Clinical results of PERICLES: A phase II trial investigating atezolizumab +/- radiotherapy for advanced squamous cell carcinoma of the penis

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Background: Patients (Pts) with advanced squamous cell carcinoma of the penis (aPeCa) have a poor prognosis (21% 2-year overall survival from moment of diagnosis) and high morbidity, due to progressive locoregional disease. Pre-clinical studies show high rates of infiltrating immune cells and high PD-L1 expression, suggesting that immunotherapy may be beneficial for these patients. In the PERICLES study, we assess the activity of atezolizumab (atezo) in aPeCa pts, with or without radiotherapy (RT) to control locoregional lymph node disease. Methods: A single-centre phase 2 study with two treatment arms (non-randomized) was conducted in 32 histologically confirmed aPeCa pts with a WHO performance status of 0-1 (NCT03686332). Any previous treatment except for immunotherapy was allowed. Study treatment consisted of atezo 1200 mg every 3 weeks (all pts). Pts expected to benefit from RT for locoregional disease control (cohort A) additionally received 33 fractions of 1.5 Gy (locoregional affected lymph node regions and penile region) and 1.8 Gy (macroscopic tumor + margin) irradiation. Response was evaluated with 12-weekly CT scans of the abdomen and thorax using RECIST1.1. Toxicity was scored by NCI-CTCAE V4. The primary endpoint was 1-year progression free survival (PFS) for the full cohort. Results: From Oct 2018 to Aug 2021, 20 pts were included in cohort A (RT + atezo) and 12 pts in cohort B (only atezo). Median follow-up was 22 months (interquartile range (IQR) 4.3-14). Median age was 67 years (IQR 60-72) and all patients had stage IV aPeCa. Pts received no prior treatment (25%), or prior RT (34%), chemoradiation (22%), chemotherapy (6%) or surgery (69%). An immunotherapy or radiotherapy-related grade 3-4 AE was observed in 3/32 (9.4%) and 1/20 (5.0%) patients, respectively. There were no grade 5 treatment-related AEs. One-year PFS was 12% (95% confidence interval (CI) 4.0-33), which did not meet the primary objective. The response rate of RECIST1.1 evaluable pts was 30% (see table). In two patients with pulmonary metastases, a complete response was observed. Initial responses with early progression were seen in 5 pts. Median overall survival (OS) was 12 months (95% CI 5.4-19). Conclusions: Anti-tumor activity of atezo was observed in aPeCa, including complete and durable responses. The trial failed to meet its primary objective (PFS). Our results suggest that a subset of aPeCa pts has incomplete immunological activity and/or early resistance to atezo. Analysis of tumor tissue collected in this trial (including on-treatment biopsies) could suggest new therapeutic strategies to overcome resistance and improve clinical outcome to immunotherapy in aPeCa. Clinical trial information: NCT03686332. [Table: see text]

First results from a randomized phase II study of cabazitaxel (CBZ) versus an androgen receptor targeted agent (ARTA) in patients with poor-prognosis castration-resistant prostate cancer (mCRPC)

