA-4), in adult patients with previously treated advanced solid tumors.

EXPERIMENTAL DESIGN

In this phase 1, multicenter, open-label study, patients received escalating doses of MEDI0562 (2.25, 7.5, or 22.5 mg) every two weeks (Q2W) in combination with durvalumab (1500 mg) or tremelimumab (75 or 225 mg) Q4W, intravenously, until unacceptable toxicity or progressive disease. Tumor assessments were performed Q8W. The primary objective was to evaluate safety and tolerability.

RESULTS

Among the 27 and 31 patients who received MEDI0562 + durvalumab or MEDI0562 + tremelimumab, 74.1% and 67.7% reported a treatment-related adverse event (AE), and 22.2% and 19.4% experienced a treatment‑emergent AE that led to discontinuation, respectively. The maximum tolerated dose of MEDI0562 + durvalumab was 7.5 mg MEDI0562 + 1500 mg durvalumab; the maximum administered dose of MEDI0562 + tremelimumab was 22.5 mg MEDI0562 + 225 mg tremelimumab. Three patients in the MEDI0562 + durvalumab arm had a partial response. The mean percentage of Ki67+CD4+ and Ki67+CD8+ memory T cells increased by >100% following the first dose of MEDI0562 + durvalumab or tremelimumab in all dose cohorts. A decrease in OX40+FOXP3 T regulatory cells was observed in a subset of patients with available paired biopsies.

CONCLUSIONS

Following dose escalation, moderate toxicity was observed in both treatment arms, with no clear efficacy signals demonstrated.

89Zr-DFO-durvalumab PET/CT prior to durvalumab treatment in patients with recurrent or metastatic head and neck cancer

Background: In the PINCH study we performed ⁸⁹Zr-DFO-durvalumab (anti-PD-L1) PET/CT in patients with recurrent or metastatic squamous cell carcinoma of the head and neck (SCCHN) prior to monotherapy durvalumab treatment. The primary aims were to assess safety and feasibility of ⁸⁹Zr-DFO-durvalumab PET-imaging and predict disease control rate during durvalumab treatment. Secondary aims were to correlate ⁸⁹Zr-DFO-durvalumab uptake to tumor PD-L1 expression, ¹⁸F-FDG uptake, and treatment response of individual lesions. Methods: In this prospective multicenter phase I-II study (NCT03829007), patients with incurable R/M SCCHN underwent baseline [¹⁸F]FDG PET and CT or MRI imaging. Subsequently, PD-L1 PET-imaging was performed 5 days after 37MBq [⁸⁹Zr]Zr-DFO-durvalumab administration. To optimize imaging conditions, dose-finding was performed in the first 14 patients. For all patients, durvalumab treatment (1500mg/4 weeks, IV) was started <1 week after PD-L1 PET imaging and continued until disease progression or unacceptable toxicity (maximum 24 months). CT evaluation was assessed according to RECIST 1.1 every 8 weeks. PD-L1-expression was determined by combined positive score (CPS) on (archival) tumor-tissue. [⁸⁹Zr]Zr-DFO-durvalumab uptake was measured in [¹⁸F]FDG-positive lesions, primary and secondary lymphoid organs, and bloodpool. Results: In total, 33 patients with locoregional recurrent (n = 12) or metastatic SCCHN (n = 21) were enrolled. [⁸⁹Zr]Zr-DFO-durvalumab injection was safe. A dose of 10mg durvalumab resulted in highest tumor-to-blood-ratios. After a median follow-up of 12.6 months, overall response rate was 26%. The disease control rate at 16 weeks was 48% with a mean duration of 7.8 months (range 1.7-21.1). On a patient level, [⁸⁹Zr]Zr-DFO-durvalumab-SUVpeak or tumor-to-blood ratio could not predict treatment response (HR 1.4 (95%CI 0.5-3.9, P = 0.54) and (HR 1.3 (95%CI 0.5-3.6, P = 0.61) respectively). Also, on a lesion level, [⁸⁹Zr]Zr-DFO-durvalumab-SUVpeak showed no substantial correlation to treatment response (Spearman ρ= 0.45, P = 0.051). Lesional [⁸⁹Zr]Zr-DFO-durvalumab-uptake did not correlate to PD-L1 CPS score, but did correlate to [¹⁸F]FDG SUV peak (Spearman ρ= 0.391, P = 0.005). Conclusion: PINCH is the first PD-L1 PET/CT study in patients with R/M SCCHN and has shown the feasibility and safety of [⁸⁹Zr]Zr-DFO-durvalumab PET/CT in a multi-center trial. [⁸⁹Zr]Zr-DFO-durvalumab-uptake did not correlate to durvalumab treatment response.

Genome-wide aneuploidy detected by mFast-SeqS in circulating cell-free DNA is associated with poor response to pembrolizumab in patients with advanced urothelial cancer

Second-line treatment with immune checkpoint inhibition in patients with metastatic urothelial cancer (mUC) has a low success rate (~ 20%). Circulating tumour-derived DNA (ctDNA) levels may guide patient stratification, provided that an affordable and robust assay is available. Here, we investigate whether the modified fast aneuploidy screening test-sequencing system (mFast-SeqS) may provide such an assay. To this end, mFast-SeqS was performed on cell-free DNA (cfDNA) from 74 patients with mUC prior to treatment with pembrolizumab. Results were associated with corresponding tissue-based profiles, plasma-based variant allele frequencies (VAFs) and clinical response. We found that plasma-derived mFast-SeqS-based aneuploidy scores significantly correlated with those observed in the corresponding tumour tissue as well as with the ctDNA level in the plasma. In multivariate logistic regression analysis, a high aneuploidy score was independently associated with lack of clinical benefit from treatment with pembrolizumab. In conclusion, mFast-SeqS provides a patient-friendly, high-throughput and affordable method to estimate ctDNA level. Following independent validation, this test could be used to stratify mUC patients for response prior to the initiation of treatment with pembrolizumab.

Comprehensive Molecular Characterization Reveals Genomic and Transcriptomic Subtypes of Metastatic Urothelial Carcinoma

Recent molecular characterization of primary urothelial carcinoma (UC) may guide future clinical decision-making. For metastatic UC (mUC), a comprehensive molecular characterization is still lacking. We analyzed whole-genome DNA and RNA sequencing data for fresh-frozen metastatic tumor biopsies from 116 mUC patients who were scheduled for palliative systemic treatment within the context of a clinical trial (NCT01855477 and NCT02925234). Hierarchical clustering for mutational signatures revealed two major genomic subtypes: GenS1 (67%), which was APOBEC-driven; and GenS2 (24%), which had a high fraction of de novo mutational signatures related to reactive oxygen species and is putatively clock-like. Significantly mutated genes (SMGs) did not differ between the genomic subtypes. Transcriptomic analysis revealed five mUC subtypes: luminal-a and luminal-b (40%), stroma-rich (24%), basal/squamous (23%), and a nonspecified subtype (12%). These subtypes differed regarding expression of key genes, SMGs, oncogenic pathway activity, and immune cell infiltration. We integrated the genomic and transcriptomic data to propose potential therapeutic options by transcriptomic subtype and for individual patients. This in-depth analysis of a large cohort of patients with mUC may serve as a reference for subtype-oriented and patient-specific research on the etiology of mUC and for novel drug development. PATIENT SUMMARY: We carried out an in-depth analysis of the molecular and genetic features of metastatic cancer involving the cells that line the urinary tract. We showed that this is a heterogeneous disease with different molecular subtypes and we identified possible targets for therapy for each subtype.

Prediction of pathological response following neoadjuvant chemotherapy in patients with muscle-invasive bladder cancer: the PRE-PREVENCYS trial

Background

The recommended treatment for patients with non-metastatic muscle-invasive bladder cancer (MIBC) is neoadjuvant chemotherapy (NAC) and radical cystectomy (RC). Following NAC, 20–40% of patients experience a complete pathological response (pCR) in the RC specimen and these patients have excellent long-term overall survival. Subject to debate is, however, whether patients with a pCR to NAC benefit from RC, which is a major surgical procedure with substantial morbidity, and if these patients might be candidates for close surveillance instead. However, currently it is not possible to accurately identify patients with a pCR to NAC in whom RC might be withheld. The objective of this study is to assess whether pathological response in the RC specimen after NAC can be predicted based on clinical, radiological, and histological variables and on a wide set of molecular biomarkers assessed in tissue, blood and urine.

