Kidney Cancer: Toxicity Management, Symptom Control, and Palliative Care

The challenges of managing the toxicities associated with the current armamentarium to combat kidney cancer continue to grow. It is therefore paramount for providers to not only have knowledge of the disease, but to also have an understanding of the potential adverse effects associated with the various treatments. In addition, it is important to incorporate palliative care strategies to help manage symptoms, improve quality of life, and support patients and their families throughout the continuum of the disease. This article will discuss the general toxicities and symptomatic issues encountered in patients with kidney cancer who are receiving targeted therapies and immunotherapies. It will also define the components of palliative care and its benefits. The recommendations in this article are from source documentation noted in various guidelines of the Oncology Nursing Society, ASCO, the National Comprehensive Cancer Network, and the Society for Immunotherapy of Cancer. We feel it is appropriate to modify and individualize management as deemed necessary to provide the best outcome for patients and their families.

Phase II study of bipolar androgen therapy (BAT) in men with metastatic castration-resistant prostate cancer (mCRPC) and progression on enzalutamide (enza)

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Background: Androgen receptor (AR) overexpression is a common adaptive resistance mechanism in mCRPC. High dose testosterone in this setting may induce tumor responses and restore normal AR expression. To evaluate BAT, we enrolled men with mCRPC progressing on enza to assess (1) responses to BAT and (2) enza re-challenge after BAT. Methods: Eligible men had minimally symptomatic mCRPC with progression on enza. Subjects received testosterone cypionate 400mg IM every 28d and continued gonadal suppression, until progression. Subjects were evaluated with PSAs each cycle, and CT/bone scans every 3 cycles. Upon progression on BAT, men were re-challenged with enza. The co-primary endpoints were > 50% PSA responses (PSA50) to BAT and PSA50 to enza re-challenge. The null hypothesis was a PSA50 rate of 5% for both endpoints, with alternative hypotheses of 20% to BAT and 25% to enza. 30 subjects were required for 90% and 83% power, respectively, with overall type 1 error of 0.1. Secondary endpoints were safety, objective response, progression-free survival (PFS), and effect on circulating tumor cell-based AR and AR-V7 expression. Results: 30 eligible subjects were accrued (2014-2016). No dose limiting toxicities were seen. 2 subjects had transient pain flares after BAT initiation. Common grade 1-2 adverse events (AE) were musculoskeletal pain (40%), increased hemoglobin (37%), breast tenderness (17%) and rash (17%). 3 Grade 3-4 AE potentially attributable to BAT occurred (pulmonary embolism, NSTEMI, and urinary obstruction). 9/30 men (30% [95% CI: 17-48%]) achieved a PSA50 to BAT. 5/14 men (36%) with measurable disease had an objective response by RECIST 1.1. The median clinical/radiographic PFS on BAT was 8.6 months. 21 subjects proceeded to enza re-challenge, yielding 15 PSA50 responses (54% by intention to treat [95% CI: 34-69%]), with a PFS of 4.8 months. 1/3 AR-V7+ subjects responded to BAT, and all had decreased AR-V7/AR ratios (2 converted to AR-V7-) after 3 cycles. Conclusions: The study met its primary endpoints, demonstrating preliminary efficacy of BAT in men with progressive mCRPC after enza. A randomized study comparing BAT to enza in mCRPC is ongoing. Clinical trial information: NCT02090114.

Prognostic factors for clinical outcomes in patients with metastatic castration resistant prostate cancer treated with sequential novel androgen receptor-directed therapies

BACKGROUND

Prognostic factors associated with clinical outcomes in patients with metastatic castration-resistant prostate cancer (mCRPC) treated with a novel androgen receptor-directed therapies (ARDT) in the second line setting has not been formally evaluated.

PATIENTS AND METHODS

We retrospectively reviewed and analyzed medical records of all patients with mCRPC who received sequential treatment with ARDT. We analyzed potential clinical factors associated with post treatment endpoints including 50% decline in prostatic-specific antigen (PSA), PSA-progression-free survival (PFS), clinical or radiographic PFS and overall survival (OS). Prognostic univariate and multivariate Cox proportional hazard models were developed and assessed.

RESULTS

One hundred twenty-six patients with mCRPC treated with a second-line novel ARDT were included. Overall, 50% decline in PSA was observed in 22% of patients and a median PSA-PFS of 2.9 months and a PFS of 3.6 months. After adjusting for potential confounders including prior exposure to docetaxel and number of prior antiandrogen agents, time to development of CRPC was an independent factor associated with PSA-PFS (hazard ratio [HR]: 0.99; 95% confidence interval [CI]: 0.99-1; P = 0.02) and PFS (HR: 0.99; CI: 0.98-1; P= 0.01). PSA response (50% decline) to first-line novel ARDT correlated negatively with PSA-PFS with second-line novel ARDT (HR: 1.7; 95% CI: 1.14-2.53; P = 0.009) and lower pre-treatment levels of albumin were associated with shorter PFS (HR: 0.56; 95% CI: 0.32-0.97; P = 0.03). Performance status, pre-treatment levels of albumin, extent of disease and time to development CRPC were associated with OS.

CONCLUSIONS

Second-line ARDT is associated with modest outcomes in patients with mCRPC. Time to development of CRPC is the strongest predictor of PSA response, PSA-PFS and OS which suggest that intrinsic resistance to AR directed treatment is the major treatment outcome factor in these patients. Future studies in patients receiving long term ARTD should include the identification of predictive biomarkers to facilitate treatment selection.

Comparison of abiraterone acetate (Abi) versus ketoconazole (Keto) in chemotherapy-naive patients (CN-pts) with metastatic castration resistant prostate cancer (mCRPC)

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Background: Abi is a standard treatment (tx) in CN-pts with mCRPC. It is a potent and selective CYP 17 inhibitor. However, in many countries where abi has not been approved yet, keto is used as an alternative CYP 17 inhibitor. Preclinical data suggests that keto is a less specific and potent inhibitor of CYP 17. Clinical data (Peer et al, Prostate 2014) suggests that in docetaxel (D) refractory mCRPC, the outcome of abi tx may be superior to keto. However, there are limited clinical data comparing both agents in CN-pts with mCRPC. We aimed to compare the clinical effectiveness of abi vs keto in CN-pts with mCRPC, who were treated after the year 2004 (approval of D for the tx of mCRPC). Methods: Records from 72 CN-pts with mCRPC treated with abi in 5 Israeli centers were reviewed retrospectively, and matched by pre-tx risk category (favorable, intermediate, poor; Keizman, Oncologist 2012) to pts treated with keto 200 - 400 mg 3x day (international database, n = 156, from 4 centers across the US and Israel). We compared the PSA response (decrease ≥ 50% from baseline), biochemical and radiological progression free survival (PFS), and overall survival (OS) between the groups. PFS and OS were determined by Cox regression. Results: The groups were matched by pre-tx risk category (favorable, intermediate, poor; Keizman, Oncologist 2012), based on pretreatment NLR and PSA doubling time, and the prior response to a gonadotropin-releasing hormone agonist. The groups were balanced regarding age (72 abi vs 70 keto), time from primary tx to disease relapse, gleason score, pre-tx disease extent (limited-axial skeleton and/or nodal vs extensive- appendicular skeleton and/or visceral), and ECOG PS. In the groups of abi vs keto, PSA response was 75% vs 47% (OR 3.8, p = 0.04), median biochemical PFS 12 vs 6 months (HR 0.62, p = 0.03), median radiological PFS 16 vs 8 months (HR 0.54, p = 0.01), median OS not reached after a median follow-up time of 18 months vs 26 months, and tx interruption d/t adverse events 10% vs 22% (0R 0.65, p = 0.05). Conclusions: In CN-pts with mCRPC, the outcome of pts treated with abi may be superior to keto.

Comparison of sunitinib (su) versus temsirolimus (tem) in patients (pts) with poor-risk metastatic renal cell carcinoma (prmRCC)

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Background: Based on a single phase 3 study, the mTOR inhibitor tem was approved as 1st line therapy for prmRCC. However, in daily practice, prmRCC pts are often treated with the VEGFR and PDGFR inhibitor su. We aimed to compare the clinical effectiveness of su vs tem in prmRCC pts. Methods: We performed an international multicenter retrospective study of pts with prmRCC (HENG criteria), who were treated in 8 centers across 2 different countries. 31 pts were treated with 1st line tem. Each tem treated pt was individually matched with a 1st line su treated pt, by clinicopathologic factors. The effect of tx type (tem vs su) on clinical benefit, progression free survival (PFS) and overall survival (OS), was tested using a chi-square test and partial likelihood test from cox model. Furthermore, univariate and multivariate analyses of association between clinicopathologic factors and tx type (tem vs su), and outcome were performed using the entire pt cohort (n=62). Results: The groups were matched by age (median 65), gender (male 68%), prior nephrectomy (58%), renal cell carcinoma histology (clear cell 81%), smoking status (active in 35%), use of angiotensin system inhibitors (42%), and pre-tx neutrophil to lymphocyte ratio >3 (58%). In tem vs su treated pts, clinical benefit (partial response + stable disease) was 61% (n=19) (partial response 6%, n=2) vs 71% (n=22) (partial response 29%, n=9) (p=0.62). Median PFS was 5 vs 8 mos (p=0.08), and median OS 9 vs 17 mos (p=0.03). In multivariate analyses of the entire pt cohort (n=62), su tx was independently associated with OS (HR 0.6, p=0.001). Conclusions: In prmRCC patient, the VEGFR inhibitor su may be associated with an improved outcome vs the mTOR inhibitor tem.

