The Double Antibody Drug Conjugate (DAD) phase I trial: sacituzumab govitecan plus enfortumab vedotin for metastatic urothelial carcinoma

BACKGROUND

The antibody-drug conjugates sacituzumab govitecan (SG) and enfortumab vedotin (EV) are standard monotherapies for metastatic urothelial carcinoma (mUC). Given the different targets and payloads, we evaluated the safety and efficacy of SG + EV in a phase I trial in mUC (NCT04724018).

PATIENTS AND METHODS

Patients with mUC and Eastern Cooperative Oncology Group performance status ≤1 who had progressed on platinum and/or immunotherapy were enrolled. SG + EV were administered on days 1 + 8 of a 21-day cycle until progression or unacceptable toxicity. Primary endpoint was the incidence of dose-limiting toxicities during cycle 1. The number of patients treated at each of four pre-specified dose levels (DLs) and the maximum tolerated doses in combination (MTD) were determined using a Bayesian Optimal Interval design. Objective response, progression-free survival, and overall survival were secondary endpoints.

RESULTS

Between May 2021 and April 2023, 24 patients were enrolled; 1 patient never started therapy and was excluded from the analysis. Median age was 70 years (range 41-88 years); 11 patients received ≥3 lines of therapy. Seventy-eight percent (18/23) of patients experienced grade ≥3 adverse event (AE) regardless of attribution at any DL, with one grade 5 AE (pneumonitis possibly related to EV). The recommended phase II doses are SG 8 mg/kg with EV 1.25 mg/kg with granulocyte colony-stimulating factor support; MTDs are SG 10 mg/kg with EV 1.25 mg/kg. The objective response rate was 70% (16/23, 95% confidence interval 47% to 87%) with three complete responses; three patients had progressive disease as best response. With a median follow-up of 14 months, 9/23 patients have ongoing response including 6 responses lasting over 12 months.

CONCLUSIONS

The combination of SG + EV was assessed at different DLs and a safe dose for phase II was identified. The combination had encouraging activity in patients with mUC with high response rates, including clinically significant complete responses. Additional study of this combination is warranted.

Axitinib versus sorafenib in advanced renal cell carcinoma: subanalyses by prior therapy from a randomised phase III trial

BACKGROUND

In the AXIS trial, axitinib prolonged progression-free survival (PFS) vs sorafenib in patients with advanced renal cell carcinoma (RCC) previously treated with sunitinib or cytokines.

METHODS

In post hoc analyses, patients were grouped by objective response to prior therapy (yes vs no), prior therapy duration (< vs ⩾median), and tumour burden (baseline sum of the longest diameter < vs ⩾median). PFS and overall survival (OS), and safety by type and duration of prior therapy were evaluated.

RESULTS

Response to prior therapy did not influence outcome with second-line axitinib or sorafenib. PFS was significantly longer in axitinib-treated patients who received longer prior cytokine treatment and sorafenib-treated patients with smaller tumour burden following sunitinib. Overall survival with the second-line therapy was longer in patients who received longer duration of prior therapy, although not significant in the sunitinib-to-axitinib sequence subgroup; OS was also longer in patients with smaller tumour burden, but not significant in the cytokine-to-axitinib sequence subgroup. Safety profiles differed modestly by type and duration of prior therapy.

CONCLUSIONS

AXIS data suggest that longer duration of the first-line therapy generally yields better outcome with the second-line therapy and that lack of response to first-line therapy does not preclude positive clinical outcomes with a second-line vascular endothelial growth factor-targeted agent in patients with advanced RCC.

Sunitinib in combination with gemcitabine for advanced solid tumours: a phase I dose-finding study

BACKGROUND

This phase I, dose-finding study determined the maximum tolerated dose (MTD), safety, and pharmacokinetics of sunitinib plus gemcitabine in patients with advanced solid tumours.

METHODS

Two schedules with sunitinib (25-50 mg per day) and IV gemcitabine (750-1250 mg m(-2)) in escalating doses were studied. First, patients received sunitinib on a 4-weeks-on-2-weeks-off schedule (Schedule 4/2) plus gemcitabine on days 1, 8, 22, and 29. Second, patients received sunitinib on a 2-weeks-on-1-week-off schedule (Schedule 2/1) plus gemcitabine on days 1 and 8. The primary endpoint was determination of MTD and tolerability.

RESULTS

Forty-four patients received the combination (Schedule 4/2, n=8; Schedule 2/1, n=36). With no dose-limiting toxicities (DLTs) at maximum dose levels on Schedule 2/1, MTD was not reached. Grade 4 treatment-related AEs and laboratory abnormalities included cerebrovascular accident, hypertension, and pulmonary embolism (n=1 each), and neutropenia (n=3), thrombocytopenia and increased uric acid (both n=2), and lymphopenia (n=1). There were no clinically significant drug-drug interactions. Antitumor activity occurred across dose levels and tumour types. In poor-risk and/or high-grade renal cell carcinoma patients (n=12), 5 had partial responses and 7 stable disease ≥ 6 weeks.

CONCLUSION

Sunitinib plus gemcitabine on Schedule 2/1 with growth factor support was well tolerated and safely administered at maximum doses of each drug, without significant drug-drug interactions.

Q-TWiST analysis to estimate overall benefit for patients with metastatic renal cell carcinoma treated in a phase III trial of sunitinib vs interferon-α

Background:

In a randomised phase III trial of treatment-naive patients with metastatic renal cell carcinoma, sunitinib showed significant improvement in progression-free survival (PFS) compared with interferon (IFN)-α. We assessed between-treatment differences in overall benefit using a quality-adjusted Time Without Symptoms of disease progression or Toxicity of treatment (TWiST; Gelber and Goldhirsch) analysis.

