Mark T. Fleming

Atezolizumab in patients with locally advanced and metastatic urothelial carcinoma who have progressed following treatment with platinum-based chemotherapy: a single-arm, multicentre, phase 2 trial

BACKGROUND Patients with metastatic urothelial carcinoma have few treatment options after failure of platinum-based chemotherapy. In this trial, we assessed treatment with atezolizumab, an engineered humanised immunoglobulin G1 monoclonal antibody that binds selectively to programmed death ligand 1 (PD-L1), in this patient population. METHODS For this multicentre, single-arm, two-cohort, phase 2 trial, patients (aged ≥18 years) with inoperable locally advanced or metastatic urothelial carcinoma whose disease had progressed after previous platinum-based chemotherapy were enrolled from 70 major academic medical centres and community oncology practices in Europe and North America. Key inclusion criteria for enrolment were Eastern Cooperative Oncology Group performance status of 0 or 1, measurable disease defined by Response Evaluation Criteria In Solid Tumors version 1.1 (RECIST v1.1), adequate haematological and end-organ function, and no autoimmune disease or active infections. Formalin-fixed paraffin-embedded tumour specimens with sufficient viable tumour content were needed from all patients before enrolment. Patients received treatment with intravenous atezolizumab (1200 mg, given every 3 weeks). PD-L1 expression on tumour-infiltrating immune cells (ICs) was assessed prospectively by immunohistochemistry. The co-primary endpoints were the independent review facility-assessed objective response rate according to RECIST v1.1 and the investigator-assessed objective response rate according to immune-modified RECIST, analysed by intention to treat. A hierarchical testing procedure was used to assess whether the objective response rate was significantly higher than the historical control rate of 10% at an α level of 0·05. This study is registered with ClinicalTrials.gov, number NCT02108652. FINDINGS Between May 13, 2014, and Nov 19, 2014, 486 patients were screened and 315 patients were enrolled into the study. Of these patients, 310 received atezolizumab treatment (five enrolled patients later did not meet eligibility criteria and were not dosed with study drug). The PD-L1 expression status on infiltrating immune cells (ICs) in the tumour microenvironment was defined by the percentage of PD-L1-positive immune cells: IC0 (<1%), IC1 (≥1% but <5%), and IC2/3 (≥5%). The primary analysis (data cutoff May 5, 2015) showed that compared with a historical control overall response rate of 10%, treatment with atezolizumab resulted in a significantly improved RECIST v1.1 objective response rate for each prespecified immune cell group (IC2/3: 27% [95% CI 19-37], p<0·0001; IC1/2/3: 18% [13-24], p=0·0004) and in all patients (15% [11-20], p=0·0058). With longer follow-up (data cutoff Sept 14, 2015), by independent review, objective response rates were 26% (95% CI 18-36) in the IC2/3 group, 18% (13-24) in the IC1/2/3 group, and 15% (11-19) overall in all 310 patients. With a median follow-up of 11·7 months (95% CI 11·4-12·2), ongoing responses were recorded in 38 (84%) of 45 responders. Exploratory analyses showed The Cancer Genome Atlas (TCGA) subtypes and mutation load to be independently predictive for response to atezolizumab. Grade 3-4 treatment-related adverse events, of which fatigue was the most common (five patients [2%]), occurred in 50 (16%) of 310 treated patients. Grade 3-4 immune-mediated adverse events occurred in 15 (5%) of 310 treated patients, with pneumonitis, increased aspartate aminotransferase, increased alanine aminotransferase, rash, and dyspnoea being the most common. No treatment-related deaths occurred during the study. INTERPRETATION Atezolizumab showed durable activity and good tolerability in this patient population. Increased levels of PD-L1 expression on immune cells were associated with increased response. This report is the first to show the association of TCGA subtypes with response to immune checkpoint inhibition and to show the importance of mutation load as a biomarker of response to this class of agents in advanced urothelial carcinoma. FUNDING F Hoffmann-La Roche Ltd.

