Validation of metastasis-free survival as a surrogate endpoint for overall survival in localized prostate cancer in the era of docetaxel for castration-resistant prostate cancer

BACKGROUND

Prior work from the Intermediate Clinical Endpoints in Cancer of the Prostate (ICECaP) consortium (ICECaP-1) demonstrated that metastasis-free survival (MFS) is a valid surrogate for overall survival (OS) in localized prostate cancer (PCa). This was based on data from patients treated predominantly before 2004, prior to docetaxel being available for the treatment of metastatic castrate-resistant prostate cancer (mCRPC). We sought to validate surrogacy in a more contemporary era (ICECaP-2) with greater availability of docetaxel and other systemic therapies for mCRPC.

PATIENTS AND METHODS

Eligible trials for ICECaP-2 were those providing individual patient data (IPD) after publication of ICECaP-1 and evaluating adjuvant/salvage therapy for localized PCa, and which collected MFS and OS data. MFS was defined as distant metastases or death from any cause, and OS was defined as death from any cause. Surrogacy was evaluated using a meta-analytic two-stage validation model, with an R2 ≥ 0.7 defined a priori as clinically relevant.

RESULTS

A total of 15 164 IPD from 14 trials were included in ICECaP-2, with 70% of patients treated after 2004. The median follow-up was 8.3 years and the median postmetastasis survival was 3.1 years in ICECaP-2, compared with 1.9 years in ICECaP-1. For surrogacy condition 1, Kendall's tau was 0.92 for MFS with OS at the patient level, and R2 from weighted linear regression (WLR) of 8-year OS on 5-year MFS was 0.73 (95% confidence interval 0.53-0.82) at the trial level. For condition 2, R2 was 0.83 (95% confidence interval 0.64-0.89) from WLR of log[hazard ratio (HR)]-OS on log(HR)-MFS. The surrogate threshold effect on OS was an HR(MFS) of 0.81.

CONCLUSIONS

MFS remained a valid surrogate for OS in a more contemporary era, where patients had greater access to docetaxel and other systemic therapies for mCRPC. This supports the use of MFS as the primary outcome measure for ongoing adjuvant trials in localized PCa.

Abstract PD3-10: Higher serum PD-L1 predicts for increased overall survival to lapatinib vs trastuzumab in the phase 3 CCTG MA.31 trial

Background: In the CCTG (Canadian Clinical Trials Group) MA.31 randomized phase 3 trial, the trastuzumab-taxane combination led to longer PFS than lapatinib-taxane in HER2-positive metastatic breast cancer (MBC). We previously reported the prognostic utility of pretreatment serum PD-L1 in the trastuzumab arm of MA.31 (ASCO 2018, #1031), and here we evaluate serum PD-L1 in the lapatinib arm, and in the whole trial. Higher serum PD-L1 has been reported to be associated with reduced response to treatment with the immune checkpoint inhibitors in melanoma and lung cancer.

Methods: MA.31 accrued 652 centrally and/or locally-identified HER2-positivepatients; 186 in the trastuzumab arm, and 202 in the lapatinib armhad pretreatment serum available. TheELLA immunoassay platform (ProteinSimple, San Jose, CA) was used to quantitate serum PD-L1. Step-wise forward Cox multivariate analysis was used for PFS and OS, and testing for treatment-biomarker interaction was based on the local partial-likelihood method (Liu Y, Jiang W, and Chen BE, Statistics in Medicine 34, 3516-3530, 2015).

Results: In the total study population, pretreatment serum PD-L1 concentration had a median of 86.2 pg/ml, and 25% and 75% interquartiles of 64.1 and 134.3 pg/ml, respectively. In univariate analysis in the whole trial, and within both treatment arms, serum PD-L1 was not a significant biomarker for PFS. For OS, higher serum PD-L1 (as a continuous variable) was significant for shorter OS within the trastuzumab arm (HR=3.84, p=0.04), but was not associated with OS in the lapatinib arm (p=0.37). In the whole trial, in multivariate analysis for OS [15 covariates included: age, race, ECOG status, anthracyclines, other chemo, endocrine, radio, other prior adjuvant therapy, disease status, ER status, PR status, Ki67 (log transformed), CK5, EGFR, treatment arm, and serum PD-L1 (with median cut point)], serum PD-L1 remained a significant independent covariate (HR= 2.27, p= 0.001 (Table).There was significant interaction between treatment arm and continuous serum PD-L1 (Bootstrap method, p=0.0025); above 214.2 pg/ml serum PD-L1 (89% percentile), higher pretreatment serum PD-L1 was associated with a shorter OS to trastuzumab treatment, but longer OS to lapatinib treatment.