Methods:

In this analysis, in which only grade 3/4 treatment-related toxicities were included, overall survival was partitioned into three health states: toxicity (time with toxicity after randomisation and before progression), time without symptoms of disease progression or toxicity, and time from progression until death. Between-treatment differences in the mean duration of each state were calculated. A threshold utility analysis was used to assess quality-adjusted TWiST (Q-TWiST) outcomes.

Results:

Q-TWiST scores showed that quality-adjusted survival time was greater with sunitinib than with IFN-α, even though certain grade 3/4 toxicities occurred more frequently with sunitinib. For both treatments, the mean number of days with toxicity was small compared with PFS. This effect was more pronounced with sunitinib in which time spent without progression or toxicity was 151 days greater than with IFN-α.

Conclusion:

Patients randomised to sunitinib had longer clinical benefit, defined as Q-TWiST scores, than patients randomised to IFN-α.

Multicenter phase II study of trabectedin in patients with metastatic castration-resistant prostate cancer

BACKGROUND

This multicenter phase II trial evaluated the efficacy and safety of trabectedin in metastatic castration-resistant prostate cancer (CRPC).

PATIENTS AND METHODS

Two schedules were evaluated in three cohorts: weekly as 3-h i.v. infusion at 0.58 mg/m(2) for 3 out of 4 weeks (Cohort A, n = 33), and every 3 weeks (q3wk) as 24-h infusion at 1.5 mg/m(2) (Cohort B1, n = 5) and 1.2 mg/m(2) (Cohort B2, n = 20). The primary end point was prostate-specific antigen (PSA) response; secondary end points included safety, tolerability and time to progression (TTP).

RESULTS

Trabectedin resulted in PSA declines ≥ 50% in 12.5% (Cohort A) and 10.5% (Cohort B2) of patients. Among men pretreated with taxane-based chemotherapy, PSA response was 13.6% (Cohort A) and 15.4% (Cohort B2). PSA responses lasted 4.1-8.6 months, and median TTP was 1.5 months (Cohort A) and 1.9 months (Cohort B2). The dose of 1.5 mg/m(2) (approved for soft tissue sarcoma) given as 24-h infusion q3wk was not tolerable in these patients. At 1.2 mg/m(2) q3wk and 0.58 mg/m(2) weekly, the most common adverse events were nausea, fatigue and transient neutropenia and transaminase increase.

CONCLUSIONS

Two different trabectedin schedules showed modest activity in metastatic CRPC. Further studies may require identification of predictive factors of response in prostate cancer.

Hand–foot syndrome (HFS) as a potential biomarker of efficacy in patients (pts) with metastatic renal cell carcinoma (mRCC) treated with sunitinib (SU)

320

Background: HFS and related skin toxicities are common side effects of tyrosine kinase inhibitors such as SU, a multitargeted inhibitor of VEGF and PDGF receptors plus other receptor tyrosine kinases. In a randomized phase III trial of treatment-naïve mRCC pts, SU showed superior progression-free survival (PFS) and objective response rate (ORR) over interferon-alfa, with a median PFS of 11 mo and median overall survival (OS) of 26.4 mo, establishing SU as a reference standard of care (Motzer et al, 2009). In this retrospective analysis, correlations between SU-associated HFS and efficacy endpoints were investigated in mRCC pts from 5 clinical trials in the first- and second-line treatment settings.

Methods: Analyses included pooled data from 770 pts who received single-agent SU as 50 mg/d on a 4-week-on/2-week-off schedule (n=544; 71%) or 37.5 mg continuous once-daily dosing (n=226; 29%). Median PFS and OS were estimated by Kaplan–Meier methods and compared between pts with vs without HFS using a log-rank test. ORR was compared by Pearson's chi-square test. Tumor response was assessed by investigators and adverse events were recorded regularly. Multivariate and time-dependent covariate analyses were performed.

Results: Of 770 pts, 179 (23%) developed any-grade HFS, compared with 591 (77%) who did not. Most instances of HFS (63%) initially occurred during the first 3 treatment cycles. Pts who developed HFS had significantly better ORR (55.6% vs. 32.7%), PFS (14.3 vs. 8.3 mo), and OS (38.3 vs. 18.9 mo) than pts who did not develop HFS (p<0.0001). In a multivariate analysis, SU-associated HFS remained a significant independent predictor of both PFS and OS (and of OS by time-dependent covariate analysis).

Conclusions: In mRCC pts, SU-associated HFS was significantly and independently associated with improved clinical outcomes. Overall, pts who did not develop HFS still had substantial benefit from SU. However, the presence of HFS identified a subset of pts that manifested highly favorable efficacy results with SU. These findings suggest that development of HFS may serve as a predictive biomarker of SU efficacy, although prospective validation is warranted.

[Table: see text]

Prognostic factors for progression-free and overall survival with sunitinib targeted therapy and with cytokine as first-line therapy in patients with metastatic renal cell carcinoma

BACKGROUND

Analysis of prognostic factors for progression-free survival (PFS) and overall survival (OS) was performed using final data from a randomized phase III trial of sunitinib versus interferon-α (IFN-α) as first-line metastatic renal cell carcinoma (RCC) therapy.

DESIGN

A multivariate Cox regression model analyzed baseline variables for prognostic significance. Each variable was investigated univariately and then multivariately using a stepwise algorithm.

RESULTS

Each treatment arm comprised 375 patients. For sunitinib, multivariate analysis of PFS identified five independent predictors, including serum lactate dehydrogenase (LDH) level, presence of ≥2 metastatic sites, no prior nephrectomy, Eastern Cooperative Oncology Group (ECOG) performance status, and baseline platelet count, while multivariate analysis of OS identified serum LDH level, corrected serum calcium level, time from diagnosis to treatment, hemoglobin level, ECOG performance status, and presence of bone metastasis as predictors. For IFN-α, LDH level and presence of ≥2 metastatic sites were common predictors of PFS to those for sunitinib, as were all predictors of OS except ECOG status.

