Molecular alterations across sites of metastasis in patients with renal cell carcinoma (RCC)

287

Background: RCC has a distinct pattern of metastatic spread with common sites of metastasis including the lung, bone, and liver. Less common sites include the brain, adrenal gland, and pancreas. While the pattern of metastatic spread has prognostic significance, the biology driving tropism to specific organ sites has not been fully characterized. We utilized a multi-institutional real-world dataset to examine genomic alterations and transcriptional signatures across the spectrum of metastatic sites in patients with RCC. Methods: RCC tissue specimens derived from the kidney and distant metastatic sites were sequenced utilizing a commercially available Clinical Laboratory Improvement Amendments (CLIA)-certified assay by Caris Life Sciences. Whole exome and transcriptome sequencing was performed. Molecular subgroups were defined according to the IMmotion151 metastatic RCC subtypes, with subgroups determined by a weighted average of gene expression levels. Molecular analysis and PD-L1 expression (SP142) were described by metastasis site. Results: 657 RCC samples from 653 patients underwent molecular profiling. The median age was 62 years (range 14-90) and the majority were male (70.6%). The most common histology was clear cell RCC (n = 509, 77.5%), followed by papillary (n = 63, 9.6%), chromophobe (n = 30, 4.6%), medullary (n = 8, 1.2%), collecting duct (n = 6, 0.9%), and mixed (n = 41, 6.2%). Specimen source included the kidney (n = 340, 51.8%), lung (n = 75, 11.4%), bone (n = 45, 6.8%), lymph nodes (n = 34, 5.2%), liver (n = 28, 4.3%), endocrine glands (adrenal, pancreas, and thyroid; n = 23, 3.5%), brain/CNS (n = 16, 2.4%), and other metastatic sites (n = 96, 14.6%). Compared to kidney, several genes were mutated at higher rates for select metastatic sites, including PBRM1 (59.5% bone, 59.1% endocrine, and 45.9% lung vs 33.8% kidney, p< 0.05) and KDM5C (27.8% endocrine, 29.2% lymph nodes, and 35.3% soft tissue vs 9.3% kidney, p< 0.05). When evaluating metastatic specimens versus kidney specimens, bone metastases had a significantly higher proportion of tumors classified as ‘Angio/stromal’ (n = 19, 42.2%; vs n = 52, 15.4%; p< 0.0001), while liver metastases had a higher proportion of the ‘complement/Ω-oxidation’ subgroup (n = 17, 60.7%; vs n = 48, 14.1%; p< 0.0001). PD-L1 expression in metastatic sites (range 6.8%-21.7%, with exception of 0% in GI; p= 0.09 to 0.99) was not significantly different from the kidney (16.6%). Conclusions: In our contemporary real-world analysis, we demonstrate differential patterns of molecular alterations among sites of metastasis in RCC. Our observations elucidate the biology underlying heterogeneous disease outcomes associated with site of metastasis. Application of predictive signatures by site of metastasis may help inform personalized therapy strategies in advanced RCC. Further studies are warranted to validate our findings.

A randomized phase IIa study of quantified bone scan response in patients with metastatic castration-resistant prostate cancer (mCRPC) treated with radium-223 dichloride alone or in combination with abiraterone acetate/prednisone or enzalutamide

BACKGROUND

In metastatic castration-resistant prostate cancer (mCRPC), assessing treatment response and bone lesions with technetium-99m is limited by image resolution and subjectivity. We evaluated bone scan lesion area (BSLA), a quantitative imaging assessment of response in patients with mCRPC receiving radium-223 alone or in combination with androgen receptor pathway inhibitors (abiraterone/prednisone or enzalutamide).

PATIENTS AND METHODS

This randomized, non-comparative phase IIa three-arm trial (NCT02034552) evaluated technetium-99m-based BSLA response rate (RR), safety, radiologic progression-free survival (rPFS), and time to first symptomatic skeletal event (SSE) in men with mCRPC and bone metastases receiving radium-223 with/without abiraterone/prednisone or enzalutamide. The primary endpoint was week 24 BSLA RR.

RESULTS

Overall, 63 patients received treatment (abiraterone/prednisone combination, n = 22; enzalutamide combination, n = 22; radium-223 monotherapy, n = 19). Median treatment duration (first to last dose of any study treatment) was 12 months (abiraterone/prednisone combination), 10 months (enzalutamide combination), and 3 months (radium-223 monotherapy). Week 24 BSLA RR was 58% [80% confidence interval (CI) 41% to 74%; one-sided P < 0.0001; 11/19 patients] with abiraterone/prednisone combination, 50% (32% to 68%; one-sided P < 0.0001; 8/16 patients) with enzalutamide combination, and 22% (10% to 40%; one-sided P = 0.0109; 4/18 patients) with radium-223 monotherapy. Median rPFS was not evaluable for combination arms and 4 months (80% CI 4 to 12) for monotherapy. SSEs were reported in 32% of patients; median time to first SSE was not estimable. Fatigue and back pain were the most commonly reported treatment-emergent adverse events (TEAEs); more patients receiving combination therapy than monotherapy had TEAEs. Fractures were reported in 18% receiving abiraterone/prednisone, 32% receiving enzalutamide, and 11% receiving radium-223 monotherapy. Fracture rates were lower in patients taking bone health agents versus not taking bone health agents at baseline.

CONCLUSIONS

Technetium-99m imaging BSLA may offer objective, quantifiable assessment of isotope uptake changes, and potentially treatment response, in patients with mCRPC and bone metastases treated with radium-223 alone or in combination with abiraterone/prednisone or enzalutamide. In this largely treatment-naive population, BSLA RR was numerically lower with radium-223 monotherapy versus combination therapy, indicating a limited role as first-line treatment. Use of radium-223 should follow evidence-based treatment guidelines and the licensed indication.

Angiogenic and T-effector subgroups identified by gene expression profiling (GEP) and propensity for PBRM1 and BAP1 alterations in clear cell renal cell carcinoma (ccRCC)

343

Background: With the emergence of multiple active treatment options in RCC, predictive biomarkers for optimal treatment selection are lacking. Gene expression data from IMmotion151 and Javelin Renal 101 clinical trials generated anti-angiogenic and immune signatures that warrant further validation. We aimed to describe the genomic and gene expression profiles in a multi-institutional database of patients with ccRCC, and its association with other biomarkers of interest. Methods: Whole transcriptome sequencing was performed for ccRCC patient samples submitted to a commercial CLIA-certified laboratory (Caris Life Sciences, Phoenix, AZ) from February 2019 to September 2020. Tumor GEP and hierarchical clustering based on the validated 66-gene signature (D’Costa et al, 2020) were used to identify patient subgroups. Samples from both primary tumors and metastatic sites were included. Results: A total of 316 patients with ccRCC, median age 62 (range 32-90), 71.8% men, were included. Tissue samples were obtained from primary tumor (46.5%), lung (12.3%), bone (9.5%), liver (4.7%) and other metastatic sites (27%). Gene expression analysis identified angiogenic, mixed and T-effector subgroups in 24.1%, 51.3% and 24.7%, respectively. Patients with angiogenic subgroup tumors compared to those with T-effector subgroup tumors were more likely to be older (63 versus 60 years, p=0.035), female (40.8% versus 16.7%, p=0.0009) and more frequently found in pancreatic/small bowel metastases (75% versus 12.5%, p=0.0103). Biomarkers of potential response to immunotherapy such as PD-L1 (p=0.0021), TMB (not significant), and dMMR/MSI-H status (not significant) were more frequent in the T-effector subgroup. PBRM1 mutations were more common in the angiogenic subgroup (62.0% vs 37.5%, p=0.0034) while BAP1 mutations were more common in the T-effector subgroup (18.6% versus 3.0%, p= 0.0035). Immune cell population abundance (e.g. NK cells, monocytes) and immune checkpoint gene expression (TIM-3, PD-L1, PD-L2, CTLA4) were also increased in the T-effector subgroup. Conclusions: Our hierarchical clustering results based on the 66-gene expression signature were concordant with results from prior studies. Patient subgroups identified by evaluation of angiogenic and T-effector signature scores exhibit significantly different mutations and immune profiles. These findings require prospective validation in future biomarker-selected clinical trials.

CANTATA: Randomized, international, double-blind study of CB-839 plus cabozantinib versus cabozantinib plus placebo in patients with metastatic renal cell carcinoma

TPS682

Background: Glutamine metabolism is upregulated in renal cell carcinoma (RCC) and important for RCC tumor cell proliferation and survival. CB-839 is a first-in-clinic, potent, oral inhibitor of the mitochondrial enzyme glutaminase (GLS), which controls a critical step in tumor cell metabolism of glutamine. CB-839 demonstrated synergistic anti-tumor activity when combined with cabozantinib, a VEGFR2/MET/AXL inhibitor, in preclinical RCC models. In a phase 1 study cohort, CB-839 plus cabozantinib as 2L+ therapy showed encouraging safety and efficacy results, with 50% overall response rate (ORR; RECIST v1.1) and 100% disease control rate in 10 patients with clear cell advanced/metastatic RCC (mRCC). A randomized, double-blind study comparing CB-839 plus cabozantinib vs. cabozantinib plus placebo has been initiated in patients with clear cell mRCC. Methods: In this ongoing international, randomized, double-blind, multi-center study, enrollment is planned for ~300 patients with clear cell mRCC. To be eligible, patients should have received 1-2 prior lines of systemic therapy for mRCC including ≥1 anti-angiogenic therapy or the combination of nivolumab + ipilimumab, have KPS ≥70%, measurable disease (RECIST v1.1), and no prior cabozantinib (or other MET inhibitor). Patients are randomized 1:1 to receive either CB-839 (800 mg twice daily per oral [PO] route) plus cabozantinib (60 mg daily PO) or cabozantinib plus placebo in 28-day cycles until disease progression or unacceptable toxicity. Patients are stratified by prior PD-1/PD-L1 inhibitor therapy and by IMDC prognostic risk group (favorable vs. intermediate vs. poor). The primary endpoint is progression-free survival (PFS) per RECIST v1.1, determined by blinded independent radiology review. Secondary endpoints are investigator-assessed PFS and overall survival. Safety, response per RECIST, and quality of life are also assessed. Findings of this randomized, international clinical trial will inform the efficacy and safety profile of CB-839, a first-in-clinic metabolic inhibitor, in combination with cabozantinib in patients with mRCC. Clinical trial information: NCT03428217.