Pharmacokinetics and Toxicity of Weekly Docetaxel in Older Patients

Purpose: To evaluate the pharmacokinetics of weekly docetaxel in a cohort of older patients with metastatic cancer and to explore the relationship of pharmacokinetic variables, Erythromycin Breath Test results, age, geriatric assessment variables, and toxicity to therapy. Experimental Design: Twenty patients ages ≥65 years with metastatic breast, prostate, or lung cancer entered an Institutional Review Board–approved protocol to evaluate the pharmacokinetics of weekly docetaxel administered at 35 mg/m2 i.v. for 3 weeks followed by a 1-week break. The Erythromycin Breath Test and geriatric assessment were done before the first dose. Blood samples were collected for pharmacokinetic analysis with the first dose of docetaxel. Results: Of the 20 patients who entered the study, 19 were evaluable. There were no age-related differences in the pharmacokinetics of weekly docetaxel. Fifty-eight percent (11 of 19) experienced grade ≥3 toxicity: 16% (3 of 19) grade ≥3 hematologic toxicity, and 53% (10 of 19) grade ≥3 nonhematologic toxicity. There was an association between the Erythromycin Breath Test results and docetaxel pharmacokinetic variables; however, there was no association between Erythromycin Breath Test results or docetaxel pharmacokinetics with frequency of grade ≥3 toxicity. Conclusions: Despite no statistically significant age-related differences in weekly docetaxel pharmacokinetics, over half of these older patients experienced a grade ≥3 toxicity at the 35 mg/m2 starting dose. We advocate a starting dose of 26 mg/m2 on this weekly schedule and dose escalating if no toxicity.

Post-therapy changes in PSA as an outcome measure in prostate cancer clinical trials

To the investigator and clinician, prostate-specific antigen (PSA) level is a seemingly perfect outcome measure because it is easily assessable, quantitative, reproducible, and inexpensive. Whether post-therapy decline in PSA reflects true clinical benefit, and whether post-therapy declines can be used as an intermediate endpoint for accelerated drug approval is still open to question. At present, no drug has been approved strictly on the basis of a post-treatment decline in PSA, as it is unproven that such PSA changes are surrogates for true clinical benefits. Post-therapy PSA changes have been associated with improved survival in patients with castrate metastatic disease. The role of PSA changes as potential surrogates of clinical benefit have only been explored to a limited degree because to date, only two prospective randomized trials showing a survival benefit have been reported. Such trials are necessary, but not a sufficient pre-requisite to explore the potential role of any outcome measure as an intermediate endpoint. The clear demonstration that a post-therapy PSA change can account for all of the treatment effects seen is not yet available. A cytotoxic drug that does not produce any PSA decline is unlikely to be effective, but the converse is not always true because not all PSA rises represent a treatment failure. It is important to recognize that there are a range of clinical benefits to patients that can improve the quality and possibly the duration of survival, independent of PSA.

Azacitidine favorably modulates PSA kinetics correlating with plasma DNA LINE-1 hypomethylation in men with chemonaïve castration-resistant prostate cancer.

BACKGROUND Azacitidine is a hypomethylating agent that activates genes repressed by promoter methylation. Preclinically, demethylating agents reverse resistance of prostate cancer to androgen ablation. A phase II trial evaluated azacitidine for men with castration-resistant prostate cancer (CRPC) progressing on combined androgen blockade (CAB). METHODS Chemonaïve patients with CRPC on CAB and PSA-doubling time (DT) < 3 months were eligible. The primary endpoint was prolongation of PSA-DT to ≥ 3 months. Correlation of biologic activity (fetal hemoglobin, plasma DNA LINE-1 methylation) with prolongation of PSA-DT was tested. CAB was continued and azacitidine 75 mg/m(2) was administered subcutaneously on days 1-5 of each 28-day cycle up to 12 cycles or until clinical progression/intolerable toxicities. RESULTS Thirty-six patients were enrolled, 80.6% had metastatic disease, and 34 were evaluable. A PSA-DT ≥ 3 months was attained in 19 patients (55.8%). Overall median PSA-DT was significantly prolonged compared to baseline (2.8 vs. 1.5 months, P < 0.01). Fourteen patients had some PSA decline during therapy and 1 patient had a ≥ 30% decline compared with baseline. The median clinical progression-free survival was 12.4 weeks. Grade 3 toxicities included fatigue (12%), and neutropenia (6%), with 4 patients discontinuing due to toxicities. A trend in decreasing plasma DNA LINE-1 methylation was seen with longer treatment duration (P = 0.06), which significantly correlated with prolongation of PSA-DT (P = 0.02). CONCLUSIONS Azacitidine favorably modulates PSA kinetics in chemonaïve CRPC that correlates with decreasing plasma DNA LINE-1 methylation. Given the excellent tolerability, further development of azacitidine for CRPC may be warranted, with exploration of combination regimens.