Conclusions: In the CCTG MA.31 trial, serum PD-L1 was a significant predictive factor: higher pretreatment serum PD-L1 was associated with a shorter OS to trastuzumab treatment, but longer OS to lapatinib treatment. Immune evasion may decrease the effectiveness of trastuzumab therapy. Further evaluation of elevated serum PD-L1 in the advanced breast cancer setting is warranted to identify HER2-positive MBC patients who may benefit from novel immune-targeted therapies in addition to trastuzumab.

Multivariate Analysis (whole trial): Significant Independent CovariatesCovariateP-ValueHRLower 95% CIHigher 95% CISerum PD-L1 (pretreatment) (>median vs <median)0.0012.271.403.68EGFR Status (continuous IHC score)0.0031.0121.0041.019Other Chemotherapy (yes vs no)0.0081.911.193.07Treatment Arm (trastuzumab vs. lapatinib)0.0100.530.330.86ECOG Performance Status (0 vs 1 or 2)0.0250.590.370.94Ki67 (log)0.0461.451.0062.081

Citation Format: Moku PR, Shepherd LE, Ali SM, Leitzel K, Parulekar WE, Zhu L, Virk S, Nomikos D, Aparicio S, Gelmon KA, Drabick JJ, Cream L, Halstead SE, Umstead T, Mckeone D, Maddukuri A, Polimera HV, Ali A, Poulose J, Pancholy N, Spiegel H, Nagabhairu V, Chen BE, Lipton A. Higher serum PD-L1 predicts for increased overall survival to lapatinib vs trastuzumab in the phase 3 CCTG MA.31 trial [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr PD3-10.

Abstract P4-14-03: Influence of competing risks of death on the interpretation of adjuvant endocrine therapy trials for breast cancer

Background: Early stage, hormone sensitive breast cancer is associated generally with a good prognosis, with only a minority of patients expected to die of breast cancer. Death from causes other than breast cancer can dilute the patients at risk of breast cancer events and result in over-estimation of risk of recurrence and consequently the benefit from breast cancer therapy, a so-called immortal time bias. The MA.17R trial (Goss et al 2016) evaluated the role of extending adjuvant treatment with letrozole from 5 to 10 years. Here we determine the effect of analyzing the MA.17R trial using methods accounting for competing risks.

Methods: We compared conventional and competing risk methods for disease-free survival (DFS) and for distant recurrence-free survival (DRFS). In Kaplan-Meier analyses death from any cause was considered an event while cumulative incidence functions (CIFs) assumed death without recurrence to be a competing risk. The complement of the survival function (one minus the survival function) was used to estimate incidence of the primary event of interest. This was compared to estimates obtained using CIFs accounting for the occurrence of competing events.

Results: Non-breast cancer death was the most common event defining DFS and DRFS. Over the course of follow-up, there was increasing discrepancy between the risk of disease recurrence measured using Kaplan-Meier and CIF. Among letrozole treated patients the estimated distant recurrence at 5 years of follow-up was 5.4% using CIF and 9.6% using Kaplan-Meier. At 10 years of follow-up, the estimated distant recurrence was 8.4% using CIF and 20.0% using Kaplan-Meier. Similar results were observed for the placebo group (8.5% vs 12.1% at 5 years and 14.8% vs 27.3% at 10 years), and in patients with baseline cardiovascular disease (see Table). Benefit from letrozole on DFS and DRFS was greater when accounting for competing risk (hazard ratio [HR] for DFS 0.66, 95%CI 0.48-0.90; DFRS HR 0.75, 0.50-1.14) compared to the conventional method (DFS HR 0.79, 0.62-0.99; DRFS HR 0.91, 0.70-1.18). In women with baseline cardiovascular risk, the benefits of extended adjuvant letrozole when considering competing risk (DFS HR 0.38, 0.16-0.89; DRFS HR 0.46, 0.16-1.35) were also greater than those observed in the conventional analysis (DFS HR 0.55, 0.32-0.93; DRFS HR 0.59, 0.33-1.04). Treatment with extended letrozole did not influence non-breast cancer death in women who died with disease recurrence (HR 1.06, 0.74 -1.50) or in those with competing risk or censored from the analysis (HR 1.05, 0.73 -1.49).