Molecular profiling of aggressive variant urothelial carcinoma

378

Background: The WHO recognizes multiple variant histologies of urothelial carcinoma (vUC), many of which have been associated with poor outcomes compared with urothelial carcinoma (UC). We aimed to explore molecular differences between aggressive vUC and UC. Methods: 23 micropapillary (MP), 16 plasmacytoid (P), 23 sarcomatoid (S), 7 nested (N), 6 clear cell (CC), and 2 giant cell (GC) vUC specimens were tested between 2012 to 2018 via a multiplatform profiling service (Caris Life Sciences, Phoenix, AZ) consisting of gene sequencing (next generation sequencing [NGS]), gene amplification (CISH or NGS), and protein expression (immunohistochemistry [IHC]). Findings were compared to 435 control UC specimens using the Chi-square test. Results: 84% of samples were from primary tumor. Alterations identified are summarized in Table 1, and are notable for high rates of TP53 mutations across histologic subtypes, varying rates of RB1, ERBB2 and FGFR mutations, and overall low rates of DNA damage repair (DDR) mutations (29 genes reported) except in S. There were more ARID1A mutations detected in MP than UC (100% [3 specimens] v. 41.3%, p=0.044), and more CDH1 mutations in P than UC (50% [4 specimens] v. 2%, p<0.001). CISH ERBB2 (HER2) amplification was seen in 27.3% MP compared with only 10.4% in UC (p=0.005). Compared to UC, PD-L1 IHC (SP142 assay) was positive (>5%) in a high proportion of S (55.6%, p=0.002) but in a lower proportion of other vUC (e.g. absent in P). Tumor mutational burden (TMB) was high in a lower proportion of vUC: 18.4% UC vs. 14.3% MP, 0% P, 16.7% S. Conclusions: Aggressive variant histology UCs have a differential profile of molecular aberrations compared to UC, with notable differences in potential targets such as HER2 and DDR genes as well as immunotherapy biomarkers. Further studies are needed to confirm these findings, and may support therapy development for these rare, aggressive UC subtypes. Aberrations (%) in Variant Histology UC. [Table: see text]

Non-urothelial bladder cancer: Genomic alterations and patient outcomes

399

Background: Adenocarcinoma (ADA) and squamous cell carcinoma (SCC) are rare, aggressive subtypes of bladder cancer, for which no clear standard of care exists. We report on survival of pts with ADA and SCC and identify potential therapeutic targets using molecular profiling via next generation sequencing (NGS). Methods: Survival trends, demographics, pt characteristics were obtained from the Surveillance, Epidemiology, and End Results (SEER) Database. In a separate cohort, NGS results from 72 specimens (50% metastatic) were also analyzed, using either a hotspot 47 gene panel or a 592 gene assay (Caris Life Sciences, Phoenix, AZ). Results: In SEER, 235,537 cases of bladder cancer were extracted from 1988-2008, of which 3096 were SCC and 671 were ADA. 90% of pts were white, although more African-American patients (15%) were seen in those with ADA. Among all stages, median overall survival (mOS) and 5-yr survival rates were 17.9 mos and 58% for ADA and 15 mos and 37% for SCC. Via NGS testing, 43 patients (28 ADA, 15 SCC) were tested with a 47 gene panel and 29 (21 ADA, 8 SCC) with a 592 gene panel. In the 47 gene panel, among ADA pts, the highest mutation rates were TP53 (57.1%), KRAS (21.4%), SMAD4 (14.8%), PIK3CA (10.7%) and BRCA2 (7.7%). Among SCC pts, the highest mutation rates were TP53 (66.7%), PIK3CA (33.3%), HRAS (14.3%), FBXW7 (6.7%) and AKT1 (6.7%). In the 592 gene assay, the genes with the highest mutation rates in pts with ADA were TP53 (81%), SMAD4 (33.3%), KRAS (23.8%), KMT2C (11.8%), ARID1A (11.1%), BRAF (9.5%), CTNNB1 (9.5%), KMT2D (9.5%), TSC1 (9.5%), KDM6A (5.9%), CDKN2A (5%). Among SCC pts, the highest mutation rates were TP53 (75%), CDKN2A (42.9%), FGFR3 (25%), PIK3CA (25%), CIC (14.3%), KDM6A (14.3%), BRAF (12.5%), BRCA1 (12.5%), FH (12.5%), HRAS (12.5%) and KMT2D (12.5%). Only 1 pt had high TMB. Conclusions: Genomic profiling identifies differences in underlying tumor biology of bladder ADA and SCC, which on a population level are rare with poor survival. Overall, the alterations in the PIK3CA/ AKT/ mTOR and TP53 pathways are similar to what has been reported in UC. Future analyses of these malignancies should investigate the emerging actionable targets, such as TSC1, FGFR3, BRCA1/2 and BRAF.

Cost of care for patients with metastatic castration-resistant prostate cancer initiating on docetaxel versus oral targeted therapies in the United States

88

Background: Abiraterone acetate + prednisone and enzalutamide are approved oral targeted therapies (OTT) for metastatic castration-resistant prostate cancer (mCRPC) which have significant clinical benefit. However, their impact on healthcare cost relative to docetaxel (DOC) is not well understood. Methods: This retrospective cohort study used combined claims data from Truven MarketScan Commercial and Medicare Supplement Plan databases. Males ≥18 years with ≥1 prostate cancer diagnosis and a subsequent metastasis diagnosis were indexed on the first claim date of DOC or OTT between 1/1/2012 and 12/31/2016. ≥1 claim for an androgen deprivation therapy during the 12-month continuous enrollment period prior to metastasis was required; patients with end stage renal disease or other primary cancer were excluded. All-cause per patient per year (PPPY) costs were estimated in 2016 US dollars. A generalized linear model was used to compare adjusted costs between DOC and OTT cohorts. Results: A total of 1,159 and 200 mCRPC patients initiated on OTT and DOC, respectively. Mean follow up time for both cohorts was 1.2 years. Mean age of OTT patients was 75.1 (Standard Deviation = 10.7) years and mean Quan-Charlson Comorbidity Index (QCI) was 3.2 (1.9). Mean age of DOC patients was 65.9 (9.1) years; mean QCI was 2.9 (1.8). 21% of OTT and 56% of DOC patients were commercially insured. Following treatment initiation, total mean unadjusted all-cause PPPY costs were $144,350 ($80,606) and $137,814 ($84,405) for OTT and DOC cohort, respectively. The primary cost drivers were utilization of treatments indicated for mCRPC, outpatient encounters and inpatient hospitalizations. Total adjusted PPPY costs were higher for OTT than DOC patients ($141,008 vs. $125,318, p = 0.0012), mainly due to higher costs of treatments indicated for mCRPC ($80,443 vs. $55,820, p < .0001). Medical costs (excluding mCRPC treatment) for OTT initiated patients were lower ($54,570 vs. $64,614, p = 0.0128). Conclusions: In a real-world setting, initiation on OTT was associated with higher overall cost of care for mCRPC compared with DOC. However, the cost of medical services was significantly lower when initiated on OTT.

TRITON2: An international, multicenter, open-label, phase II study of the PARP inhibitor rucaparib in patients with metastatic castration-resistant prostate cancer (mCRPC) associated with homologous recombination deficiency (HRD)

TPS388

Background: Up to 25% of patients with advanced prostate cancer, including mCRPC, have a deleterious germline or somatic mutation in BRCA1, BRCA2, ATM or another homologous recombination (HR) DNA repair gene that can serve as a molecular marker to select those who may respond to poly(ADP-ribose) polymerase inhibitors (PARPis). PARPis are lethal to cells with HRD, and PARPi treatment has shown preliminary evidence of an antitumor effect in patients with mCRPC who harbor a mutation in an HR DNA repair gene (Mateo et al. N Engl J Med. 2015;373:1697-708). These data provide a compelling rationale for evaluating rucaparib, a potent PARP1, PARP2 and PARP3 inhibitor, in patients with mCRPC associated with HRD. Methods: TRITON2 (NCT02952534) is a phase 2 study evaluating rucaparib 600 mg BID in patients with mCRPC. Patients with a deleterious germline or somatic BRCA1, BRCA2 or ATM mutation (per prior local test or central test during screening) will be enrolled into 1 of 2 cohorts based on the presence or absence of measurable visceral and/or nodal disease. An exploratory cohort will enroll patients with an alteration in any of 12 other prespecified HR genes (eg, RAD51C, RAD51D and PALB2), with or without measurable visceral and/or nodal disease. Patients must have progressed on androgen receptor signaling–directed therapy and 1 prior taxane-based chemotherapy for mCRPC. Patients who received prior treatment with a PARPi, mitoxantrone, cyclophosphamide or platinum-based chemotherapy are excluded. The primary endpoint is objective response rate measured using modified RECIST v1.1/PCWG3 for patients with soft-tissue disease and prostate-specific antigen response for patients with nonmeasurable disease. Secondary endpoints include duration of response, radiographic progression-free survival, overall survival, clinical benefit rate and safety. Pretreatment blood samples collected from all patients will enable development of a plasma-based companion diagnostic to select patients who may benefit from rucaparib treatment. Patients (≈160) will be enrolled at > 100 sites worldwide. Clinical trial information: NCT02952534.

Molecular profiles of small cell bladder and prostate cancer and comparisons with small cell lung cancer

264

Background: Small cell bladder cancer (SCBC) and small cell prostate cancer (SCPC) are rare and aggressive cancers. Standard therapy remains a platinum agent combined with etoposide, with few options after recurrence. Advances in molecular genomics and drug development have altered our approach to cancer. These same novel approaches may alter how we approach SCBC and SCPC. The purpose of this study is to identify potential targets and compare molecular profiles of SCBC and SCPC to SCLC. Methods: In total, 21 SCBC and 19 SCPC were identified from a de-identified database (Caris Life Sciences). Specimens were evaluated for genetic aberrations (Sanger or next generation sequencing [NGS], ISH) and/or protein expression (immunohistochemistry [IHC]). Comparisons were made against a de-identified cohort of SCLC (n = 428). Results: Pathogenic/presumed pathogenic mutations in SCBC were found in TP53 (91.7%, 11/12), RB1 (18.2%, 2/11), PTEN (8.3%, 1/12), EGFR (7.7%, 1/13), and PIK3CA (7.1%, 1/14). SCPC genetic aberrations were detected in TP53 (72.7%, 8/11) and RB1 (25.0%, 2/8). No carcinomas in this cohort had a high mutational burden or MSI-high status (0%, 0/7). Amplified genes found in SCBC included DDR2 (50%, 1/2) and EGFR (25.0%, 1/4). In SCPC, gene amplification was found in AKT2 (20%, 1/5), CCNE1 (20%, 1/5), FGFR1 (20%, 1/5), and MYC (20%, 1/5). The highest protein expression rates in SCBC involved MRP1 (100%, 5/5), TOP2A (94.1%, 16/17), and RRM1 (81.3%, 13/16). The highest protein expression rates in SCPC were MRP1 (100%, 6/6), TUBB3 (100%, 9/9), and TOP2A (94.4%, 17/18). Comparisons between SCBC and SCPC with SCLC revealed more similarities than differences. Significant differences were found in RRM1 by IHC between SCBC and SCLC. Also, significant differences were found between SCPC and SCLC in AR and PTEN by IHC. Conclusions: Comparisons of GU small cell carcinomas reveal similarities to SCLC. Both TP53 and RB1 mutations were found in both SCBC and SCPC. Amplification in genes CCNE1 and FGFR1, frequently identified in SCLC, were also found in SCPC. The high protein expression in biomarkers like MRP1 may explain the poor response to cytotoxic chemotherapy. Prospective studies are urgently needed.