CONCLUSIONS

This analysis identified prognostic factors for PFS and OS with sunitinib as first-line metastatic RCC therapy and confirmed that the Memorial Sloan-Kettering Cancer Center model is applicable in the era of targeted therapy.

Health-related quality of life in patients with metastatic renal cell carcinoma treated with sunitinib vs interferon-alpha in a phase III trial: final results and geographical analysis

BACKGROUND

In a randomised phase III trial, sunitinib significantly improved efficacy over interferon-alpha (IFN-alpha) as first-line therapy for metastatic renal cell carcinoma (mRCC). We report the final health-related quality of life (HRQoL) results.

METHODS

Patients (n=750) received oral sunitinib 50 mg per day in 6-week cycles (4 weeks on, 2 weeks off treatment) or subcutaneous IFN-alpha 9 million units three times weekly. Health-related quality of life was assessed with nine end points: the Functional Assessment of Cancer Therapy-General and its four subscales, FACT-Kidney Symptom Index (FKSI-15) and its Disease-Related Symptoms subscale (FKSI-DRS), and EQ-5D questionnaire's EQ-5D Index and visual analogue scale. Data were analysed using mixed-effects model (MM), supplemented with pattern-mixture models (PMM), for the total sample and the US and European Union (EU) subgroups.

RESULTS

Patients receiving sunitinib reported better scores in the primary end point, FKSI-DRS, across all patient populations (P<0.05), and in nine, five, and six end points in the total sample, in the US and EU groups respectively (P<0.05). There were no significant differences between the US and EU groups for all end points with the exception of the FKSI item 'I am bothered by side effects of treatment' (P=0.02). In general, MM and PMM results were similar.

CONCLUSION

Patients treated with sunitinib in this study had improved HRQoL, compared with patients treated with IFN-alpha. Treatment differences within the US cohort did not differ from those within the EU cohort.

Prognostic factors for overall survival with sunitinib as first-line therapy in patients with metastatic renal cell carcinoma (mRCC)

5042

Background: Sunitinib demonstrated superior progression-free survival (PFS; the primary endpoint) over interferon-alfa (IFN-α) as first-line mRCC therapy (NEJM 2007;356:115). Median overall survival (OS) with sunitinib compared to IFN-α was: 26.4 vs. 21.8 months (HR=0.821; P=0.051 by unstratified log-rank test; Proc ASCO 2008;26, May 20 suppl; abstr 5024). An analysis of prognostic factors for OS was performed on data from this trial. Methods: 750 treatment-naïve mRCC patients were randomized 1:1 to receive sunitinib or IFN-α. By Cox proportional hazards model, selected pretreatment variables were evaluated univariately and in a multivariate model for each treatment arm. Multivariate models for each treatment arm were based on a stepwise algorithm with a type I error of 0.25 for entry and 0.15 for elimination. Further elimination was applied to identify variables significant at P<0.05. Results: In multivariate analysis of sunitinib patients, factors associated with longer OS include: interval from diagnosis to treatment ≥1 yr, ECOG PS of 0, lower corrected calcium, absence of bone metastases, lower lactic dehydrogenase (LDH), and higher hemoglobin (Hgb) ( table ). For the IFN-α treatment arm, male gender, absence of bone or lymph node metastases, lower LDH, higher Hgb, lower corrected calcium, higher neutrophil count, and interval from diagnosis to treatment ≥1 yr were associated with longer OS. Conclusions: For patients in the sunitinib treatment arm, prognostic factors identified were similar to the factors previously identified in the MSKCC risk groups (J Clin Oncol 2002;20:289). Additional prognostic factors were identified for the IFN-α arm. Further studies are warranted to independently validate these findings as well as to identify tumor-specific prognostic factors.

[Table: see text]

[Table: see text]

Quality of life (QOL) with sunitinib versus interferon-alfa (IFN-α) as first-line therapy in patients with metastatic renal cell carcinoma (mRCC): Final results

6529

Background: In an international, randomized phase 3 trial (Figlin et al, ASCO. 2008), sunitinib showed superior progression-free survival (the primary endpoint) and objective response rate over IFN-α (11 vs. 5 mo and 47% vs. 12%, respectively; p < 0.000001) as first-line mRCC therapy, with a median overall survival of more than 2 years. Here, we report the final health-related QOL results from this trial. Methods: 750 treatment-naïve mRCC patients were randomized 1:1 to receive sunitinib 50 mg orally once-daily in recurring cycles of 4 weeks on drug and 2 weeks off or IFN-α 9 MU subcutaneously thrice-weekly. QOL was measured by the Functional Assessment of Cancer Therapy-General (FACT-G), which has 4 subscales, the FACT-Kidney Symptom Index-15 item (FKSI-15), which includes a Disease-Related Symptoms (FKSI-DRS) subscale, and the EQ-5D questionnaire's utility index (EQ-5D Index) and visual analog scale (EQ-VAS). The primary QOL endpoint was FKSI-DRS. Higher scores indicated better outcomes. Patients completed questionnaires on days 1 and 28 of each cycle. Data were analyzed for the intent-to-treat population using mixed-effects models (MM), supplemented with pattern-mixture models (PMM). We also compared QOL of patients in the United States (US) with patients in the European Union (EU; France, Germany, Italy, Poland, Spain and United Kingdom). Results: Patients on sunitinib reported better FKSI-15 and FKSI-DRS scores than those on IFN-α, with a significant difference in the overall means across cycles (4.06 and 2.36, respectively; p < 0.0001; MM). Similarly, differences in means for FACT-G (and all subscales), EQ-5D Index, and EQ-VAS all significantly favored sunitinib (p < 0.05). Based on pre-set, required minimum score differences, between-treatment differences in the mean scores were clinically meaningful for FKSI-15, FKSI-DRS, FACT-G, and the FACT-G functional well-being subscale. Between-treatment differences were similar for both the US and EU populations. Across all analyses, results from PMM were similar to those from MM. Conclusions: Sunitinib provides superior QOL over IFN-α, in addition to superior efficacy, as first-line mRCC therapy.