Methods

This is a multicentre, prospective cohort study, including patients with cT2a-T4a N0-N1 M0 urothelial cell MIBC who are scheduled to undergo cisplatin-based NAC followed by RC. Prior to start of therapy, a 2-Deoxy-2-[18F] fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) is performed. Response to NAC is evaluated by CT-scan. Blood and urine, including cytology, are prospectively collected for biomarker analyses before and after NAC. Immediately before RC, participants undergo cystoscopy with bimanual examination and a re-staging transurethral resection (TUR) of all visible cancerous lesions or with biopsies from scar tissue. Subsequently, RC is performed in all patients. Tissue from the diagnostic TUR, the re-staging TUR, and the RC specimen is examined for the presence of urothelial cancer carcinoma and DNA and RNA is isolated for molecular analysis. The primary endpoint is the pathological stage (ypTN) in the RC and ePLND specimen and its association with clinical response.

Discussion

If the PRE-PREVENCYS trial shows that the absence of residual disease after NAC in patients with MIBC is accurately predicted, a randomized controlled trial is scheduled comparing the overall survival of NAC plus RC versus NAC followed by close surveillance for patients with a clinically complete response (PREVENCYS trial).

Trial registration

Netherlands Trial Register: NL8678; Registered 20 May 2020 https://www.trialregister.nl/trial/8678

Anti-PD-1 Efficacy in Patients with Metastatic Urothelial Cancer Associates with Intratumoral Juxtaposition of T Helper-Type 1 and CD8+ T cells

PURPOSE

PD-1 inhibition results in durable antitumor responses in a proportion of patients with metastatic urothelial cancer (mUC). The majority of patients, however, do not experience clinical benefit. In this study, we aimed to identify early changes in T-cell subsets that underlie anti-PD-1 efficacy in patients with mUC.

EXPERIMENTAL DESIGN

Paired samples were collected from peripheral blood, plasma, and metastatic lesions of 56 patients with mUC at baseline and weeks 6 and 12 after initiating pembrolizumab treatment (200 mg intravenously, every 3 weeks). Samples were analyzed using multiplex flow cytometry, ELISA, and in situ stainings, including cellular network analysis. Treatment response was evaluated as best overall response according to RECIST v1.1, and patients were classified as responder (complete or partial response) or nonresponder (progressive disease).

RESULTS

In responders, baseline fractions of CD4⁺ T cells expressing cosignaling receptors were higher compared with nonresponders. The fraction of circulating PD-1⁺ CD4⁺ T cells decreased at weeks 6 and 12, whereas the fraction of 4-1BB⁺ CD28⁺ CD4⁺ T cells increased at week 12. In metastatic lesions of responders, the baseline density of T helper-type 1 (Th1) cells, defined as T-bet⁺ CD4⁺ T cells, was higher as compared to non-responders. Upon treatment, Th1 cells became localized in close proximity to CD8⁺ T cells, CD11b⁺ myeloid cells, and tumor cells.

CONCLUSIONS

A decrease in the fraction of circulating PD-1⁺ CD4⁺ T cells, and juxtaposition of Th1, CD8⁺, and myeloid cells was associated with response to anti-PD-1 treatment in patients with mUC.

Symptom monitoring in cancer and fully automated advice on supportive care: Patients' perspectives on self-management strategies and the eHealth self-management application Oncokompas

Objective

The web‐based application Oncokompas was developed to support cancer patients to self‐manage their symptoms. This qualitative study was conducted to obtain insight in patients' self‐management strategies to cope with cancer and their experiences with Oncokompas as a fully automated behavioural intervention technology.

Methods

Data were collected from semi‐structured interviews with 22 participants (10 head and neck cancer survivors and 12 incurably ill patients). Interview questions were about self‐management strategies and experiences with Oncokompas. Interviews were audio‐recorded, transcribed verbatim and analysed using thematic analysis.

Results

Participants applied several self‐management strategies, among which trying to stay in control and make the best of their situation. They described Oncokompas' added value: being able to monitor symptoms and having access to a personal online library. Main reasons for not using Oncokompas were concentration problems, lack of time or having technical issues. Recommendations were made for further development of Oncokompas, relating to its content, technical and functional aspects.

Conclusions

Survivors and incurably ill patients use various self‐management strategies to cope with cancer. The objectives of self‐management interventions as Oncokompas correspond well with these strategies: taking a certain responsibility for your well‐being and being in charge of your life as long as possible by obtaining automated information (24/7) on symptoms and tailored supportive care options.

Abstract 2190: Integrative genomic and transcriptomic characterization of metastatic urothelial carcinoma

Metastatic urothelial carcinoma (mUC) is a lethal cancer with limited therapeutic options available. To identify novel targets for therapy, large-scale sequencing efforts are needed. The Cancer Genome Atlas (TCGA) initiative substantially improved our knowledge on the genomic and transcriptomic characteristics of primary UC (Robertson et al. Cell 2017), however, the molecular landscape of mUC still remains largely unexplored.

We performed whole genome sequencing (WGS) on 116 biopsies of UC metastases and matched mRNA sequencing (RNAseq) for 90 samples. We applied genomic alteration analysis on the WGS data and consensus clustering on the RNAseq data.

We compared the molecular alterations of mUC with the data of the TCGA cohort and found that most affected driver genes were similar between primary UC and mUC. However, we identified CNTNAP5, RARG and MGP as exclusively mutated driver genes in the metastatic setting, and TP53 alterations were more prevalent in mUC than in primary UC. APOBEC induced mutation signatures in coding and non-coding regions were identified in 91% of the mUC samples and correlated with ploidy, mutational burden and copy number alterations. Based on the etiology of observed mutational signatures, five genomic subtypes were identified in mUC and validated in the TCGA cohort. APOBEC mutagenesis was the main mutational process in genomic subtype 1, which was the most common subtype (67%, N = 78). Moreover, APOBEC deamination mutations were found to be increased over time in paired biopsies from eight patients, indicating that APOBEC enzyme activity is ongoing in the metastatic setting. Unsupervised clustering and comparing phenotypic markers between the groups revealed five clinically-relevant transcriptomic subtypes: luminal-a (20%), luminal-b (20%), stroma-rich (24%), basal/squamous (23%) and a non-specified phenotype (12%). The basal/squamous and stroma-rich subtypes showed highly similar molecular characteristics as the TCGA subtypes, but with enrichment of the stroma-rich and reduction of the basal/squamous subtype. Based on genomic alterations, potential therapeutic targets were identified in 111/116 mUC patients, of which FGFR3 alterations (18%) and fusions (6%), and CDKN2A (44%), ERBB2 (20%), and TSC1 (14%) alterations were most common. By integrating the genomic and transcriptomic data, we propose potential novel therapeutic options per transcriptomic subtype, like addition of a TGF-β inhibitor to immune checkpoint inhibition for the stroma-rich and basal/squamous subtypes that showed the highest TGF-β pathway activity.

Using WGS and RNAseq analyses, we provide a comprehensive overview of the molecular landscape of mUC that may serve as a reference for more subgroup-oriented and patient-specific research on the etiology of mUC and future drug development.

Citation Format: Maud Rijnders, J Alberto Nakauma-González, Job van Riet, Michiel S. van der Heijden, Jens Voortman, Edwin P. J. G Cuppen, Niven Mehra, Sandra van Wilpe, Sjoukje F. Oosting, L Lucia Rijstenberg, Ellen C. Zwarthoff, Ronald de Wit, Astrid A. van der Veldt, Harmen J. van de Werken, Martijn P. Lolkema, Joost L. Boormans. Integrative genomic and transcriptomic characterization of metastatic urothelial carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2190.

Health-related quality of life and overall survival: a prospective study in patients with head and neck cancer treated with radiotherapy

Purpose

We aimed to examine whether pre-treatment, post-treatment and change in health-related quality of Life (HRQoL) is associated with survival, in patients with head and neck cancer (HNC).

Methods

We included 948 newly diagnosed HNC patients treated with primary or adjuvant (chemo)radiotherapy with curative intent. The EORTC QLQ-C30 questionnaire was assessed pre-treatment and at 6 weeks, 6 months and 12 months post-treatment. Multivariable Cox regression analyses were performed to examine whether HRQoL at all time points and changes in HRQoL over time were associated with survival, after adjusting for demographic, clinical and lifestyle-related variables.