Costs of skeletal-related events (SREs) in patients with metastatic castrate-resistant prostate cancer (mCRPC) treated with oral therapies

e16539

Background: SREs are associated with increased mortality and costs for mCRPC patients. The impact of mCRPC oral therapies on SREs is not well understood in the real world. This study examined the occurrence of and health care costs associated with SREs among mCRPC patients treated with abiraterone acetate + prednisone (ABI) or enzalutamide (ENZ). Methods: A retrospective study of a large national health claims database identified patients initiated on ABI or ENZ from 9/2012- 6/2015. Patients included had: ≥1 claim with prostate cancer diagnosis (ICD-9-CM 185.x) from 6 mo. pre- to 30 days post-index; ≥6 mo. pre- + ≥3 mo. post-index health plan enrollment. Index was date initiated on first oral therapy (ABI/ENZ). SREs (spinal cord compression, radiation to bone, pathological fracture, bone surgery) were assessed and health care cost calculated for patients with/without SREs in baseline/follow-up. Descriptive analyses and Cox proportional hazards examined SREs; generalized linear models assessed costs. Models adjusted for ABI/ENZ, age, region, baseline comorbidities, bone/brain/visceral metastases, docetaxel, and statin use. Results: The table below summarizes unadjusted results. Total all-cause per patient per month (PPPM) costs of 1,516 patients were highest for those with follow-up SREs. A significant difference in cost exists when comparing across all groups. Among patients without baseline SREs, adjusted analysis found greater hazards of follow-up SREs for baseline bone metastases (HR: 1.62, P = 0.003), baseline visceral metastases (HR: 1.68, P < 0.001), prior docetaxel (HR: 1.46, P = 0.004), and ENZ (vs. ABI) as first treatment (HR: 1.35, P = 0.013). Patients with follow-up SREs (with/without baseline SREs) had 19% higher adjusted costs compared to those without baseline or follow-up SREs (P < 0.001 each). Conclusions: SREs were common among mCRPC patients and associated with a significant financial burden. [Table: see text]

Costs of pre-hospice care among metastatic castration-resistant prostate cancer (mCRPC) patients treated with abiraterone + prednisone (ABI) and enzalutamide (ENZ)

e16534

Background: mCRPC patients are likely to receive oral therapies such as ABI or ENZ prior to hospice care. Payers and clinicians perceive hospice care as improving the quality of life for advanced prostate cancer patients dying of cancer, but literature suggests that it may be underutilized. A previous study found a longer time to starting hospice for patients initiated on ABI (vs. ENZ) with no significant difference in time spent in hospice. Understanding the active-treatment period prior to hospice may shed light on the overall burden of treatment without discounting the benefits of hospice. This study examined total pre-hospice per patient per month (PPPM) costs among mCRPC patients who utilized hospice care and treated with ABI or ENZ. Methods: A retrospective study of a large national health claims database identified patients initiated on ABI or ENZ from 09/2012 to 06/2015. Patients included had: ≥1 claim with a prostate cancer diagnosis (ICD-9-CM 185.xx) from 6 mo. pre- to 30 days post-index; ≥6 mo. pre- and ≥3 mo. post-index health plan enrollment. Index was date initiated on first oral therapy (ABI/ENZ). The subset of patients who entered hospice care were identified. Descriptive analyses assessed total PPPM costs (pharmacy, ambulatory, ER, inpatient, other medical costs) for subset of pre-hospice patients and all patients. Generalized linear model (GLM) assessed adjusted pre-hospice costs. Since the GLM used a log-link function with cost as a dependent variable, results are interpreted as a ratio of costs. Results: Among 1,516 mCRPC patients, 213 had utilized hospice care (ABI: 161, ENZ: 52). Total pre-hospice PPPM cost was greater for patients initiated on ENZ (ENZ = $19,485 ABI = $13,252; p = 0.048). Adjusted analysis found a 25.8% greater PPPM cost for those patients (Cost Ratio = 1.26, p = 0.038). Among all 1,516 patients, total all-cause PPPM cost was higher in ENZ but not statistically significant (ENZ = $11,268 ABI = $10,520; p = 0.090). Total prostate cancer related PPPM cost was statistically significant (ENZ = $10,327 ABI = $9,477, p = 0.038). Conclusions: Total pre-hospice PPPM cost is 26% lower for mCRPC patients initiated on ABI vs. ENZ.

Adjuvant androgen deprivation (AD) +/- mitoxantrone + prednisone (MP) in patients with high-risk prostate cancer (PC) post radical prostatectomy (RP): Phase III intergroup trial S9921

5019

Background: Patients (pts) with high-risk PC post RP are at risk of systemic relapse with related morbidity/mortality. Adjuvant AD can reduce this risk. In 1999, based on available data, we hypothesized that adjuvant MP + 2 years (ys) of AD can further reduce mortality. Methods: Eligible pts had cT1-T3, N0 PC with post RP > = 1 high risk factors defined as Gleason sum (GS) ≥ 8, pT3b, pT4, pN+, GS 7 + positive margin or any of these preoperative findings (in pts with neoadjuvant AD): preoperative PSA of > 15 ng/ml, bx GS score > 7, or PSA of > 10 ng/ml + bx GS > 6. Pts had to have post RP PSA = < 0.2 ng/ml, were stratified by T, N, GS, and adjuvant radiation plan and randomized: Arm 1 AD (bicalutamide + goserelin for 2 ys) or Arm 2 AD + 6 cycles m 12 mg/m2 + P 5mg BID. Primary endpoint: overall survival (OS). Median OS was estimated to be 10 ys in AD arm requiring 680 pts/arm to detect a hazard ratio (HR) of 1.30 with 92% power and one-sided α = 0.05. Results: 983 pts (961 eligible intent to treat) with median age 60 ys and median PSA 7.6 ng/ml were randomized to AD or AD + MP from 10/99 -1/07 when the DSMC recommended stopping accrual due to higher leukemia rate in Arm 2. 16% had N1 (Group “Gr” 1), 61% GS ≥8 or pT3b (Gr 2),23% other risk factors (Gr 3). Median time to testosterone recovery was 9.5 months. Median follow-up (f/u) 11.2 ys. Conclusions: OS was higher than anticipated in both arms; MP did not improve OS and increased other malignancy risk. These data illustrate that systemic therapy benefit cannot be extrapolated from different disease stages and the importance of adequate f/u in adjuvant PCa trials. The remarkable DFS and 10 y OS, irrespective of risk extent, may be result of risk definition, and/or 2 ys AD. Pending definitive data 2 ys adjuvant AD for high-risk PCa post RP is a reasonable option to consider. Clinical trial information: NCT00004124. [Table: see text]

Long-term follow-up from STAMP, a phase II trial, evaluating sipuleucel-T and concurrent (CON) vs sequential (SEQ) abiraterone acetate + prednisone in metastatic castration-resistant prostate cancer patients (pts)

190

Background: The optimal sequence and combination of life-extending anticancer therapies in mCRPC pts remains unknown. Sipuleucel-T (sip-T), an autologous cellular immunotherapy approved for the therapy of asymptomatic or minimally symptomatic metastatic castration-resistant prostate cancer (mCRPC) pts, was evaluated in combination with abiraterone acetate and prednisone (abi) in the phase II STAMP trial (NCT01487863), with pts randomly assigned to receive CON sip-T + abi or SEQ sip-T followed by abi. The combination was well-tolerated and did not alter the immune response parameters that correlate with overall survival (OS) (Small Clin Can Res 2015). Here, we present long-term follow-up of clinical outcomes, including OS. Methods: mCRPC pts were randomized 1:1 to CON or SEQ therapy with sip-T and abi. Abi began 1 day after (CON) or at wk 10 (SEQ) after the first sip-T infusion and continued for 26 wk of therapy, after which continued abi therapy was permitted. Long-term clinical outcomes included OS, disease-specific death (DSS), progressive disease (PD), time to first anticancer intervention (tACI), and safety. Results: 69 pts were enrolled (35 CON; 34 SEQ). Median OS was 34.0 mo (95% CI, 24.4-not estimable [NE]; 30.0 mo CON; 34.2 mo SEQ; p = 0.921), and median time to DSS was not reached (CON vs SEQ; p = 0.733). Median time to PD was 17.3 mo (95% CI, 9.7–NE; 17.7 mo CON vs 13.9 mo SEQ; p = 0.914; consistent with higher rates of abi discontinuation due to PD in SEQ [26.5% vs 14.3% in CON]). tACI was similar between arms at 15.4 mo (95% CI, 11.0–19.9). No new safety signals were observed with the combination, and no discernable difference in clinical outcomes was observed with CON or SEQ treatments. Conclusions: Long-term follow-up data confirm that sip-T + CON or SEQ abi is well-tolerated, with no new safety signals. No clear differences were observed in clinical outcomes between arms, although the study was not powered to detect these differences. Future and more appropriately powered studies on the effect of sip-T + continuous abi for responding pts may provide further insights on the benefit of combination therapy. Clinical trial information: NCT01487863.