Conclusion: Over the course of follow-up, estimates of DFS and DRFS differ increasingly if measured using Kaplan-Meier or CIF, with CIF estimates of risk being substantially lower. Using a competing risk model, the reduction in distant recurrence at 8 years with extended letrozole is less than 1%. Additional competing risk analyses of the MA.17 (Goss 2006) and MA.27 (Goss 2013) trials are ongoing.

Cumulative incidence of disease recurrence in patients with baseline cardiovascular riskTime (years)CIF (%)1-KM (%)Letrozole11.51.534.46.555.813.8Placebo13.53.538.311.8512.520.3

Citation Format: Ethier J-L, Parulekar W, Shepherd L, Summers L, Strasser-Weippl K, Tu D, Amir E. Influence of competing risks of death on the interpretation of adjuvant endocrine therapy trials for breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-14-03.

Significance of baseline and change in quality of life scores in predicting clinical outcomes in an international phase III trial of advanced pancreatic cancer: NCIC CTG PA.3

BACKGROUND

There is insufficient information regarding the prognostic significance of baseline and change in quality of life (QoL) scores on overall survival (OS) in advanced pancreatic cancer.

METHODS

QoL was assessed prospectively using the EORTC QLQ-C30 as part of the PA.3 trial of gemcitabine + erlotinib (G + E) vs. gemcitabine + placebo (G + P). Relevant variables and QoL scores at baseline and change at 8 weeks were analyzed by Cox stepwise regression to determine predictors of OS.

RESULTS

222 of 285 patients (pts) treated with G + E and 220 of 284 pts treated with G + P completed baseline QoL assessments. In a multivariable Cox analysis combining all pts, better QoL physical functioning (PF) score independently predicted longer OS (HR 0.86; CI: 0.80-0.93), as did non-white race (HR 0.64; CI: 0.44-0.95), PS 0-1 (HR 0.65; CI: 0.50-0.85), locally advanced disease (HR 0.55; CI: 0.43-0.71) and G + E (HR 0.78; CI: 0.64-0.96). Improvement in physical function at week 8 also predicted for improved survival (HR 0.89; CI: 0.81-0.97 for 10 point increase in score, p = 0.02).

CONCLUSION

In addition to clinical variables, patient reported QoL scores at baseline and change from baseline to week 8 added incremental predictive information regarding survival for advanced pancreatic cancer patients.

P5-14-01: Differences in Efficacy by Assessment Method: NCIC CTG Adjuvant Breast Cancer Trials MA.5, MA.12, MA.14, MA.21, MA.27 Meta-Analysis

Background: Based on recent breast cancer literature, we hypothesized that there could be substantive differences in apparent efficacy estimates using a log-normal (LN) survival model rather than with standard Kaplan-Meier (K-M) or Cox model methods. While both Cox and LN survival analyses offer greater specification by individual patient characteristics, the LN model may more robustly estimate survival under model misspecification. Methods: We recently pooled data for 5 NCIC CTG primary breast cancer trials: MA.5, MA.12, MA.14, MA.21, and MA.27. The total patient count for patients who received at least 1 dose of trial therapy is 11,253. Compilation included definition of STEEP endpoints (C Hudis, JCO, 2008) and standardized factor categorizations. The primary endpoint is Breast Cancer Free Interval (BCFI) defined as the time from randomization until recurrence: first local invasive or DCIS; regional, or distant; contralateral invasive or DCIS; or death from breast cancer. We found substantive evidence of non-proportionality for 7 factors compiled for the meta-analyses. In this work, we fit multivariate Cox and LN models with these 7 factors, lymph node status and pathologic T status. We then compare BCFI efficacy estimates for patient and tumour characteristics at 1-, 3-, and 5-years obtained with K-M, Cox, and LN models. Results: There was evidence that the Cox assumption of proportional hazards was violated for 7 factors: age, menopausal status, hormone receptor status, anthracycline use, chemotherapy use, race, and ECOG performance status. Differences between models were intrinsically affected by timing and extent of non-proportionality; there was no consistent pattern. In particular, investigations to date indicate efficacy estimates with absolute differences between K-M, Cox and LN estimates which varied by time of assessment: at 1-year 0.0 to 6.7%, at 3-years 0.4 to 18.6%, and at 5-years 0.2 to 17.0%. BCFI estimates with the K-M were inconsistently closer to those with the LN or Cox model: for K-M to Cox at 1-year 0.4 to 5.2%, at 3-years 0.4 to 15%, at 5-years 0.4 to 14.3%; for K-M to LN at 1-year 0.0 to 6.7%, at 3-years 0.5 to 18.6%, at 5-years 0.2 to 17.0%; for Cox to LN at 1-year 0.8 to 1.8%, at 3-years 1.9 to 6.0%, at 5-years 0.6 to 5.7%. K-M and Cox models have step-wise adjustments at events for K-M and Cox, rather than smooth modeling with the LN. Discussion: Even with reasonably large population subgroups, there were substantive differences in apparent survival (0.0 to 18.6%) between K-M, Cox and LN model types. The magnitude of differences in survival estimates was large enough to be clinically relevant and warrant further consideration as we evaluate new therapies and prognostic/predictive factors. We will be statistically investigating framework robustness under differing levels of model misspecification.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P5-14-01.

