Purpose: Neuroendocrine prostate cancer (NEPC) is an aggressive form of prostate cancer with poor prognosis and limited treatment options. As NEPC aberrantly expresses delta-like ligand 3 (DLL3), the activity of tarlatamab, a bispecific T-cell engager (BiTE®) that directs cytotoxic T cells to DLL3‑positive (DLL3+) cells, was evaluated in the DeLLpro-300 study (NCT04702737). Patients and methods: This was a phase 1b, open-label study evaluating tarlatamab monotherapy in patients with metastatic de novo or treatment-emergent NEPC defined by histologic, genomic, or immunohistochemistry (IHC) criteria. Tarlatamab was administered intravenously every 2 weeks at a dose of 100 mg with a 1-mg step dose. The primary objective was safety, and a secondary objective was objective response rate (ORR) per RECIST v.1.1; DLL3 expression was retrospectively assessed by IHC. Results: Forty patients were enrolled (DLL3+ tumors, n=18; DLL3- tumors, n=14; DLL3 unknown tumors, n=8). The most common treatment-related adverse events were cytokine release syndrome (CRS; 82.5%), dysgeusia (42.5%), and decreased appetite (40.0%). CRS was predominantly low grade (grade 1/2/3/4+, 62.5%/15%/5%/0%), occurred exclusively in cycle 1, and was transient in duration (median duration, 3 days). ORR was 10.5% (95% CI, 2.9–24.8); the median duration of response was 7.3 months in the overall cohort. Patients with DLL3+ tumors (vs patients with DLL3-/DLL3 unknown tumors) acheived a higher ORR (22.2% [95% CI, 6.4–47.6] vs 0% [95% CI, 0–15.4]) and radiographic progression-free survival rate at 6 months (27.7% [95% CI, 8.7–50.9] vs 0%). Conclusions: The DeLLpro-300 study provides preliminary evidence for the safety and antitumor activity of tarlatamab in DLL3+ NEPC.

Androgen receptor (AR) signaling remains crucial in castration-resistant prostate cancer (CRPC). Since it is also essential in immune cells, we studied whether the expression of AR full-length (ARFL) and its splicing variant ARV7 in peripheral blood mononuclear cells (PBMC) predicts systemic treatment response in mCRPC in comparison with circulating-tumor cells (CTC). We measured ARFL and ARV7 mRNA in PBMC and CTC from patients prior to receiving abiraterone (AA), enzalutamide (E), or taxanes by a pre-amplification plus quantitative reverse-transcription PCR. They were also tested in LNCaP-ARV7-transfected and in 22RV1 docetaxel-resistant (22RV1DR) cells. We studied 171 PBMC from 136 patients and from 24 non-cancer controls, and 47 CTC from 22 patients. High PBMC ARV7 levels correlated with worse AA/E and better taxane response. In taxane-treated patients high PBMC ARFL also correlated with longer progression-free survival (PFS). High ARV7 and ARFL expression were independently associated with better biochemical-PFS. Conversely, high CTC ARV7 and ARFL correlated with shorter radiological-PFS and overall survival, respectively. High ARV7 in 22RV1DR and LNCaP-ARV7 cells correlated with taxane resistance. In conclusion, ARFL and ARV7 at PBMC or CTC have a different predictive role in the taxane response, suggesting a potential influence of the AR pathway from PBMC in such response modulation.

Direct stimulation of the antitumor activity of immune system through checkpoint inhibitors (ICIs) has demonstrated efficacy in the treatment of different cancer types. The activity of these antibodies takes place in the immunological synapse blocking the binding of the negative immunoregulatory proteins, thus leading to the finalization of the immune response. Despite having a favorable toxicity profile, its mechanism of action impedes the negative regulation of the immune activity which can potentially favor autoimmune attacks to normal tissues. Renal toxicity has been described in several ICI but not with atezolizumab, an IgG1 monoclonal antibody targeting PD-L1 (programmed death ligand 1), approved by FDA as a second-line therapy for advanced urothelial carcinoma. Here we present a patient with a single kidney and metastatic renal cell carcinoma treated with atezolizumab and bevacizumab combination, with biopsy-proven acute interstitial nephritis, who had a complete resolution of renal dysfunction after steroid therapy.