Adjuvant androgen deprivation (ADT) versus mitoxantrone plus prednisone (MP) plus ADT in high-risk prostate cancer (PCa) patients following radical prostatectomy: A phase III intergroup trial (SWOG S9921) NCT00004124

2

Background: High risk localized Pca patients are more likely to relapse and suffer morbidity/mortality from metastatic disease after prostatectomy. Adjuvant ADT can reduce this risk. We hypothesized that MP in addition to two years of ADT could further reduce mortality from PCa. Methods: Participants with clinically localized (T1-T3, N0, M0) PCa received radical prostatectomy. Eligibility required ≥ 1 high risk criteria defined as Gleason sum ≥8; pT3b or pT4 or N1; Gleason 7 with positive margin; any one of these preoperative findings: PSA>15ng/ml, biopsy Gleason >7, biopsy Gleason >6 with PSA>10. ADT arm consisted of bicalutamide and goserelin for 2 years. ADT+MP arm received ADT plus 6 cycles of M 12mg/m2+ P 5mg BID. Primary endpoint was survival (OS). Median OS was anticipated to be 10 years in ADT arm requiring 680 patients/arm to detect a hazard ratio of 1.30 with 92% power and one-sided α=0.05. Results: S9921 enrolled patients from 10/99 to 1/07 when the DSMC recommended stopping due to increased incidence of leukemia in the ADT+MP arm. Of 983 patients randomized, 22 ineligible. 481 eligible on ADT and 480 on ADT+MP. Patients were stratified by stage (≤pT2, ≥pT3, N0 or N+), Gleason score, and intent to receive adjuvant radiation (RT) (Y/N). Median age was 60 years, 84% were white, presurgical PSA was 7.6 ng/ml, 16% had positive nodes, 26% intended to receive RT, 63% had positive margins. 11 ADT and 20 ADT+ MP received no protocol treatment. Median follow-up is 11.2 years. Conclusions: Survival was greater than anticipated in both arms. MP increases the risk of leukemia. There is no evidence that MP improves PCa specific survival when added to 2 years of adjuvant ADT. Clinical trial information: NCT00004124. [Table: see text]

Pembrolizumab (pembro) plus low-dose ipilimumab (ipi) for patients (pts) with advanced renal cell carcinoma (RCC): Phase 1 KEYNOTE-029 study

510

Background: The CTLA-4 antibody ipi and the PD-1 antibody pembro have demonstrated efficacy in pts with advanced malignancies. While these immune checkpoint inhibitors have shown robust activity as monotherapy, combination therapy may further improve outcomes. KEYNOTE-029 (NCT02089685) is a phase 1/2 study designed to assess the safety and efficacy of pembro + ipi or pegylated interferon alfa-2b (IFN-α) in pts with advanced melanoma or RCC. Here we report data from the phase 1 portion of the study in pts with RCC treated with pembro + ipi. Methods: Pts ≥18 years with advanced/unresectable or metastatic clear cell RCC who received ≥1 prior therapy for metastatic disease, had ≥1 measurable lesion per RECIST v1.1, and ECOG PS 0-1 were enrolled. Pts received pembro 2 mg/kg Q3W + low-dose ipi (1 mg/kg Q3W for 4 doses) until disease progression, unacceptable toxicity, investigator/patient decision, or 2 years of pembro treatment. AEs were monitored throughout treatment and for 30 days thereafter and graded per NCI CTCAE v4.0. Primary end point was safety; primary efficacy end point was ORR assessed per RECIST v1.1 by independent central imaging vendor review. Results: As of the March 17, 2016, data cutoff, 10 pts with RCC received pembro + low-dose ipi. 60% were male, 70% were white, median age was 61 years (range, 48-70 years), 40% received 2 prior lines of therapy, and 40% received prior immunotherapy. With a median follow-up of 17.4 months (0.9-23.5 months), 70% of pts experienced treatment-related AEs (TRAEs) of any grade, most commonly fatigue (30%); and 50% experienced grade 3/4 TRAEs, most commonly increased lipase (20%). 50% of pts discontinued pembro because of TRAEs, most commonly increased lipase (40%). There were no treatment-related deaths. ORR was 20% (2 partial responses); median duration of response was not reached (14.1+-17.1 months+). An additional 3 pts had stable disease; disease control rate was 50%. Conclusions: The combination of pembro + low-dose ipi for 4 doses, followed by pembro monotherapy, demonstrates a manageable toxicity profile and preliminary antitumor activity in pts with advanced RCC. Clinical trial information: NCT02089685.

Atezolizumab (atezo) as first-line (1L) therapy in cisplatin-ineligible locally advanced/metastatic urothelial carcinoma (mUC): Primary analysis of IMvigor210 cohort 1

LBA4500

Background: Cisplatin-based chemo is a standard 1L treatment (tx) for mUC and the only tx that prolongs OS; however, age or comorbidities render many pts ineligible, and 30-50% receive no tx. Atezo (MPDL3280A) is active and well tolerated in platinum-treated mUC, justifying testing atezo as 1L tx in cisplatin-ineligible pts. Methods: Pts were chemo naive in the metastatic setting and cisplatin ineligible (renal [GFR > 30 but < 60 mL/min]/hearing impairment, ≥ G2 peripheral neuropathy [PN] or ≥ ECOG PS2). Atezo 1200 mg was given IV q3w until PD (RECIST v1.1). Centrally assessed PD-L1 on tumor infiltrating immune cells (IC; SP142 IHC assay) was scored IC2/3, 1 or 0. The primary efficacy endpoint was confirmed ORR assessed per RECIST v1.1 (central independent review facility) using a data cutoff of Sep 14, 2015. Results: 119 efficacy/safety-evaluable pts of any PD-L1 IC had a median age of 73 y: 21% ≥ 80 y. 18% had prior systemic tx (21% [neo]adjuvant); 10% had radiotherapy. 66% had visceral mets. 71% had CrCl < 60 mL/min; 13% had hearing loss ≥ 25 dB; 6% had prior PN ≥ G2; 20% had ECOG PS2. ORR was 19% (95% CI 13-28; 5% CR), and responses occurred in all IC subgroups (Table; includes DCR/PFS/OS) and in pts with poor prognostic factors. 22/23 responses were ongoing with mDOR not reached. Median follow-up was 8.5 mo (range 0.2-14.3); median tx duration was 15 wk. Atezo was generally well tolerated. Tx-related all-G and G3-4 AEs were seen in 64% and 12% of pts, respectively. Related all-G AEs ≥ 10% included fatigue, pruritus, diarrhea. 1 G5 related AE occurred (sepsis). 3% had a G3-4 immune-mediated AE. Conclusions: Atezo has clinically meaningful activity in 1L cisplatin-ineligible mUC pts, and preliminary OS is encouraging. The durable nature of response and favorable AE profile makes this an attractive alternative to chemo. NCT02108652. Clinical trial information: NCT02108652. [Table: see text]

Observation of CNS events in real-world use of enzalutamide (ENZ) and bicalutamide (BIC)

235

Background: TERRAIN, a randomized, double-blind, multi-center, phase II trial compared efficacy and safety of ENZ to BIC in men with mCRPC. Although ENZ and BIC fall within the same drug classification, rates of seizure and other central nervous system (CNS) events, observed in non-clinical trial populations have not been explored. The objective of this study was to compare rates of real world CNS events in patients treated with ENZ or BIC. Methods: Retrospective claims from Truven Health MarketScan database were used to identify patients with a PC diagnosis; ≥1 claim for ENZ or BIC (index date) after 9/1/2012; > 6 months of continuous eligibility prior to index date (baseline period) and no use of ENZ or BIC prior to index. Patients were followed until 12/2014 or loss to follow-up. Patients were excluded if they had a CNS condition or another cancer diagnosis during the baseline period. CNS conditions were defined as a diagnosis for amnesia or memory impairment, anxiety, ataxia, cognitive disorders, confusion, convulsions, disturbance in attention, dizziness, falls, fatigue/asthenia, hallucinations, headaches, insomnia, pain, paresthesia, seizures, weakness, or other CNS disorders. Kaplan-Meier (KM) survival curves were used to compare the KM rates of developing any CNS conditions between patients who initiated ENZ relative to patients who initiated BIC. A subgroup analysis of patients with metastatic disease was performed. Results: The table below compares the development of CNS conditions between ENZ and BIC patients. Conclusions: This study shows that rates of CNS events are significantly higher in patients initiating ENZ as compared to BIC, even when controlling for metastatic status. [Table: see text]

Comparison of survival of African-American (AA) patients (pts) in docetaxel (D)-based combination therapies in metastatic castrate-resistant prostate cancer (mCRPC)

272

Background: AA pts experience greater prostate cancer (PC) incidence and mortality compared to Caucasian (C) pts but are underrepresented in clinical trials (CTs). Greater representation of AAs is required to explore differences in clinical benefit in advanced disease where recent data has reaffirmed the role of D. Methods: In a retrospective analysis, baseline characteristics, Gleason score (GS), ECOG PS, number of cycles (cys), maximum prostate-specific antigen (PSA) declines, radiographic responses, overall survival (OS) and progression-free survival (PFS) were captured in 2 recent D based CTs. Results: Of 136 pts, 28 (21%) self-identified as Black or AA. Median age of AA pts is 66 (50-78 yrs). Median GS is 8 (5-10). Median ECOG PS is 1 (0-2). 15 pts have bone and soft tissue disease; 13 pts have bone only disease. Median number of cys is 28.5 (1-63). Of 27 evaluable pts, 26 had PSA declines (-26 to -99%). Radiographic responses include 11 (39%) partial responses and 16 (57%) pts with stable disease. Median OS for AAs is 29.0 months (mos) (95% CI: 20.9-34.7 mos); median PFS is 21.5 mos (95% CI: 13.7-28.9 mos). Median OS for all non-AA pts is 24.8 mos (95% CI: 21.8-29.5 mos); median PFS is 16.1 mos (95% CI: 14.1-20.1 mos). The VEGF-634G > C SNP, associated with a more aggressive phenotype of PC, was evaluated in 54 pts. No evidence was found that genotype frequency varies between C and AA pts. Conclusions: In this analysis, AA pts did not have inferior OS (29 mos) or PFS (21.5 mos) outcomes compared to non-AA pts (24.8, 16.1 mos). Further analysis from larger studies is required to determine differential benefits of D for AA pts compared to non-AA pts. Clinical trial information: NCT00089609, NCT00942578.