[Table: see text]

Sunitinib therapy for patients (pts) with metastatic renal cell carcinoma (mRCC): Updated results of two phase II trials and prognostic factor analysis for survival

5095

Background: Two single-arm phase 2 trials reported a 42% objective response rate (ORR) with sunitinib as second-line therapy in mRCC pts (JAMA 2006;295:2516–24). Efficacy results were updated and an analysis of prognostic factors for survival was performed on pooled data. Methods: Eligibility criteria and treatment plan were nearly identical for both trials. Pts with mRCC who failed =1 prior cytokine-based therapy received sunitinib in repeated 6-week cycles of 50 mg/day orally for 4 weeks, followed by 2 weeks off treatment. Response was assessed by investigators according to RECIST. Pretreatment clinical and biochemical features were examined for prognostic factors by univariate and multivariate analysis (p<0.05 significance level was used in the backward stepwise selection procedure). Results: Updated efficacy data for 168 evaluable pts showed an ORR of 45% (95% CI: 39%, 54%), median progression-free survival (PFS) of 8.4 months (95% CI: 7.9, 10.7), and median overall survival (OS) of 22.3 months (95% CI: 14.8, 36.0). Twenty pts remain on treatment with sunitinib with the longest pt on the drug for >3.5 years with partial response for >3 years. The median duration of response was 11.6 months (95% CI: 9.9, 15.2), and included 1 pt with a complete response for >2 years. The proportion of pts alive at 2 years is 48%. Final prognostic factors for survival in the multivariate model were ECOG PS 0 vs. =1 (p=0.0034); time interval from diagnosis to sunitinib treatment =1 yr vs. <1 yr (p=0.0002); hemoglobin =13 vs. <13 g/dL for males and =11.5 vs. <11.5 g/dL for females (p=0.0002). Conclusions: Median survival is nearly 2 years, which compares favorably to the historical experience (12.7 months) in second-line therapy with other agents (JCO 2004;22:454–63). The influence of sunitinib therapy on patient survival is being investigated in a randomized phase 3 trial compared to interferon-a in first-line therapy for mRCC. Further study of prognostic factors to sunitinib therapy is warranted in the first-line setting.

No significant financial relationships to disclose.

Exposure-response of sunitinib in metastatic renal cell carcinoma (mRCC): A population pharmacokinetic/pharmacodynamic (PKPD) approach

5027

Background: Sunitinib malate (SU) is an oral, multitargeted tyrosine kinase inhibitor of VEGFRs and PDGFRs, and has shown substantial antitumor activity in mRCC (Motzer et al, JAMA 2006 and ASCO 2006). This analysis describes SU, and total drug (TD; SU+SU12662 [active metabolite]) exposure-response relationships in mRCC using a population PKPD approach. Methods: PK and efficacy data from 3 studies (phase II and III) of SU (25–62.5 mg/day; 4 wks dosing followed by 2 wks off) in treatment-naïve (N=44) and cytokine-refractory mRCC pts (N=148) were analyzed. SU and SU12662 concentrations were fitted to a population PK model (a 2- compartment model for both parent and metabolite). Estimates of pt PK were used to calculate steady-state Area Under the Curve (AUCss) for SU, SU12662 and TD, which were used as the exposure measure in a PKPD analysis of partial response (PR) rates, time to tumor progression (TTP), overall survival (OS), and tumor volume changes. Results: The probability of a PR for cytokine-refractory pts increased with increasing AUCss for SU and TD. The odds-ratio suggested a 2.6-fold increase in PR frequency for each unit increase in AUCss. Longer TTP and OS were also noted in pts with high SU and TD AUCss. In treatment-naïve pts on SU, there was very little observed tumor progression or death (only 5 pts progressed and only 1 death) limiting the ability to analyze exposure-response. A tumor growth dynamics model (developed to describe changes in tumor volume [by CT or MRI] in response to treatment, as a function of AUCss) provided a good description of tumor volume changes with SU for both treatment-naïve and cytokine-refractory pts. Efficacy was not related to baseline tumor volume, gender, or race. Based on this model, clinical trial simulations assuming perfect pt compliance predict that 62% of pts would achieve a PR with SU 50 mg/day. Conclusions: SU and TD AUCss correlated significantly with the probability of a PR in cytokine- refractory pts, and longer TTP and OS. Limited data were available for treatment-naïve pts. The tumor growth dynamics model provided a good description of tumor volume changes with SU for both populations. This exposure-response analysis indicates that increased exposure to SU is associated with clinical benefit.

