Atezolizumab and chemotherapy for advanced or recurrent endometrial cancer (AtTEnd): a randomised, double-blind, placebo-controlled, phase 3 trial.

BACKGROUND: At the time of AtTEnd trial design, standard treatment for advanced or recurrent endometrial cancer included carboplatin and paclitaxel chemotherapy. This trial assessed whether combining atezolizumab with chemotherapy might improve outcomes in this population. METHODS: AtTEnd was a multicentre, double-blind, randomised, placebo-controlled, phase 3 trial done in 89 hospitals in 11 countries across Europe, Australia, New Zealand, and Asia. Enrolled patients were aged 18 years or older, and had advanced or recurrent endometrial carcinoma or carcinosarcoma, an Eastern Cooperative Oncology Group performance status of 0-2, and received no previous systemic chemotherapy for recurrence. Patients were randomly assigned (2:1) using an interactive web response system (block size of six) to either atezolizumab 1200 mg or placebo given intravenously with chemotherapy (carboplatin at area under the curve of 5 or 6 and paclitaxel 175 mg/m2 intravenously on day 1 every 21 days) for 6-8 cycles, then continued until progression. Stratification factors were country, histological subtype, advanced or recurrent status, and mismatch repair (MMR) status. Participants and treating clinicians were masked to group allocation. The hierarchically tested co-primary endpoints were progression-free survival (in patients with MMR-deficient [dMMR] tumours, and in the overall population) and overall survival (in the overall population). Primary analyses were done in the intention-to-treat population, defined as all randomly assigned patients who gave their full consent to participation in the study and data processing. Safety was assessed in all patients included in the intention-to-treat population who received at least one dose of study treatment. Here, we report the primary progression-free survival and the interim overall survival results. This study is ongoing and is registered with ClinicalTrials.gov, NCT03603184. FINDINGS: Between Oct 3, 2018, and Jan 7, 2022, 551 patients were randomly assigned to atezolizumab (n=362) or placebo (n=189). Two patients in the atezolizumab group were excluded from all analyses due to lack of consent. Median follow-up was 28·3 months (IQR 21·2-37·6). 81 (23%) patients in the atezolizumab group and 44 (23%) patients in the placebo group had dMMR disease by central assessment. In the dMMR population, median progression-free survival was not estimable (95% CI 12·4 months-not estimable [NE]) in the atezolizumab group and 6·9 months (6·3-10·1) in the placebo group (hazard ratio [HR] 0·36, 95% CI 0·23-0·57; p=0·0005). In the overall population, median progression-free survival was 10·1 months (95% CI 9·5-12·3) in the atezolizumab group and 8·9 months (8·1-9·6) in the placebo group (HR 0·74, 95% CI 0·61-0·91; p=0·022). Median overall survival was 38·7 months (95% CI 30·6-NE) in the atezolizumab group and 30·2 months (25·0-37·2) in the placebo group (HR 0·82, 95% CI 0·63-1·07; log-rank p=0·048). The p value for the interim analysis of overall survival did not cross the stopping boundary; therefore, the trial will continue until the required number of events are recorded. The most common grade 3-4 adverse events were neutropenia (97 [27%] of 356 patients in the atezolizumab group vs 51 [28%] of 185 in the placebo group) and anaemia (49 [14%] vs 24 [13%]). Treatment-related serious adverse events occurred in 46 (13%) patients in the atezolizumab group and six (3%) patients in the placebo group. Treatment-related deaths occurred in two patients (pneumonia in one patient in each group). INTERPRETATION: Atezolizumab plus chemotherapy increased progression-free survival in patients with advanced or recurrent endometrial carcinoma, particularly in those with dMMR carcinomas, suggesting the addition of atezolizumab to standard chemotherapy as first-line treatment in this specific subgroup. FUNDING: F Hoffmann-La Roche.

Specific microRNA signatures in exosomes of triple-negative and HER2-positive breast cancer patients undergoing neoadjuvant therapy within the GeparSixto trial.