Association of rash with outcomes in a randomized phase II trial evaluating cetuximab in combination with mitoxantrone plus prednisone after docetaxel for metastatic castration-resistant prostate cancer

PURPOSE Cetuximab (C), a chimeric monoclonal antibody that binds epidermal growth factor receptor (EGFR), is active against androgen-independent prostate cancer cell lines and might enhance the activity of chemotherapy. The efficacy of combining cetuximab with mitoxantrone (M) plus prednisone (MP) was evaluated in progressive metastatic castrate-resistant prostate cancer (CRPC) after receiving docetaxel. MATERIALS AND METHODS Patients with progression after receiving docetaxel were eligible and randomized 2:1 to CMP or MP. Therapy was mitoxantrone 12 mg/m(2) intravenously (I.V.) on day 1, oral prednisone 10 mg daily in both arms, and cetuximab 250 mg/m(2) I.V. (400 mg/m(2) day 1, cycle 1) on days 1, 8, and 15 in the CMP arm. Cycles were repeated every 21 days. Radiologic assessments of disease and PSA (prostate-specific antigen) occurred every 4 cycles. The primary endpoint was time to progression (TTP). RESULTS A total of 115 patients were enrolled, 75 in the CMP and 40 in the MP arm: the median TTP was 4.9 and 6.6 months, respectively; the measurable disease response rate was 2% and 4%, the PSA response rate 7.7% and 17.6%, and median survival 11.9 and 15.7 months, respectively. Key grade 3-4 toxicities were neutropenia 44% and 25.6%, anemia 6.7% and 7.7%, thrombocytopenia 6.7% and 2.6%, and fatigue 8% in both arms. In an unplanned exploratory analysis, median TTP with (n = 24) and without rash (n = 51) in the CMP arm was 10.3 months vs. 2.8 months (P = .004). On multivariable analysis,rash was significantly associated with TTP (hazard ratio [HR] = 0.43; P = .01). CONCLUSIONS The treatment with CMP is not recommended in unselected men with docetaxel-treated CRPC, although rash might help develop tailored therapy.

Prostate-specific membrane antigen antibody drug conjugate (PSMA ADC): A phase I trial in metastatic castration-resistant prostate cancer (mCRPC) previously treated with a taxane.

119 Background: The abundant expression of prostate specific membrane antigen (PSMA) on prostate cancer cells provides a rationale for antibody therapy. PSMA ADC, a fully human antibody to PSMA linked to the microtubule disrupting agent monomethyl auristatin E (MMAE), binds PSMA and is internalized within the prostate cancer cell where cleavage by lysosomal enzymes release free MMAE, causing cell cycle arrest and apoptosis. We have completed a phase 1 dose escalation study of PSMA ADC in subjects with taxane-refractory mCRPC. METHODS Eligibility requirements include progressive mCRPC following taxane-containing chemotherapy and ECOG status of 0 or 1. PSMA ADC was administered by IV infusion Q3W for up to 4 cycles. Safety, pharmacokinetics (PK), PSA, circulating tumor cells (CTC), clinical disease progression and immunogenicity to PSMA ADC were assessed. Serum PSMA ADC and total antibody were measured by ELISA, and free MMAE was measured by LC/MS/MS.The dosing cohorts ranged from 0.4 mg/kg to 2.8 mg/kg. RESULTS 52 subjects with mCRPC were dosed in nine dose levels. All subjects received prior docetaxel, 5 also received cabazitaxel and 3 subjects also received paclitaxel. PSMA ADC was generally well tolerated with the most commonly seen adverse events being anorexia and fatigue. Peripheral neuropathy was reported by 7 subjects after repeated doses. Two were grade 3. Dose limiting toxicities (DLT) seen at 2.8 mg/kg were neutropenia (one death) and reversible liver function tests (LFTs) elevations. Antitumor activity was manifested as reductions either in PSA or CTCs at ≥ 1.8 mg/kg PSMA ADC in approximately 50% of patients. Exposure to PSMA ADC increased with dose and was ~1,000-fold greater than MMAE exposure and no accumulation was observed. CONCLUSIONS PSMA ADC in this study was generally well tolerated in doses up to 2.8 mg/kg every three weeks in subjects with mCRPC, previously treated with taxane. Antitumor activity was seen at higher dose levels. DLTs were neutropenia and reversible LFT abnormalities. The maximum tolerated dose of PSMA ADC was determined to be 2.5 mg/kg. A phase 2 trial in taxane refractory mCRPC has been initiated. CLINICAL TRIAL INFORMATION NCT01414283.

