Incomplete Cross-Resistance Between Taxanes for Advanced Urothelial Carcinoma: Implications for Clinical Practice and Trial Design.

BACKGROUND: Taxanes such as paclitaxel and docetaxel are commonly used for second- or third-line salvage systemic therapy for metastatic UC. Although trials have generally excluded previous exposure to taxanes when using a taxane in a salvage therapy trial, taxanes might not be completely cross-resistant. Hence, we aimed to study outcomes with docetaxel after previous paclitaxel and the reverse sequence, to identify the level of cross-resistance between these taxanes. PATIENTS AND METHODS: Data from a randomized phase II trial that compared salvage therapy with docetaxel combined with either placebo or vandetanib for advanced UC were analyzed. Both arms were combined for analysis because no differences in any outcomes were observed. Data were also requested from institutions for patients who received paclitaxel after previous docetaxel treatment. Descriptive statistics were used to summarize patient and treatment characteristics and outcomes. The primary clinical end point of interest was overall survival (OS). RESULTS: Of 148 patients who received docetaxel with either vandetanib or placebo, 21 had received previous paclitaxel treatment. No difference in OS, progression-free survival, or response rate was observed with docetaxel based on previous paclitaxel treatment after adjusting for known prognostic factors. Among the 8 patients who received paclitaxel after previous docetaxel treatment, partial response was observed in 1 patient (12.5%) and stable disease in 2 patients (25%). CONCLUSION: Docetaxel treatment after previous paclitaxel treatment and the reverse sequence demonstrates activity in advanced UC. There is no strong evidence to disallow patients with previous exposure to a taxane to enroll in a clinical trial involving another taxane.

Complete response as an intermediate end point in patients receiving salvage systemic therapy for urothelial carcinoma.

BACKGROUND: The complete remission (CR) rate with salvage systemic therapy for urothelial carcinoma (UC) is unclear, and its value as an intermediate end point and association with survival are unknown. MATERIALS AND METHODS: Data from phase II trials of salvage chemotherapy and/or biologic agents were pooled. Data regarding response, overall survival (OS), progression-free survival (PFS), time from prior chemotherapy, hemoglobin, performance status, and liver metastasis status were collected. Cox proportional hazards regression was used to evaluate the association of CR and other prognostic factors with outcomes. RESULTS: A total of 789 of 818 patients enrolled in 12 phase II trials had evaluable data. CR and partial response were seen in 14 (1.8%) and 109 (13.8%) patients. Median (95% confidence interval) OS for those with a CR was 21.5 (14.2-34.3) months, compared with 6.7 (6.0-7.0) months in those without a CR (P < .001). Median (95% confidence interval) PFS for those with a CR was 15.7 (8.2-27.1) months, compared with 2.6 (2.4-2.8) months for those without a CR (P < .001). Prior cisplatin and time from prior chemotherapy of ≥ 3 months were associated with CR (P < .05). The presence of poor prognostic factors and suboptimal response to prior therapy did not preclude CR. CONCLUSION: CR occurs in 1.8% of patients receiving salvage therapy for advanced UC and is strongly associated with durable OS and PFS. CR warrants validation as an intermediate end point and may help select agents for further investigation and tumors for molecular interrogation.

Six-month progression-free survival as the primary endpoint to evaluate the activity of new agents as second-line therapy for advanced urothelial carcinoma.

OBJECTIVE: Second-line systemic therapy for advanced urothelial carcinoma (UC) has substantial unmet needs, and current agents show dismal activity. Second-line trials of metastatic UC have used response rate (RR) and median progression-free survival (PFS) as primary endpoints, which may not reflect durable benefits. A more robust endpoint to identify signals of durable benefits when investigating new agents in second-line trials may expedite drug development. PFS at 6 months (PFS6) is a candidate endpoint, which may correlate with overall survival (OS) at 12 months (OS12) and may be applicable across cytostatic and cytotoxic agents. METHODS: Ten second-line phase II trials with individual patient outcomes data evaluating chemotherapy or biologics were combined for discovery, followed by external validation in a phase III trial. The relationship between PFS6/RR and OS12 was assessed at the trial level using Pearson correlation and weighted linear regression, and at the individual level using Pearson chi-square test with Yates continuity correction. RESULTS: In the discovery dataset, a significant correlation was observed between PFS6 and OS12 at the trial (R(2) = 0.55, Pearson correlation = 0.66) and individual levels (82%, Қ = 0.45). Response correlated with OS12 at the individual level less robustly (78%, Қ = 0.36), and the trial level association was not statistically significant (R(2) = 0.16, Pearson correlation = 0.37). The correlation of PFS6 (81%, Қ = 0.44) appeared stronger than the correlation of response (76%, Қ = 0.17) with OS12 in the external validation dataset. CONCLUSIONS: PFS6 is strongly associated with OS12 and appears more optimal than RR to identify active second-line agents for advanced UC.

Impact of response to prior chemotherapy in patients with advanced urothelial carcinoma receiving second-line therapy: implications for trial design.