Outcome of octogenarian versus (vs) young patients (pts) with metastatic renal cell carcinoma (mRCC), treated with sunitinib (su)

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Background: Su is a standard treatment (tx) for mRCC. Octogenarian pts (aged ≥ 80) are often considered to be unfit for su tx, and recommendations for their tx is limited by the paucity of clinical trials data in this population. We aimed to study baseline characteristics and outcome of octogenarian vs young (aged ≤45) pts with mRCC treated with su. Methods: We performed an international multicenter retrospective study of pts with mRCC, who were treated with su in 8 centers across 2 different countries. We compared baseline characteristics and outcome of octogenarian versus young pts. The effect of very old age on response rate (RR), progression free survival (PFS) and overall survival (OS), was tested with adjustment of other known confounding risk factors using a chi-square test and partial likelihood test from cox model. Furthermore, univariate and multivariate analyses of association between clinicopathologic factors and age, and outcome were performed using the entire pt cohort. Results: Between 2004-2013, 36 octogenarian (group 1; median age 83) and 37 young (group 2; median age 42) mRCC were treated with su. The groups were balanced regarding the following baseline clinicopathologic characteristics: gender, HENG risk, past nephrectomy, mRCC histology, ≥ 2 metastatic sites, lung/liver/bone metastasis, prior targeted tx, smoking status, use of angiotensin system inhibitors (ASIs), pre-tx neutrophil to lymphocyte ratio (NLR) >3, and sunitinib induced hypertension (HTN). In group 1 vs 2, 53% vs 27% (p=0.006) had dose reduction/treatment interruption d/t side effects. Clinical benefit (partial response + stable disease) in group 1 vs 2 was 76% vs 84%, while 24% vs 16% had disease progression within the first 3 months of tx (p=0.09). Median PFS was 11 vs 8 months (p=0.1). Median OS was 22 vs 20 months (p=0.7). In multivariate analyses of the entire pt cohort (n=73), age was not significantly associated with PFS or OS. Conclusions: Su is active in octogenarian mRCC pts. Vs young pts, a significantly higher proportion of octogenarian pts had dose reduction/treatment interruption d/t side effects.

Metformin use and outcome of sunitinib treatment in diabetic patients with metastatic renal cell carcinoma

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Background: Sunitinib (Su) is a standard treatment (tx) for metastatic renal cell carcinoma (mRCC). Pre-clinical and clinical studies in several cancer types suggest that the antidiabetic agent metformin (Met) has antitumor activity. Met may negatively regulate mTOR activity. Its effect on the outcome of targeted therapies in mRCC is poorly defined. We analyzed the effect of Met use on the outcome sunitinib tx in diabetic patients (pts) with mRCC. Methods: We performed a retrospective study of an unselected cohort of diabetic pts with mRCC, who were treated with Su in 7 centers across 2 countries. Pts were divided into 2 groups: (1) Met users and (2) Met naive. The effect of Met use on response rate (RR), progression free survival (PFS) and overall survival (OS), was tested with adjustment of other known confounding risk factors using a chisquare test and partial likelihood test from Cox model. Furthermore, univariate and multivariate analyses of association between clinicopathologic factors and Met use, and outcome were performed using the entire pt cohort. Results: Between 2004-2014, 108 diabetic pts with mRCC were treated with sunitinib. There were 52 Met users (group 1) and 56 nonusers (group 2). The groups were balanced regarding the following clinicopathologic factors: age, gender, HENG risk, past nephrectomy, mRCC histology, ≥2 metastatic sites, lung/liver/bone metastasis, prior targeted tx, smoking status, use of angiotensin system inhibitors (ASIs), pre-tx neutrophil to lymphocyte ratio (NLR) >3, Su-induced hypertension (HTN), and Su dose reduction/tx interruption. Clinical benefit (partial response + stable disease) in group 1 vs. group 2 was 96% vs. 84%, while 4% vs. 16% had disease progression within the first 3 months of tx (p=0.054). Median PFS was 15 vs. 11.5 months (p=0.1). Median OS was 32 vs. 21 months (p=0.001). In multivariate analyses of the entire pt cohort (n=108), factors associated with PFS were active smoking (HR=2.7, p<0.0001) and pre-tx NLR >3 (HR 1.8, p=0.012). Factors associated with OS were Met use (HR 0.2, p<0.0001), HENG risk (HR 3.3, p=0.008), active smoking (HR=2.9, p<0.0001), liver metastases (HR 1.8, p=0.004), and pre-tx NLR >3 (HR 3.3, p<0.0001). Conclusions: Met use may improve the OS of diabetic pts with mRCC that are treated with Su.

Patients with metastatic chromophobe renal cell carcinoma treated with sunitinib therapy: Analysis of an international database regarding outcome and comparison to clear cell histology (mccRCC)

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Background: Sunitinib (Su) is a standard therapy (tx) for mccRCC. Data on its activity in the rare variant of metastatic chromophobe renal cell carcinoma (mchRCC) are limited by very small or heterogeneous (mixed histology with papillary type, or mixed targeted therapies) studies. We analyzed the activity of Su in a relatively large and homogenous international cohort of mchRCC pts, in terms of outcome and comparison to mccRCC. Methods: Records from mchRCC pts treated with first-line Su in 9 centers across 4 countries were retrospectively reviewed. Univariate and multivariate analyses of association between clinicopathologic factors and outcome were performed. Subsequently, mchRCC pts were individually matched to mccRCC pts. We compared the response rate (RR), progression free survival (PFS), and overall survival (OS) between the groups. Results: Between 2004-2014, 33 pts (median age 64, 45% male) with mchRCC were treated with Su as first-line tx. 76% had a prior nephrectomy. HENG risk was good 27%, intermediate 55%, and poor 18%. 33% were active smokers, and 30% users of angiotensin system inhibitors (ASIs). 55%, 27%, and 33% had lung, liver, and bone metastases, respectively. 48% had a pre-tx neutrophil to lymphocyte ratio (NLR) >3. 42% had dose reduction/tx interruption (DR/TI). Su-induced hypertension (HTN) occurred in 48%. 75% achieved a clinical benefit (partial response + stable disease), while 25% had disease progression within the first 3 months of tx. Median PFS and OS were 10 and 26 months, respectively. Factors associated with PFS were the HENG risk (HR 3.8, p=0.025) and pre-tx NLR >3 (HR 0.6, p=0.012). Factors associated with OS were the HENG risk (HR 4.27, p=0.027), liver metastases (HR 4.6, p=0.029), and pre-treatment NLR <3 (HR 0.5, p=0.04). Tx outcome was not significantly different between mchRCC pts and mccRCC pts, who were individually matched by HENG risk, nephrectomy/smoking status, pre-tx NLR, use of ASIs, DR/TI, and Su induced HTN. In mccRCC pts (p value versus mchRCC), 70% achieved a clinical benefit (p=0.58), and median PFS and OS were 9 (p=0.7) and 24 (p=0.6) months, respectively. Conclusions: In mchRCC pts, Su tx may have similar outcome to mccRCC pts.

American Cancer Society prostate cancer survivorship care guidelines

Prostate cancer survivors approach 2.8 million in number and represent 1 in 5 of all cancer survivors in the United States. While guidelines exist for timely treatment and surveillance for recurrent disease, there is limited availability of guidelines that facilitate the provision of posttreatment clinical follow-up care to address the myriad of long-term and late effects that survivors may face. Based on recommendations set forth by a National Cancer Survivorship Resource Center expert panel, the American Cancer Society developed clinical follow-up care guidelines to facilitate the provision of posttreatment care by primary care clinicians. These guidelines were developed using a combined approach of evidence synthesis and expert consensus. Existing guidelines for health promotion, surveillance, and screening for second primary cancers were referenced when available. To promote comprehensive follow-up care and optimal health and quality of life for the posttreatment survivor, the guidelines address health promotion, surveillance for prostate cancer recurrence, screening for second primary cancers, long-term and late effects assessment and management, psychosocial issues, and care coordination among the oncology team, primary care clinicians, and nononcology specialists. A key challenge to the development of these guidelines was the limited availability of published evidence for management of prostate cancer survivors after treatment. Much of the evidence relies on studies with small sample sizes and retrospective analyses of facility-specific and population databases.

Characteristics and outcome of octogenarian versus young patients (pts) with metastatic castrate-resistant prostate cancer (mCRPC) treated with ketoconazole

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Background: Standard treatment options for patients (pts) with metastatic castrate-resistant prostate cancer (mCRPC) include docetaxel based chemotherapy, abiraterone, and radium 223. Octogenarian pts (age 80 and older) are often considered to be unfit for chemotherapy. However, recommendations for their management is limited by the paucity of clinical trials data in this population. In countries where abiraterone in the pre-chemotherapy setting has not been approved yet, or for pts who can’t afford it, the CYP 17 inhibitor ketoconazole is used as an alternative advanced hormonal tx. We aimed to study baseline characteristics and outcome of octogenarian versus young (age 60 or younger) pts with mCRPC treated with ketoconazole. Methods: We performed an international multicenter retrospective study of pts with mCRPC, who were treated with ketoconazole at four centers across two different countries. We compared baseline characteristics and outcome of octogenarian versus young pts. The effect of very old age on prostate-specific antigen (PSA) response, progression free survival (PFS), and overall survival (OS), was tested with adjustment of other known confounding risk factors using a chi-square test and partial likelihood test from Cox model. Results: Between 2004 and 2013, 35 octogenarians (median age 83) and 33 young pts with (median age 57) mCRPC were treated with ketoconazole. The groups were balanced regarding the following baseline clinicopathologic characteristics: extent of disease (limited-axial skeleton and/or nodal versus extensive-appendicular skeleton and/or visceral), combined gleason score, pre-treatment risk category (Keizman, Oncologist 2012; based on pre-tx neutrophil to lymphocyte ratio/prostate-specific antigen doubling time, and prior response to ADT), pain intensity, ECOG performance status, alkaline phosphatase level, hemoglobin level, PSA level. In octogenarian versus young pts, PSA response (greater than or equal to 50% decline from baseline) was 40% versus 61% (OR 3.5, p=0.04), median PFS 7 versus 8 months (HR 0.91, p=0.44), and median OS 31 versus 36 months (HR 0.66, p=0.31). Conclusions: In very old vs young mCRPC patients treated with ketoconazole, PSA response was lower. Baseline clinicopathologic characteristics, PFS, and OS were not significantly different between the groups.