Comorbidity, age and overall survival in patients with advanced pancreatic cancer - results from NCIC CTG PA.3: a phase III trial of gemcitabine plus erlotinib or placebo

BACKGROUND

The effect of comorbidity, age and performance status (PS) on treatment of advanced pancreatic cancer is poorly understood. We examined these factors as predictors of outcome in advanced pancreatic cancer patients treated with gemcitabine +/- erlotinib.

PATIENTS AND METHODS

Comorbidity was evaluated by two physicians using the Charlson Comorbidity Index (CCI) and correlated with clinical outcome data from the NCIC Clinical Trials Group (NCIC CTG) PA.3 clinical trial.

RESULTS

Five hundred and sixty-nine patients were included; 47% were aged ≥ 65 years old, 36% had comorbidity (CCI>0). In multivariate analysis, neither age (p=0.22) nor comorbidity (p=0.21) was associated with overall survival. The baseline presence of better PS and lower pain intensity scores was associated with better overall survival (p < 0.0001 and p=0.01, respectively). An improvement in survival with the addition of erlotinib therapy was seen in patients age < 65 (adjusted hazard ratio (HR) 0.73, p=0.01) or in the presence of comorbidity (adjusted HR 0.72, p=0.03). However, neither age nor CCI score was predictive of erlotinib benefit after test for interaction. Patients treated with gemcitabine plus erlotinib who were ≥ 65 years of age or those with comorbidity had a higher rate of infections ≥ grade 3.

CONCLUSION

Low baseline pain intensity and better PS were associated with improved overall survival, while age and comorbidity were not independent prognostic factors for patients treated with gemcitabine-based therapy.

NCIC-CTG MA.20: An intergroup trial of regional nodal irradiation in early breast cancer

LBA1003

Background: Randomized trials have demonstrated that locoregional radiation after mastectomy reduces locoregional recurrence and improves overall survival (OS) in women with node positive breast cancer treated with adjuvant systemic therapy. MA.20 evaluated the addition of regional nodal irradiation (RNI) to whole breast irradiation (WBI) following breast conserving surgery (BCS). Methods: Women with high risk node-negative or node-positive breast cancer treated with BCS and adjuvant chemotherapy and/or endocrine therapy were stratified by positive nodes, axillary nodes removed, chemo- and endocrine therapy and randomized to WBI (50Gy in 25 fractions +/- boost irradiation) or WBI plus RNI (45Gy in 25 fractions) to the internal mammary, supraclavicular, and high axillary lymph nodes. The primary outcome was OS. The Data Safety Monitoring Committee approved the analysis plan for the protocol specified interim analysis of relapse patterns, survival and toxicity at 5 years. Upon review of the data, they recommended release of the results. Results: Between March 2000 to March 2007, 1,832 women were randomly assigned to WBI+RNI (916) or WBI (916). Median follow-up was 62 months. Characteristics of the study population were: mean age, 53.3 years; node negative, 10%; 1-3 positive nodes, 85%; > 4 positive nodes, 5%; adjuvant chemotherapy, 91%; and adjuvant endocrine therapy, 71%. WBI+RNI in comparison to WBI alone was associated with an improvement in isolated locoregional disease free survival (DFS; HR=.59, p=.02, 5 year risk: 96.8% and 94.5% respectively), distant DFS (HR=.64, p=.002, 5 year risk: 92.4% and 87.0% respectively), DFS (HR=.68, p=.003, 5 year risk: 89.7% and 84.0% respectively) and OS (HR=.76, p=.07, 5 year risk: 92.3% and 90.7% respectively). WBI+RNI in comparison to WBI was associated with an increase in grade 2 or greater pneumonitis (1.3% and 0.2% respectively, p=.01), and lymphedema (7.3% and 4.1% respectively, p=.004). Conclusions: The majority of women with node positive breast cancer are now managed by BCS followed by WBI and adjuvant systemic therapy. Results from MA.20 demonstrate that additional RNI reduces the risk of locoregional and distant recurrence, and improves DFS with a trend in improved OS.