Gaps in treatment amongst metastatic castration resistant prostate cancer (mCRPC) patients taking abiraterone acetate or enzalutamide

334

Background:Abiraterone acetate (ABI) and enzalutamide (ENZ) are novel oral therapies offering survival benefit to metastatic castration-resistant prostate cancer (mCRPC) patients. The efficacy of cancer treatments rely on patient consistency and adherence to recommended dosage regimens. Factors such as drug-drug interactions and intolerance or toxicities can result in patients or their providers reducing the drug dosage. This study aims to describe treatment discontinuation patterns observed for ABI and ENZ. Methods: The Truven Health MarketScan Research Databases were used to conduct a retrospective analysis of mCRPC patients initiated on ABI or ENZ (index date) between 10/01/2012 to 12/31/2014 with ≥6 months of continuous eligibility prior to index date and a PC diagnosis during the period of continuous eligibility. Patients were observed until loss to follow-up, or end of data availability. Kaplan-Meier (KM) survival curves were used to compare the rates of having a refill gap (i.e., ≥14 days, ≥30 days, or ≥60 days) in patients initiated on ABI or ENZ. Results: The table below summarizes the KM probabilities of having a refill gap among patients initiated on ABI or ENZ. Conclusions: Significantly higher rates of refill gaps ≥30 days and ≥ 60 days were observed for patients initiating ENZ as compared to ABI after 6 months of observation in this initial analysis. Additional research is needed to understand the reasons for gaps in treatment in patients treated with mCRPC therapies. [Table: see text]

Cabozantinib (C) plus docetaxel (D) and prednisone (P) in metastatic castrate-resistant prostate cancer (mCRPC)

235

Background: Docetaxel (D) improves overall survival in metastatic castrate-resistant prostate cancer (mCRPC), but benefits remain short-lived. Clinical data suggests patients (pts) with mCRPC treated with anti-androgen therapy like abiraterone (AA) or enzalutamide (ENZA) have decreased responses to subsequent therapy due to cross-resistance in the androgen pathway targeted by D, AA, or ENZA(van Soest et al, Eur J Cancer 49:18, 2013). Combining D with other agents, like cabozantinib (C), could target different cellular signaling pathways potentially minimizing tumor resistance. Methods: D naive pts receive 75 mg/m2 IV on day 1 of a 21 day cycle, and prednisone (P) 5 mg po q12 hours with C at 3 dose levels: 20, 40, or 60 mg po daily until maximum tolerated dose (MTD) is defined. In phase 2, pts who have progressed on AA or ENZA, enroll on a randomized 2 arm cohort comparing D plus C to D alone. Results: 20 pts have been accrued; 4 at 20 mg C, 8 at 40 mg C, and 7 at 60 mg C. On phase 2, 1 pt is randomized to D alone. Median age is 68 (44-84 yrs). Median baseline PSA is 94.7 (0.01-754.1 ng/mL). Gleason score is 9 (7-10). Median cycles is 9.5 (1-33). 8 pts have bone only disease, 12 pts have bone and soft tissue disease. Common grade 2 and grade 3 adverse events possibly related to C: hand/foot syndrome (4/16), oral mucositis (4/16), hypophosphatemia (4/16), and fatigue (3/16). The MTD of C is 40 mg daily with D. 15 pts were previously treated with AA or ENZA. In 13 patients previously treated with AA, median PFS has not been reached, with a median potential follow up of 12.4 months. Six month PFS is 77.8% and 9 month PFS is 60.5%. Conclusions: D plus P may have limited benefits after disease progression on AA as seen in 3 retrospective analyses demonstrating a median PFS survival of 4.6 months or less (Mezynski J, et al. Ann Oncol 23;11, 2012) (Aggarwal R, et al. Clin Genitourin Cancer 12;5, 2014) (Schweizer MT, et al. Eur Urol 66;4, 2014). PFS results seen in this trial compare favorably to previously published data of treatment with D after AA in mCRPC, suggesting the addition of C to D may help overcome acquired resistance. Further randomized trials will determine if C in combination with D will enhance clinical outcomes. Clinical trial information: NCT01683994.

Phase II randomized, double-blind, placebo-controlled study of tivantinib in men with asymptomatic or minimally symptomatic metastatic castrate-resistant prostate cancer (mCRPC)

146

Background: Tivantinib is a putative non-ATP competitive inhibitor of c-MET receptor tyrosine kinase that has additional cytotoxic mechanisms including tubulin inhibition. Prostate cancer demonstrates higher c-MET expression as the disease progresses to more advanced stages and to castration resistance. Methods: 80 patients (pts) with asymptomatic or minimally symptomatic mCRPC were assigned (2:1) to either tivantinib 360 mg PO BID or placebo (P). The primary endpoint was progression free survival. PCWG2 guidelines were utilized for determining eligibility and progression. Results: Of the 80 pts enrolled, 78 (52 tivantinib, 26 P) received treatment and were evaluated. Median age was 67 yrs (range: 43 to 85). Baseline characteristics were balanced between arms for ECOG PS, Gleason score, PSA, LDH, hemoglobin, Alk Phos, prior treatment, bone and organ involvement. More African Americans and those with lymph node involvement were randomly assigned to placebo. Median follow up is 8.2 months (range: 1.4 to 27.6). To date 59 patients have progressed. Patients treated with tivantinib had significantly better PFS vs. those treated with placebo (medians: 5.6 mo vs 3.8 mo, respectively; HR = 0.53, 95% CI: 0.32 to 0.89; p=0.015). Toxicity was mild overall. Grade 3 febrile neutropenia was seen in 1 patient on tivantinib while grade 3 and 4 neutropenia were recorded in 1 patient each on tivantinib and placebo. Grade 3 sinus bradycardia was recorded in two men on the tivantinib arm. 8 deaths (3 P and 5 tivantinib) have been recorded and were all considered unrelated to therapy. Conclusions: Tivantinib significantly improved PFS in men with asymptomatic or minimally symptomatic mCRPC. Given the favorable toxicity profile and evidence of anti-tumor activity, investigation of tivantinib with other agents may be a rational strategy. Clinical trial information: NCT01519414.

A phase II study of cabozantinib in patients (pts) with relapsed or refractory metastatic urothelial carcinoma (mUC)

307

Background: Translational studies have shown that shed MET levels in serum and urine of pts with UC correlate with stage and visceral metastases and that cabozantinib reverses HGF-driven UC cell growth and invasion. These data support the evaluation of cabozantinib in pts with mUC. Methods: In this phase II study, pts receive cabozantinib 60 mg daily in 28-day cycles. There are 3 study cohorts (1) mUC, (2) bone only mUC (3) metastatic rare bladder histology. The primary objective is to determine the response rate (RR) by RECIST. Response is assessed every 2 cycles. Tissue, blood, and urine were collected on all pts to test for MET/HGF and immune subsets. Results: 26 out of 55 pts have enrolled (19 M, 7 F): median age 62 (42-82) and median KPS of 80%. Primary sites include bladder (77%) and upper tract UC (23%). Prior therapy includes 30% pts with 1 regimen, 39% with 2, 15% with 3, 8% with 4 and 8% with 6. 81% of pts had visceral metastases (lung, liver and bone) and 19% lymph node only metastases. 23 pts (19 in cohort 1, 3 in cohort 2 and 1 in cohort 3) were evaluable for response after completing at least 4 weeks of therapy. In cohort 1, 2 pts achieved PR (1 remained on study for 10 months and 1 remains on study after >12 months of therapy); 7 pts had SD for at least 16 weeks (1 remained on study for 11 months); 10 had PD; 1 is too early to assess for response; 1 was removed before restaging for toxicity and 1 was removed for not meeting eligibility. The objective RR is 11% and SD 37% for a clinical benefit of 48%. In cohort 2, 1 of 3 pts had a near resolution of bone lesions on NaF PET/CT for 11 months. In cohort 3, only pt enrolled (squamous cell carcinoma of the bladder) achieved SD for 16 weeks. Mixed responses with regression of lung, bone or lymph nodes were observed in 30% of pts with PD. Grade 3/4 toxicities included: fatigue (8%), hyponatremia (8%), hypophosphatemia (8%) diarrhea (4%), thromboembolism (4%), transaminitis (4%), hypothyroidism (4%), thrombocytopenia (4%), dysphonia (4%), hypomagnesemia (4%), creatinine increase (4%) and proteinuria (4%). Conclusions: Cabozantinib has clinical activity in pts with relapsed or refractory mUC with manageable toxicities. Further studies are underway to correlate response to therapy with MET expression. Clinical trial information: NCT01688999.

A phase I study of the multikinase inhibitor cabozantinib (C) plus docetaxel (D) and prednisone (P) in metastatic castrate-resistant prostate cancer (mCRPC)

108

Background: Cabozantinib (C) is a multikinase inhibitor of c-Met, vascular endothelial growth factor receptor two and RET. C has shown activity in metastatic castrate resistant prostate cancer (mCRPC), with resolution of bone lesions on bone scan (BS), regression of soft tissue/visceral disease (STD), reductions in circulating tumor cells and bone biomarkers. Combining docetaxel (D) with other agents, without overlapping toxicities, can target different cellular signaling pathways necessary for tumor survival. Methods: Patients (pts), with no prior D for CRPC, receive a fixed dose of D (75 mg/m2 IV day one of each 21 day cycle) and prednisone (P) (5 mg po q12 hours) with C at three escalating dose levels: 20 mg, 40 mg, or 60 mg (all po daily). Using a standard three-plus-three design, three to six pts are treated at each dose level until the maximum tolerated dose (MTD) has been defined. Results: Thirteen pts have been accrued; four on dose level one, six on dose level two, and three on dose level three. Median age 69 (45 to 84). Four pts have an Eastern Cooperative Oncology Group Performance Status (ECOG PS) of zero and nine pts have a PS of one. Median Gleason score is nine (7 to 10). Median on-study prostate-specific antigen (PSA) is 129.2 ng/mL (0.01-508.5 ng/mL). Median cycles is six (1 to 17). Grade 1 adverse events (AEs), possibly related to C; dysgeusia (4/12), oral mucositis (4/12), increased ALT (3/12), and epistaxis (3/12). Grade 2 AEs; nausea (2/12), hand/foot syndrome (2/12), fatigue (2/12), dysgeusia (2/12), oral mucositis (2/12), hypophosphatemia (2/12), and anemia (2/12). Grade 3 AE is hypophosphatemia (2/12). Grade 4 AE is neutropenia (1/12). MTD of C is 60 mg. Of nine evaluable pts, six have bone only disease. Of these six, three pts have PSA declines of less than 30% with improvement on BS (two pts) or stable BS (one pt). The other three pts have PSA declines of greater than 30% and bone scan improvement. Three pts have STD and bone disease; one patient had a PSA decline of greater than 30% with improvement on BS and SD by CT scan. One patient had an increase in PSA of less than 30% with improvement on BS and CT. The third pt had PD by CT and an increase in PSA equal to 30%. PFS probability at six months is 90.0% and is 67.5% at eight months and beyond. Conclusions: The addition of C to D and P, has an acceptable toxicity profile. CT scan and BS improvements did not correlate with PSA declines in all pts. An expansion cohort will combine D plus P with C at the MTD (60 mg) to determine clinical benefit. Clinical trial information: NCT01683994.