Phase 2 Trial of Gemcitabine, Cisplatin, plus Ipilimumab in Patients with Metastatic Urothelial Cancer and Impact of DNA Damage Response Gene Mutations on Outcomes

BACKGROUND Chemotherapy may exert immunomodulatory effects, thereby combining favorably with the immune checkpoint blockade. The pharmacodynamic effects of such combinations, and potential predictive biomarkers, remain unexplored. OBJECTIVE To determine the safety, efficacy, and immunomodulatory effects of gemcitabine and cisplatin (GC) plus ipilimumab and explore the impact of somatic DNA damage response gene alterations on antitumor activity. DESIGN, SETTING, AND PARTICIPANTS Multicenter single arm phase 2 study enrolling 36 chemotherapy-naïve patients with metastatic urothelial cancer. Peripheral blood flow cytometry was performed serially on all patients and whole exome sequencing of archival tumor tissue was performed on 28/36 patients. INTERVENTION Two cycles of GC followed by four cycles of GC plus ipilimumab. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS The primary endpoint was 1-yr overall survival (OS). Secondary endpoints included safety, objective response rate, and progression-free survival. RESULTS AND LIMITATIONS Grade ≥3 adverse events occurred in 81% of patients, the majority of which were hematologic. The objective response rate was 69% and 1-yr OS was 61% (lower bound 90% confidence interval: 51%). On exploratory analysis, there were no significant changes in the composition and frequency of circulating immune cells after GC alone. However, there was a significant expansion of circulating CD4 cells with the addition of ipilimumab which correlated with improved survival. The response rate was significantly higher in patients with deleterious somatic DNA damage response mutations (sensitivity=47.6%, specificity=100%, positive predictive value=100%, and negative predictive value=38.9%). Limitations are related to the sample size and single-arm design. CONCLUSIONS GC+ipilimumab did not achieve the primary endpoint of a lower bound of the 90% confidence interval for 1-yr OS of >60%. However, within the context of a small single-arm trial, the results may inform current approaches combining chemotherapy plus immunotherapy from the standpoint of feasibility, appropriate cytotoxic backbones, and potential predictive biomarkers. TRIAL REGISTRATION ClinicalTrials.gov NCT01524991. PATIENT SUMMARY Combining chemotherapy and immune checkpoint blockade in patients with metastatic urothelial cancer is feasible. Further studies are needed to refine optimal combinations and evaluate tests that might identify patients most likely to benefit.

Neoadjuvant dasatinib for muscle-invasive bladder cancer with tissue analysis of biologic activity

OBJECTIVES Preclinical urothelial carcinoma models suggest activity of dasatinib, an oral SRC-family kinase (SFK) inhibitor. We sought to determine the feasibility and biologic activity of neoadjuvant dasatinib (Neo-D) in patients with muscle-invasive urothelial carcinoma of the bladder (miUCB) preceding radical cystectomy (RC). MATERIALS AND METHODS A prospective multisite phase II trial was conducted. Key eligibility criteria included: resectable miUCB (T2-T4a, N0, M0), and Eastern Cooperative Oncology Group performance status 0 to 1. Patients received oral Neo-D 100mg once daily for 28±7 days followed by RC 8 to 24 hours after the last dose. The primary end point was feasibility, defined as≥60% of patients with miUCB completing therapy without treatment-related dose-limiting toxicity (DLT). Pre- and posttreatment tumor immunohistochemistry of phosphorylated SFK (pSFK), Ki-67, and cleaved caspase (Cas)-3 results were analyzed by paired t test. RESULTS The study completed full accrual with enrollment of 25 patients of whom 23 were evaluable for feasibility. The study achieved its primary end point with 15 patients (65%) completing therapy without treatment-related DLTs. DLTs included: fatigue (n = 2), pulmonary embolism, abdominal pain, supraventricular tachycardia, enteric fistula, hematuria, and dyspnea (n = 1 each). At RC, 5 patients (23%) had<pT2 disease. Analysis of pre- and posttreatment tumors demonstrated significantly decreased pSFK (P = 0.003) but no overall significant changes in Ki-67 or Cas3. In total, 4 cases demonstrated a nonsignificant decrease in Ki-67, of which 3 cases also demonstrated a decrease in pSFK and 2 cases had marginal increase in Cas3. CONCLUSIONS Neo-D in miUCB patients was feasible and safe. Overall, significant inhibition of pSFK was observed without overall reduction of cellular proliferation or increase of apoptosis, although biologic anti-tumor activity may exist in a small subset of patients. These results highlight the potential utility of the neoadjuvant trial paradigm and suggest that clinical benefit of single-agent SFK inhibition in unselected patients with miUCB is unlikely.