Intergroup randomized phase III study of androgen deprivation therapy (ADT) plus radiation therapy (RT) in locally advanced prostate cancer (CaP) (NCIC-CTG, SWOG, MRC-UK, INT: T94-0110; NCT00002633)

CRA4504

Background: The impact of radiotherapy on overall survival (OS) in men with locally advanced CaP is unclear. The SPCG-7 trial recently showed a benefit to RT for CaP specific mortality. Our primary objective was to assess the effect of RT on OS when added to lifelong ADT in men with locally advanced CaP.

Methods: Patients with T3/T4 (1057) or T2, PSA > 40 μ g/l (119) or T2 PSA > 20 μ g/l and Gleason ≥ 8 (25) and N0 /NX, M0 prostate adenocarcinoma were randomized to lifelong ADT (bilateral orchiectomy or LHRH agonist) with or without RT (65-69 Gy to prostate ± seminal vesicles with or without 45Gy to pelvic nodes). The primary endpoint was OS and secondary endpoints included disease specific survival (DSS), time to disease progression and quality of life.

Results: 1205 patients were randomized from 1995 to 2005, 602 to ADT and 603 to ADT+RT (well balanced with respect to baseline characteristics). A protocol specified second interim analysis on OS was performed in Aug 2009 (data cut-off Dec 31 2008). The DSMC recommended release of the results to the Trial Committee for publication. The median follow-up is 6.0 years and 320 patients have died (175 ADT and 145 ADT+RT). 10% of patients had no follow-up data beyond 2006. The addition of RT to ADT significantly reduced the risk of death (hazard ratio [HR] 0.77, 95% CI 0.61-0.98, p=0.033). 140 patients died of disease and/or treatment (89 on ADT and 51 on ADT+RT) The disease specific survival HR was 0.57 (95% CI 0.41-0.81, p=0.001) favoring ADT+RT. The 10 year cumulative disease specific death rates were estimated at 15% with ADT+ RT and 23% with ADT alone. Grade ≥2 late GI toxicity rates were similar in both arms (proctitis, 1.3% ADT alone, 1.8% ADT+RT).

Conclusions: The trial results indicate a substantial overall survival and disease specific survival benefit for the combined modality approach (ADT+RT) in the management of patients with locally advanced prostate cancer with no significant increase in late treatment toxicity. In view of this data combined modality therapy (ADT+RT) should be the standard treatment approach for these patients. Supported by NCI-US Grant #5U10CA077202-12, CCSRI Grant #15469.

No significant financial relationships to disclose.

A retrospective analysis of tumor size (TS) as a continuous rather than discrete variable in advanced pancreatic cancer

e15565

Background: Objective “response rate” (RR) dichotomizes patients into categories of “response” (complete or partial) and “non-response”. This ignores a lot of data captured within the trial on tumor size changes, and may miss clinically important effects on tumor growth may occur in the absence of a response. Analyzing TS as a continuous variable (TS-CV) has been suggested as a more robust indicator of efficacy. Methods: Tumor size data from 2 randomized controlled trials in advanced pancreatic cancer conducted by NCIC.CTG were analyzed; NCIC.PA1 randomized patients to BAY12–9566 (MMPI) or Gemcitabine (Gem) and demonstrated a large and significant survival (OS) benefit for Gem (6.7 vs 3.4 months), NCIC.PA.3 randomized patients to Gem ± Erlotinib and showed a modest OS benefit for the combination (HR =0.81). In PA1, an early interim analysis (IA) using absence of progression as the primary measure did not halt accrual. Measures of TS at baseline and 8 wks were transformed and represented as a logarithm of the sum of the longest diameters. The difference in logarithms (d-LTS) from baseline to 8 weeks was calculated to indicate change in tumor size. Groups were compared using Wilcoxon rank-sum test. Results: In PA1, TS was significantly decreased in the Gem arm (mean d-LTS 0.087 on MMPI vs. -0.066 on Gem; p<0.0001), in keeping with the OS benefit (p<0.001). The decrease was also significant in the interim analysis cohort (p=0.007) and this result would, if used, have halted accrual earlier. In PA3, for all patients, decrease in TS was significantly larger for the combination arm (mean d- LTS -0.148 on combination vs. -0.114 on Gem; p=0.04), consistent with the OS benefit (p=0.038). Analysis on the 1st 130 patients yielded similar results (p=0.02) Conclusions: Tumor size changes may be a reasonable endpoint for screening efficacy trials in advanced pancreatic cancer. These results support further assessment of this alternate efficacy endpoint.