[Table: see text]

Phase II trial of sunitinib in bevacizumab-refractory metastatic renal cell carcinoma (mRCC): Updated results and analysis of circulating biomarkers

5035

Background: Sunitinib malate is an oral, multitargeted tyrosine kinase inhibitor with antiangiogenic and antitumor activity. This study evaluated the safety and activity of sunitinib in mRCC patients (pts) previously treated with the VEGF-neutralizing antibody, bevacizumab. Levels of angiogenic biomarkers, including plasma VEGF and soluble VEGFR-3 (sVEGFR-3), were assessed for predictive significance with clinical response. Methods: Pts were required to have mRCC with disease progression following bevacizumab- based therapy, measurable disease, ECOG performance status 0 or 1, and adequate organ function. Pts were treated with sunitinib 50 mg daily in 6-week cycles (4 weeks on, followed by 2 weeks off). The primary endpoint was objective response according to RECIST. Plasma VEGF and sVEGFR-3 levels were measured in pre-treatment samples and at multiple timepoints on study. Results: A total of 61 pts were enrolled. The objective partial response rate was 23% (95% CI: 13%, 36%); 35 pts (57%) demonstrated stable disease. The median duration of response was 36 weeks (95% CI: 26, NA) and progression-free survival was 30 weeks (95% CI: 18, 34). Plasma VEGF levels increased from baseline (3-fold mean elevation), while plasma sVEGFR-3 levels decreased from baseline (40% mean reduction). Pre-treatment VEGF levels were significantly higher in pts (n=34) with <10 weeks between cessation of bevacizumab and start of sunitinib (p<0.001); ELISA specificity suggests that detected VEGF is not bevacizumab-bound. Pre-treatment sVEGFR-3 levels were significantly lower at baseline in responding pts vs. non-responding pts (p<0.0318). A greater reduction in sVEGFR-3 levels was seen in responding pts vs. non-responding pts (p<0.10). Pretreatment VEGF and VEGF fold-changes did not differ according to clinical response. Conclusions: Sunitinib has significant antitumor activity in bevacizumab-refractory mRCC pts, suggesting absence of cross-resistance between bevacizumab and sunitinib. Biomarkers including plasma VEGF and sVEGFR-3 may have predictive potential in sunitinib-treated patients.

No significant financial relationships to disclose.

Quality of life (QOL) predicts for progression-free survival (PFS) in patients with metastatic renal cell carcinoma (mRCC) treated with sunitinib compared to interferon-alpha (IFN-α)

6594

Background: In a recent international, randomized phase III trial, sunitinib malate, an oral multitargeted receptor tyrosine kinase inhibitor of VEGFRs, PDGFRs, KIT, RET and FLT3 with both antitumor and antiangiogenic effects, was associated with statistically superior clinical efficacy and superior health-related QOL vs. IFN-a as first-line therapy in patients with mRCC (Motzer et al, Proc ASCO 2006;24:2s [Abstract LBA3]). Here we report a substudy of baseline QOL variables predicting PFS. Methods: 750 mRCC patients were randomized 1:1 to receive either sunitinib 50 mg orally once daily in repeated 6-week cycles (4 weeks on treatment followed by 2 weeks off) or IFN-a (9 MU via subcutaneous injection 3 times weekly). QOL was measured by the Functional Assessment of Cancer Therapy-General (FACT-G), the FACT-Kidney Symptom Index's Disease-Related Symptoms subscale (FKSI-DRS), and the patient self-rated overall health state (EQ-VAS) from the EuroQol Group's EQ-5D self-report questionnaire. For all QOL endpoints, higher scores indicated better outcomes (better QOL or fewer symptoms). Cox proportional-hazards model was used to test which baseline QOL variables predict PFS while controlling for other baseline demographic and clinical factors as well as treatment. Because the three QOL scores are correlated (r=0.61–0.69), three separate univariate models were fitted. Results and Conclusions: All three baseline QOL variables were predictive of PFS: better baseline FACT-G, FKSI-DRS and EQ-VAS scores were associated with longer PFS. When QOL and other baseline variables were controlled in the models, the superior treatment effect of sunitinib on PFS remained robust and large (See the table below).

[Table: see text]

Phase III randomized trial of sunitinib malate (SU11248) versus interferon-alfa (IFN-α) as first-line systemic therapy for patients with metastatic renal cell carcinoma (mRCC)

LBA3

Background: Two multicenter phase II trials of 2nd line monotherapy with sunitinib (SU11248) in patients (pts) with mRCC showed a response rate of approximately 40% (JCO 2006;24:16–24; Proc ASCO 23, 380s). This international, randomized phase III trial compared the efficacy and safety of sunitinib to IFN-α in treatment naïve pts with mRCC. Methods: Untreated pts with clear-cell mRCC were randomized 1:1 to receive sunitinib (6-week cycles: 50 mg orally once daily for 4 weeks, followed by 2 weeks off) or IFN-α (6-week cycles: subcutaneous injection 9 MU given three times weekly). The primary endpoint was progression-free survival (PFS). Secondary endpoints included objective response rate, overall survival, and adverse events. Based on a planned sample size of 690 patients, the trial was designed to have 90% power to detect a 35% improvement in median PFS from 20 weeks to 27 weeks (4.6 months to 6.2 months; 2-sided unstratified log-rank test; significance level 0.05). Results of a planned analysis on the primary endpoint, PFS, are presented in this report. Results: From Aug 2004 to Oct 2005, 750 patients were randomized: 375 to sunitinib, 375 to IFN-α. Baseline characteristics were well balanced, and included pooled median age = 60 and prior nephrectomy = 90%. Median PFS assessed by third-party independent review was 47.3 weeks (95% CI 40.9, not yet reached) for sunitinib vs. 24.9 weeks (95% CI 21.9, 37.1) for IFN-α [hazard ratio 0.394 (95% CI 0.297, 0.521) (p < 0.000001)]. The objective response rate by third-party independent review was 24.8% (95% CI 19.7, 30.5) for sunitinib vs. 4.9% (95% CI 2.7, 8.1) for IFN-α (p < 0.000001). The objective response rate by investigator assessment was 35.7% (95% CI 30.9, 40.8) for sunitinib vs. 8.8% (95% CI 6.1, 12.1) for IFN-α (p < 0.000001). 632 pts (85%) are alive, with 49 deaths on sunitinib arm and 65 deaths on IFN-α arm. 8% withdrew from the study due to adverse event on sunitinib arm vs. 13% on IFN-α arm. Conclusions: These results demonstrate a statistically significant improvement in PFS and objective response rate for sunitinib over IFN-α in first-line treatment of pts with mRCC.