Patients with metastatic papillary renal cell carcinoma (RCC) who may benefit from sunitinib therapy (tx): Results from an international metastatic RCC database

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Background: The VEGFR inhibitor sunitinib is a standard tx for metastatic clear cell RCC. Data on the activity of sunitinib in metastatic non clear cell RCC, is limited by small or heterogeneous (mixed histology or targeted therapies) studies, that revealed a lower antitumor activity than in patients with clear cell histology. We aimed to analyze the activity of sunitinib in a large international cohort of patients with metastatic papillary RCC, and to characterize patients who may benefit for this therapy. Methods: Records from metastatic papillary RCC patients treated with sunitinib in 10 centers across 3 countries were retrospectively reviewed. Univariate and multivariate analyses of association between clinicopathologic factors and clinical outcome were performed using Cox regression. Results: Between 2004-2013, 74 patients (median age 60, 68% male) with metastatic papillary RCC were treated with sunitinib. 78% had a prior nephrectomy. HENG risk was good 11%, intermediate 56%, and poor 33%. 21% were active smokers, and 31% users of angiotensin system inhibitors. 24% and 41% had liver and bone metastases, respectively. 55% had a pre-treatment neutrophil to lymphocyte ratio (NLR) >3. 40% had dose reduction/treatment interruption. Sunitinib induced hypothyroidism and hypertension (HTN) occurred in 30% and 43%, respectively. 70% achieved a clinical benefit (partial response + stable disease), while 30% had disease progression within the first 3 months of therapy. Median progression free survival (PFS) and overall survival (OS) were 5 and 12 months, respectively. 27% had a PFS ≥ 1 year, and 26% survived ≥ 2 years. Factors associated with PFS were sunitinib induced HTN (HR 0.31, p=0.002), pre-treatment NLR >3 (HR 5.3, p=0.001), and active smoking (HR 2.5, p=0.01). Factors associated with OS were sunitinib induced hypothyroidism (HR 0.4, p=0.024), past nephrectomy (HR 0.41, p=0.02), pre-treatment NLR >3 (HR 2.25, p=0.036), and active smoking (HR 2.3, p=0.027). Conclusions: Clinicopathologic factors may be used to identify patients with metastatic papillary RCC who may benefit from sunitinib tx. A prolonged PFS and OS were noted in 26-27% of patients.

Clinicopathologic factors associated with the development of sunitinib induced hypertension (HTN) in patients (pts) with metastatic renal cell carcinoma (mRCC)

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Background: The VEGFR inhibitor sunitinib is a standard treatment for metastatic renal cell carcinoma (mRCC). HTN, an on-target class effect of VEGF signaling-pathway inhibitors, has been shown to correlate with clinical outcome. Studies have shown the association between genetic polymorphisms in several genes, and the development of HTN in patients treated with targeted therapies. We aimed to study the association between readily available clinicopathologic factors and the development of sunitinib induced HTN in mRCC patients. Methods: Records from mRCC patients treated with sunitinib in 9 centers across 2 countries were retrospectively reviewed. Sunitinib induced HTN was defined as systolic blood pressure ≥ 140 mmHg and/or diastolic blood pressure ≥ 90 mmHg. Analysis of the association between clinicopathologic factors and the development of HTN was performed using logistic regression. Results: Between 2004-2013, 302 patients with mRCC were treated with sunitinib. The incidence of sunitinib induced HTN was 50% (n=152). Clinicopathologic factors included in the analysis were age (median 63), gender (67% male), HENG risk (good 22%, intermediate 59%, poor 19%), smoking status (active 21%), BMI (obese=BMI ≥30, 28%; overweight=BMI 25-29.9, 37%; normal weight= BMI <25, 35%), pre-treatment HTN (58%), past nephrectomy (83%), histology (73% clear cell), > 1 metastatic site (82%), metastatic site (lung 72%, liver 25%, bones 40%), pre-treatment neutrophil to lymphocyte ratio (>3 in 45%), treatment line (first vs advanced), sunitinib dose reduction/treatment interruption (45%). Absence of liver metastases (OR 3.5, p=0.02), pre-treatment neutrophil to lymphocyte ratio ≤ 3 (OR 5.5, p=0.001), and BMI (overweight and normal weight vs obese, OR 2.2 and 2.3 respectively, p=0.01 both) were independently associated with the development of HTN. Conclusions: In metastatic renal cell carcinoma patients treated with sunitinib, readily available clinicopathologic factors may be used to identify patients who are prone to the development of HTN.

Potential impact of prior high-dose IL-2 on the outcomes of sunitinib (Su) treatment (tx) in patients (pts) with metastatic renal cell carcinoma (mRCC)

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Background: Targeted txs are the tx of choice in most mRCC pts. However, HDIL2 which may produce durable responses in a small percentage of cases, is still an option in carefully selected pts. While the effect of prior HDIL2 on the outcome of targeted txs in mRCC pts is poorly defined, a recent single center report (Birkhäuser FD, Cancer J 2013) revealed an improved disease-specific survival in pts treated with prior HDIL2. We aimed to study the effect of prior HDIL2 tx on outcome of mRCC pts treated with sunitinib. Methods: Records from 302 mRCC pts treated with Su from 2004 to 2013 in 9 centers across 2 countries were retrospectively reviewed. We compared the response rate, progression free survival (PFS), and overall survival (OS), between post HDIL2 pts (n=27) and individually matched tx naïve pts (n=27). Progression free survival and overall survival were determined by Cox regression. Results: All pts had prior nephrectomy and clear cell histology. The groups were matched by age (median 61), gender (male 74%), Heng risk (favorable 37%, intermediate 59%, poor 4%), sunitinib induced hypertension (67%), sunitinib dose reduction/treatment interruption (41%), smoking status (active 7%), use of angiotensin system inhibitors (41%), the presence of more than one metastases site (96%), and pre-tx neutrophil to lymphocyte ratio (> 3 in 22%). Furthermore, they were balanced regarding the presence of lung (68%), liver (31%), and bone (43%) metastases, and the use of bisphosphonates (32%). In prior HDIL2 versus tx naïve pts, objective response was partial response/stable disease 89% (n=24) versus 74% (n=20), and progressive disease at first imaging evaluation within the first 3 months (mos) 11% (n=3) versus 26% (n=7) (p=0.29, OR 2.4). Median progression free survival was 21 versus 12 mos (HR 2.3, p=0.005), and median overall survival 25 versus 20 mos (HR 2.2, p=0.013). Conclusions: In metastatic renal cell carcinoma patients treated with sunitinib, prior high dose IL-2 therapy may improve the outcome.

Comparison of abiraterone acetate (Abi) versus ketoconazole (Keto) in patients (pts) with metastatic castration resistant prostate cancer (mCRPC) refractory to docetaxel (D)

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Background: Abi is a standard treatment (tx) in pts with mCRPC refractory to D. It is a potent and selective CYP 17 inhibitor, that blocks the synthesis of androgens in the testis, adrenal glands, and prostate. However, in many countries where abi has not been approved yet, keto is used as an alternative CYP 17 inhibitor. Although preclinical data suggests that keto is a less specific and potent inhibitor of CYP 17, there are limited clinical data comparing both agents. Aims: To compare the clinical effectiveness of abi vs keto in pts with mCRPC refractory to D. Methods: Records from 156 mCRPC pts treated with keto 200 - 400 mg 3x day, in 4 centers across the US and Israel, were reviewed retrospectively. 26 pts treated post D were individually matched by clinicopathologic factors to pts treated with abi (selected from a multicenter Israeli database, n=120). We compared the PSA response (decrease ≥50% from baseline), biochemical and radiological progression free survival, and overall survival between the groups. Progression free survival and overall survival were determined by Cox regression. Results: The groups were matched by Gleason score, pre-tx disease extent (limited-axial skeleton and/or nodal vs extensive- appendicular skeleton and/or visceral), ECOG PS, pre-tx risk category (favorable, intermediate, poor; Keizman, Oncologist 2012). Furthermore, they were balanced regarding median age (71 abi vs 69 keto), time from primary tx to disease relapse, time to progression on prior GnRH-a and antiandrogen, PSA response and time to progression on prior D, pre-tx pain score/alkaline phosphatase/hemoglobin/neutrophil to lymphocyte ratio/PSADT/PSA. In the groups of abi vs keto, PSA response was 46% vs 19% (OR 4.4, p=0.043), median biochemical PFS 7 vs 2 months (HR 0.65, p=0.02), median radiological PFS 6 vs 2.5 months (HR 0.63, p=0.016), median overall survival 17 vs 12 months (HR 0.53, p=0.79), and tx interruption d/t adverse events 12% vs 23% (0R 0.6, p=0.023). Conclusions: In mCRPC refractory to D, the outcome of pts treated with abiraterone was superior to ketoconazole.