Alterations in the tumor suppressor genes (TSGs) RB1, PTEN, and TP53 are associated with treatment resistance, worse survival, and aggressive variants of prostate cancer (AVPC). We previously developed and validated a signature reflecting low TSG expression (TSG_low) that was associated with poor outcomes in patients with metastatic hormone-sensitive prostate cancer (mHSPC) treated with androgen deprivation therapy (ADT) ± docetaxel. The aim of this multicenter retrospective study was to validate the TSG_low signature in patients with mHSPC treated with ADT and an androgen receptor pathway inhibitor (ARPI) and to explore clinical characteristics at progression according to TSG status. TSG mRNA expression in formalin-fixed, paraffin-embedded samples was assessed via nCounter. Correlation of expression levels with castration-resistant prostate cancer–free survival (CRPC-FS; primary endpoint) and overall survival (OS) was investigated via Kaplan-Meier and multivariate Cox analyses. Of the 137 patients included, 77.4% had de novo stage IV cancer and 44.5% had high-risk disease. TSG_low (16.8%) was correlated with visceral metastases (p = 0.013), high-risk disease (p = 0.038), higher Gleason score (p = 0.026), shorter CRPC-FS (hazard ratio 1.9; p = 0.046) and higher AVPC frequency (p = 0.01). Our results confirm that a TSG_low signature is an adverse prognostic factor and is associated with AVPC development in patients with mHSPC treated with ADT + ARPI. Further prospective validation is needed to define specific therapeutic strategies for these patients. We looked at outcomes for patients with metastatic hormone-sensitive prostate cancer treated with hormone therapies. We found that patients with low expression of two out of three tumor suppressor genes (TP53, RB1, PTEN) had worse clinical outcomes and had aggressive variants of prostate cancer. Measuring the expression of these genes in early-stage prostate cancer could help in finding better treatments for these patients.

Androgen deprivation therapy (ADT) with docetaxel (D) and/or antiandrogen receptor therapies (ARTs) are the standard therapies in metastatic hormone-sensitive prostate cancer (mHSPC). Alterations in the tumor suppressor genes (TSGs) RB1, PTEN, and TP53 are associated with an aggressive evolution and treatment resistance in castration-resistant prostate cancer (CRPC). To study the clinical implications of TSG mRNA expression in mHSPC patients. This is a multicenter retrospective biomarker study in mHSPC patients. TSG_low status was defined when two or more out of the three TSGs presented low RNA expression by nCounter in formalin-fixed paraffin-embedded samples and TSG_wt for the remaining cases. The microarray data from the CHAARTED trial were analyzed as an independent validation cohort. Molecular data were correlated with CRPC-free survival (CRPC-FS) and overall survival (OS) by the Kaplan-Meier method and multivariate Cox analysis. A total of 226 patients were included, of whom 218 were eligible: 93 were treated with ADT and 125 with ADT + D; 75.7% presented de novo stage IV and 67.9% high-volume disease. TSG_low (19.2%) was independently correlated with shorter CRPC-FS (hazard ratio [HR] 1.8, p = 0.002) and OS (HR 2, p = 0.002). In the CHAARTED trial, TSG_low was independently correlated with lower CRPC-FS (HR 2.2, p = 0.02); no differences in clinical outcomes according to treatment were observed in TSG_low patients, while a significant benefit was observed for ADT + D in the TSG_wt group for CRPC-FS (HR 0.4, p < 0.001) and OS (HR 0.4, p = 0.001). However, no interaction was observed between TSG signature and treatment in either series. Study limitations are the retrospective design, small sample size, and lack of inclusion of patients treated with ADT + ART. TSG_low expression correlates with adverse outcomes in patients with mHSPC. The investigation of new therapeutic strategies in these patients is warranted. The low RNA expression of tumor suppressor genes in the tumors is correlated with adverse outcomes in patients with metastatic hormone-sensitive prostate cancer.

Altered metabolism is a hallmark of cancer. Malignant cells metabolise glutamine to fulfil their metabolic needs. In prostate cancer, androgen receptor signalling promotes glutamine metabolism, which is also involved in cholesterol homeostasis. We aimed to determine whether the plasma glutamine levels correlate with the blood lipid profile, clinical characteristics and outcomes in patients with metastatic castration resistance prostate cancer (mCRPC) undergoing taxanes. We retrospectively assessed the glutamine and glutamate levels in plasma samples by a bioluminescent assay. Pre-treatment glutamine, glutamate, cholesterol and triglycerides levels were correlated with patients’ clinical characteristics, taxanes response and clinical outcomes. Seventy-five patients with mCRPC treated with taxanes were included. The plasma glutamine levels were significantly higher in patients that received abiraterone or enzalutamide prior to taxanes (p = 0.003). Besides, patients with low glutamine levels were more likely to present a PSA response to taxanes (p = 0.048). Higher glutamine levels were significantly correlated with shorter biochemical/clinical progression-free survival (PSA/RX-PFS) (median 2.5 vs. 4.2 months; p = 0.048) and overall survival (OS) (median 12.6 vs. 20.3; p = 0.008). High cholesterol levels independently predicted early PSA/RX-PFS (p = 0.034). High glutamine and cholesterol in the plasma from patients with mCRPC were associated with adverse clinical outcomes, supporting the relevance of further research on metabolism in prostate cancer progression.