[Table: see text]

Clinical outcome of taxane-resistant (TR) hormone refractory prostate cancer (HRPC) patients (pts) treated with subsequent chemotherapy (ixabepilone (Ix) or mitoxantrone/prednisone (MP)

4558

Background: The clinical course of TR HRPC pts has not previously been evaluated in a large, prospective study. No standard treatment exists for this pt population, although MP is frequently used. Ix is an epothilone B analogue with activity against TR cell lines. Methods: Metastatic HRPC pts with disease progression during or within 60 days of stopping T chemotherapy were eligible. In a 2-arm, non-comparative randomized phase II study, pts were assigned to receive either: 1) M 14 mg/m2 IV q3wks and P 5 mg PO BID or 2) I × 35 mg/m2 IV q3wks. Crossover was allowed for progression or toxicity. The study’s primary endpoint was to detect a ≥ 50% PSA decline by Consensus Criteria in at least 25% of 2nd-line pts (H0 = 10%, α = 0.04, β = 0.18 for each arm). Pts were followed for survival. Results: Forty-one evaluable pts each were accrued to Ix and to MP. The median follow-up is 5.0 months (range: 0.3–19.5). The median number of cycles administered to each 2nd-line arm is 3 (range: Ix: 1–8, MP: 1–12). Median survival from protocol entry is 13.0 months with Ix and 12.5 months with MP. Confirmed 2nd-line post-therapy (rx) ≥50% PSA declines were observed in 17% of Ix pts (95% CI = 7–32) and 20% of MP pts (95% CI = 9–35). Of pts with measurable disease, partial responses were observed in 1/18 pts on 2nd-line Ix (6%; 95% CI = 0.1–27.3) and in 1/15 pts on 2nd-line MP (7%; 95% CI = 0.2–31.9). Median duration on 2nd-line Ix and MP was 2.2 months and 2.3 months, respectively. Crossover to 3rd-line rx occurred in 39% of Ix pts and 68% of MP pts. Confirmed 3rd-line post-rx ≥50% PSA declines were observed in 3/24 Ix pts and in 4/13 MP pts. The most common grade 3/4 toxicity associated with 2nd-line rx was neutropenia as previously reported (41% of Ix pts, 54% of MP pts). Conclusions: This prospective trial has characterized TR HRPC pts as having an observed median survival of approximately 1 year. This may be a useful reference for the screening of effective agents in the 2nd-line setting for TR HRPC. Both Ix and MP appear to have only modest activity as 2nd- and 3rd-line rx in this highly selected TR HRPC population. This study was supported by Bristol-Myers Squibb and the Prostate Cancer Foundation.

No significant financial relationships to disclose.

Pharmacokinetics (PK) and efficacy of sunitinib in patients with metastatic renal cell carcinoma (mRCC)

4531

Background: Sunitinib malate (SU11248) is an oral, multi-targeted tyrosine kinase inhibitor of VEGFR, PDGFR, KIT, FLT3, and RET. Clinical studies have demonstrated efficacy of sunitinib in patients with multiple tumor types including two phase II studies in mRCC, where second-line monotherapy with sunitinib showed a response rate of greater than 40% by RECIST, with an additional ≥25% of pts exhibiting prolonged stable disease. A population PK analysis was performed to assess the exposure-response relationship between PK and tumor volume changes, clinical response, and time to tumor progression (TTP) in these two mRCC studies. Methods: In these two studies, 169 patients with mRCC were treated with sunitinib 50 mg/day for 4 weeks, followed by a 2-week off period (Schedule 4/2). Response to treatment was assessed by measuring tumor volume. Clinical response was assessed using RECIST and TTP using logistic regression and Kaplan-Meier survival analysis. A previously described population PK model of sunitinib and its primary active metabolite SU12662 was updated using additional data from three trials, including the two RCC trials. Using the model and trough plasma concentrations, steady-state AUCs of sunitinib plus SU12662 were estimated for each mRCC patient and tested as a predictor of response. Results: PK profiles were evaluable for 149 patients in the two mRCC trials. Plasma clearance (CL) decreased by an average of 28% in mRCC patients relative to healthy volunteers. Covariates, such as gender, age, and ECOG score also affected CL, however all of these changes were less than the estimated inter-individual variability in CL of 43%. Improved clinical response and longer TTPs were associated with greater AUCs. Within 12 weeks of treatment, mean tumor volume decreased by 24–32% in each trial. Conclusions: Individual patient exposures to sunitinib and SU12662 can be predicted with sparse concentration measurements using population PK analysis, and an exposure-response relationship is evident in mRCC. Dose adjustment is not warranted based upon any evaluated covariate. Over the first 12 weeks of treatment at 50 mg daily on Schedule 4/2, increased exposure was associated with improved clinical response and decreased tumor volumes.