Influence of concurrent medications on PSA doubling time (PSADT) in patients (pts) with nonmetastatic biochemically relapsed prostate cancer (BRPC M0) after local therapy (tx)

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Background: In patients with BRPC(M0) after local tx, the most important prognostic factor is probably the PSADT (high risk < 3, intermediate risk 3–8.9, low risk ≥9.0 months). Pre-clinical and clinical studies in several cancer types have shown that commonly prescribed medications may inhibit tumor growth. The effect of commonly prescribed medications on PSADT in pts with BRPC(M0) is poorly defined. Aims: To study the effect of commonly prescribed medications on PSADT in pts with BRPC (M0) after local tx. Methods: We reviewed the records of 156 BRPC(M0) pts enrolled in 1 prospective (Keizman, CCR 2010) and two retrospective (Keizman, prostate 2012; Mermershtain, EMUC 2011) studies, in 2 centers across 2 countries. The effect of clinicopathologic factors and the use of statins, aspirin, and angiotensin system inhibitors (ASIs; ACE-I and ARBs) on initial PSADT (from the time of first PSA relapse to the initiation of any systemic tx) was analyzed using the Mann-Whitney or Kruskal-Wallis tests and regression analyses. Results: In the whole patient cohort (n=156), median age was 62, prior local tx consisted of radical prostatectomy in128 pts and EBRT in 28, and median PSADT was 6.7 months (mos). Median PSADT in ASIs users (n=48) vs non users (n=108) was 7.85 vs 5.6 mos (p=0.011). In multivariate analysis, the use of ASIs and Gleason score were associated with median PSADT. The use of statins (n=58) or aspirin (n=72), primary tx modality, and time from primary tx to PSA relapse had no significant effect on median PSADT. PSADT risk grouping in ASIs users vs non users was low 48% vs 27%, intermediate 42% vs 49%, and high 10% vs 24% (p=0.02). In multivariate analysis, the use of ASIs, Gleason score, and prior ADT were associated with PSADT risk grouping. The use of statins or aspirin, primary tx modality, and time from primary tx to PSA relapse had no significant effect on PSADT risk grouping. Conclusions: The use of ASIs, Gleason score, and prior ADT may be associated with PSADT (median and risk grouping) of pts with BRPC (M0) after local tx. This should be investigated prospectively, and if validated, applied in clinical practice and clinical trials.

Comparison between the outcome of metastatic RCC patients treated with sunitinib as part of clinical trials and matched nonparticipants receiving sutent as standard therapy

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Background: Several studies have suggested the existence of a “trial effect”, in which for a given treatment, participation in a clinical trial is associated with a better outcome of cancer patients. The VEGFR inhibitor sunitinib is a standard treatment for mRCC. The effect of clinical trial participation on the outcome of sunitinib treatment in mRCC is poorly defined. Aims: To study the effect of clinical trial participation on outcome of mRCC patients treated with sunitinib. Methods: Records from 275 mRCC patients treated with sunitinib from 2004 to 2012 in 7 centers across 2 countries were reviewed. We compared the response rate, progression free survival, and overall survival, between clinical trial participants (n=49) and a matched cohort of non participants (n=49) who who received standard therapy. Each patient participating in a clinical trial was individually matched with a non participant by clinicopathologic factors. Progression free survival and overall survival were determined by Cox regression. Results: The groups were matched by age (median 64), gender (male 67%), Heng risk (favorable 24%, intermediate 60%, poor 16%), ECOG performance status (0-1 92%), prior nephrectomy (92%), renal cell carcinoma histology (clear cell 80%), sunitinib induced hypertension (56%), and sunitinib dose reduction/treatment interruption (41%). In clinical trial participants versus non participants, objective response was partial response/stable disease 80% (n=39) versus 73% (n=36), and progressive disease at first imaging evaluation within the first 3 months (mos) 20% (n=10) versus 27% (n=13) (p=0.63, OR 1.2). Median progression free survival was 10 versus 11 mos (HR=0.96, p=0.84), and median overall survival 23 versus 24 mos (HR=0.97, p=0.89). Conclusions: In mRCC patient treated with sunitinib, the outcome of clinical trial participants was similar to matched non participants who received standard therapy.

Are there geographic differences in the outcome of patients (pts) with metastatic renal cell carcinoma (mRCC) treated with sunitinib (su)?

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Background: Geographic differences in the outcome of pts have been described in various cancers. The VEGFR inhibitor su is a standard treatment (tx) for mRCC. The effect of geographic differences on the outcome of su tx in mRCC is poorly defined. Aims: To study the effect of geographic differences on outcome of su tx in mRCC. Methods: We performed an international multicentre retrospective study of unselected cohort of 275 mRCC pts, who were treated with su from 2004 to 2012 in 7 centers across the US and Middle East (ME; Israel). Clinicopathologic and prognostic factors, and tx outcome were compared between US (n=133) and ME (n=142) pts. Chi-square and Fisher's exact tests were used to compare categorical variables, and two-sample t-test was used to compare continuous endpoints. Progression free survival (PFS) and overall survival (OS) were determined by Cox regression. Results: Median age was 61 (US) vs 65 (ME, p=0.01). The groups were balanced regarding gender, Heng risk, past nephrectomy, RCC histology, presence of ≥ 2 metastatic sites, lung/liver/bone metastasis, use of angiotensin system inhibitors (ASI), prior cytokines/ targeted txt, su induced HTN, and su dose reduction/tx interruption secondary to side effects. The incidence of active smokers (28% vs 15%, p=0.01), bisphosphonates users (23% vs 13%, p=0.03) and pts with pre-tx neutrophil to lymphocyte ratio (NLR) ≤ 3 (63% vs 49%, p=0.04) was higher among ME pts. In US vs ME pts, objective response was partial response/stable disease 77% (n=102) vs 79% (n=112), and progressive disease at first imaging evaluation within the first 3 months (mos) 23% (n=31) vs 21% (n=30) (p=0.77, OR 1.1). Median PFS was 8 vs 12 mos (HR=1.8, p<0.0001), and median OS 21 vs 22 mos (HR=0.94, p=0.9) in US vs ME pts. Factors associated with PFS in multivariate analysis of the entire cohort (n=275) were geographic location (US vs ME), Heng risk, RCC histology, su induced HTN, ASI use, pre-tx NLR, and smoking status. Conclusions: Geographic differences in clinicopathologic factors and PFS of pts with mRCC treated with su may exist. This should be further investigated, and if validated, applied in clinical practice and clinical trials.

Comparison of abiraterone acetate (Abi) versus ketoconazole (Keto) in patients (pts) with metastatic castration-resistant prostate cancer (mCRPC) refractory to docetaxel (D)

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Background: Abi is a standard treatment (tx) in pts with mCRPC refractory to deocetaxel. It is a potent and selective CYP 17 inhibitor that blocks the synthesis of androgens in the testis, adrenal glands, and prostate. However, in many countries where abi has not been approved yet, keto is used as an alternative CYP 17 inhibitor. Although preclinical data suggests that keto is a less specific and potent inhibitor of CYP 17, there are limited clinical data comparing both agents. We aimed to compare the clinical effectiveness of abi vs keto in pts with mCRPC refractory to D. Methods: Records from 156 mCRPC pts treated with keto 200 - 400 mg 3x day, in 4 centers across the US and Israel, were reviewed retrospectively. 26 pts treated post D were individually matched by clinicopathologic factors to pts treated with abi (selected from a multicenter Israeli database, n=120). We compared the PSA response (decrease ≥50% from baseline), biochemical and radiological progression free survival, and overall survival between the groups. Progression free survival and overall survival were determined by Cox regression. Results: The groups were matched by Gleason score, pre-tx disease extent (limited-axial skeleton and/or nodal vs extensive- appendicular skeleton and/or visceral), ECOG PS, pre-tx risk category (favorable, intermediate, poor; Keizman, Oncologist 2012). Furthermore, they were balanced regarding median age (71 abi vs 69 keto), time from primary tx to disease relapse, time to progression on prior GnRH-a and antiandrogen, PSA response and time to progression on prior D, pre-tx pain score/alkaline phosphatase/hemoglobin/ neutrophil to lymphocyte ratio/PSADT/PSA. In the groups of abi vs keto, PSA response was 46% vs 19% (OR 4.4, p=0.043), median biochemical PFS 7 vs 2 months (HR 0.65, p=0.02), median radiological PFS 6 vs 2.5 months (HR 0.63, p=0.016), median overall survival 17 vs 12 months (HR 0.53, p=0.79), and tx interruption d/t adverse events 12% vs 23% (0R 0.6, p=0.023). Conclusions: In mCRPC refractory to D, the outcome of pts treated with abiraterone was superior to ketoconazole.

Are there geographic differences in the outcome of patients (pts) with metastatic renal cell carcinoma (mRCC) treated with sunitinib (su)?

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Background: Geographic differences in the outcome of pts have been described in various cancers. The VEGFR inhibitor su is a standard treatment (tx) for mRCC. The effect of geographic differences on the outcome of su tx in mRCC is poorly defined. We aimed to study the effect of geographic differences on outcome of su tx in mRCC. Methods: We performed an international multicenter retrospective study of unselected cohort of 275 mRCC pts, who were treated with su from 2004 to 2012 in 7 centers across the United States and Middle East (ME; Israel). Clinicopathologic and prognostic factors, and tx outcome were compared between United States (n=133) and ME (n=142) pts. Chi-square and Fisher's exact tests were used to compare categorical variables, and two-sample t-test was used to compare continuous endpoints. Progression free survival (PFS) and overall survival (OS) were determined by Cox regression. Results: Median age was 61 (United States) vs. 65 (ME, p = 0.01). The groups were balanced regarding gender, Heng risk, past nephrectomy, RCC histology, presence of ≥ 2 metastatic sites, lung/liver/bone metastasis, use of angiotensin system inhibitors (ASI), prior cytokines/ targeted txt, su induced HTN, and su dose reduction/tx interruption secondary to side effects. The incidence of active smokers (28% vs. 15%, p =0.01), bisphosphonates users (23% vs. 13%, p = 0.03) and pts with pre-tx neutrophil to lymphocyte ratio (NLR) ≤ 3 (63% vs. 49%, p = 0.04) was higher among ME pts. In United States vs. ME pts, objective response was partial response/stable disease 77% (n=102) vs. 79% (n=112), and progressive disease at first imaging evaluation within the first 3 months (mos) 23% (n=31) vs. 21% (n=30) (p = 0.77, OR 1.1). Median PFS was 8 vs. 12 mos (HR=1.8, p < 0.0001), and median OS 21 vs. 22 mos (HR=0.94, p = 0.9) in United States vs ME pts. Factors associated with PFS in multivariate analysis of the entire cohort (n=275) were geographic location (United States vs. ME), Heng risk, RCC histology, su induced HTN, ASI use, pre-tx NLR, and smoking status. Conclusions: Geographic differences in clinicopathologic factors and PFS of pts with mRCC treated with su may exist. This should be further investigated, and if validated, applied in clinical practice and clinical trials.