Results

Higher HRQoL scores were significantly associated with improved 5-year overall survival at all time points, except for the subscale global QoL at 6 weeks. Changes in HRQoL at 6 weeks post-treatment compared to pre-treatment were not significantly associated with survival. Changes in physical (HR: 0.88 95% CI: 0.82–0.96) and emotional functioning (HR: 0.90 95% CI: 0.85–0.96) from pre-treatment to 6 months post-treatment and changes in global QOL, and physical, emotional, and social functioning from pre-treatment to 12 months post-treatment were significantly associated with survival.

Conclusion

Higher HRQoL reported pre-treatment and post-treatment (6 weeks, 6 months and 12 months) are significantly associated with improved survival, as well as changes in HRQoL at 6 and 12 months compared to pre-treatment. Our results highlight the value of monitoring HRQoL and to identify those patients that report decreased or deteriorated HRQOL. This may help to further improve cancer care in a timely and efficient manner.

Expression of let-7i and miR-192 is associated with resistance to cisplatin-based chemoradiotherapy in patients with larynx and hypopharynx cancer

OBJECTIVES

The majority of patients with locally advanced larynx or hypopharynx squamous cell carcinoma are treated with organ-preserving chemoradiotherapy (CRT). Clinical outcome following CRT varies greatly. We hypothesized that tumor microRNA (miRNA) expression is predictive for outcome following CRT.

METHODS

Next-generation sequencing (NGS) miRNA profiling was performed on 37 formalin-fixed paraffin-embedded (FFPE) tumor samples. Patients with a recurrence-free survival (RFS) of less than 2 years and patients with late/no recurrence within 2 years were compared by differential expression analysis. Tumor-specific miRNAs were selected based on normal mucosa miRNA expression data from The Cancer Genome Atlas database. A model was constructed to predict outcome using group-regularized penalized logistic ridge regression. Candidate miRNAs were validated by RT-qPCR in the initial sample set as well as in 46 additional samples.

RESULTS

Thirteen miRNAs were differentially expressed (p < 0.05, FDR < 0.1) according to outcome group. Initial class prediction in the NGS cohort (n = 37) resulted in a model combining five miRNAs and disease stage, able to predict CRT outcome with an area under the curve (AUC) of 0.82. In the RT-qPCR cohort (n = 83), 25 patients (30%) experienced early recurrence (median RFS 8 months; median follow-up 42 months). Class prediction resulted in a model combining let-7i-5p, miR-192-5p and disease stage, able to discriminate patients with good versus poor clinical outcome (AUC:0.80).

CONCLUSION

The combined miRNA expression and disease stage prediction model for CRT outcome is superior to using either factor alone. This study indicates NGS miRNA profiling using FFPE specimens is feasible, resulting in clinically relevant biomarkers.

Comparison of Carboplatin With 5-Fluorouracil vs. Cisplatin as Concomitant Chemoradiotherapy for Locally Advanced Head and Neck Squamous Cell Carcinoma

Background: Chemoradiotherapy (CRT) including three cycles of cisplatin is considered the standard of care for locally advanced head and neck squamous cell carcinoma (LA-HNSCC). However, around one-third of the patients cannot complete cisplatin because of toxicity. Carboplatin plus 5-fluorouracil (carbo-5FU) is another accepted treatment option with a different toxicity profile. We compared tolerability and efficacy of concomitant carbo-5FU and cisplatin. Patients and Methods: We conducted a retrospective analysis of LA-HNSCC patients treated with CRT in two Dutch cancer centers between 2007 and 2016. All patients received intensity-modulated radiotherapy. One center routinely administered carboplatin 300-350 mg/m² at day 1, 22, and 43 followed by 5FU 600 mg/m²/day for 96 h. The other center used cisplatin 100 mg/m² at day 1, 22, and 43. The primary endpoint of this study was chemotherapy completion rate. Secondary endpoints included overall survival (OS), disease-free survival (DFS), locoregional control (LRC) and distant metastasis-free interval (DMFS), toxicity, and unplanned admissions. Results: In the carbo-5FU cohort (n = 211), 60.2% of the patients completed chemotherapy vs. 76.7% (p < 0.001) of the patients in the cisplatin cohort (n = 223). Univariate analysis showed a higher risk of death in the carbo-5FU cohort [hazard ratio (HR) 1.53, 95% CI, 1.09-2.14, p = 0.01] with a 3-year OS of 65.4 vs. 76.5% for cisplatin. OS was independently associated with T and N stage and p16 status, but not with chemotherapy regimen (HR 1.08, 95% CI, 0.76-1.55, p = 0.65). Three-year DFS was 70.0% for carbo-5FU vs. 78.6% for cisplatin (HR 1.37, 95% CI, 0.93-2.01, p = 0.05). A similar outcome was observed for both LRC (HR 1.27, 95% CI, 0.74-2.09, p = 0.4) and DMFS (HR 1.08, 95% CI 0.62-1.90, p = 0.77). The risk of discontinuation for chemotherapy-associated toxicity was higher in the carbo-5FU cohort than in the cisplatin cohort (relative risk = 1.69). Conclusion: LA-HNSCC patients treated with concomitant carbo-5FU completed chemotherapy less frequently than patients treated with cisplatin. Treatment regimen was not an independent prognostic factor for OS.

Early response marker during pembrolizumab treatment in metastatic urothelial cancer: Temporal shift in peripheral CD4 T cells expressing chemokine receptors

5033

Background: Approval of PD1 blockade greatly improved treatment possibilities for patients with platinum-resistant metastatic urothelial cancer (mUC), however the current response rate for pembrolizumab is less than 25%. Since PD-L1 expression does not have predictive value in this setting, the aim of this study was to identify new markers to improve patient selection. Methods: Between Sept 2017 and Jan 2020, 84 mUC patients received pembrolizumab in a prospective biomarker discovery study (NCT03263039). Peripheral blood samples (n = 22) taken prior to and at 6 and 12 weeks after start of treatment were analyzed for frequencies of CD4 and CD8 T cells expressing co-inhibitory, co-stimulatory and chemokine receptors using multiplex flow cytometry. Plasma chemokine levels were determined using ELISA (n = 38), and fresh tumor biopsies obtained prior to and during treatment (n = 26) were analyzed for densities and phenotypes of T cells using multiplex immunofluorescence staining. T cell receptor clonality was analyzed in peripheral blood (n = 10) and tumor biopsies (n = 6) using RNA sequencing. Patients were classified as responder (complete or partial response) or non-responder (progressive disease) according to RECIST v1.1 after 12 weeks of treatment. Results: Longitudinal sampling revealed that upon treatment the frequency of CXCR3+ CD4 T cells decreased in responders, whereas the frequency of CXCR3+ CCR1+ CD4 T cells drastically increased in non-responders. Before treatment, the frequency of CD4 T cells co-expressing CXCR3 and CCR1 was already decreased in responders. Notably, in responders, the treatment-related decrease in frequency of CD4 T cells expressing chemokine receptors was accompanied by a decrease in the frequency of CD4 T cells expressing the co-inhibitory receptor PD1, whereas an increase in the frequency of CD4 T cells expressing the co-stimulatory receptor 4-1BB was observed. These findings will be complemented with chemokine levels in plasma, contexture of T cells in tumor biopsies, and T cell receptor clonality analysis. Conclusions: mUC patients responding to pembrolizumab treatment demonstrated an on-treatment decrease in frequency of CD4 T cells expressing chemokine receptors that is accompanied by a changed frequency of co-signaling receptor expressing CD4 T cells. These data show that dynamic immune phenotyping can distinguish effective from less effective immune activation by pembrolizumab, and may provide early markers for benefit from PD1 blockade in mUC patients.