No significant financial relationships to disclose.

The relationship of K-ras mutations and EGFR gene copy number to outcome in patients treated with Erlotinib on National Cancer Institute of Canada Clinical Trials Group trial study PA.3

4521

Background: The National Cancer Institute of Canada Clinical Trials Group (NCIC CTG) PA.3 study compared treatment with the EGFR tyrosine kinase inhibitor erlotinib to placebo in patients with advanced stage pancreatic carcinoma who were receiving gemcitabine. This study demonstrated a significant advantage in survival [HR=0.82; P<0.04] and in progression free survival [HR=0.77; P<0.004] for patients who received erlotinib [Moore MJ et al, J Clin Oncol 2007]. While high-level expression of EGFR is common in pancreatic cancer, EGFR protein expression level as evaluated by immunohistochemistry did not predict which patients might benefit from erlotinib. In non- small cell lung cancer (NSCLC) where erlotinib has shown a survival benefit; the use of EGFR copy number measured by FISH is a better predictive factor for benefit, and patients whose tumor had a K-ras mutation do not respond nor benefit. Methods: The NCIC-CTG PA.3 trial had a sample size of 569 and NCIC.CTG has collected 280 archival formalin-fixed and paraffin embedded tumor biopsy or primary resection specimens from patients randomized on study. Many were fine needle aspirates and a total of 181 had sufficient tissue to allow molecular analysis. We performed a K-ras mutation analysis by PCR of exon 2 followed by sequencing, with negative results being validated by DHPLC. EGFR gene copy number was analysed by fluorescent in situ hybridization. Both methods were performed on all tumor samples adequate for analysis. Results: Overall 146 cases were suitable for K-ras mutation analysis and preliminary results have identified K-ras mutation in 90 patients [76%] and wild type KRAS in 29 patients; the remainder are pending. A total of 118 cases are suitable for EGFR FISH analysis, results have been obtained in 73 patients, and the remaining cases are pending. The correlations between K-ras mutational status and EGFR copy number, and outcomes [survival and disease control] in patients randomized to both erlotinib and placebo will be presented.

[Table: see text]

Competing causes of death in NCIC CTG MA.17, a placebo-controlled trial of letrozole as extended adjuvant therapy for breast cancer patients

540

Background: Risk of death from other malignancies (OM) and other causes (OC) than breast cancer (BC) increases with age. Effects of baseline factors on type of death were assessed with competing risks analyses. Methods: In NCIC CTG MA.17, 5,187 women free of recurrent breast cancer after 5 years of tamoxifen were randomized to letrozole (L, 2,593 women) or placebo (P, 2,594 women). The primary endpoint was disease free survival (DFS), and secondary, overall survival (OS). Follow-up was to October 9, 2005: median 3.9 years, range <0.1 to 7.0 years. Effects of competing risks were examined for endpoints of BC, OM, and OC for 11 baseline trial factors: treatment, age, menopausal status, duration of prior tamoxifen, adjuvant radiotherapy, bone fracture, osteoporosis, cardiovascular disease, hormone receptor status, nodal status, adjuvant chemotherapy. Lagakos’ hierarchical method (Lagakos, Appl. Statist. 1978; 27:235–241) was used to test for differential effects of baseline factors on type of death (BC, OM, OC). Results: Rate of censoring was 97.8%, with 256 deaths (BC, 102; OM, 50; OC, 100; unknown, 4). Non-breast cancer deaths accounted for 60% of known deaths; 72%, for those ≥70 years; and 48%, for those <70 years. Two baseline factors differentially affected type of death. Women with cardiovascular disease were more likely to die from OC (p=0.02), while those with osteoporosis were more likely to die of OM (p=0.03). Age and nodal status had directionally similar effects. Older women had shorter survival from all 3 causes of death (p=0.01). Lymph node positivity was associated with worse survival (p=0.003). Conclusions: Extended L provides similar proportional benefit in improving DFS for all ages of women (Muss ref abstract SABCS 2006). However, the magnitude of competing non-breast cancer, and non-treatment related, causes of death needs to be considered more frequently, since with early detection and improved therapies, breast cancer patients may increasingly be expected to survive their disease to die from another cause. The novel association between baseline osteoporosis and other malignancies is being explored quantitatively.

No significant financial relationships to disclose.