Use of supportive measures to improve outcome and decrease toxicity in docetaxel-based antiangiogenesis combinations in metastatic castrate resistant prostate cancer (mCRPC)

e16017

Background: We have completed accrual of 63 patients (pts) to our study combining lenalidomide (L), with bevacizumab (B), docetaxel (D), and prednisone (P) (ART-P) in mCRPC. Due to the lack of improved survival and the increased toxicity of anti-angiogenic docetaxel combinations in the MAINSAIL and CALGB 90401 trials, we attempted to compare and contrast our studies with these failed phase III trials. Methods: Among the first 52 pts on ART-P, 3 received L 15 mg daily, 3 received 20 mg daily, and the others received 25 mg daily for 14 days of every 21−day cycle (C). We then enrolled 11 pts at L 15 mg. All pts received D 75 mg/m2 and B 15 mg/kg on day 1 with P 10 mg and enoxaparin daily. Pegfilgrastim was given on day 2. Patients on CALGB 90401 received D 75 mg/m2 and B 15 mg/kg on day 1, with P 10 mg. On MAINSAIL, pts received D 75 mg/m2, L 25 mg daily for 14 days of every 21−day cycle with daily P. Patients on CALGB 90401 and MAINSAIL did not receive enoxaparin or pegfilgrastim prophylactically. Results: The median number of Cs on ART-P is 18 (1-52). Median PFS is 19.1 months. Twenty-seven pts had a PR, and one pt with measurable disease had a CR. Two patients (3%) had deep vein thromboses. Of 1,334 Cs given, 14 cycles were complicated by febrile neutropenia (FN) (1%). There were no treatment related deaths. In comparison, median number of Cs in MAINSAIL L+DP arm was 6, with a PFS of 45 weeks and an OS of 77 weeks. Thirty-four pts (6.5%) developed pulmonary emboli and there were 2 deaths due to toxicity in the experimental arm. Nearly 12% of Cs were complicated by FN. In the experimental arm of CALGB 90401 trial, median OS was 22.6 months with median PFS of 9.9 months. The median number of Cs were 8 and 19 pts developed thrombosis/emboli (3.6%). In addition, 37 patients developed FN and treatment related deaths were reported at 4%. Conclusions: The use of supportive care allowed longer treatment duration with the ART-P combination as compared to D+L (MAINSAIL) and D+B (CALGB 90401), potentiating a longer PFS, RR and possibly OS with an improved safety profile. This data demonstrates the potential importance of supportive measures and is hypothesis generating for future combination studies. Clinical trial information: NCT00942578.

A randomized phase II trial of sipuleucel-T with concurrent or sequential abiraterone acetate (AA) plus prednisone (P) in metastatic castrate-resistant prostate cancer (mCRPC)

5047^

Background: Sipuleucel-T and AA + P are FDA-approved for asymptomatic/minimally symptomatic mCRPC. Suppression of the androgen axis can be immunostimulatory and AA suppresses circulating androgen levels; AA plus sipuleucel-T may therefore be synergistic. However P used with AA, which may be immunosuppressive, has not been studied with concurrent sipuleucelET and could impair sipuleucel-T production and/or immunologic response. P11-3 (NCT01487863) is the 1st study to evaluate the combination of sipuleucel-T and AA + P Methods: Patients (pts) with asymptomatic/minimally symptomatic mCRPC were randomized (1:1) to sipuleucel-T (3 infusions at approx 2-wk intervals) with up to 26 wks of AA + P (AA 1000mg QD + P 5mg BID) starting 1 day after the 1st sipuleucel-T infusion (concurrent, arm A) or at 10 wks following the 1st sipuleucel-T infusion (sequential, arm B). Endpoints included the effect of AA + P on product (sipuleucel-T) characteristics eg antigen presenting cell (APC) activation, measured as CD54 upregulation (primary endpoint), APC (measured as CD54+ cells) and total nucleated cell (TNC) counts, as well as safety and immunologic responses. Results: 31 pts in arm A and 32 pts in arm B completed sipuleucel-T treatment by the interim analysis (Nov 2012). Baseline characteristics were similar in the 2 arms. 60/63 pts received all 3 infusions of sipuleucel-T. No significant differences in median cumulative APC activation, APC count or TNC count were seen between the arms. Increased CD54 upregulation with the 2nd and 3rd treatments were indicative of a prime boost effect in both arms. Similar profiles of antigen-specific humoral and cellular immune responses were generated with no difference in magnitude of response between the arms (p>0.05). The incidence of adverse events (AEs) and serious AEs was similar in both arms. Conclusions: These data suggest sipuleucel-T can be successfully manufactured during concurrent AA + P. Product potency and prime boost effect were similar to sipuleucel-T alone. Immune responses and AEs were similar in both arms. It is not known if sipuleucel-T will provide similar efficacy with concurrent or sequential AA + P. Clinical trial information: NCT01487863.

Intermittent versus continuous androgen deprivation in prostate cancer

BACKGROUND

Castration resistance occurs in most patients with metastatic hormone-sensitive prostate cancer who are receiving androgen-deprivation therapy. Replacing androgens before progression of the disease is hypothesized to prolong androgen dependence.

METHODS

Men with newly diagnosed, metastatic, hormone-sensitive prostate cancer, a performance status of 0 to 2, and a prostate-specific antigen (PSA) level of 5 ng per milliliter or higher received a luteinizing hormone-releasing hormone analogue and an antiandrogen agent for 7 months. We then randomly assigned patients in whom the PSA level fell to 4 ng per milliliter or lower to continuous or intermittent androgen deprivation, with patients stratified according to prior or no prior hormonal therapy, performance status, and extent of disease (minimal or extensive). The coprimary objectives were to assess whether intermittent therapy was noninferior to continuous therapy with respect to survival, with a one-sided test with an upper boundary of the hazard ratio of 1.20, and whether quality of life differed between the groups 3 months after randomization.

RESULTS

A total of 3040 patients were enrolled, of whom 1535 were included in the analysis: 765 randomly assigned to continuous androgen deprivation and 770 assigned to intermittent androgen deprivation. The median follow-up period was 9.8 years. Median survival was 5.8 years in the continuous-therapy group and 5.1 years in the intermittent-therapy group (hazard ratio for death with intermittent therapy, 1.10; 90% confidence interval, 0.99 to 1.23). Intermittent therapy was associated with better erectile function and mental health (P<0.001 and P=0.003, respectively) at month 3 but not thereafter. There were no significant differences between the groups in the number of treatment-related high-grade adverse events.

CONCLUSIONS

Our findings were statistically inconclusive. In patients with metastatic hormone-sensitive prostate cancer, the confidence interval for survival exceeded the upper boundary for noninferiority, suggesting that we cannot rule out a 20% greater risk of death with intermittent therapy than with continuous therapy, but too few events occurred to rule out significant inferiority of intermittent therapy. Intermittent therapy resulted in small improvements in quality of life. (Funded by the National Cancer Institute and others; ClinicalTrials.gov number, NCT00002651.).

Use of supportive measures to improve outcome and decrease toxicity in docetaxel-based antiangiogenesis combinations

128

Background: We have recently completed accrual of 63 patients (pts) to our study combining lenalidomide (L), with bevacizumab (B), docetaxel (D), and prednisone (P) (ART-P). Due to the lack of improved survival and the increased toxicity of anti-angiogenic docetaxel combinations in the MAINSAIL and CALGB 90410 trials we attempted to contrast and compare our studies with the failed phase III trials. Methods: Among the first 52 pts on the ART-P, 3 received L 15 mg daily, 3 had 20 mg daily, and the rest had 25 mg daily for 14 days of every 21−day cycle (C). We later enrolled 11 more pts at L 15 mg. All pts received D 75 mg/m2 and B 15 mg/kg on day 1 with P 10 mg and enoxaparin daily throughout each C. Pegfilgrastim was given on day 2. Patients on CALGB 90410 received D 75 mg/m2 and B 15 mg/kg on day 1 with P 10 mg and on MAINSAIL received D 75 mg/m2, L 25 mg daily for 14 days of every 21−day cycle with daily P. Patients on CALGB 90410 and MAINSAIL did not receive enoxaparin or pegfilgrastim prophylactically. Results: Median number of Cs in ART-P was 16 (3−38). PFS was 22 months and median OS has not been reached. Pts with measurable disease had 1 CR and 25 PR (86.7% RR). Two patients (3%) had deep vein thromboses. Of 1,219 cycles given, 14 cycles were complicated by febrile neutropenia (FN) (1.1%). There were no treatment related deaths. In comparison, median number of Cs in MAINSAIL L+DP arm was 6, with a PFS of 45 weeks and an OS of 77 weeks. Thirty-four pts (6.5%) developed pulmonary emboli and there were 2 deaths due to toxicity in the experimental arm. Nearly 12% of Cs were complicated by FN. In the experimental arm of CALGB 90410 trial, median OS was 22.6 months with median PFS of 9.9 months. Median number of Cs was 8, and 19 pts developed thromboses/emboli (3.6%). In addition, 7% of patients developed FN and treatment related deaths were reported at 4%. Conclusions: The use of supportive care allows the ART-P combination to be given for more cycles than were given in MAINSAIL and CALGB 90401 potentiating a longer PFS, RR and possibly OS with an improved toxicity profile. This data demonstrates the potential importance of supportive measures and is hypothesis generating for future combination studies. Clinical trial information: NCT00942578.