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Annual zoledronic acid to prevent gonadotropin-releasing hormone agonist-induced bone loss in men with prostate cancer: A randomized placebo-controlled trial

4515

Background: Gonadotropin-releasing hormone (GnRH) agonists decrease bone mineral density (BMD) and increase fracture risk in men with prostate cancer. Zoledronic acid (4 mg IV every 3 months) increases BMD in GnRH agonist treated men. Intermittent zoledronic acid (4 mg IV once annually) increases BMD in postmenopausal women with osteoporosis but the efficacy of the annual treatment schedule in hypogonadal men is unknown. Methods: In a 12-month open-label study, men with nonmetastatic prostate cancer (n = 44) who were receiving a GnRH agonist were assigned randomly to zoledronic acid (4 mg IV × 1) or placebo. BMD of the posteroanterior lumbar spine and total hip were measured by dual energy x-ray absorptiometry at baseline and month 12. Serum N-telopeptide, a marker of osteoclast activity, was measured every 3 months. Results: Mean (± SE) BMD of the posteroanterior lumbar spine increased by 4.0 ± 0.9 in men treated with zoledronic acid and decreased by 3.1 ± 0.9 percent in men who received placebo (P < 0.001 for between-group comparison). BMD of the total hip decreased by 0.7 ± 0.6 percent in men treated with zoledronic acid and decreased by 1.9 ± 0.7 percent in men who received placebo (P = 0.005). Compared to placebo, zoledronic acid significantly decreased serum N-telopeptide throughout the 12-month study (P < 0.05). Conclusions: In men receiving a GnRH agonist for prostate cancer, a single treatment of zoledronic acid significantly increased bone mineral density of the total hip and spine at 12 months. Annual zoledronic acid may provide a convenient and effective strategy to prevent bone loss in hypogonadal men. This study was supported in part by Novartis Oncology and by the Prostate Cancer Foundation.

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Efficacy and safety of sunitinib malate (SU11248) in bevacizumab-refractory metastatic renal cell carcinoma (mRCC)

4522

Background: Sunitinib malate (SU11248) is an oral, multitargeted tyrosine kinase inhibitor of the vascular endothelial growth factor receptor (VEGFR) family, platelet-derived growth factor receptor (PDGFR) and other related receptors. It has demonstrated anti-tumor activity in cytokine-refractory mRCC patients (pts). The activity of sunitinib in pts refractory to VEGF binding agents such as bevacizumab, however, has not been evaluated. It was hypothesized that tumor resistance to bevacizumab may be driven, in part, through pathways sensitive to inhibition by sunitinib. A phase II study evaluating the activity of sunitinib in bevacizumab-refractory mRCC was thus conducted. Methods: Pts with mRCC who demonstrated RECIST-defined disease progression within 3 months after bevacizumab-based therapy were treated with sunitinib (50 mg daily, 4 weeks of a 6-week cycle). Additional eligibility included measurable disease, clear cell histology, ≤ 2 prior systemic regimens, prior nephrectomy, performance status 0 or 1 and adequate organ function. The primary endpoint was objective response by RECIST criteria. A single-stage design was employed to test the null hypothesis that the true response rate is ≤ 5% versus the alternative hypothesis that the true response rate is ≥ 15%. Results: Accrual of 60 patients has been completed. Baseline characteristics include a median age of 59 years; 92% of pts had ≥ 2 metastatic sites and 23% had prior radiotherapy. Thirty-two of 60 pts enrolled are evaluable for response; 28 pts are too early for assessment. Twenty-six pts (81%) demonstrated some degree of tumor shrinkage, including, 4 pts (13%; 95% CI 4%, 29%) demonstrating an objective partial response. The most common treatment-related adverse events (AEs) included fatigue, diarrhea, dysgeusia, and nausea. Serious treatment-related AEs included fatigue, diarrhea, nausea and one fatal cerebral hemorrhage; 3 pts withdrew due to an AE. Conclusions: Sunitinib has substantial antitumor activity in bevacizumab-refractory mRCC pts, suggesting that sunitinib may inhibit signaling pathways involved in bevacizumab resistance. The precise mechanisms of response to sunitinib in bevacizumab-refractory tumors will require additional studies.

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Selective bladder preservation for muscle-invasive transitional cell carcinoma of the urinary bladder

Invasive transitional cell carcinoma (TCC) of the urinary bladder is traditionally treated with radical cystectomy. This approach results in great morbidity and lifestyle changes, and approximately half of the patients treated in this way will experience recurrent TCC despite surgery. An alternative approach using selective bladder-preservation techniques incorporates transurethral resection of bladder tumours, radiation therapy, and chemotherapy. Over the past 20 years, international experience has demonstrated that this approach is feasible, safe, and well tolerated. Furthermore, the long-term outcomes of overall survival and disease-free survival compare favourably with the outcomes from radical cystectomy. The most important predictor of response is stage, with significantly higher long-term survival in patients with T2 disease. Another important positive predictor of complete response to therapy is the ability of the urologic oncologist to remove all visible tumour through a transurethral approach prior to initiation of radiation therapy. A negative predictive factor is the presence of hydronephrosis, and age and gender do not affect disease-free survival. The majority of patients who enjoy long-term survival do so with an intact native bladder. Quality of life studies have demonstrated that the retained bladder functions well in nearly all of these patients. Selective bladder preservation will not entirely take the place of radical cystectomy, but should be offered as an important alternative to patients newly diagnosed with muscle-invasive TCC.

Retinal ischemia leads to apoptosis which is ameliorated by aurintricarboxylic acid

Transient retinal ischemia results in a delayed cell death of the inner retinal layers. This study demonstrates that this ischemic cell death occurs, at least in part, through apoptosis. The general endonuclease inhibitor, aurintricarboxylic acid, protected rat retinal cells from ischemic cell damage when administered before the onset of ischemia and, more importantly, when administered 6 hr after the insult. Thus, the demonstration that transient retinal ischemia results in cell damage as a result of apoptosis opens new therapeutic strategies aimed at lessening retinal damage as a result of this process.