Early closure of clinical trials: The experience of the National Cancer Institute of Canada Clinical Trials Group

6053

Background: Phase III studies require a significant commitment on behalf of researchers and patients. Closure of a study before the originally planned number of patients have been enrolled may be due to a number of reasons such as poor accrual, information within the study that precludes continuation such as excess toxicity, an interim futility or extreme efficacy analysis or data from outside sources that render the study question obsolete. Methods: We reviewed the phase III activity of our group since inception. Reasons for early closure were classified in the following manner: accrual failure (AF), external information (EI), internal information (II). Studies were grouped by site and time period of study activation to demonstrate any trends over time. Results: 94 phase III studies led by our group were identified from our roster. Reasons for early closure are presented below. Other sites include brain with an early closure due to AF, head/neck where 1 of 3 studies closed due to AF, melanoma where 1 of 3 studies closed due to EI and sarcoma where 2 studies were successfully completed. Several of the studies that closed for accrual failure were nevertheless published either singly or as part of a meta-analysis. Conclusions: Slightly over one third of studies closed prior to achievement of the targeted sample size. Accrual failure continues to be the main cause of early study closure (27/34 or 80%) with a trend towards decreasing frequency of occurrence over time. Emerging data within or external to a study leading to study closure are important but relatively rare reasons for early closure.

[Table: see text]

No significant financial relationships to disclose.

Use of placebo in cancer medicine: The experience of a National Clinical Trials organization

6104

Background: The use of placebos in cancer clinical trials requires careful evaluation. Factors that must be considered include the impact of placebo on endpoint measurement, the efficacy of placebo relative to standard of care treatment, patient altruism/acceptance of a non-active intervention and the resulting increase in complexity of study conduct with respect to randomization, drug supply, data management, analysis and the unblinding process. Methods: We reviewed the experience of the National Cancer Institute of Canada Clinical Trials Group with the use of placebo in the randomized phase III setting from 1982–2005. Results: Since 1982, 34 studies were identified that utilized a placebo as part of study design. Data is presented below according to the type of study and date of study activation. The numbers in brackets represent those studies in which placebo was used alone in the control arm. Supportive care studies were the most common type of study employing a placebo as part of study design and constituted almost 50% of our Group’s experience. Therapeutic studies involving placebo were conducted in multiple sites including breast (4), lung (6), myeloma (1), melanoma (1), ovary (1) and pancreas (1). Conclusion: Phase III studies involving a placebo constitute an important part of our clinical trial activity and cross the spectrum of supportive care, therapeutic and prevention trials. The use of placebo in cancer studies may increase due to the relative ease of blinding in studies that evaluate targeted, oral therapies with minimal toxicities as well as the need for unbiased assessment of increasingly used endpoints such as time to progression.

[Table: see text]

No significant financial relationships to disclose.

Left ventricular function following adjuvant chemotherapy for breast cancer: The NCIC CTG MA5 experience

522

Background: Cardiac toxicity associated with anthracylines and more recently herceptin used in adjuvant breast cancer treatment is well recognized. Little is known about long term cardiac function as measured by left ventricular ejection fraction (LVEF) in patients post therapy. We analyzed the database of a randomized Phase 3 NCIC CTG study to assess changes over time in LVEF. Methods: Between 1989–1993, 710 pre/perimenopausal patients with node positive breast cancer were allocated to receive CEF (cyclophosphamide (C) 75 mg/m2 po d 1–14, epirubicin (E) 60 mg/m2 IV and fluorouracil (F) 500mg/m2 IV d1,d8) or CMF (C 100mg/m2 po d1–14, methotrexate (M) 40mg/m2 and F 600mg/m2 IV d1,8) given every 28 days for 6 cycles. The 10 year relapse-free survival was 52% (CEF) vs 45% (CMF), HR 1.31; stratified log rank, P=.007 (JCO, 2005,23;5166). LVEF was measured on both arms at baseline, months 6, 12, 36, and 60. Results: Compliance was good with measurements available on 100% of women at baseline, and 39% and 40% of patients at 60 months on the CEF and CMF arms respectively. Changes in LVEF from baseline are shown in the table . Conclusion: Changes in cardiac function as measured by a decrease in LVEF are not infrequent in patients after adjuvant therapy, even in the absence of anthracyclines. At 60 months, decreases of >10% were seen in up to 25% of patients receiving epirubicin administered at a cumulative dose of 720mg/m2 and in up to 10% of patients receiving CMF on whom measurements were available. The clinical significance of these findings needs to be assessed. Acknowledgements: This study was supported by funding from the Canadian Cancer Society through the National Cancer Institute of Canada and Pfizer Inc.