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Background: In the OSTRICh trial, poor-prognosis mCRPC patients were randomized between CBZ and ARTA, following progression on docetaxel (DOC) treatment. Methods: The OSTRICh trial is an open label, multicenter, phase IIb study. Patients with poor-prognosis mCRPC (visceral metastases AND/OR < 12 months responsive to androgen deprivation AND/OR progressing during or within 6 months after DOC completion), were randomized 1:1 between CBZ (25 mg/m2 IV Q3W and prednisone 2 d 5 mg PO) and ARTA (daily abiraterone 1000 mg and prednisone 2 d 5 mg PO OR enzalutamide 160 mg PO). Life prolonging therapy between DOC and randomization was not allowed. Primary endpoint was to establish the Clinical Benefit Rate (no radiotherapy, no ECOG PS increase ≥2, no change of therapy AND no radiological progression) at 12 weeks (CBR) in the study arms, while formal comparison of the CBR was a secondary endpoint. A Fisher Exact test was used to assess differences in rates and a log rank test to assess differences in progression free and overall survival. All time to event endpoints were estimated with the Kaplan-Meier method and censored at last follow-up. Results: A total of 106 patients were randomized, 53 in each arm. Baseline median age was 70 (IQR 67-75) years and PSA 79.4 (IQR 29.0 - 160) ng/ml. ECOG PS score was 0/1 in 99 (93%) and 2 in 7 (7%) patients. Al patients fulfilled the criteria for poor-prognosis disease. Thirty-six (34%) patients received DOC in the metastatic hormone sensitive stage, while 41 (39%) previously received ARTA. Twenty-six of 43 evaluable patients in the CBZ arm had clinical benefit at 12 weeks (CBR: 60%, 95% CI: 44%-75%) and 20 of 39 (CBR: 51%, 95% CI: 35%-68%) in the ARTA arm (p = 0.50). At 12 weeks, 30 of 34 (88%, 95% CI: 73% - 97%) patients in the CBZ arm and 24 of 36 (67%, 95% CI: 49% - 81%) patients in the ARTA arm had no radiological progression (p = 0.046). After a median follow-up of 16.4 months (95% CI: 13.6–27.8), a serum PSA decrease ≥50% from baseline was established in 12 (23%, 95% CI: 12% - 36%) and 26 (49%, 95% CI: 35% - 63%)(p = 0.008) patients treated with CBZ and ARTA, respectively. Median radiological progression free survival (rPFS) was 6.0 months (95%CI: 4.11-14.5) in the CBZ arm and 5.8 months (95% CI: 5.22-10.2) months in the ARTA arm (p = 0.5), while median overall survival (OS) was 15.3 months (95%CI 9.49-22.4) and 13.8 months (95%CI 11.7-16.4) in CBZ and ARTA treated patients, respectively (p = 0.8). Grade ≥3 adverse events (AEs) occurred in 15 (29%) and 8 (15%) of patients treated with CBZ and ARTA, respectively. Conclusions: No significant difference in CBR was established between CBZ and ARTA treated patients. However, at 12 weeks significantly more CBZ treated patients had no radiological progression, while ≥50% PSA response rates were higher in ARTA treated patients. Clinical trial information: NCT03295565.

Biomarker analysis and updated clinical follow-up of preoperative ipilimumab (ipi) plus nivolumab (nivo) in stage III urothelial cancer (NABUCCO)

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Background: Encouraging pathological complete response (pCR) rates were observed in trials testing neoadjuvant pembrolizumab or atezolizumab in urothelial cancer (UC). In cT3-4N0 tumors, pCR to atezolizumab was only 17% and restricted to tumors showing characteristics of preexisting T cell immunity. In NABUCCO, we aimed to increase response to pre-operative checkpoint blockade, particularly in high risk patients (pts), by combining ipi plus nivo in stage III UC. We previously reported pCR in 46% and downstaging to no remaining invasive disease in 58% (ESMO2019). Here, we present biomarker analyses and updated clinical follow-up (FU) data. Methods: Twenty four stage III (cT3-4aN0 or cT2-4aN1-3) UC pts who were unfit to receive cisplatin-based chemotherapy or refused, were treated with ipi 3 mg/kg (day 1), ipi 3 mg/kg + nivo 1 mg/kg (day 22), and nivo 3 mg/kg (day 43), followed by resection. The primary endpoint was feasibility (resection < 12 weeks). Efficacy (pCR), safety and biomarker analysis were secondary endpoints. Whole-exome sequencing (WES) was done on baseline tumor samples and local lymph node (LN) metastases showing no response. RNA-seq and multiplex immunofluorescence (mIF) for immune cell markers were done pre- and post-therapy. Results: After a median FU of 15.6 months, 2 pts relapsed (both non-pCR); 1 of these 2 pts died of metastatic disease. Tumors showing complete response (CR, for biomarker analysis defined as pCR, CIS or pTa) had a significantly higher tumor mutational burden than non-CR tumors. CR to ipi+nivo was independent of baseline CD8 T-cell presence. There was no difference between CR and non-CR tumors in baseline immune gene signatures, such as interferon gamma and T-effector signatures. Surprisingly, exploratory gene expression analysis revealed that non-CR was associated with a baseline B cell immune signature, particularly immunoglobulins and genes involved in B cell receptor signaling. CD20 positive cells (by mIF) and presence of tertiary lymphoid structures (TLS) at baseline were also associated with non-CR. Upon treatment with ipi+nivo, early and mature TLS increased significantly in responding tumors. A subset of pts showed CR in the bladder, but non-CR in a local LN tumor focus. WES revealed that these LN metastases were genetically different from the primary tumor bulk. Conclusions: At 15.6 months follow-up, recurrence after pre-operative ipi+nivo was low. Pathological complete response was not restricted to tumors exhibiting preexisting T cell immunity. Clinical trial information: NCT03387761 .