Is there a "trial effect" on outcome of patients with metastatic renal cell carcinoma (mRCC) treated with sunitinib?

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Background: Several studies have suggested the existence of a trial effect, in which for a given treatment, participation in a clinical trial is associated with a better outcome of cancer patients. The VEGFR inhibitor sunitinib is a standard treatment for mRCC. The effect of clinical trial participation on the outcome of sunitinib treatment in mRCC is poorly defined. We aimed to study the effect of clinical trial participation on outcome of mRCC patients treated with sunitinib. Methods: Records from 275 mRCC patients treated with sunitinib from 2004 to 2012 in 7 centers across 2 countries were reviewed. We compared the response rate, progression free survival, and overall survival, between clinical trial participants (n=49) and a matched cohort of non participants (n=49) who received standard therapy. Each patient participating in a clinical trial was individually matched with a non-participant by clinicopathologic factors. Progression free survival and overall survival were determined by Cox regression. Results: The groups were matched by age (median 64), gender (male 67%), Heng risk (favorable 24%, intermediate 60%, poor 16%), ECOG performance status (0-1 92%), prior nephrectomy (92%), renal cell carcinoma histology (clear cell 80%), sunitinib induced hypertension (56%), and sunitinib dose reduction/treatment interruption (41%). In clinical trial participants vs. non participants, objective response was partial response/stable disease 80% (n=39) vs. 73% (n=36), and progressive disease at first imaging evaluation within the first 3 months (mos) 20% (n=10) vs. 27% (n=13) (p = 0.63, OR 1.2). Median progression free survival was 10 vs. 11 mos (HR=0.96, p = 0.84), and median overall survival 23 vs. 24 mos (HR=0.97, p=0.89). Conclusions: In mRCC patient treated with sunitinib, the outcome of clinical trial participants was similar to matched non participants who received standard therapy.

Influence of concurrent medications on PSA doubling time (PSADT) in patients (pts) with nonmetastatic biochemically relapsed prostate cancer (BRPC M0) after local therapy (tx)

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Background: In patients with BRPC(M0) after local tx, the most important prognostic factor is probably the PSADT (high risk < 3, intermediate risk 3–8.9, low risk ≥9.0 months). Pre-clinical and clinical studies in several cancer types have shown that commonly prescribed medications may inhibit tumor growth. The effect of commonly prescribed medications on PSADT in pts with BRPC(M0) is poorly defined. We aimed to study the effect of commonly prescribed medications on PSADT in pts with BRPC (M0) after local tx. Methods: We reviewed the records of 156 BRPC(M0) pts enrolled in 1 prospective (Keizman, CCR 2010) and two retrospective (Keizman, prostate 2012; Mermershtain, EMUC 2011) studies, in 2 centers across 2 countries. The effect of clinicopathologic factors and the use of statins, aspirin, and angiotensin system inhibitors (ASIs; ACE-I and ARBs) on initial PSADT (from the time of first PSA relapse to the initiation of any systemic tx) was analyzed using the Mann-Whitney or Kruskal-Wallis tests and regression analyses. Results: In the whole patient cohort (n=156), median age was 62, prior local tx consisted of radical prostatectomy in128 pts and EBRT in 28, and median PSADT was 6.7 months (mos). Median PSADT in ASIs users (n=48) vs non users (n=108) was 7.85 vs 5.6 mos (p=0.011). In multivariate analysis, the use of ASIs and Gleason score were associated with median PSADT. The use of statins (n=58) or aspirin (n=72), primary tx modality, and time from primary tx to PSA relapse had no significant effect on median PSADT. PSADT risk grouping in ASIs users vs non users was low 48% vs 27%, intermediate 42% vs 49%, and high 10% vs 24% (p=0.02). In multivariate analysis, the use of ASIs, Gleason score, and prior ADT were associated with PSADT risk grouping. The use of statins or aspirin, primary tx modality, and time from primary tx to PSA relapse had no significant effect on PSADT risk grouping. Conclusions: The use of ASIs, Gleason score, and prior ADT may be associated with PSADT (median and risk grouping) of pts with BRPC (M0) after local tx. This should be investigated prospectively, and if validated, applied in clinical practice and clinical trials.

Influence of risk factors for renal cell carcinoma (RCC) on outcome of patients (pts) with metastatic disease (mRCC) treated with sunitinib (Su)

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Background: Obesity, smoking, hypertension (HTN) and diabetes (DM) are risk factors for RCC development. Their presence has been associated with a worse outcome of therapy (tx) in various metastatic cancers. We sought to determine their influence on the progression free survival (PFS) and overall survival (OS) of Su tx in mRCC. Methods: We performed an international multicenter retrospective study of pts with mRCC, who were treated with Su. We analyzed the pre-tx status of smoking (active vs past vs never), BMI (obese= BMI≥30 vs overweight=BMI 25-29.9 vs normal weight= BMI <25), HTN, DM, and known prognostic factors including past nephrectomy, clear cell vs non clear cell histology, initial diagnosis to Su tx initiation time, ≥ 2 metastasis (mets) sites, lung/liver/bone mets, ECOG performance status, anemia, calcium level > 10, elevated alkaline phosphatase (AP), pre-tx neutrophil to lymphocyte ratio (NLR) >3, Su induced HTN, use of angiotensin system inhibitors (ASIs), past cytokines/targeted tx, and median Su dose/cycle. PFS and OS were determined by the Kaplan-Meier method. Multivariate analyses using Cox Regression model were performed to determine their independent effect. Results: Between 2004-2011, 244 pts with mRCC were treated with Su. 51 pts were active smokers, 58 obese, 62 diabetic, and 145 had pre-tx HTN. In the entire pt cohort, median PFS was 9 months (mos) and OS 21 mos. Factors associated with PFS were active smoking (HR 2.29, p= 0.003, median PFS 4 vs 10 mos in past smokers vs 12 mos in never smokers), non clear cell histology (HR 1.7, p=0.042), pre-tx NLR >3 (HR 1.92, p<0.0001) and the use of ASIs (HR 0.58, p=0.03). Factors associated with OS were were active smoking (HR 1.85, p= 0.018, median OS 11 vs 25 mos in past smokers vs 27 mos in never smokers), AP (HR 1.9, p=0.017), pre-tx NLR >3 (HR 2.5, p<0.0001), and liver mets (HR 1.86, p=0.021). BMI, DM, and pre-tx HTN were not associated with PFS or OS. Conclusions: Active smoking may decrease the PFS and OS of pts with mRCC that are treated with Su. BMI, DM, and pre-tx HTN were not found to be associated with outcome. These results should be investigated prospectively, and if validated applied in clinical practice and clinical trials.

Pretreatment (pre-tx) neutrophil to lymphocyte ratio (NLR) in metastatic castration-resistant prostate cancer (mCRPC) patients (pts) treated with ketoconazole (keto): Association with outcome and predictive model

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Background: The CYP17 inhibitor keto is active in mCRPC. The NLR, an index of systemic inflammation, is associated with prognosis in several types of cancer. We assessed the association between pre-tx NLR and outcome of mCRPC pts treated with keto. Methods: We performed an international multicenter retrospective study of pts with mCRPC, who were treated with keto. We analyzed the pre-tx NLR and previously described factors associated with keto tx outcome as prior response to hormonal tx, pre-tx PSADT, and extent of metastatic disease (limited vs extensive). Progression free survival (PFS) was determined by the Kaplan-Meier method. Multivariate analyses using Cox regression model were performed to determine their independent effect, and to form a predictive model. A survival tree analysis was used to find the best NLR cut-off value. Results: From 1999-2011, 156 mCRPR pts (median age 69) were treated with keto. 78/156 (50%) had ≥ 50% PSA decline. Overall median PFS was 8 months (mos) (range 1-144). Excluded from the analysis were 23 pts without available data on pre-tx NLR, and those with recent (≤1 mos) health event or tx (surgery, steroids, radiation) associated with a change of blood counts. 133 pts were included in the analysis. 62 (47%) had an elevated pre-tx NLR >3. Risk factors associated with PFS (table) were pre-tx NLR >3, prior response to GnRH-a <24 mos and to antiandrogen (AA) <6 mos, and pre-tx PSADT <3 mos. The number of risk factors was used to categorize patients into three risk groups (table): favorable (0-1 factors), intermediate (2 factors), and poor (3-4 factors). Conclusions: In mCRPC pts treated with keto, pre-tx NLR, prior response to hormonal tx, and pre-tx PSADT are associated with PFS, and may be used to categorize pts into risk groups. [Table: see text]

Use of bisphosphonates (Bis) combined with sunitinib (Su) to improve the response rate (RR), progression-free survival (PFS), and overall survival (OS) of patients (pts) with bone metastases (mets) from renal cell carcinoma (RCC)