BACKGROUND: The focus of this study is to identify particular microRNA (miRNA) signatures in exosomes derived from plasma of 435 human epidermal growth factor receptor 2 (HER2)-positive and triple-negative (TN) subtypes of breast cancer (BC). METHODS: First, miRNA expression profiles were determined in exosomes derived from the plasma of 15 TNBC patients before neoadjuvant therapy using a quantitative TaqMan real-time PCR-based microRNA array card containing 384 different miRNAs. Forty-five miRNAs associated with different clinical parameters were then selected and mounted on microRNA array cards that served for the quantification of exosomal miRNAs in 435 BC patients before therapy and 20 healthy women. Confocal microscopy, Western blot, and ELISA were used for exosome characterization. RESULTS: Quantification of 45 exosomal miRNAs showed that compared with healthy women, 10 miRNAs in the entire cohort of BC patients, 13 in the subgroup of 211 HER2-positive BC, and 17 in the subgroup of 224 TNBC were significantly deregulated. Plasma levels of 18 exosomal miRNAs differed between HER2-positive and TNBC subtypes, and 9 miRNAs of them also differed from healthy women. Exosomal miRNAs were significantly associated with the clinicopathological and risk factors. In uni- and multivariate models, miR-155 (p = 0.002, p = 0.003, respectively) and miR-301 (p = 0.002, p = 0.001, respectively) best predicted pathological complete response (pCR). CONCLUSION: Our findings show a network of deregulated exosomal miRNAs with specific expression patterns in exosomes of HER2-positive and TNBC patients that are also associated with clinicopathological parameters and pCR within each BC subtype.

Identification and Characterization of Cancer Cells That Initiate Metastases to the Brain and Other Organs.

Specific biological properties of those circulating cancer cells that are the origin of brain metastases (BM) are not well understood. Here, single circulating breast cancer cells were fate-tracked during all steps of the brain metastatic cascade in mice after intracardial injection over weeks. A novel in vivo two-photon microscopy methodology was developed that allowed to determine the specific cellular and molecular features of breast cancer cells that homed in the brain, extravasated, and successfully established a brain macrometastasis. Those BM-initiating breast cancer cells (BMIC) were mainly originating from a slow-cycling subpopulation that included only 16% to 20% of all circulating cancer cells. BMICs showed enrichment of various markers of cellular stemness. As a proof of principle for the principal usefulness of this approach, expression profiling of BMICs versus non-BMICs was performed, which revealed upregulation of NDRG1 in the slow-cycling BMIC subpopulation in one BM model. Here, BM development was completely suppressed when NDRG1 expression was downregulated. In accordance, in primary human breast cancer, NDRG1 expression was heterogeneous, and high NDRG1 expression was associated with shorter metastasis-free survival. In conclusion, our data identify temporary slow-cycling breast cancer cells as the dominant source of brain and other metastases and demonstrates that this can lead to better understanding of BMIC-relevant pathways, including potential new approaches to prevent BM in patients. IMPLICATIONS: Cancer cells responsible for successful brain metastasis outgrowth are slow cycling and harbor stemness features. The molecular characteristics of these metastasis-initiating cells can be studied using intravital microscopy technology.

Lack of an immune response against the tetracycline-dependent transactivator correlates with long-term doxycycline-regulated transgene expression in nonhuman primates after intramuscular injection of recombinant adeno-associated virus.

We previously documented persistent regulation of erythropoietin (Epo) secretion in mice after a single intramuscular (i.m.) injection of a recombinant adeno-associated virus (rAAV) vector harboring both the tetracycline-dependent transactivator (rtTA) and the Epo cDNA (D. Bohl, A. Salvetti, P. Moullier, and J. M. Heard, Blood 92:1512-1517, 1998). Using the same vector harboring the cynomolgus macaque Epo cDNA instead, the present study evaluated the ability of the tetracycline-regulatable (tetR) system to establish long-term transgene regulation in nonhuman primates. The vector was administered i.m., after which 5-day induction pulses were performed monthly for up to 13 months by using doxycycline (DOX), a tetracycline analog. We show that initial inductions were successful in all individuals and that there was a tight regulation and a rapid deinduction pattern upon DOX withdrawal. For one macaque, regulation of Epo secretion was maintained during the entire experimental period; for the five remaining macaques, secreted Epo became indistinguishable from endogenous Epo upon repeated DOX inductions. We investigated the mechanism involved and showed that, except in the animal in which secretion persisted, delayed humoral and cellular immune responses were directed against the rtTA transactivator protein associated with the reduction of vector DNA in transduced muscles. This study provides some evidence that, when the immune system is not mobilized against the rtTA transactivator, the tetR-regulatable system is able to support long-term transgene regulation in the context of an rAAV in nonhuman primates. In addition, our results suggest potential improvements for vector design.