89Zr-durvalumab PD-L1 PET in recurrent or metastatic (R/M) squamous cell carcinoma of the head and neck

3573

Background: Immune checkpoint inhibitors (ICI) targeting programmed cell death protein-1/ligand-1 (PD-1/PD-L1) have shown activity in R/M squamous cell carcinoma of the head and neck (SCCHN). Positron-emission-tomography (PET) with 89Zr-labeled anti-PD-L1 antibodies could aid in predicting response to ICI. We present the dose-finding results of the first-in-human 89Zr-durvalumab PD-L1 PET-imaging in patients with SCCHN participating in the ongoing phase II PINCH study (NCT03829007). Methods: Following baseline [18F]FDG-PET and CT/MRI imaging, patients with incurable R/M SCCHN received 37 MBq 89Zr-durvalumab and protein dose 2mg, 10mg or 50mg durvalumab. 89Zr-durvalumab PD-L1 PET-scan was acquired day 5 post-injection. Plasma pharmacokinetic analyses were performed at day 0 and 5. Standardized uptake values (SUV, mean ± SD) were measured in [18F]FDG-positive tumor lesion, liver, spleen, bone marrow and bloodpool. PD-L1-expression was assessed on archival tumor tissue using the Ventana PD-L1 (SP263) assay. Results: 14 patients were enrolled and no adverse events were reported. High tracer-retention was observed in liver and spleen, most prominent in patients receiving 2 or 10mg durvalumab. 89Zr-durvalumab accumulation within tumors and between patients was heterogeneous and not all [18F]FDG-positive lesions showed 89Zr-durvalumab uptake. Tumor lesions were visualized best using 10 or 50mg durvalumab (SUVpeak 2mg: 3.86 ± 0.79, 10mg: 7.46 ± 2.18, 50mg: 5.57 ± 1.74). Tumor-to-blood-ratios for 10mg durvalumab were highest (2mg: 2.27 ± 0.33, 10mg: 3.44 ± 0.76, 50mg: 1.73 ± 0.99; p = 0.019). PK-analyses confirmed visual prolonged tracer-retention in bloodpool with increasing protein dose. PD-L1-expression was equally distributed amongst dose-groups. Conclusions: This is the first study to show feasibility of 89Zr-durvalumab PD-L1 PET in SCCHN patients, demonstrating the highest tumor-to-blood radio with a total dose of 10mg durvalumab. So far, no correlation of tumor PD-L1 expression with 89Zr-durvalumab-uptake and PD-L1 expression on archival tissue was found. Next step will be to correlate 89Zr-durvalumab PD-L1 PET tumor uptake with durvalumab treatment response in the phase 2 part of the PINCH study. Clinical trial information: NCT03829007 .

Atezolizumab (atezo) therapy for locally advanced/metastatic urinary tract carcinoma (mUTC) in patients (pts) with poor performance status (PS): Analysis of the prospective global SAUL study

5035

Background: Pts with PS > 1 have a poor prognosis and are often excluded from clinical trials. The single-arm SAUL study (NCT02928406) evaluated atezo in a ‘real-world’ population. Overall, safety and efficacy were consistent with prior trials. However, ECOG PS 2 pts had worse overall survival (OS) but fewer adverse events (AEs) than ECOG PS 0/1 pts [Sternberg, 2019], likely reflecting shorter treatment duration and warranting exploration. Methods: Pts with mUTC received atezo 1200 mg q3w until loss of clinical benefit or unacceptable toxicity. The primary endpoint was safety. Post hoc analyses compared baseline factors, AEs and efficacy in pts with ECOG PS 2 vs 0/1. In this analysis, AE incidences were restricted to the first 45 days of atezo to adjust for differing treatment exposure. Results: None of the baseline factors explored was significantly associated with worse OS or disease control rate (DCR) in ECOG PS 2 pts. However, pts with visceral metastases and ECOG PS 2 had particularly poor outcomes. Safety appeared similar between subgroups. Conclusions: ECOG PS 2 pts have a dismal prognosis. The higher proportion with poor prognostic factors despite similar age in ECOG PS 2 vs 0/1 pts may suggest that poor PS was related to disease rather than comorbidities. Risk/benefit should be considered especially carefully when treating pts with ECOG PS 2 due to high-burden/visceral disease. Clinical trial information: NCT02928406 . [Table: see text]

Safety and tolerability of MEDI0562 in combination with durvalumab or tremelimumab in patients with advanced solid tumors

3003

Background: We report safety and tolerability of MEDI0562, a humanized IgG1κ OX40 monoclonal antibody (mAb), in combination with durvalumab (durva; anti-PD-L1 mAb) or tremelimumab (treme; anti-CTLA-4 mAb) in patients (pts) with previously treated advanced solid tumors. Methods: In this phase 1, open-label study (NCT02705482), adult pts received escalating doses of MEDI0562 (2.25, 7.5 or 22.5 mg/kg) every 2 wks (Q2W) in combination with durva (1500 mg/kg) or treme (75 or 225 mg/kg) Q4W, until confirmed disease progression or unacceptable toxicity. Tumor assessments were performed Q8W with immune-related Response Evaluation Criteria in Solid Tumors. Results: In total, 27 and 31 pts received MEDI0562 + durva or treme, across 5 dose combination cohorts (3 + 3 design), with a maximum tolerated dose of 7.5 mg MEDI0652 + 1500 mg durva and maximum administered dose of 10 mg MEDI0562 + 225 mg treme. Median duration of exposure was 12.0 (range 2.0–80.9) and 8.0 (range 2.0–42.0) wks, respectively. Two (22.5 mg MEDI10562 + durva) and 3 (2.25 mg MEDI0652 + 225 mg treme, 22.5 mg MEDI0562 + 75 and 225 mg treme) dose limiting toxicities were observed. For MEDI0562 + durva and MEDI0562 + treme groups respectively, treatment-emergent adverse events (TEAEs) were reported in 96.3% and 100% of pts; most common TEAEs were fatigue (55.6%) and pruritus (45.2%), Gr 3/4 TEAEs occurred in 74.1% and 67.7%; and MEDI0562-related AEs were reported in 20 (74.1%) and 24 (77.4%) pts. Six TEAEs in each group led to MEDI0562 discontinuation (22.2% and 19.4%, respectively), 2 led to death (renal failure [7.5 mg MEDI0562 + durva], multiple organ dysfunction syndrome [22.5 mg MEDI0562 + 225 mg treme]). Three response evaluable pts had PR (11.5% [7.5 and 22.5 mg MEDI0562 + durva, n = 26]). Median overall survival was 17.4 and 11.9 mos for MEDI0562 + durva and MEDI0562 + treme, with stable disease seen in 9 pts from each group, 34.6% vs 29.0%, respectively. Serum exposure of MEDI0562 increased dose proportionally. Post treatment serum antidrug antibody (ADA) was detected in 20 pts from MEDI0562 + durva and MEDI0562 + treme (74.1% and 71.4%, respectively). The impact of ADA on MEDI0562 pharmacokinetics was seen at all doses. Mean percentage of Ki67+CD4+ and Ki67+CD8+ memory T cells increased, while mean percentage of OX40+CD4+ memory T cells decreased following the first dose of MEDI0562 + durva or treme. Conclusions: The safety profile of MEDI0562 in combination with durva or treme was similar between groups. Clinical activity was observed with MEDI0562 + durva in pts with advanced solid tumors. Clinical trial information: NCT02705482 .

Repeatability of Quantitative 18F-DCFPyL PET/CT Measurements in Metastatic Prostate Cancer

Quantitative evaluation of radiolabeled prostate-specific membrane antigen (PSMA) PET scans may be used to monitor treatment response in patients with prostate cancer (PCa). To interpret longitudinal differences in PSMA uptake, the intrinsic variability of tracer uptake in PCa lesions needs to be defined. The aim of this study was to investigate the repeatability of quantitative PET/CT measurements using ¹⁸F-DCFPyL ([2-(3-(1-carboxy-5-[(6-¹⁸F-fluoro-pyridine-3-carbonyl)-amino]-pentyl)-ureido)-pentanedioic acid], a second-generation ¹⁸F-PSMA-ligand) in patients with PCa. Methods: Twelve patients with metastatic PCa were prospectively included, of whom 2 were excluded from final analyses. Patients received 2 whole-body ¹⁸F-DCFPyL PET/CT scans (median dose, 317 MBq; uptake time, 120 min) within a median of 4 d (range, 1-11 d). After semiautomatic (isocontour-based) tumor delineation, the following lesion-based metrics were derived: mean, peak, and maximum tumor-to-blood ratio; SUV_mean, SUV_peak, and SUV_max normalized to body weight; tumor volume; and total lesion uptake (TLU). Additionally, patient-based total tumor volume (TTV) (sum of PSMA-positive tumor volumes) and total tumor burden (TTB) (sum of all lesion TLUs) were derived. Repeatability was analyzed using repeatability coefficients (RC) and intraclass correlation coefficients. Additionally, the effect of point-spread function (PSF) image reconstruction on the repeatability of uptake metrics was evaluated. Results: In total, 36 ¹⁸F-DCFPyL PET-positive lesions were analyzed (≤5 lesions per patient). The RCs for mean, peak, and maximum tumor-to-blood ratio were 31.8%, 31.7%, and 37.3%, respectively. For SUV_mean, SUV_peak, and SUV_max, the RCs were 24.4%, 25.3%, and 31.0%, respectively. All intraclass correlation coefficients were at least 0.97. Tumor volume delineations were quite repeatable, with an RC of 28.1% for individual lesion volumes and 17.0% for TTV. TTB had an RC of 23.2% and 33.4% when based on SUV_mean and mean tumor-to-blood ratio, respectively. Small lesions (<4.2 cm³) had worse repeatability for volume measurements. The repeatability of SUV_peak, TLU, and all patient-level metrics was not affected by PSF reconstruction. Conclusion: ¹⁸F-DCFPyL uptake measurements are quite repeatable and can be used for clinical validation in future treatment response assessment studies. Patient-based TTV may be preferred for multicenter studies because its repeatability was both high and robust to different image reconstructions.