The pharmacologic approach to the treatment of obesity

Obesity is a major risk factor for morbidity and mortality, and a series of pharmacologic approaches are available for helping to manage the problem. Obesity is caused by an imbalance between caloric intake and energy expenditure, which is influenced by both environmental and genetic factors. Pharmacologic treatments include anorexigenic agents, which fall into two broad categories: those that act via brain catecholamine pathways and those that act via serotonin pathways. The most recent oral agents approved are dexfenfluramine, which is currently being marketed, and sibutramine. Both agents inhibit the control reuptake of serotonin but in addition may have effects on thermogenesis. Under investigation are agents that increase energy expenditure: the beta 3-adrenergic receptor agonists and drugs that prevent the intestinal absorption of free fatty acids and cholesterol. In development are innovative approaches to influence leptin and its receptors, various obesity genes, and biologic substances thought to influence satiety (neuropeptide Y, enterostatin, cholecystokinin, bombesin, and amylin). Obesity has now become a major target for drug development not only for affecting obesity per se but also for managing and preventing comorbid conditions such as diabetes and cardiovascular disease.

Use of calcium antagonists in patients with ischemic heart disease and systemic hypertension

Ischemic heart disease (IHD) and systemic hypertension commonly coexist in a large number of patients, and the presence of hypertension is a risk factor for worsening IHD. A monotherapy that would effectively treat both is thus an attractive idea, and calcium antagonists have been evaluated in this role. Calcium antagonists exert therapeutic effects through a combination of actions, including systemic and peripheral vasodilation, negative inotropy, and reduced nodal conduction. In randomized, double-blind clinical trials, verapamil compares favorably with propranolol in the alleviation of angina and hypertension. Both diltiazem and nifedipine, as well as long-acting diltiazem, are also effective in treating the combined condition. In addition, each of these drugs enhances exercise tolerance and favors compliance with calcium antagonist therapy. Recent questions regarding the safety of this class of drug have tempered the enthusiasm for their use as first-line therapy in cardiovascular disease. In particular, short-acting dihydropyridine derivatives, including nifedipine and isradipine, may increase cardiovascular morbidity and mortality because of reflex sympathetic stimulation. The results of appropriately controlled, prospective clinical trials will provide more definitive conclusions. For now, we must be cautious in the use of calcium antagonist monotherapy for combined IHD and hypertension.

Interleukin-7 is trophic for embryonic neurons and is expressed in developing brain

Interleukin-7 (IL7) is a hematopoietic cytokine with critical functions in both B- and T-lymphocyte development. In this study, we find that IL7 exhibits trophic properties in the developing brain as well. Treatment of cultures of embryonic brain with exogenous IL7 increases neuronal survival and results in greater numbers of cells manifesting neurite outgrowth. As demonstrated with single-cell cultures, IL7 acts directly to promote neuronal survival. Expression of the mRNA encoding the high-affinity IL7 receptor (IL7R) is observed in vitro in neurons as well as in subventricular zone progenitor cells. Phosphorylation of p59fyn, which is activated by IL7 in pre-B cells and is thought to be important in neural development, occurs rapidly following IL7 treatment of cultured embryonic neurons. Additionally, the expression of c-myc mRNA, which is modulated by IL7 in lymphoid cells, is upregulated by IL7 in the same CNS cultures. Finally, the messenger RNAs encoding IL7 and IL7R are expressed in vivo in developing brain. The direct neurotrophic properties of IL7 combined with the expression of ligand and receptor in developing brain suggest that IL7 may be a neuronal growth factor of physiological significance during central nervous system (CNS) ontogeny.

CSF-1 deficiency in mice results in abnormal brain development

Colony stimulating factor-1 (CSF-1) was initially identified as a growth factor for mononuclear phagocytes. This study examines the role of CSF-1 in the development of the central nervous system (CNS). CSF-1 treatment of neurons cultured from embryonic brain promoted survival and process outgrowth in a dose-dependent manner. By contrast, CSF-1 treatment of neurons cultured from the osteopetrotic (op/op) mouse, a null mutant for CSF-1, promoted significantly less process outgrowth, suggesting that there are neural abnormalities in op/op animals. Nuclease protection assays were used to determine whether CSF-1 and its receptor are expressed at times appropriate to regulate neural development. Both CSF-1 and its receptor are expressed in developing mouse brain, with a unique pattern of CSF-1 mRNA splice variant expression encoding secreted, and not membrane-bound, growth factor. To determine whether brain function is altered by null mutation of CSF-1, op/op mice were examined using electrophysiologic assays. Brainstem auditory and visual evoked potentials were both abnormal in op/op mice. Further, intracortical recordings revealed aberrant neuronal function within visual cortex and alterations in the cortical circuitry that balances excitation and inhibition. Daily CSF-1 injection of postnatal op/op mice largely rescued the abnormal neural phenotype, confirming that the absence of CSF-1 during development is responsible for the abnormalities. The effects of CSF-1 on cultured embryonic neural cells, the developmentally appropriate expression of CSF-1 and its receptor, and the neurological abnormalities in op/op mice suggest a role for CSF-1 in brain development.

Cytokine-induced programmed death of cultured sympathetic neurons

Programmed cell death (PCD) of sympathetic neurons is inhibited by nerve growth factor. However, factors that induce PCD of these cells are unknown. Leukemia inhibitory factor (LIF) and ciliary neurotrophic factor, neuropoietic cytokines known to regulate sympathetic neuron gene expression, were examined for effects on survival of cultured sympathetic neurons. Treatment with LIF or ciliary neurotrophic factor caused neuronal death in a dose-dependent fashion. Inhibition of RNA or protein synthesis, or treatment with potassium, all of which prevent PCD after nerve growth factor deprivation, prevented LIF-induced death. The morphologic and ultrastructural characteristics of the neuronal death induced by LIF and by nerve growth factor deprivation were similar. Furthermore, LIF treatment resulted in DNA fragmentation with a characteristic "ladder" on Southern blot analysis. These observations suggest that neuron numbers may be regulated by factors which initiate PCD, as well as by factors which prevent it.