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Background: Bis are used to prevent skeletal events of bone mets, and may exhibit anti tumor effects. We aimed to evaluate whether Bis can bring a RR, PFS, and OS benefit to pts with bone mets from RCC that are treated with Su. Methods: We performed an international multicenter retrospective study of pts with bone mets from RCC who were treated with Su. Pts were divided into Bis users (group 1) and nonusers (group 2). The effect of Bis on RR, PFS and OS, was tested with adjustment for known prognostic factors using a chisquare test from contingency table and partial likelihood test from Cox regression model. Results: Between 2004-2011, 244 pts with metastatic RCC were treated with Su. 92 pts had bone mets, 41 group 1 and 51 group 2. The groups were balanced regarding the following known prognostic factors: past nephrectomy, clear cell vs non clear cell histology, initial diagnosis to sunitinib treatment (tx) time, presence of ≥ 2 mets sites, presence of lung/liver mets, ECOG performance status, anemia, calcium level > 10 mg/dL, elevated alkaline phosphatase (AP), pre-tx neutrophil to lymphocyte ratio (NLR) >3, sunitinib induced HTN, and the use of angiotensin system inhibitors. They were also balanced with regard to past cytokines/targeted tx, and mean sunitinib dose/cycle. Objective response was partial response/stable disease 85% (n=35) vs 71% (n=36), and progressive disease 15% (n=6) vs 29% (n=15) (OR 3.287, p=0.07) in group 1 vs 2 respectively. Median PFS was 15 vs 5 months (HR 0.433, p=0.035), and median OS not reached with a median folloup time of 43 mos vs 12 months (HR 0.398, p=0.003), in favor of group 1. In multivariate analysis of the entire pt cohort (n=92), factors associated with PFS were Bis use (HR 0.433, p=0.035), pre-tx NLR ≤3 (HR 0.405, p=0.016), and elevated AP (HR=3.63, p=0.012). Factors associated with OS were Bis use (HR 0.32, p=0.003), elevated AP (HR 3.18, p=0.002), and Su induced HTN (HR 0.193, p< 0.001). Conclusions: Bis may improve the outcome of Su tx in RCC with bone mets. This should be investigated prospectively, and if validated applied in clinical practice and clinical trials.

Changes in prostate-specific antigen doubling time (PSADT) prior to and after treatment with hormonal therapy (HT) in men with biochemically recurrent prostate cancer (BRPC): A preliminary analysis

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Background: PSADT is an important prognostic parameter in all clinical states of PCA. Intra -subject changes in PSADT prior to and after HT remains undefined. Methods: Men with rising serum PSA levels after local therapy were longitudinally followed from the hormone-sensitive (HS) to the castration-resistant (CR) state. PSADT was calculated according to standard formulas ( Pound et al., JAMA 1999) and previously identified prognostic subgroups (Antonarakis et al., BJU Int 2012; Freedland et al., JCO 2007) were used to evaluate the potential clinical significance of PSADT according to the following subgroups: [1] < 3 months (mo); [2] 3-8.9 mo, [3] 9-14.9 mo, and [4] ≥ 15 mo). Results: 55 men with BRPC who eventually developed CR disease on HT were retrospectively analyzed. The median age of HS men was 60 y (range (r) 43-78); CR men 66 y (r 43-87). Of all men, 28 had prior surgery (S), 5 had radiation (R), 14 had S+R, 7 had neoadjuvant /adjuvant HT + local therapy, and 1 had no local therapy. PSADT in the CR state was shorter than PSADT in the HS state (signed –rank test; p=0 .012). HS men with PSADT < 4 m had shorter overall survival than those with PSADT ≥ 4 mo ( 13.9 vs. 20.1 mo; HR ; 8.46). Changes in PSADT from the HS to the CR state are summarized in the Table below. The majority of men converted from a more favorable to a less favorable PSADT subgroup as they progressed from HS to CR states. Conclusions: PSADT tends to shorten from the HS to the CR states. The prediction of clinical outcome based on PSADT needs to account for the clinical state the patient is in, as PSADT may change within the same patient from state to state. [Table: see text]

Preclinical and clinical studies with the multi-kinase inhibitor CEP-701 as treatment for prostate cancer demonstrate the inadequacy of PSA response as a primary endpoint

PURPOSE

CEP-701 is a potent inhibitor of trk receptors that causes cell death in prostate cancer (PC) models. CEP-701 binds to serum proteins and a preprostatectomy study was performed to assess prostate tissue penetration and clinical response to CEP-701.

METHODS

Growth assays and Western blot analyses were performed to evaluate CEP-701 kinase inhibition. In a preprostatectomy study, patients received CEP-701 for five days prior to prostatectomy and prostate tissue analyzed for CEP-701 levels. A phase II dose escalation study was performed in patients with hormone refractory PC with rising PSA and no metastases. Endpoints included PSA response and safety.

RESULTS

CEP-701 binds to serum proteins limiting tissue penetration. An oral dose of 40 mg bid of CEP-701 for five days produced levels of 219 +/- 38 nM in prostate at time of prostatectomy. No patients in the Phase II study met the primary response criteria of >50% PSA decline. 7/9 patients had increase in PSA slope on CEP-701 compared to PSA slope prestudy. 5/9 patients had a decrease in PSA levels after stopping CEP-701. Laboratory studies showed increased PSA production by CEP-701 growth arrested human PC cells in vitro and in vivo.

CONCLUSIONS

Evaluation of PSA response is an inadequate indicator of response in CEP-701 treated PC patients. Therefore, the effectiveness of CEP-701 as treatment for prostate cancer has not been adequately tested. Based on a strong preclinical rationale, further clinical studies with CEP-701 using alternative endpoints are indicated.

Docetaxel treatment in the elderly patient with hormone refractory prostate cancer

Docetaxel is an anti-microtubular agent in the family of the taxanes, now FDA approved as first line chemotherapy for the treatment of hormone refractory metastatic prostate cancer. Recent data from two large randomized Phase III trials showed a survival advantage in hormone refractory prostate cancer patients treated with docetaxel. This discovery changed the perceptions about utilization of chemotherapy for this devastating disease and introduced a new paradigm/standard of care treatment for this patient population. The management of elderly patients with metastatic prostate cancer is an important issue because according to data from the Surveillance, Epidemiology, and End Results (SEER) program, the American Cancer Society, and the United Nations, the incidence of prostate cancer in elderly men is expected to increase since people are living longer. In this paper we will review the results of trials evaluating docetaxel in hormone refractory prostate cancer and the implications of these trials as they relate to diagnosis and management of this disease in the elderly man.

Phase II Evaluation of Docetaxel Plus Exisulind in Patients With Androgen Independent Prostate Carcinoma

OBJECTIVES

In this phase II study, the combination of docetaxel and exisulind (a GMP phosphodiesterase inhibitor) was given to patients with metastatic androgen independent prostate cancer (AIPC) to establish efficacy, assess toxicity, and determine pharmacokinetics of docetaxel administered alone and in combination with exisulind.

METHODS

Fourteen patients with metastatic AIPC were registered to receive weekly docetaxel for 4 weeks, followed by 2 weeks of rest; repeated up to a maximum of 6 cycles. Exisulind 250 mg was given orally twice a day starting on day 8 of the study and taken continuously.

RESULTS

All patients were evaluable for toxicity, response and survival. Grade 3 reversible toxicities included: fatigue, nausea, diarrhea, abdominal pain, rash, syncope, pulmonary edema, deep vein thrombosis, congestive heart failure, and elevations in transaminases, requiring therapy delays and/or dose reductions, or removal from therapy. Only 3 out of 14 patients (21.4%) had a 50% decline in prostate specific antigen (PSA) level that lasted > or =4 weeks; 1 out of 14 patients (7%) had a lymph node response. Median survival was 17.28 months. Docetaxel pharmacokinetics for 11 patients demonstrated mean +/- SD clearance values that were similar during week 1 and week 3 when exisulind had been added.

CONCLUSIONS

: Overall, our trial indicated that the toxicity profile and efficacy of this regimen is unlikely to be substantially better than single agent docetaxel.

Phase II evaluation of docetaxel plus one-day oral estramustine phosphate in the treatment of patients with androgen independent prostate carcinoma

BACKGROUND

Recent clinical trials have shown antitumor activity with the combination of docetaxel plus estramustine phosphate (EMP) in the treatment of patients with androgen independent prostate carcinoma (AIPC). However, the most commonly employed treatment schedules with EMP have been associated with significant gastrointestinal, cardiovascular, and thromboembolic toxicity. The authors hypothesized that the therapeutic index of the combination of docetaxel plus EMP for patients with prostate carcinoma could be enhanced by reducing the incidence and severity of EMP-associated toxicity, which could be accomplished by shortening the duration of exposure to EMP. To preserve the therapeutic synergism between docetaxel and EMP, they designed a regimen employing higher doses of oral EMP administered on the day of the docetaxel infusion.

METHODS

From June 1, 1998 through September 28, 2000, 42 patients with AIPC were registered to receive docetaxel (70 mg/m2 intravenously over 1 hour) and EMP (280 mg orally every 6 hours x 5 doses) every 21 days, up to a maximum of 6 cycles. Dexamethasone was administered prior to docetaxel and coumadin 2 mg orally every day was taken during the study treatment period. Patient characteristics included a median age of 68 years, a median Eastern Cooperative Oncology Group performance status of 1, a median prostate specific antigen (PSA) level at study entry of 110.5 ng/mL, and a median of 2 prior hormonal manipulations. Ten patients (25%) had received prior chemotherapy, and 14 patients (33%) had received prior palliative radiation therapy.

RESULTS

Forty patients were evaluable for response and toxicity. Eighteen patients (45%; 95% confidence interval, 29-62%) had a decline > 50% in PSA level that lasted > 4 weeks with a median time to PSA progression and a median duration of PSA response of approximately 4.0 months. Four of 20 patients (20%) had partial soft tissue responses. Ten of 17 symptomatic patients (59%) had improvement in pain. The median survival for all patients was 13.5 months. The most prominent Grade 3 and 4 toxicities were reversible myelosuppression and fatigue. Nausea, emesis, diarrhea, and peripheral edema were minimal. No thromboembolic or hepatic complications were seen.