Incidence and risk factors for acute kidney injury in head and neck cancer patients treated with concurrent chemoradiation with high-dose cisplatin

Background

Three-weekly high-dose cisplatin (100 mg/m²) is considered the standard systemic regimen given concurrently with postoperative or definitive radiotherapy in locally advanced squamous cell carcinoma of the head and neck (LA-SCCHN). Concurrent chemoradiation (CRT) with high-dose cisplatin is associated with significant acute and late toxicities, including acute kidney injury (AKI). The aims of this study were to investigate the incidence of AKI in patients with LA-SCCHN during and after treatment with high-dose cisplatin-based CRT, to identify risk factors for cisplatin-induced AKI, and to describe the impact of AKI on long-term renal function and treatment outcomes.

Methods

This is a retrospective cohort study with measurements of renal function before CRT, weekly during CRT, every 1 or 2 days during hospitalizations, and 3 and 12 months after CRT in patients with LA-SCCHN. AKI was defined as increase in serum creatinine (sCr) of ≥1.5 times baseline or by ≥0.3 mg/dL (≥26.5 μmol/L) using the Kidney Disease Improving Global Outcomes (KDIGO) classification. Logistic regression models were estimated to analyze renal function over time and to identify predictors for AKI.

Results

One hundred twenty-four patients completed all measurements. AKI was reported in 85 patients (69%) with 112 episodes of AKI. Sixty of 85 patients experienced 1 AKI episode; 20 patients experienced ≥2 AKI episodes. Ninety-three (83%) AKI episodes were stage 1, 13 (12%) were stage 2, and 6 (5%) AKI episodes were stage 3. Median follow-up time was 29 months (Interquartile Range, IQR 22–33). Hypertension (Odds Ratio, OR 2.7, 95% Confidence Interval, CI 1.1–6.6; p = 0.03), and chemotherapy-induced nausea and vomiting (CINV; OR 4.3, 95% CI 1.6–11.3; p = 0.003) were associated with AKI. In patients with AKI, renal function was significantly more impaired at 3 and 12 months post-treatment compared to patients without AKI. AKI did not have a negative impact on treatment outcomes.

Conclusion

AKI occurred in 69% of patients with LA-SCCHN undergoing CRT with high-dose cisplatin. Long-term renal function was significantly more impaired in patients with AKI. Hypertension and CINV are significant risk factors. Optimizing prevention strategies for CINV are urgently needed.

Sensitivity of 18F-fluorodihydrotestosterone PET-CT to count statistics and reconstruction protocol in metastatic castration-resistant prostate cancer

Objectives

Whole body [¹⁸F]-fluorodihydrotestosterone positron emission tomography ([¹⁸F]FDHT PET) imaging directly targets the androgen receptor and is a promising prognostic and predictive biomarker in metastatic castration-resistant cancer (mCRPC). To optimize [¹⁸F]FDHT PET-CT for diagnostic and response assessment purposes, we assessed how count statistics and reconstruction protocol affect its accuracy, repeatability, and lesion detectability.

Methods

Whole body [¹⁸F]FDHT PET-CT scans were acquired on an analogue PET-CT on two consecutive days in 14 mCRPC patients harbouring a total of 336 FDHT-avid lesions. Images were acquired at 45 min post-injection of 200 MBq [¹⁸F]FDHT at 3 min per bed position. List-mode PET data were split on a count-wise basis, yielding two statistically independent scans with each 50% of counts. Images were reconstructed according to current EANM Research Ltd. (EARL1, 4 mm voxel) and novel EARL2 guidelines (4 mm voxel + PSF). Per lesion, we measured SUVpeak, SUVmax, SUVmean, and contrast-to-noise ratio (CNR). SUV was normalized to dose per bodyweight as well as to the parent plasma input curve integral. Variability was assessed with repeatability coefficients (RCs).

Results

Count reduction increased liver coefficient of variation from 9.0 to 12.5% and from 10.8 to 13.2% for EARL1 and EARL2, respectively. SUVs of EARL2 images were 12.0–21.7% higher than EARL1. SUVs of 100% and 50% count data were highly correlated (R² > 0.98; slope = 0.97–1.01; ICC = 0.99–1.00). Intrascan variability was volume-dependent, and count reduction resulted in higher intrascan variability for EARL2 than EARL1 images. Intrascan RCs were lowest for SUVmean (8.5–10.6%), intermediate for SUVpeak (12.0–16.0%), and highest for SUVmax (17.8–22.2%). Count reduction increased test-retest variance non-significantly (p > 0.05) for all SUV types and normalizations. For SUVpeak at 50% of counts, RCs remained < 30% when small lesions were excluded. Splitting data reduced CNR by median 4.6% (interquartile range 1.2–8.7%) and 4.6% (interquartile range 1.2–8.7%) for EARL1 and EARL2 images, respectively.

Conclusions

Reducing [¹⁸F]FDHT PET acquisition time from 3 min to 1.5 per bed position resulted in a repeatability of SUVpeak (bodyweight) remaining ≤ 30%, which is generally acceptable for response monitoring purposes. However, EARL2 reconstruction was more affected, especially for SUVmax whose repeatability tended to exceed 30%. Lesion detectability was only slightly impaired by reducing acquisition time, which might not be clinically relevant in mCRPC.

Electronic supplementary material

The online version of this article (10.1186/s13550-019-0531-8) contains supplementary material, which is available to authorized users.

Abstract 1801: MicroRNA expression profiling predicts clinical outcome in patients with locally advanced larynx and hypopharynx cancer treated with chemoradiotherapy

Background

For patients with locally advanced larynx and hypopharynx cancer, organ preservation chemoradiotherapy (CRT) protocols are frequently applied. However, some tumors are resistant to CRT or will recur within a short time frame. For these patients upfront surgical resection may result in an improved cure rate. Currently, there are no molecular markers that can predict CRT response. In this study, tumor microRNA (miRNA) profiling was performed to predict clinical outcome in patients with locally advanced larynx or hypopharynx cancer treated with CRT.

Methods

First, matched fresh frozen (FF) and formalin-fixed paraffin-embedded (FFPE) tumor biopsies from 12 patients were profiled by Next Generation Sequencing (NGS) to ensure valid miRNA results from FFPE. Next, miRNA profiles of FFPE tumor biopsies from 37 patients with larynx or hypopharynx cancer, treated with primary CRT, were determined. Clinicopathological data, including response to CRT, tumor stage and nodal stage, was collected of all patients. Differential expression analysis was performed to compare patients with poor clinical outcome, i.e residual tumor after treatment or progression free survival (PFS) &lt; 2 years versus patients with good clinical outcome, i.e. complete response and PFS &gt; 2 years. The median follow up of this cohort was 60 months (range 6 - 118). The Cancer Genome Atlas (TCGA) head and neck miRNA expression data of larynx and hypopharynx tumors and normal squamous cell tissues were used to select tumor specific miRNAs. By group-regularized penalized logistic ridge regression analysis, a model to predict clinical outcome was generated using tumor specific miRNAs combined with clinical covariates.

Results

In total, 324 novel candidate and 2,262 mature miRNAs were detected. A comparative analysis of miRNA profiles generated using matched FF and FFPE tumor biopsies showed a high correlation (mean r2=0.75). Using only FFPE samples, 13 miRNAs were significantly differentially expressed between patients with good versus poor clinical outcome (p&lt;0.05, FDR&lt;0.1). Class prediction resulted in a model of three miRNAs combined with AJCC stage, able to predict recurrence with an area under the curve of 0.83. Further validation of the model is ongoing in an additional cohort of patients with larynx or hypopharynx cancer treated with CRT.