Intermittent (IAD) versus continuous androgen deprivation (CAD) in hormone sensitive metastatic prostate cancer (HSM1PC) patients (pts): Results of S9346 (INT-0162), an international phase III trial

4

Background: Castration resistance occurs in the vast majority of HSM1PC pts treated with AD, with a median survival of 2.5 years (y). It is in part an adaptive process with activation of genes resulting in the production of autocrine/paracrine growth factors that contribute to maintaining the viability of PC cells. Replacing androgens before castration resistance is hypothesized to maintain PC androgen-dependence. Preclinically IAD prolonged time to castration resistance and early clinical data indicated feasibility and potential for better quality of life. Methods: HSM1PC pts with performance status (PS) 0-2, PSA ≥ 5 ng/ml were treated with 7 months (m) of goserelin + bicalutamide. Pts achieving PSA ≤4 ng/ml on m 6 and 7 were stratified by prior neoadjuvant AD/finasteride, PS and disease extent (minimal, extensive) and randomized to CAD or IAD. Primary objective: To assess if overall survival (OS) with IAD is noninferior to CAD using a one-sided test with an upper bound hazard ratio=1.20, adjusting for stratification factors. Sample size: 756 pts/arm, type I and II error rates of 0.05 and 0.10. Results: 3,040 pts were accrued by SWOG, CALGB, ECOG, NCIC, and EORTC (5/95- 9/08). After 7 m of CAD, 1535 eligible pts achieved PSA ≤4.0 (median age 70 yrs, 4% PS 2, 48% extensive disease, 12% prior neoadjuvant AD) and were randomized to CAD (759 pts) or IAD (770 pts). Grade 3/4 related adverse events: IAD 30.3%, CAD 32.6%. Median follow-up was 9.2 yrs. Median and 10 yr OS: All eligible pts from study entry: 3.6 yrs, 17%; from randomization CAD: 5.8 yrs, 29%; IAD: 5.1 yrs, 23%, HR (IAD/CAD) = 1.09 (95% CI 0.95, 1.24). No interaction with therapy was significant (p>0.25) except suggestion with disease extent (p=0.08): extensive disease HR=0.96 (95% CI 0.79, 1.15, p=0.64); minimal disease: HR=1.23 (95% CI 1.02, 1.48, p=0.035). PC was cause of death in 56% of CAD and 64% IAD pts. OSby race was not different (p=0.44). Conclusions: In HSM1PC, IAD is not proven to be noninferior to CAD. For extensive disease pts IAD was noninferior; however, IAD was statistically inferior in minimal disease pts suggesting that CAD is the preferred treatment in this group.

Dual antiangiogenic therapy using lenalidomide and bevacizumab with docetaxel and prednisone in patients with metastatic castration-resistant prostate cancer (mCRPC)

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Background: Previously, we had shown the potent anti−tumor activity of dual anti-angiogenic therapy by combining bevacizumab (B) and thalidomide (T) with docetaxel (D) and prednisone (P) in mCRPC (Ning JCO 2010). We hypothesized that combining lenalidomide (L), an analogue of T, with B, D, and P would have a more favorable efficacy/toxicity profile. Methods: All patients (pts) had chemotherapy−naïve mCRPC. Among the first 52 pts, 3 received L 15 mg daily, 3 had 20 mg daily, and the rest had 25 mg daily for 14 days of every 21−day cycle (C). The protocol was recently amended to enroll 11 more pts at L 15 mg; 2 pts have now been enrolled in this expansion cohort. All pts received D 75 mg/m2 and B 15 mg/kg on day 1 with P 10 mg and enoxaparin daily throughout each C. Pegfilgrastim was given on day 2. PSA each C with imaging after C2 and after every 3C. Dental exams with mandible CT scan at baseline, after C5, and every 6C. Results: 54 of 62 pts have been enrolled. Median age 65.5 (51−82), Gleason score 8 (5−10), on−study PSA 85.2 ng/ml (0.15−3520), and pre−study PSA doubling time 1.49 months (0.52−6.73). Median number of Cs was 16 (3−38). PFS was 22 months and probability of survival at 12 months was 90%. Forty-six (85.2%) and 42 (77.8%) pts had PSA declines of ≥50% and ≥75%, respectively. Of 30 pts with measurable disease there were 1 CR and 25 PR (86.7% overall RR). 17/54 pts were off study for radiographic disease progression and 8/54 for other reasons. Grade ≥2 toxicities included neutropenia (34/54), anemia (23/54), thrombocytopenia (7/54), hypertension (12/54), perianal fistula (3/54), rectal fissure (1/54), myocardial infarction (1/54), and osteonecrosis of the jaw (ONJ) (12/54, 22.0%). At the time of diagnosis of ONJ, 7/12pts were on bisphosphonates (BP), 2/12 had used BP previously, and 3/12 never used BP. The incidence of ONJ was comparable to 18.3% reported by Ning et al. A recent study of carboplatin plus weekly docetaxel reported an incidence of 29.3%. Conclusions: Dual anti-angiogenic therapy with, B and L, plus D and P was associated with high PSA (85.2%) and tumor (86.7%) responses in mCRPC, with manageable toxicities. The incidence of ONJ is comparable to other studies.

Intermittent (IAD) versus continuous androgen deprivation (CAD) in hormone sensitive metastatic prostate cancer (HSM1PC) patients (pts): Results of S9346 (INT-0162), an international phase III trial

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The full, final text of this abstract will be available at abstract.asco.org at 12:01 AM (EDT) on Sunday, June 3, 2012, and in the Annual Meeting Proceedings online supplement to the June 20, 2012, issue of Journal of Clinical Oncology. Onsite at the Meeting, this abstract will be printed in the Sunday edition of ASCO Daily News.

Phase II trial of bevacizumab and lenalidomide with docetaxel and prednisone in patients with metastatic castration-resistant prostate cancer (mCRPC)

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Background: Angiogenesis may be vital to mCRPC. Previously, we had shown the potent anti−tumor activity of dual antiangiogenic therapy by combining thalidomide (T) and bevacizumab (B) with docetaxel (D) and prednisone (P) in mCRPC (Ning JCO 2010). We hypothesized that combining lenalidomide (L), an analogue of T, with B, D, and P would have a more favorable efficacy/toxicity profile.

Methods: All patients (pts) had chemotherapy−naïve mCRPC. 3 pts received R 15 mg daily, 3 pts had 20 mg daily, and the rest had 25 mg daily for 14 days of every 21−day cycle (C). All pts received D 75 mg/m2 and B 15 mg/kg on day 1 with P 10 mg and enoxaparin daily throughout each C. Pegfilgrastim was given on day 2. PSA was assayed each C with imaging after C2 and then after every 3C.

Results: 47 of the planned 51 pts have been enrolled. Median age was 66 (51−82), Gleason score 8 (5−10), on−study PSA 91.6 ng/ml (0.15−3520), pre−study PSA doubling time 1.43 months (0.52−6.73), number of Cs 14 (1−31), and PFS was 19.3 months as of this analysis. Among 45 pts who have completed ≥2 cycles, 39 (86.7%) and 30 (66.7%) had PSA declines of ≥50% and ≥75%, respectively. Of 29 pts with measurable disease there were 2 CR, 21 PR, and 6 SD (79.3% overall RR). 10/47 pts were taken off study for radiographic disease progression and 5/47 for other reasons. Grade ≥3 toxicities included neutropenia (24/47), anemia (9/47), thrombocytopenia (5/47), weight loss (1/47), hypertension (3/47), and febrile neutropenia (4/47). Other toxicities included perianal fistula (3/47), rectal fissure (1/47), myocardial infarction (1/47), and osteonecrosis of the jaw (ONJ) (16/47, 34.0%). At the time of diagnosis of ONJ, 9/16 pts were on bisphosphonates and 3/16 had used bisphosphonates previously. Although the incidence of ONJ was higher than the 18.3% reported by Ning, a recent study of carboplatin plus weekly docetaxel reported an incidence of 29.3%.

Conclusions: Dual antiangiogenic therapy with, B and L, plus D and P was associated with high PSA (86.7%) and tumor (79.3%) responses with manageable toxicities. Further studies are underway to explore the high incidence of ONJ.

Epothilones in prostate cancer: review of clinical experience

BACKGROUND

Hormone-refractory prostate cancer (HRPC) is a progressive chemotherapy-resistant disease that remains a challenge to manage. Despite the recent approval of docetaxel (Taxotere) for the treatment of HRPC, the need exists for additional novel agents that can further improve patient outcomes. The epothilones are potent antimicrotubule agents that have demonstrated activity in the setting of taxane resistance. They are structurally distinct compounds that appear to lack cross-resistance with the taxanes.

DESIGN

This review summarizes current preclinical and clinical data on the safety and efficacy of the epothilones ixabepilone (BMS-247550) and patupilone (EPO906) for the treatment of prostate cancer. Data were identified by searches of PubMed and the Proceedings of the American Society of Clinical Oncology annual meetings from 2000 to 2006.

RESULTS

The epothilones have demonstrated potent antitumor activity in vitro and in experimental animal models of prostate cancer. In clinical studies, the epothilones have demonstrated potent activity in HRPC, including no cross-resistance with the taxanes and a manageable toxicity profile. Phase II studies of single-agent ixabepilone in patients with HRPC have reported a confirmed prostate-specific antigen (PSA) response rate of 33%. Higher PSA response rates have been reported in studies that assessed the combination of ixabepilone and estramustine in patients with HRPC.

CONCLUSIONS

The epothilones are promising new chemotherapeutic agents that have demonstrated single-agent antitumor activity in HRPC in the phase II setting. Phase III trials are needed to confirm the activity of the epothilones in tandem with docetaxel, given the experience to date.

The management of localized prostate cancer

At this point in time, the only possibility of curing prostate cancer is through the early detection and treatment of localized disease. The large number of treatment options available for localized prostate cancer, including radical prostatectomy, radiotherapy (either external beam or interstitial), hormone therapy and watchful waiting, can be confusing for the patient. These treatments are associated with different adverse effects, further complicating the treatment decision. As there will inevitably be a trade-off between expected cure and acceptable adverse effects, it is important to discuss all options with the patient. The doctor and patient must together decide the appropriate treatment for him and his tumor.

New agents for the treatment of renal cell carcinoma

One-third of patients with renal cell carcinoma present with unresectable or metastatic disease. Immunotherapy, the current standard treatment, induces response in only 10-20% of patients. Chemotherapy with current agents is minimally effective. Other approaches including allogeneic stem cell transplant, vaccine and gene therapy and signal transduction inhibitors, offer promise in early Phase studies. This paper reviews the current treatment options and promising new agents in development.

Intermittent androgen deprivation

Intermittent androgen deprivation is a controversial approach to management of prostate cancer. Preclinical models have demonstrated delay in time to prostate-specific antigen (PSA) progression in athymic mice bearing LNCaP tumors and a delay in time to androgen independence in androgen-dependent Shionogi carcinoma tumors in castrated animals exposed to intermittent androgen. Phase II clinical trials have demonstrated improved sexual function and quality of life in men discontinuing androgen deprivation. The average percentage of time spent off androgen deprivation ranges from 37% to 58%. Most men respond to retreatment with hormonal therapy. Current ongoing phase III clinical trials of intermittent versus continuous androgen deprivation in men with metastatic disease or recurrent disease after localized therapy will assess the comparative impact on quality of life and survival. Final analyses of these critical trials will define the ultimate role of this approach in prostate cancer. In the interim, intermittent androgen deprivation should be considered an experimental approach.