Enzalutamide in combination with docetaxel in men with prostate cancer (PC): Preliminary results from a phase I study.

63 Background: Enzalutamide (ENZA), a novel oral androgen receptor (AR) inhibitor, inhibits AR signaling via inhibition of androgen binding to the AR, AR nuclear translocation, and nuclear AR-DNA binding. ENZA demonstrated a survival benefit in men with metastatic castration-resistant prostate cancer (mCRPC) who had received prior docetaxel (Scher et al, NEJM 2012; 367:1187). A Phase III study in men with progressive chemotherapy-naïve disease (PREVAIL), is ongoing. Docetaxel (DOC) is the current standard first-line chemotherapy for mCRPC. CYP3A4, which plays a role in DOC clearance, is induced by ENZA. Patients (pts) eligible to receive DOC may benefit from continued AR inhibition with ENZA, provided the combination is well tolerated with no unacceptable drug-drug interactions. METHODS This study evaluated the safety and pharmacokinetics (PK) of DOC co-administered with ENZA in men with mCRPC on androgen deprivation therapy. Pts received DOC (75 mg/m2) by 1-h infusion every 3 weeks, with corticosteroids. ENZA (160 mg/d) was started 24 h after the first DOC infusion. Plasma PK samples were collected for 24 h after Cycle (C) 1 and C2 DOC infusions to enable within-subject comparisons of DOC PK ± ENZA. A sample size of 18 pts able to receive ≥ 2 full doses of DOC was specified for PK analyses. RESULTS As of 21 Sept. 2012, 22 pts have been enrolled, 3 did not complete both C1 and C2; PK and C1 and C2 safety data are currently available from 15 pts reported here. The median age was 65 (range 46-80 yrs); 11 had ECOG performance status 1 (vs 0). Prior primary therapy included surgery (n=2), radiation (n=4) or both (n=5); median PSA was 44.7ng/mL (1.9-585). ANC<1000mm3 was reported in 14 pts (1 febrile neutropenia), other adverse events in ≥4 pts included fatigue (11), dyspnea (6), alopecia (5), peripheral neuropathy (5), anemia (4) and dysgueusia (4). No seizures were reported. Preliminary PK data (n=15) show similar DOC exposure (within 20%) for DOC in combination with ENZA vs. DOC alone. CONCLUSIONS This is the first evaluation of ENZA given in combination with DOC.In mCRPC pts ENZA does not appear to affect tolerability of DOC or have a clinically meaningful impact on DOC PK. CLINICAL TRIAL INFORMATION NCT01565928.

Long-term responders to enzalutamide (ENZA) during the phase III AFFIRM trial: Baseline characteristics and efficacy outcomes.

20 Background: ENZA, an oral androgen receptor inhibitor, was shown to significantly increase overall survival by 4.8 mo (P <0.001, HR 0.63) vs placebo (PBO) in AFFIRM, a phase III trial in patients (pts) with castration resistant prostate cancer (CRPC) post- docetaxel. Here we report the baseline characteristics and efficacy outcomes of long-term responders (LTR, ≥12 months on ENZA) in the AFFIRM trial. METHODS Pts were randomized 2:1 to ENZA 160 mg/day or PBO. The primary endpoint was overall survival (OS). The study was stopped at the pre-specified interim analysis (520 events). Pts in the ENZA group were allowed to continue on ENZA post unblinding. The LTR group was defined by Aug 2012 data cut-off. Efficacy data are from interim analysis data cut-off from Sep 2011. RESULTS 35% (276/800) of the ENZA group were on therapy for ≥ 12 months; 22% (174/800) for > 18 months. Comparing the LTR subgroup to the all ENZA group, the LTR subgroup had been living with prostate cancer longer (7.9 vs 5.9 yrs) and had lower disease burden at baseline (Table). Pts in the LTR subgroup had improved efficacy outcomes compared to all ENZA group. Of note, 50% PSA response was 87% in LTR subgroup vs 54% in the all ENZA group. Results are preliminary, updated results will be presented. CONCLUSIONS 35% of pts in AFFIRM received ENZA for ≥12 months. Compared to the all ENZA group, LTR pts had less disease burden at baseline and had improved efficacy outcomes. CLINICAL TRIAL INFORMATION NCT00974311. [Table: see text].