BACKGROUND: The prognostic impact of response to prior chemotherapy independent of performance status (PS), hemoglobin (Hb), liver metastasis (LM), and time from prior chemotherapy (TFPC) in the context of second-line therapy for advanced urothelial carcinoma (UC) is unknown. METHODS: Six phase II trials evaluating second-line therapy (n = 504) were pooled. Patients who received prior therapy for metastatic disease were eligible for analysis if Hb, LM, PS, and TFPC were available. Response by Response Evaluation Criteria in Solid Tumors 1.0 to first-line therapy was recorded. Progression-free survival (PFS) and overall survival (OS) were calculated from the date of registration using the Kaplan-Meier method. RESULTS: A total of 275 patients were evaluable for analysis. Patients received gemcitabine-paclitaxel, cyclophosphamide-paclitaxel, pazopanib, docetaxel plus vandetanib/placebo, or vinflunine (2 trials). Those with prior response (n = 111) had a median OS of 8.0 months (95% confidence interval [CI], 6.8-9.4), compared with 5.9 months (95% CI, 5.0-6.6) for those without prior response (n = 164). Those with prior response had a median PFS of 3.0 months (95% CI, 2.6-4.0) compared with 2.6 months (95% CI, 2.0-2.8) in patients without response. Multivariable analysis did not reveal a significant independent impact of prior response on PFS and OS. CONCLUSIONS: Best prior response in patients receiving prior chemotherapy for metastatic disease did not confer an independent prognostic impact with second-line therapy for advanced UC. Given that the setting of prior chemotherapy (metastatic or perioperative) has not appeared significant in a prior study, patients who received prior chemotherapy in perioperative or metastatic settings may be enrolled in the same second-line trial stratified for PS, Hb, LM, and TFPC.

Time from prior chemotherapy enhances prognostic risk grouping in the second-line setting of advanced urothelial carcinoma: a retrospective analysis of pooled, prospective phase 2 trials.

BACKGROUND: Outcomes for patients in the second-line setting of advanced urothelial carcinoma (UC) are dismal. The recognized prognostic factors in this context are Eastern Cooperative Oncology Group (ECOG) performance status (PS) >0, hemoglobin level (Hb) <10 g/dl, and liver metastasis (LM). OBJECTIVES: The purpose of this retrospective study of prospective trials was to investigate the prognostic value of time from prior chemotherapy (TFPC) independent of known prognostic factors. DESIGN, SETTING, AND PARTICIPANTS: Data from patients from seven prospective trials with available baseline TFPC, Hb, PS, and LM values were used for retrospective analysis (n=570). External validation was conducted in a second-line phase 3 trial comparing best supportive care (BSC) versus vinflunine plus BSC (n=352). OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Cox proportional hazards regression was used to evaluate the association of factors, with overall survival (OS) and progression-free survival (PFS) being the respective primary and secondary outcome measures. RESULTS AND LIMITATIONS: ECOG-PS >0, LM, Hb <10 g/dl, and shorter TFPC were significant prognostic factors for OS and PFS on multivariable analysis. Patients with zero, one, two, and three to four factors demonstrated median OS of 12.2, 6.7, 5.1, and 3.0 mo, respectively (concordance statistic=0.638). Setting of prior chemotherapy (metastatic disease vs perioperative) and prior platinum agent (cisplatin or carboplatin) were not prognostic factors. External validation demonstrated a significant association of TFPC with PFS on univariable and most multivariable analyses, and with OS on univariable analyses. Limitations of retrospective analyses are applicable. CONCLUSIONS: Shorter TFPC enhances prognostic classification independent of ECOG-PS >0, Hb <10 g/dl, and LM in the setting of second-line therapy for advanced UC. These data may facilitate drug development and interpretation of trials.

Carbonic anhydrase IX as a potential biomarker of efficacy in metastatic clear-cell renal cell carcinoma patients receiving sorafenib or placebo: analysis from the treatment approaches in renal cancer global evaluation trial (TARGET).

OBJECTIVE: Retrospective data analyses have suggested that carbonic anhydrase IX (CAIX) may have a predictive role in patients with metastatic clear cell renal cell carcinoma (ccRCC) receiving high dose interleukin-2 or sorafenib. We examined the predictive value of CAIX in estimating treatment outcome in patients receiving sorafenib vs. placebo as part of the Treatment Approaches in Renal Cancer Global Evaluation Trial (TARGET) study. MATERIALS AND METHODS: Paraffin embedded tumor tissues were collected from 133 patients from the TARGET study (n = 903). The percentage of CAIX-positive cells was assessed by a single pathologist. The impact of CAIX expression on progression-free survival (PFS, primary endpoint) and tumor shrinkage (TS, secondary endpoint) was analyzed. RESULTS: Clinical characteristics were similarly distributed between patients with low vs. high CAIX staining, as well as patients with available CAIX data vs. not. Median PFS for patients with high CAIX vs. low CAIX expression was 5.5 and 5.4 months, respectively, on the sorafenib arm (P = 0.97), and 1.5 and 1.7 months on the placebo arm (P = 0.76). Median TS for patients with high CAIX status was -14.9% vs. -12.6% in patients with low CAIX status (P = 0.63) on the sorafenib arm, and +1.3% (high CAIX) vs. +4.8% (low CAIX) in patients on the placebo arm (P = 0.60). CONCLUSIONS: Despite suggestive retrospective evidence, data from the TARGET study did not find CAIX expression status to be either predictive of clinical benefit for treatment with sorafenib or of prognostic value in patients with metastatic ccRCC following cytokine therapy.