A randomized study comparing standard versus moderately high dose megestrol acetate for patients with advanced prostate carcinoma: cancer and leukemia group B study 9181

BACKGROUND

Megestrol acetate (MA) is a synthetic progestin with reported activity in both hormone-sensitive and hormone-refractory prostate carcinoma (HRPC). Based on limited data suggesting a possible dose-response effect, a trial was initiated to compare standard versus moderately high dose MA in HRPC.

METHODS

One hundred forty-nine men with hormone-refractory prostate carcinoma were randomized to receive oral MA either at 160 mg/day (low dose) or 640 mg/day (high dose). Patients were stratified by performance status and measurable versus evaluable disease. The primary end point was tumor response. Secondary end points were survival, quality-of-life measures, and prostate specific antigen (PSA) decline.

RESULTS

The median survival times of 11.2 months for patients who received the low dose and 12.1 months for patients who received the high dose therapy were not significantly different. Best response was equivalent in the 2 arms: 2 partial responses and 22 patients with stable disease for the 160 mg/day dose, and 1 partial response and 28 patients with stable disease for the 640 mg/day dose. A greater than 50% decline in PSA occurred in 13.8% and 8.8% of patients in the low and high dose treatment arms, respectively. There were no differences in the toxicity or quality-of-life outcomes between the two arms. Poorer performance status (2 vs. 0-1), greater than 5% weight loss, higher baseline PSA, and measurable disease all predicted shorter survival.

CONCLUSIONS

MA has limited activity in hormone-refractory prostate carcinoma, and there is no apparent dose-response correlation.

Depsipeptide (FR901228): a novel therapeutic agent with selective, in vitro activity against human B-cell chronic lymphocytic leukemia cells

Therapy of B-cell chronic lymphocytic leukemia (CLL) has been limited by both the nonselectivity of therapeutic agents toward normal residual immune cells and inherent drug resistance. Identification of agents that spare normal immune effector cells, thus facilitating addition of immune-based therapies, and that modulate factors associated with drug resistance in CLL might represent a major therapeutic advance. Depsipeptide (FR901228) is a novel agent entering clinical trials that has selective in vitro activity against resistant leukemia cell lines. To assess its in vitro activity in CLL, we exposed peripheral mononuclear cells from CLL patients (n = 10) to varying concentrations of this agent. Viability of the CLL cells was reduced by 50% (LC(50)) at 4 hours, 24 hours, and 4 days at depsipeptide concentrations of 0.038, 0.024, and 0.015 micromol/L, respectively. Depsipeptide had marked selective cytotoxicity when compared with normal blood mononuclear cells, in which the LC(50) was 3.44 micromol/L at 4 hours (P =.03), 0.965 micromol/L at 24 hours (P =.01), and 0.0318 micromol/L at 96 hours (P =.04). Inhibition of bone marrow progenitor cell growth was also minimal after incubation with 0.015 micromol/L (19% inhibition of colony forming unit-granulocyte-macrophage [CFU-GM]; 17% inhibition burst forming unit-erythroid [BFU-E]) and 3.44 micromol/L (24% inhibition of CFU-GM; 57% inhibition BFU-E) of depsipeptide for 4 hours, followed by a 14-day incubation period. Expression of apoptotic proteins after depsipeptide exposure (0.015 micromol/L) included no change in bcl-2, elevation of bax, and decreased expression of p27. These data demonstrate that depsipeptide has significant selective in vitro activity against human CLL cells concurrent with favorable alterations of the bcl-2:bax protein ratio and decrease in p27 expression. Such findings strongly support the early introduction of depsipeptide into clinical trials for patients with CLL.

Response criteria in prostatic carcinoma

Assessment of response in advanced prostate cancer is hampered by the preponderance of nonmeasurable, "bone-only" disease. Although bone scans are accurate in assessing new lesions, they are frequently unreliable in evaluating tumor regression. Alternatively, evaluation of response based on changes in prostate-specific antigen (PSA), a biochemical marker, is now routinely incorporated into clinical trials as a surrogate end point for response. However, despite general acceptance of its use as an end point in clinical trials, there is no standardized definition of PSA response. Furthermore, changes in PSA do not always correlate with regression of measurable tumor, especially in response to noncytotoxic agents. PSA changes are most defensibly used to define initial hints of a drug's potential usefulness, rather than as a validation of benefit. Improvement in quality of life has emerged as a clinically relevant endpoint, especially in the setting of hormone-refractory disease, in which therapy has yet to have an impact on survival. There is a current trend toward reporting response to therapy as reflecting changes in biochemical markers, measurable disease, bone-only disease, and quality of life separately, rather than trying to pigeon-hole "response" into traditional categories of "complete" and "partial." This independent reporting of outcome parameters provides a more accurate picture of the potential therapeutic benefit of the assessed new treatments, and allows more informed decision-making by physicians and their patients.

A prognostic score for hormone-refractory prostate cancer: analysis of two cancer and leukemia group B studies

Previously, we have shown that serial measurements of prostate-specific antigen (PSA) in hormone-refractory prostate cancer (HRPC) can be used to calculate an average relative velocity (rva) of PSA. Together, the level of PSA and the rva formed a two-variable model for survival time that worked at any time during the course of HRPC. Here, we have added serial measurements of hemoglobin and weight to test whether they improve the prior model based on PSA alone. Data from two Cancer and Leukemia Group B studies (9181 and 9182) on HRPC were combined to study the relationship between survival and serial measurements of PSA, serum hemoglobin, and patient weight. Altogether, there were 348 patients who could be evaluated. We used the Cox proportional hazard model for survival time with the interval censored method to accommodate time-dependent covariates, and tests for significance were two sided. Log (PSA), rva, log (hemoglobin), and log [weight (in kg)] were all significantly related to survival time during the course of HRPC (P < 3.0 x 10(-5)). Together, they formed a prognostic score based upon the relative hazard. Higher values of this score implied higher probability of death as the next observed event. Serial measurements of PSA, hemoglobin, and weight provide a prognostic score that can be applied continuously during the course of HRPC. Changes in the score may provide a reproducible measure of treatment effect.

The dynamics of prostate specific antigen in hormone refractory prostate carcinoma: an analysis of cancer and leukemia group B study 9181 of megestrol acetate

BACKGROUND

Although many physicians measure serum prostate specific antigen (PSA) during the follow-up of patients with hormone refractory prostate carcinoma (HRPC), little has been done to formalize the determination of how these serial values of PSA impact on prognosis. To understand HRPC fully, make decisions about choices of treatment as well as about clinical research on treatments for HRPC patients, and design appropriate measures of PSA response, it seems that first it would be necessary to understand how these serial measures of PSA relate to survival. The purpose of this study was to determine how repeated measurements of PSA impact on the probability of imminent death for patients with HRPC.

METHODS

One hundred forty-eight men with HRPC were enrolled in Cancer and Leukemia Group B Study 9181, in which they were treated with either a low dose (160 mg/day) or a high dose (640 mg/day) of megestrol acetate (MA). Because preliminary data analysis indicated that these treatments had no effect on survival, the authors pooled the data to analyze the overall dynamics of PSA and survival during the follow-up period. The authors attempted to correlate initial and monthly PSA measurements, which were mandated by the study protocol, with the probability of death at any time during follow-up. For statistical analysis, the Cox proportional hazards model and the general linear model were used. In addition to the level of PSA, the authors used the relative velocity of PSA, which was defined as (dy/dt)/y, with "y" symbolizing serum PSA and "t" symbolizing time.

RESULTS

Both log(PSA) and the average relative velocity of PSA (rva) were significantly correlated with survival time (P=0.0001 and P=0.0008, respectively), and the analysis performed with the Cox proportional hazards model yielded the following formula for a PSA hazard score: PSA hazard score =0.251*(log(PSA) - mean log(PSA)) + 24.5*(rva - mean rva) This hazard score tended to be higher for patients who were about to die. For example, there was a close correlation between the hazard score and the probability of death as the next observed event. Furthermore, the hazard score provided a dynamic measure of how PSA was affected by treatment.

CONCLUSIONS

The average relative velocity of PSA has been identified by the authors as a new measure of the dynamics of PSA in HRPC. It can be determined from sequential values of PSA. This average, together with the log(PSA), are significantly related to the probability of imminent death.

Apples and oranges: building a consensus for standardized eligibility criteria and end points in prostate cancer clinical trials

PURPOSE

To survey eligibility and response criteria for clinical trials in hormone-refractory prostate cancer (HRPC).

METHODS

Thirty-five established investigators of HRPC completed a 125-question survey.

RESULTS

There was a general consensus that criteria for clinical trial entry would include progression based on an increasing prostate-specific antigen (PSA) level (94% of investigators), an increase in measurable disease (91%), and/or appearance of new bone lesions on bone scan (83%). Most believed that castrate levels of testosterone (77%) and progression after antiandrogen withdrawal (97%) should be documented before study enrollment. Continuation of testicular androgen suppression would be required by 82%. Seventy-seven percent favored separate reports on response rates in bone, measurable disease, symptoms, and biochemical markers (primarily PSA levels), rather than a composite response. Ninety-four percent of the investigators accepted changes in PSA level as a surrogate end point of response. However, interpretation by these investigators of a PSA data set similar to what might be observed in a clinical trial showed marked discordance. Survival is the end point of most importance to 94% of these investigators. Response based on changes in measurable disease, time to progression, response duration, PSA level decrease, or quality-of-life improvement were of similar weighted value as a clinical trial end point and were rated as less important to these investigators than survival (P < 10(-8)).

CONCLUSION

This survey indicates some consensus on eligibility and concomitant treatments for clinical studies in HRPC. The use of multiparameter assessment of response and PSA level as a surrogate end point have been widely adopted.

Management of progressive metastatic prostate cancer

Metastatic prostate cancer is a growing health problem and is the second leading cause of cancer death in men. While the response of patients with metastatic prostate cancer to initial hormonal manipulation is excellent, the majority of patients eventually progress. As a result, a growing number of patients and their physicians need-to-find acceptable therapeutic alternatives. Fortunately, the number of therapies in the management armamentarium is growing and includes: alternative hormonal therapies, chemotherapy, radioisotopes, and investigational agents. The major focus of treatment has shifted to palliation and quality of life. The decline of prostate-specific antigen (PSA) has become another important end point as evidence supporting a correlation with prolonged survival mounts. Enrolling eligible patients in clinical trials is critical to the development of new treatment strategies for this difficult disease.