CONCLUSIONS

Docetaxel plus 1 multidose day of oral EMP was active in patients with AIPC and was associated with an acceptable toxicity profile. Overall, the therapeutic index of this regimen compared favorably with regimens that employed a longer administration of EMP.

Clinical conduct and nursing quality of life in prostate cancer

Recent advances in cancer therapy and supportive care have increased patient survival and improved quality of life. These advances have led to an increase in the responsibilities of nurses caring for these patients. Knowledge of new drugs, mode of action, expected side effects, and benefits, including effects on QOL, are essential. Nurses are vital to the safety and the quality of life that patients may experience while participating in clinical trials.

Complete androgen blockade for prostate cancer: what went wrong?

PURPOSE

We summarized and critically assessed all available data from phase III clinical trials on complete androgen blockade versus surgical or medical castration alone.

MATERIALS AND METHODS

Published results in journals and abstracts of phase III trials, and published meta-analyses were reviewed. We also reviewed quality of life and toxicity issues associated with the addition of antiandrogens to medical or surgical castration. Finally, we discuss the original rationale for complete androgen blockade in the context of current knowledge.

RESULTS

A total of 27 clinical trials using various combinations of androgen deprivation were identified, of which 3 showed a statistically significant benefit for the complete androgen blockade arm. There were 5 publications of meta-analyses that each used different selection criteria for the inclusion of studies in the final analysis. Toxicity and quality of life have not been widely investigated in prospective fashion but the available data suggest a higher toxicity rate and decreased quality of life with complete androgen blockade.

CONCLUSIONS

The extensive body of data does not support routine use of antiandrogens in combination with medical or surgical castration as first line hormonal therapy in patients with metastatic prostate cancer.

Preliminary evaluation of a short course of estramustine phosphate and docetaxel (Taxotere) in the treatment of hormone-refractory prostate cancer

Preclinical data suggest that small quantities of estramustine phosphate are synergistic with taxanes and may be useful in the treatment of hormone-refractory prostate cancer. The current trial was designed to reduce the duration of exposure to estramustine phosphate, which carries with it the risk of anorexia and gastrointestinal, cardiovascular, and thromboembolic toxicity during long-term treatment. Patients with histologically confirmed adenocarcinoma of the prostate showing evidence of progressing disease 4 to 6 weeks after antiandrogen withdrawal were enrolled into the study. Patients may have received up to two prior chemotherapy regimens. Patients received estramustine phosphate 280 mg orally every 6 hours for a total of five doses (24-hour exposure), docetaxel (Taxotere; Rhône-Poulenc Rorer, Collegeville, PA) 70 mg/m2 intravenously over 1 hour, coumadin 2 mg orally every day, and dexamethasone as premedication for docetaxel. Cycles were repeated every 21 days, up to a maximum of 6. Of the 18 evaluable patients, seven showed more than 50% declines in prostate-specific antigen for a duration > or =4 weeks; two of eight patients had soft tissue partial responses. Nine of 11 had improvement in pain and/or urinary symptoms. In a total of 98 cycles, grade 3 toxicities observed included leukopenia (N = 7), neutropenia (N = 6), fatigue (N = 13), headache (N = 1), local skin reactions after extravasation (N = 2), nail changes (N = 1), diarrhea (N = 2), and hyperglycemia (N = 3); grade 4 toxicities included neutropenia/fever requiring admission (N = 2), leukopenia (N = 2), and neutropenia (N = 6). No thromboembolic complications were seen. All toxicities were reversible within 1 week after occurrence. Thus, preliminary evidence suggests that in this heavily pretreated patient population 1-day treatment with an estramustine/docetaxel combination is active and has acceptable toxicity.

Rapid disease progression after the administration of bicalutamide in patients with metastatic prostate cancer

We report 5 patients with advanced metastatic prostate cancer who took bicalutamide 50 mg/day for "second-line" hormonal manipulation and demonstrated a rapid rise in prostate-specific antigen (PSA) shortly after the initiation of bicalutamide. After discontinuation of the drug, PSA levels declined in 4 patients and stabilized in the fifth. In 2 of the patients, the PSA rise was associated with an increase in pain level, which subsided after the treatment was stopped. The timing of the rapid changes in PSA and pain levels suggests a direct effect of bicalutamide. The most probable explanation for this observation is a very early agonist activation of androgen receptor by bicalutamide, similar to the underlying mechanism of the "antiandrogen withdrawal syndrome."

Evaluation of biomarkers of survival response in hormone-refractory prostate cancer patients treated with suramin

Hormone-refractory prostate cancer (HRPC) patients often have nonmeasurable disease. In such patients, predictive biomarkers other than tumor response may be required to compare therapeutic effects. We examined the predictive value for survival of various clinical and laboratory parameters, including prostate-specific antigen (PSA), in HRPC patients treated with suramin. Data from 103 HRPC patients were analyzed using various survival analyses, the likelihood ratio approach, and logistic regression analyses. When pretreatment factors, percentage decrease in PSA at 4 weeks from start of treatment (deltaPSA), and updated survival data were fit by a multivariate Cox proportional hazards model, acid phosphatase, lactate dehydrogenase, and deltaPSA were significant, with risk ratios close to 1. There was a decrease in likelihood ratio with increasing APSA. A logistic regression model was developed to predict the probability of <1 year of survival from the start of treatment. Hemoglobin and deltaPSA were found to be significant variables. However, in view of the complexities involving the relationship between PSA expression and prostate cancer growth and possible selective effect of treatment on PSA, further prospective testing is necessary. Therefore, deltaPSA cannot necessarily be used as a biomarker for survival response in individual patients during the evaluation of the therapeutic response of HRPC to new antineoplastic drugs.

A prospective study of suramin-induced peripheral neuropathy

Suramin is an investigational drug that has shown therapeutic activity in hormone-refractory metastatic prostate cancer in Phase I/II trials. Dose-limiting neurotoxicity remains the most serious complication of suramin treatment. We performed a prospective study to define the incidence, severity, characteristics, and dose relationships of suramin-induced peripheral neuropathy. Twenty-two patients who received suramin in a Phase-I trial underwent baseline and serial follow-up neurological evaluations consisting of history, examination, nerve conduction studies and quantitative sensory testing (QST). Suramin was administered intravenously in escalating dosages by using a 5-day schedule (repeated monthly), with the dose, determined by a population pharmacokinetic model, to accomplish 30-min post-infusion concentrations of 300 micrograms ml-1 (cohort I), 350 micrograms m-1 (cohort II) and 400 micrograms ml-1 (cohort III). Twelve patients developed a mild, axonal, length-dependent, sensory-motor poly-neuropathy. Three other patients developed a subacutely progressive, functionally disabling, demyelinating neuropathy; sural nerve biopsy in two patients showed lymphocytic inflammation. These three patients improved after drug discontinuation and plasmapheresis. Although there was no apparent correlation between the cumulative dose and the severity of the neuropathy, no patient from cohort I, but 88% of patients from cohorts II and III, developed neuropathy. We conclude that when suramin is used at peak concentrations of > or = 350 micrograms ml-1 its administration is associated with two patterns of neuropathy, a distal axonal neuropathy and an inflammatory demyelinating neuropathy that is partially reversible. Neurological monitoring for development of neuropathy will improve the safety of suramin use in future clinical studies.

Ocular symptoms and signs associated with suramin sodium treatment for metastatic cancer of the prostate

PURPOSE

Therapy with suramin sodium has been associated with photophobia, iritis, optic atrophy, and vortex keratopathy. We studied the ocular findings in patients who underwent treatment with suramin sodium for metastatic cancer of the prostate.

METHODS

In a prospective study, 114 patients who underwent treatment with suramin sodium for cancer of the prostate had an ophthalmologic examination with two weeks of onset of treatment and two weeks after termination of therapy. Additional examinations were performed on patients who developed ocular symptoms during suramin sodium therapy.

RESULTS

Nineteen (16.6%) of 114 patients developed ocular symptoms and signs while taking suramin sodium. Thirteen of these patients developed bilateral corneal epithelial whorllike deposits. In ten patients, the corneal deposits were associated with foreign body sensation and lacrimation. Symptoms in all of these patients resolved with topical lubricants. Three patients developed asymptomatic corneal deposits. Seven patients had blurred vision and were found to have a mean hyperopic shift in refractive error of 1.13 +/- 0.45 diopters (range, 0.75 to 2.00 diopters) that persisted throughout their treatment course. None of these patients had a decrease in best-corrected visual acuity.

CONCLUSIONS

In this study, ocular symptoms and signs associated with suramin sodium were common but were not considered a dose-limiting toxicity. Hyperopic shift in refractive error is a previously unreported ocular finding in association with suramin sodium therapy.

Evaluation of prostate-specific antigen as a surrogate marker for response of hormone-refractory prostate cancer to suramin therapy

PURPOSE

We evaluated the surrogate role of serum prostate-specific antigen (PSA) using prospectively collected information from patients with hormone-refractory prostate cancer (HRPC) treated with suramin.

MATERIALS AND METHODS

Data from 103 patients were analyzed using survival analysis, exploratory analysis, and regression analysis.

RESULTS

There was a significant survival difference between groups of patients with a PSA decrease of < or = 0% or greater than 0% (P = .018). There were no significant overall survival differences between groups of patients with PSA decreases less than 50% or > or = 50% and less than 75% or > or = 75%. Tree-based modeling did not define a specific threshold percentage PSA change as a response criterion. For a response of 1-year survival, sensitivity increased (0.91 v 0.69), but specificity decreased (0.37 v 0.62), with a 75% versus 50% PSA decrease used as classification criterion. Differences between the area under the receiver-operating curves (ROCs) with 50% and 75% PSA decreases as threshold values were small. For a response of 1-year survival, attributable proportions were 0.38 and 0.68, respectively, with 50% and 75% PSA decreases as threshold values. When pretreatment variables were assessed by Cox proportional hazards model, hemoglobin level was the most significant predictor of survival. When percentage PSA change was included in the model, hemoglobin level remained the most significant factor, but percentage PSA change was also a weak, but statistically significant, factor. PSA was a weak, but statistically significant, predictor of survival in Cox proportional hazards model with PSA as a time-variant covariate.