Conclusion

NGS miRNA profiling using FFPE tumor biopsies from patients with head and neck cancer is technically feasible, resulting in high quality miRNA expression data comparable to fresh frozen tissue. Based on miRNA expression profiling, candidate miRNAs were identified predictive for clinical outcome following treatment with CRT. A validation study is ongoing.

Citation Format: Dennis Poel, Francois Rustenburg, Daoud Sie, Hendrik F. van Essen, Paul P. Eijk, Elisabeth Bloemena, Teresita E. Benites, Bauke Ylstra, Brakenhoff H. Ruud, René C. Leemans, Tineke E. Buffart, Henk M. Verheul, Jens Voortman. MicroRNA expression profiling predicts clinical outcome in patients with locally advanced larynx and hypopharynx cancer treated with chemoradiotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1801.

Simplified Methods for Quantification of 18F-DCFPyL Uptake in Patients with Prostate Cancer

Radiolabeled prostate-specific membrane antigen (PSMA) PET has demonstrated promising results for prostate cancer (PCa) imaging. Quantification of PSMA radiotracer uptake is desired as it enables reliable interpretation of PET images, use of PSMA uptake as an imaging biomarker for tumor characterization, and evaluation of treatment effects. The aim of this study was to perform a full pharmacokinetic analysis of 2-(3-(1-carboxy-5-[(6-¹⁸F-fluoro-pyridine-3-carbonyl)-amino]-pentyl)-ureido)-pentanedioic acid (¹⁸F-DCFPyL), a second-generation ¹⁸F-labeled PSMA ligand. On the basis of the pharmacokinetic analysis (reference method), simplified methods for quantification of ¹⁸F-DCFPyL uptake were validated. Methods: Eight patients with metastasized PCa were included. Dynamic PET acquisitions were performed at 0-60 and 90-120 min after injection of a median dose of 313 MBq of ¹⁸F-DCFPyL (range, 292-314 MBq). Continuous and manual arterial blood sampling provided calibrated plasma tracer input functions. Time-activity curves were derived for each PCa metastasis, and ¹⁸F-DCFPyL kinetics were described using standard plasma input tissue-compartment models. Simplified methods for quantification of ¹⁸F-DCFPyL uptake (SUVs; tumor-to-blood ratios [TBRs]) were correlated with kinetic parameter estimates obtained from full pharmacokinetic analysis. Results: In total, 46 metastases were evaluated. A reversible 2-tissue-compartment model was preferred for ¹⁸F-DCFPyL kinetics in 59% of the metastases. The observed k ₄ was small, however, resulting in nearly irreversible kinetics during the course of the PET study. Hence, k ₄ was fixated (0.015) and net influx rate, K_i, was preferred as the reference kinetic parameter. Whole-blood TBR provided an excellent correlation with K_i from full kinetic analysis (R ² = 0.97). This TBR could be simplified further by replacing the blood samples with an image-based, single measurement of blood activity in the ascending aorta (image-based TBR, R ² = 0.96). SUV correlated poorly with K_i (R ² = 0.47 and R ² = 0.60 for SUV normalized to body weight and lean body mass, respectively), most likely because of deviant blood activity concentrations (i.e., tumor tracer input) in patients with higher tumor volumes. Conclusion: ¹⁸F-DCFPyL kinetics in PCa metastases are best described by a reversible 2-tissue-compartment model. Image-based TBRs were validated as a simplified method to quantify ¹⁸F-DCFPyL uptake and might be applied to clinical, whole-body PET scans. SUV does not provide reliable quantification of ¹⁸F-DCFPyL uptake.

Phase I Dose-Escalation Study of Once Weekly or Once Every Two Weeks Administration of High-Dose Sunitinib in Patients With Refractory Solid Tumors

PURPOSE

Dose and schedule optimization of treatment with tyrosine kinase inhibitors is of utmost importance. On the basis of preclinical data, a phase I clinical trial of once weekly or once every 2 weeks administration of high-dose sunitinib in patients with refractory solid malignancies was conducted.

PATIENTS AND METHODS

Patients with advanced cancer refractory to standard treatment were eligible. With use of a standard 3 + 3 phase I design, patients received escalating doses of sunitinib, in 100 mg increments, starting at 200 mg once weekly. In both the once weekly and once every 2 weeks cohorts, 10 more patients were included at the maximum tolerated dose level. Primary end points were safety and tolerability.

RESULTS

Sixty-nine patients with advanced cancer, predominantly colorectal cancer (42%), were treated with this alternative dosing regimen. Maximum tolerated dose was established at 300 mg once weekly and 700 mg once every 2 weeks, resulting in nine- and 18-fold higher maximum plasma concentrations compared with standard dose, respectively. Treatment was well tolerated, with fatigue (81%), nausea (48%), and anorexia (33%) being the most frequent adverse events. The only grade 3 or 4 treatment-related adverse event in 5% or more of patients was fatigue (6%). Sixty-three percent of patients had significant clinical benefit, with a 30% progression-free survival of 5 months or more.

CONCLUSION

Sunitinib administered once weekly at 300 mg or once every 2 weeks at 700 mg is feasible, with comparable tolerability as daily administration. Administration of 700 mg once every 2 weeks can be considered as the most optimal schedule because of the highest maximum plasma concentration being reached. The promising preliminary antitumor activity of this alternative schedule in heavily pretreated patients warrants further clinical evaluation and might ultimately indicate a class characteristic of tyrosine kinase inhibitors.

Efficacy of BGJ398, a Fibroblast Growth Factor Receptor 1-3 Inhibitor, in Patients with Previously Treated Advanced Urothelial Carcinoma with FGFR3 Alterations

BGJ398, a potent and selective pan-FGFR antagonist, was prospectively evaluated in patients with metastatic urothelial carcinoma bearing a diverse array of FGFR3 alterations. Patients (N = 67) who were unable to receive platinum chemotherapy were enrolled. The majority (70.1%) had received two or more prior antineoplastic therapies. BGJ398 was administered orally at 125 mg/day on a 3 weeks on, 1 week off schedule until unacceptable toxicity or progression. The primary endpoint was the response rate. Among 67 patients treated, an overall response rate of 25.4% was observed and an additional 38.8% of patients had disease stabilization, translating to a disease control rate of 64.2%. The most common treatment-emergent toxicities were hyperphosphatemia, elevated creatinine, fatigue, constipation, and decreased appetite. Further examination of BGJ398 in this disease setting is warranted.Significance: BJG398 is active in patients with alterations in FGFR3, resulting in both reductions in tumor volume and stabilization of disease. Our data highlight putative mechanisms of resistance to the agent, which may be useful in following disease status. Cancer Discov; 8(7); 812-21. ©2018 AACR.This article is highlighted in the In This Issue feature, p. 781.

Evaluation of several methodological challenges in circulating miRNA qPCR studies in patients with head and neck cancer

Circulating microRNAs (ci-miRNAs) in blood have emerged as promising diagnostic, prognostic and predictive biomarkers in cancer. Many clinical studies currently incorporate studies that assess ci-miRNAs. Validation of the clinical significance of candidate biomarker miRNAs has proven to be difficult, potentially resulting from vast discrepancies in the detection methodology as well as biological variability. In the current study, the influence of several methodological factors on ci-miRNA detection was evaluated as well as short-term biological variability in patients with head and neck cancer. RNA was isolated from 124 serum and plasma samples originating from patients with head and neck cancer and healthy volunteers. The miRNA levels were measured using RT-qPCR and the influence of pre-analytical factors, different normalization strategies and temporal reproducibility was assessed. RNA carriers improved ci-miRNA detection in serum and plasma specimens. A prolonged pre-processing time correlated with an increased hemolytic index in serum samples only. Hemolysis differentially affected the detection of individual miRNAs. Optimal normalization was achieved using the averaged detection values of spike-in cel-miR-39-3p and endogenous miR-16-5p. Comparing biological replicates from patients with head and neck cancer, the intra-individual miRNA levels were relatively stable (average interval 7 days). Differences in the ci-miRNA detection methodology and limitations of currently used technologies can greatly affect the results and may explain inconsistent outcomes between studies. Prior to the implementation of ci-miRNAs as useful clinical biomarkers, further advances in the standardization of the detection methodology and reduction of technical variability are needed.