[Table: see text]

[Table: see text]

Randomized, double-blind, controlled trial of mitoxantrone/prednisone and clodronate versus mitoxantrone/prednisone and placebo in patients with hormone-refractory prostate cancer and pain

PURPOSE

To compare the incidence of palliative response in patients with hormone-resistant prostate cancer (HRPC) treated with mitoxantrone and prednisone (MP) plus clodronate with that of patients treated with MP plus placebo.

MATERIALS AND METHODS

Men with HRPC, bone metastases, and bone pain were randomly assigned to receive clodronate 1,500 mg administered intravenously (IV) or placebo every 3 weeks, in combination with mitoxantrone 12 mg/m2 IV every 3 weeks and prednisone 5 mg orally bid. Patients completed the present pain intensity (PPI) index and Prostate Cancer-Specific Quality-of-Life Instrument at each treatment visit and used a diary to record analgesic use on a daily basis. The primary end point was a reduction to zero or of two points in the PPI or a decrease of 50% in analgesic intake, without increase in either.

RESULTS

The study accrued 209 eligible patients over 44 months. One hundred sixty patients (77%) had mild PPI scores (1 or 2), and 49 (24%) had moderate PPI scores (3 or 4). The primary end point of palliative response was achieved in 46 (46%) of 104 patients on the clodronate arm and in 41 (39%) of 105 patients on the placebo arm (P =.54). The median duration of response, symptomatic disease progression-free survival, overall survival, and overall quality of life were similar between the arms. Subgroup analysis suggested possible benefit in patients with more severe pain.

CONCLUSION

MP provides useful palliation in symptomatic men with HRPC. Clodronate does not increase the rate of palliative response or overall quality of life. Clodronate may be beneficial to patients who have moderate pain, but this requires further confirmation.

Use of small-bore vs large-bore chest tubes for treatment of malignant pleural effusions

STUDY OBJECTIVE

To evaluate the efficacy of small-bore (12 French vanSonnenberg) catheters compared with standard large-bore chest tubes in the drainage and sclerotherapy of malignant pleural effusions.

DESIGN

Retrospective review.

SETTING

An academic tertiary care hospital.

PATIENTS

Adult patients with documented neoplasms and malignant pleural effusions, treated between 1986 and 1995.

INTERVENTION

All patients included in the study underwent drainage of malignant pleural effusions either by large-bore chest tube or by ultrasound-guided small-bore catheter. After drainage, pleurodesis was performed.

RESULTS

Outcome as defined by recurrence of effusion was determined by blinded examination of all postpleurodesis chest radiographs. We identified 58 cases of malignant pleural effusion in which small-bore catheters were used and 44 in which large-bore chest tubes were used. The majority of patients had breast (n = 56, 55%) or lung cancer (n = 29, 28%). The median age was 65 years. Fifty-nine patients were actively being treated with chemotherapy at the time of pleurodesis. The following sclerosing agents were used: talc, 27 (26%); tetracycline, 72 (70%); bleomycin, 2 (2%); and interferon, 1 (1%). Actuarial probabilities of recurrence at 6 weeks and 4 months were 45% and 53% for the small tubes vs 45% and 51% for the large tubes. Univariate and multivariate analyses failed to demonstrate that tube size had any influence on the rate of recurrence.

CONCLUSIONS

We were unable to detect any major differences in outcomes with the use of either size of chest tube. Our study suggests that small-bore catheters may be effective in the treatment of malignant pleural effusions and deserve further evaluation in prospectively designed trials.

Scoring oral mucositis

Oral mucositis is a common, dose limiting and potentially serious complication of both radiation and chemotherapy. Both these therapies are non-specific, interfering with the cellular homeostasis of both malignant and normal host cells. An important effect is the loss of the rapidly proliferating epithelial cells in the oral cavity, gut and in the bone marrow. Within the mouth, the loss of these cells leads to mucosal atrophy, necrosis and ulceration. Although post-treatment healing is generally uneventful, severe mucositis can be life threatening, especially if complicated by dehydration or secondary infection. Accurate and reproducible evaluation of oral mucositis is important in order to monitor patient toxicity during therapy, to document the toxicity of conventional therapy and to critically assess the effects of alternative therapies. A number of oral toxicity scoring systems have been described, but direct comparisons have rarely been undertaken and little data exist regarding inter- and intra-user reliability. This paper reviews a number of oral mucositis scoring systems that are commonly used and will also discuss, briefly, the biological basis of its development and management.