CONCLUSION

Reduction in PSA level has weak prognostic significance with respect to survival in HRPC patients, but, currently, PSA reduction cannot be used as a reliable response criterion to evaluate treatment efficacy in individual patients. Prospective, randomized studies, including prospective measurement of other indices related to symptomatic clinical benefits, are required.

Phase I and clinical evaluation of a pharmacologically guided regimen of suramin in patients with hormone-refractory prostate cancer

PURPOSE

This phase I study was designed with the following objectives: (1) to describe the overall and dose-limiting toxicity (DLT) of suramin administered by intermittent short intravenous infusions until DLT or disease progression; (2) to determine the ability of an adaptive control with feedback (ACF) dosing strategy to maintain suramin plasma concentrations within a preselected range; (3) to develop a population model of suramin pharmacokinetics; and (4) to identify preliminary evidence of antitumor activity.

PATIENTS AND METHODS

Seventy-three patients with advanced, incurable, solid tumors (including 69 with hormone-refractory prostate cancer) received an initial 5- to 7-day daily loading treatment followed by intermittent infusions individually determined by ACF using a Bayesian algorithm and relying on population models of suramin pharmacokinetics. Treatment was given to three cohorts of patients based on target plasma suramin concentration ranges (peak, 30 minutes postsuramin, and trough on morning of the treatment day), as follows: cohort 1, 175 to 300 micrograms/mL (27 patients); cohort 2, 150 to 250 micrograms/mL (23 patients); and cohort 3, 100 to 200 micrograms/mL (23 patients). All patients were to receive suramin until DLT or disease progression.

RESULTS

The DLT was most commonly seen in cohort 1 and included a syndrome of malaise and fatigue, associated with weight loss, anorexia, and changes in taste. Other reversible toxicities were neurologic, renal, cutaneous, edema, lymphopenia and anemia, ophthalmologic, and alopecia. Forty of 67 assessable patients (60%) had a 50% reduction and 25 of 67 (37%) a 75% reduction in prostate-specific antigen (PSA) levels that lasted more than 4 weeks, seven of 18 (40%) had measurable responses, and 18 of 37 (49%) demonstrated major pain improvement. The overall times to disease progression and survival were 170 and 492 days, respectively.

CONCLUSION

We have characterized all toxicities with suramin in a pharmacologically guided phase I study designed to maintain plasma suramin concentrations of 100 to 300 micrograms/mL (cohorts 1 to 3). The incidence of grade 3 to 4 neurologic abnormalities was relatively low, particularly in cohorts 2 and 3 (100 to 250 micrograms/mL). Evidence of significant and durable antitumor activity was seen in all three cohorts.

Development and validation of a pharmacokinetically based fixed dosing scheme for suramin

PURPOSE

We used population pharmacokinetic-parameter estimates and designed a fixed dosing schedule to maintain plasma suramin concentrations between 100 and 300 micrograms/mL and then evaluated its performance.

MATERIALS AND METHODS

On day 1, patients received a 200-mg test dose and 1,000-mg/m2 loading dose. On days 2, 3, 4, and 5, patients received 1-hour infusions of 400, 300, 250, and 200 mg/m2, respectively. Subsequent 1-hour infusions of 275 mg/m2 were given on days 8, 11, 15, 19, 22, 29, 36, 43, 50, 57, 67, and 78. Therapy was discontinued for dose-limiting toxicity (DLT) or progressive disease (PD). Patients were to be removed from the fixed dosing schedule if, after day 5, three consecutive peak plasma suramin concentrations were greater than 300 micrograms/mL.

RESULTS

Forty-two patients, including 40 with hormone-refractory prostate cancer (HRPC), received 700 infusions. Forty patients were assessable for toxicity; 38 were assessable for response. Two patients with preexisting pulmonary disease died early of respiratory insufficiency. Treatment was discontinued in five patients due to DLT and in seven due to PD. No patient had treatment discontinued due to repeated peak plasma suramin concentrations > or = 300 micrograms/mL. The fixed dosing schedule was precise, unbiased, and well tolerated. DLT consisted of grade 4 nephrotoxicity (n = 2), neurotoxicity (n = 2), and corticosteroid-induced psychosis (n = 1). Three patients, who received all 18 doses of suramin per protocol, developed severe, but not dose-limiting, malaise, fatigue, and lethargy. Twenty-four of 36 assessable patients with elevated serum prostate-specific antigen (PSA) levels had a > or = 50% reduction, lasting more than 4 weeks, and 18 had a > or = 75% reduction, lasting more than 4 weeks. Twelve of 23 (52%) symptomatic HRPC patients noted a subjective improvement in pain. There were no measurable responses in four patients with measurable disease. The estimated median survival time in 38 assessable patients with HRPC was 18.8 months. The estimated median time to progression in 35 patients, for whom data were available, was 10.1 months.

CONCLUSION

This easily implemented schedule allowed suramin to be administered safely as an intermittent bolus injection. Toxicity was manageable and reversible.

Suramin: development of a population pharmacokinetic model and its use with intermittent short infusions to control plasma drug concentration in patients with prostate cancer

PURPOSE

This study aimed to (1) develop a population pharmacokinetic model for suramin; (2) use Bayesian methods to assess suramin pharmacokinetics in individual patients; (3) use individual patients' pharmacokinetic parameter estimates to individualize suramin dose and schedule and maintain plasma suramin concentrations within predetermined target ranges; and (4) assess the feasibility of outpatient administration of suramin by intermittent, short infusions.

METHODS

Plasma suramin concentrations were measured by high-performance liquid chromatography (HPLC), and compartmental pharmacokinetic models were fit using a Bayesian algorithm. Population pharmacokinetic models were developed using an iterative two-stage approach. Estimates of each patient's central-compartment volume were used to calculate suramin dosage. Simulation of that patient's suramin clearance was used to predict the time of his next dose. Using this approach, plasma suramin concentration was maintained at between 200 and 300, 175 and 275, 150 and 250, or 100 and 200 microgram/mL in four sequential patient cohorts. The ability of two- and three-compartment, open, linear models to fit the pharmacokinetic data was compared. Population pharmacokinetic parameters were estimated, using both two- and three-compartment structural models in 69 hormone-refractory prostate cancer patients.

RESULTS

Target plasma suramin concentrations in individual patients were rapidly achieved. Concentrations were maintained within desired ranges for > or = 85% of treatment duration in all cohorts. A three-compartment, open, linear model described suramin pharmacokinetics better than did a two-compartment, open, linear model. Population pharmacokinetic estimates generated for two- and three-compartment pharmacokinetic models demonstrated modest interpatient pharmacokinetic variability and the long terminal half-life of suramin.

CONCLUSION

Suramin can be administered by intermittent short infusion. Adaptive-control-with-feedback dosing facilitated precise control of plasma suramin concentrations and allowed a number of different concentration ranges to be studied. This approach is expensive and labor-intensive. Although we have demonstrated the ability to control drug exposure, simpler dosing schedules require critical evaluation. Population pharmacokinetic parameters generated in men with hormone-refractory prostate cancer will facilitate rational design of such schedules.

Suramin, an active drug for prostate cancer: interim observations in a phase I trial

BACKGROUND

Previous studies indicate that suramin may be an active agent for treatment of solid tumors. The clinical use of suramin is complicated by a broad spectrum of toxic effects and complex pharmacology. Studies have suggested that the dose-limiting neurotoxicity of this agent is closely related to sustained plasma drug concentrations of 350 micrograms/mL or more.

PURPOSE

This phase I clinical trial in patients with solid tumors was designed to determine whether plasma concentrations resulting in both antitumor activity and manageable toxicity could be achieved with short, intermittent infusions of suramin.

METHODS

Thirty-seven patients, including 33 with metastatic, hormone-refractory prostate cancer, collectively received 43 courses of suramin designed to maintain a plasma concentration range of 200-300, 175-275, or 150-250 micrograms/mL. Patients received a test dose of 200 mg and an initial loading dose of 1000 mg/m2 on day 1 of therapy. Subsequent suramin doses and schedules were individually determined using a strategy of adaptive control with feedback, which used a maximum a posteriori Bayesian algorithm to estimate individual pharmacokinetic parameters. Patients were treated until dose-limiting toxicity or progressive disease developed.

RESULTS

Thirty-five of the 37 study patients and 31 of the 33 with prostate cancer were assessable for toxicity and response. Treatment was discontinued in 28 patients because of dose-limiting toxicity consisting of a syndrome of malaise, fatigue, and lethargy; recurrent reduction in creatinine clearance of 50% or more; or axonal neuropathy. Evidence of major antitumor activity was observed in patients with prostate cancer treated at all three plasma drug concentrations. Measurable responses (one complete response and five partial responses) were noted in six of 12 patients with measurable disease. Twenty-four (77%) of 31 patients had a reduction in prostate-specific antigen of 50% or more, and 17 (55%) of 31 had a reduction of 75% or more. Twenty (83%) of 24 patients reported reduction in pain.

CONCLUSIONS

Suramin can be safely administered as an intermittent bolus injection by use of adaptive control with feedback to control plasma drug concentrations; toxicity is significant but manageable and reversible. Suramin is active against hormone-refractory prostate cancer.

IMPLICATIONS

Future trials should address the role and necessary extent of therapeutic drug monitoring; the optimal plasma drug concentration range and duration of therapy; and the activity of suramin in combination with other agents, in earlier stages of prostate cancer, and in other tumor types.