A phase 1/2 study of intermittent, high dose sunitinib in patients with advanced solid tumors

2591

Background: Despite widespread clinical integration, refinement of treatment with sunitinib is actively pursued. Sub-therapeutic blood levels rather than true resistance and tumor adaptation through drug accumulation have been accounted as reasons for treatment failure. Based on our preclinical data with high dose sunitinib and prospective analyses supporting the concept of intermittent dosing, we designed a phase 1 trial to investigate the feasibility and tolerability of high dose, once weekly (1w) or once every two weeks (2w) sunitinib (NCT02058901). Methods: Eligible were patients (pts) with advanced solid tumors, refractory to standard treatment, measurable disease, WHO ≤ 1. Sunitinib was administered orally 1w or 2w. Starting dose was 200 mg, with cohorts escalating in 100 mg steps until maximum tolerated dose (MTD). Response was evaluated by RECIST 1.1. Treatment continued until progression or unacceptable toxicity. Dedicated PK sampling was performed. Sunitinib plasma concentration was measured by LC-MS. Results: 34 (w) and 24 (2w) pts were included, predominantly with mCRC [56% (1w) and 55% (2w)]. MTD was set at 300 mg (1w) and 700 mg (2w). Most common adverse events were fatigue (79%, one pt with G3), nausea (71%, all G1-2), anorexia (29%, all G1-2). Median PFS of evaluable pts was 2.7 mo (1w) and 2.6 mo (2w), while 39% pts (1w) and 25% pts (2w) had PFS > 5 mo. CT scans in pts with treatment benefit showed extensive tumor necrosis. Mean sunitinib plasma Cmax was 190 [300 mg (1w), range: 185-295] and 476 ng/mL [(700 mg (2w), range: 323-580]. Accumulation was minimal. Conclusions: Once weekly or once every two weeks, high dose sunitinib is feasible and clinically efficacious in heavily pretreated pts with advanced solid tumors, while toxicity remains well manageable. Importantly, no accumulation was recorded and sunitinib exposure was significantly increased, compared to the universal, flat dose. Since increased sunitinib exposure has been correlated to improved outcome, we consider this alternative scheduling as promising strategy to produce enduring clinical benefit in a wider patient population. Expansion cohorts are ongoing. Clinical trial information: NCT02058901.

Abstract 1621: Short-time exposure to high concentrations of sunitinib causes tumor cell death

Background: Sunitinib, although initially developed as an antiangiogenic agent, has been shown to exert direct anti-tumor effects. Previously we demonstrated that sunitinib inhibits proliferation of various tumor cell lines in a dose-dependent manner. We here studied whether short exposure to high peak concentrations of sunitinib would induce tumor cell death.

Methods: 786-O renal cancer cells were incubated with increasing concentrations of sunitinib (5, 10 and 20 μM) for various time intervals (1 hour, 3, 6, 9, 24, 48, 72 hours). At prespecified time points, sunitinib was removed and cells were subsequently allowed to grow in drug-free culture medium. Viability of these cells one week after short time sunitinib exposure and sensitivity of recovered cells after repetitive treatment with high sunitinib concentrations were determined by MTT assays. Flow cytometry with Propidium Iodide staining was employed to determine apoptosis.

Results: Short-time exposure to high concentrations of sunitinib significantly induced cell death. Exposure to 20 μM of sunitinib for 9 hours provoked cell death in a manner identical to the prolonged exposure of 24, 48 or 72 hours. Flow cytometry confirmed the significant increase in cell death (60%) after 9-hour treatment with 20 μM sunitinib, compared to the untreated control (2%). Tumor cells that were repetitively treated with high concentrations of sunitinib retain their sensitivity to the drug identical to its parental cell line. Analysis of the key signaling pathways involved in sunitinib-induced cell death is ongoing.

Conclusion: We here report that repetitive short-time exposure to high concentration sunitinib causes cell death without inducing resistance. Interestingly, single-dose sunitinib up to 300 mg was previously reported to be well tolerated by patients. Based on these findings, administration of high dose intermittent sunitinib may result in cytotoxic antitumor activity irrespective of angiogenesis inhibition. A phase I trial to test this hypothesis in patients with cancer will start shortly.

Citation Format: Maria Rovithi, Dennis Poel, Jens Voortman, Mariette Labots, Henk Dekker, Kristy J. Gotink, Henk J. Broxterman, Henk M.W. Verheul. Short-time exposure to high concentrations of sunitinib causes tumor cell death. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1621. doi:10.1158/1538-7445.AM2013-1621

Detection and therapeutic implications of c-Met mutations in small cell lung cancer and neuroendocrine tumors

BACKGROUND

We evaluated the mutation status of c-Met in small cell lung cancer (SCLC) and neuroendocrine tumors (NET), for which relatively limited therapeutic targets have been explored.

MATERIALS AND METHODS

c-Met was re-sequenced using cell lines and clinical samples. For in vitro studies, DNA constructs containing a juxtamembrane domain (JMD) and tyrosine kinase domain (TKD) were generated. Detected mutations were introduced into the construct and effects on c-Met phosphorylation and interaction with tyrosine kinase inhibitor drugs BMS777607 and SU11274 were assessed.

RESULTS

97 specimens were analyzed: 13 SCLC and 2 pulmonary carcinoid cell lines, 46 SCLC and 36 NET clinical specimens. Mutations were only detected in the JMD. No mutations were detected in the TKD. Found mutations consisted of the previously reported R988C and T1010I mutations. One novel JMD mutation, P996S, was detected in a SCLC specimen. The mutation rate in SCLC cell lines was 25% (31% including a derivative cell line), and 6.5% in clinical specimens. The mutation rate in NET was 8.3%. In vitro, there were no differences between wild type, R988C or T1010I mutants regarding c-Met phosphorylation at Y1003, located in the JMD, and at Y1234/1235, located in the TKD. BMS777607 and SU11274 were shown to inhibit phosphorylation of c-Met in wild type and R988C and T1010I mutants in a similar fashion.

CONCLUSIONS

In SCLC and neuroendocrine tumors MET mutations are relatively rare. Detected mutations were located in the juxtamembrane domain and were of no functional relevance as they did not influence c-Met phosphorylation, regardless of TKI treatment.

Hepatic morphopathologic findings of lead poisoning in a drug addict: a case report

We describe the case of a 40-year old Iranian man who was admitted to our hospital with severe abdominal pain, abnormal liver function tests and normocytic anemia. Suffering from multiple sclerosis, he was a regular user of opium for pain relief. Basophilic stippling of erythrocytes pointed towards the diagnosis of lead intoxication, the most likely source being contaminated Iranian opium. Serum lead and zinc protoporphyrin levels were strongly elevated. To assess the hepatotoxic effects of lead poisoning a liver biopsy was performed. Pathomorphologic findings of hepatotoxicity, rarely reported in humans, included active hepatitis together with extensive microvesicular and macrovesicular steatosis, hemosiderosis and cholestasis, and a lymphocytic cholangitis. Whilst treated with chelating therapy, liver enzymes returned to normal, suggesting reversibility of the histological findings.

Bortezomib induces schedule-dependent modulation of gemcitabine pharmacokinetics and pharmacodynamics in non-small cell lung cancer and blood mononuclear cells

Bortezomib combination with gemcitabine/cisplatin in patients with advanced tumors, predominantly non-small cell lung cancer (NSCLC), showed an unexpected transient drop in the deoxycytidine plasma levels, a marker for gemcitabine activity. This study investigates the pharmacokinetic/pharmacodynamic effect of bortezomib on gemcitabine in NSCLC and peripheral blood mononuclear cells (PBMC). Gemcitabine metabolites, including difluoro-dCTP (dFdCTP), were studied in PBMCs from bortezomib/gemcitabine/cisplatin-treated patients and from volunteers and NSCLC cells (H460 and SW1573) exposed to 4 h simultaneous or sequential treatments of gemcitabine (50 μmol/L, 4 h) and bortezomib (100 nmol/L, 2 h). Gemcitabine total phosphate levels measured by liquid chromatography-tandem mass spectrometry in PBMCs from bortezomib/gemcitabine/cisplatin-treated patients were strongly reduced after 90 min (-82.2%) up to 4 h post-gemcitabine infusion compared with gemcitabine/cisplatin-treated patients. Accordingly, bortezomib/gemcitabine combinations reduced dFdCTP in PBMCs treated ex vivo. Surprisingly, differential effects were observed in NSCLC cells. dFdCTP decreased after 4 h following gemcitabine removal in H460 but continued to increase for 24 h in SW1573. However, dFdCTP significantly increased (2-fold) in both cell lines in the bortezomib → gemcitabine exposure, coinciding with a major reduction in cell growth compared with single drugs, and the highest increase of deoxycytidine kinase expression, possibly mediated via E2F-1. Bortezomib affects differently gemcitabine pharmacokinetics/pharmacodynamics in PBMCs and NSCLC cells, suggesting that PBMCs are not adequate to evaluate the anticancer activity of bortezomib/gemcitabine combinations. The bortezomib → gemcitabine/cisplatin schedule appeared a safe and active combination for the treatment of advanced NSCLC and the bortezomib → gemcitabine was the most cytotoxic combination in NSCLC cells. The increase of deoxycytidine kinase and dFdCTP might contribute to this synergistic interaction and supports its further clinical investigation.

TRAIL therapy in non-small cell lung cancer cells: sensitization to death receptor-mediated apoptosis by proteasome inhibitor bortezomib

Activation of the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) receptor pathway is a promising therapeutic strategy to selectively eradicate cancer cells, including non-small cell lung cancer (NSCLC) cells. Recombinant human (rh) TRAIL/Apo-2L, a TRAIL-encoding adenovirus, and monoclonal antibodies directed against TRAIL receptors R1 and R2 were used to study cytotoxicity of TRAIL therapy in NSCLC cells. NSCLC cells showed differential sensitivity to TRAIL therapy, regardless of the agent used. Combination treatment of bortezomib and rhTRAIL led to synergistic apoptosis induction in NSCLC cell lines. Enhancement of rhTRAIL-induced apoptosis by bortezomib was caspase dependent, implicating extrinsic as well as intrinsic apoptosis activation, as shown by increased processing of caspase-8 as well as caspase-9, and could be abrogated completely by overexpression of caspase-8 inhibitor cytokine response modifier A (CrmA), and partially by overexpression of Bcl-2. Enhanced surface expression of TRAIL-R2, but also TRAIL-R1, was associated with bortezomib treatment, which is likely to contribute to the increased processing of caspase-8 in the combination treatment. Furthermore, TRAIL-induced activation of prosurvival transcription factor nuclear factor-kappaB was prevented by cotreatment with bortezomib, which may contribute to the observed synergistic apoptosis induction. Our preclinical data indicate that combination therapy of TRAIL and bortezomib may be an effective strategy for NSCLC.

Bortezomib, but not cisplatin, induces mitochondria-dependent apoptosis accompanied by up-regulation of noxa in the non-small cell lung cancer cell line NCI-H460

Defects in the apoptotic machinery may contribute to chemoresistance of non-small cell lung cancer (NSCLC) cells. We have previously showed a deficiency in mitochondria-dependent caspase-9 activation in NSCLC H460 cells after exposure to cisplatin, a drug widely used to treat NSCLC. Here we show that, unlike cisplatin, the novel anticancer agent bortezomib efficiently induces caspase-9 activation and apoptosis in H460 cells. A comparative analysis of molecular events underlying cell death in bortezomib-treated versus cisplatin-treated H460 cells revealed that bortezomib, but not cisplatin, caused a rapid and abundant release of cytochrome c and Smac/DIABLO from mitochondria. This was associated with a marked increase in levels of the BH3-only proapoptotic protein Noxa and the antiapoptotic protein Mcl-1. Taken together, our data show that bortezomib, by promoting a proapoptotic shift in the levels of proteins involved in mitochondrial outer-membrane permeabilization, is a potent activator of the mitochondrial pathway of apoptosis in NSCLC cells. Our preclinical results support further investigation of bortezomib-based therapies as a possible new treatment modality for NSCLC.

A Parallel Dose-Escalation Study of Weekly and Twice-Weekly Bortezomib in Combination with Gemcitabine and Cisplatin in the First-Line Treatment of Patients with Advanced Solid Tumors

PURPOSE

To establish maximum tolerated dose (MTD) and tolerability of two schedules of bortezomib in combination with cisplatin and gemcitabine as first-line treatment of patients with advanced solid tumors.

EXPERIMENTAL DESIGN

Patients were assigned to increasing doses of bortezomib days 1 and 8 (weekly schedule) or days 1, 4, 8, and 11 (twice-weekly schedule), in addition to gemcitabine 1,000 mg/m(2) days 1 and 8 and cisplatin 70 mg/m(2) day 1, every 21 days. Maximum of six cycles. Plasma pharmacokinetics of cisplatin and gemcitabine were determined at MTD.

RESULTS

Thirty-four patients were enrolled of whom 27 had non-small cell lung cancer (NSCLC). Diarrhea, neutropenia, and thrombocytopenia were dose-limiting toxicities leading to an MTD of bortezomib 1.0 mg/m(2) in the weekly schedule. Febrile neutropenia and thrombocytopenia with bleeding were dose-limiting toxicities in the twice-weekly schedule, leading to an MTD of bortezomib 1.0 mg/m(2) as well. Most common > or =grade 3 treatment-related toxicities were thrombocytopenia and neutropenia. No grade > or =3 treatment-related sensory neuropathy was reported. Of 34 evaluable patients, 13 achieved partial responses, 17 stable disease, and 4 progressive disease. Response and survival of NSCLC patients treated with twice weekly or weekly bortezomib were similar. However, increased dose intensity of bortezomib led to increased gastrointestinal toxicity as well as myelosuppression. Pharmacokinetic profiles of cisplatin and gemcitabine were not significantly different in patients receiving either schedule.

CONCLUSIONS

Weekly bortezomib 1.0 mg/m(2) plus gemcitabine 1,000 mg/m(2) and cisplatin 70 mg/m(2) is the recommended phase 2 schedule, constituting a safe combination, with activity in NSCLC.

Severe reversible cardiac failure after bortezomib treatment combined with chemotherapy in a non-small cell lung cancer patient: a case report

BACKGROUND

Bortezomib (Velcade), a dipeptide boronate proteasome inhibitor, is a novel anti-cancer agent registered for multiple myeloma (MM). It has also shown promising clinical activity in non-small cell lung cancer (NSCLC). Clinical experience with bortezomib so far indicates that overall incidence of cardiac failure associated with bortezomib therapy remains incidental. Nevertheless, acute development or exacerbation of congestive cardiac failure has been associated with bortezomib treatment.

CASE PRESENTATION

We present here a case of severe, but reversible, congestive cardiac failure in a lung cancer patient who had no prior cardiac history, after receiving an experimental treatment of bortezomib combined with chemotherapy. Elevated levels of N-terminal pro-B-type natriuretic peptide (NT-proBNP), as retrospectively measured in archived serum samples, were suggestive of pre-existent (sub-clinical) left ventricular dysfunction.

CONCLUSION

Based on literature, we hypothesize that baseline presence of sub clinical cardiomyopathy, characterized by a dysregulation of the ubiquitin-proteasome system, could have predisposed this patient for a cardiac side effect induced by systemic proteasome inhibition. Patients with heart disease or risk factors for it should be closely monitored when being submitted to treatment with proteasome inhibition therapy such as bortezomib. Caution is therefore warranted in lung cancer patients who often present with cardiac comorbidities.

Tetraspanin CD82 regulates compartmentalisation and ligand-induced dimerization of EGFR

We have previously shown that CD82, a transmembrane protein of the tetraspanin superfamily is associated with EGFR and has a negative effect on EGF-induced signalling (Odintsova, E., Sugiura, T. and Berditchevski, F. (2000) Curr. Biol. 10, 1009-1012). Here we demonstrate that CD82 specifically attenuates ligand-induced dimerization of EGFR. The recombinant soluble large extracellular loop of CD82 has no effect on the dimerization thereby suggesting that other parts of the protein are required. Although CD82 is also associated with ErbB2 and ErbB3, ligand-induced assembly of the ErbB2-ErbB3 complexes is not affected in CD82-expressing cells. Furthermore, in contrast to the CD82-EGFR association, CD82-ErbB2 and CD82-ErbB3 complexes are stable in the presence of ErbB3 ligand. The effect of CD82 on the formation of EGFR dimers correlates with changes in compartmentalisation of the ErbB receptors on the plasma membrane. Expression of CD82 causes a significant increase in the amount of EGFR and ErbB2 in the light fractions of the sucrose gradient. This correlates with the increased surface expression of gangliosides GD1a and GM1 and redistribution of GD1a and EGFR on the plasma membrane. Furthermore, in CD82-expressing cells GD1a is co-localised with EGFR and the tetraspanin. Taken together our results offer a molecular mechanism of the attenuating activity of CD82 towards EGFR, whereby GD1a functions as a mediator of CD82-dependent compartmentalisation of the receptor.