Adjuvant treatment in renal cell carcinoma

In parallel with advances in the treatment of metastatic renal cell carcinoma (RCC), multiple adjuvant treatments have been tested for RCC. Adjuvant approaches now extend beyond conventional immunotherapies, such as interferon alfa and interleukins, to targeted therapies and immune checkpoint inhibitors. Most treatment approaches before the targeted treatment era did not improve patient outcomes, or study results were mixed. For example, a recent study found that disease-free survival was longer with sunitinib than with placebo in high-risk clear cell RCC, which led to the regulatory approval of sunitinib. However, another large study of adjuvant sunitinib in a slightly different patient population did not confirm these results. Ongoing studies of targeted treatments and immune checkpoint inhibitors may clarify the effectiveness of these agents in the near future. This review presents a comprehensive, chronologic examination of studies addressing adjuvant treatment in RCC, focusing on the key differences between similar approaches. It also discusses the future of adjuvant treatment in RCC.

The Clinical Activity of PD-1/PD-L1 Inhibitors in Metastatic Non-Clear Cell Renal Cell Carcinoma

Programmed death 1 (PD-1) and PD ligand 1 (PD-L1) inhibitors have shown activity in metastatic clear cell renal cell carcinoma (ccRCC). Data on the activity of these agents in patients with non-clear cell RCC (nccRCC) or patients with sarcomatoid/rhabdoid differentiation are limited. In this multicenter analysis, we explored the efficacy of PD-1/PD-L1 inhibitors in patients with nccRCC or sarcomatoid/rhabdoid differentiation. Baseline and follow-up demographic, clinical, treatment, and radiographic data were collected. The primary endpoint was objective response rate. Secondary endpoints include time-to-treatment failure (TTF), overall survival (OS), and biomarker correlates. Forty-three patients were included: papillary (n = 14; 33%), chromophobe (n = 10; 23%), unclassified (n = 9; 21%), translocation (n = 3; 7%), and ccRCC with sarcomatoid differentiation (n = 7, 16%). Of those 43 patients, 11 patients (26%) had sarcomatoid and/or rhabdoid differentiation (n = 7 with ccRCC; n = 4 nccRCC). Overall, 8 patients (19%) objectively responded, including 4 patients (13%) who received PD-1/PD-L1 monotherapy. Responses were observed in patients with ccRCC with sarcomatoid and/or rhabdoid differentiation (n = 3/7, 43%), translocation RCC (n = 1/3, 33%), and papillary RCC (n = 4/14, 29%). The median TTF was 4.0 months [95% confidence interval (CI), 2.8-5.5] and median OS was 12.9 months (95% CI, 7.4-not reached). No specific genomic alteration was associated with clinical benefit. Modest antitumor activity for PD-1/PD-L1-blocking agents was observed in some patients with nccRCC. Further prospective studies are warranted to investigate the efficacy of PD-1/PD-L1 blockade in this heterogeneous patient population. Cancer Immunol Res; 6(7); 758-65. ©2018 AACR.

The Clinical Activity of PD-1/PD-L1 Inhibitors in Metastatic Non-Clear Cell Renal Cell Carcinoma

Programmed death 1 (PD-1) and PD ligand 1 (PD-L1) inhibitors have shown activity in metastatic clear cell renal cell carcinoma (ccRCC). Data on the activity of these agents in patients with non-clear cell RCC (nccRCC) or patients with sarcomatoid/rhabdoid differentiation are limited. In this multicenter analysis, we explored the efficacy of PD-1/PD-L1 inhibitors in patients with nccRCC or sarcomatoid/rhabdoid differentiation. Baseline and follow-up demographic, clinical, treatment, and radiographic data were collected. The primary endpoint was objective response rate. Secondary endpoints include time-to-treatment failure (TTF), overall survival (OS), and biomarker correlates. Forty-three patients were included: papillary (n = 14; 33%), chromophobe (n = 10; 23%), unclassified (n = 9; 21%), translocation (n = 3; 7%), and ccRCC with sarcomatoid differentiation (n = 7, 16%). Of those 43 patients, 11 patients (26%) had sarcomatoid and/or rhabdoid differentiation (n = 7 with ccRCC; n = 4 nccRCC). Overall, 8 patients (19%) objectively responded, including 4 patients (13%) who received PD-1/PD-L1 monotherapy. Responses were observed in patients with ccRCC with sarcomatoid and/or rhabdoid differentiation (n = 3/7, 43%), translocation RCC (n = 1/3, 33%), and papillary RCC (n = 4/14, 29%). The median TTF was 4.0 months [95% confidence interval (CI), 2.8-5.5] and median OS was 12.9 months (95% CI, 7.4-not reached). No specific genomic alteration was associated with clinical benefit. Modest antitumor activity for PD-1/PD-L1-blocking agents was observed in some patients with nccRCC. Further prospective studies are warranted to investigate the efficacy of PD-1/PD-L1 blockade in this heterogeneous patient population. Cancer Immunol Res; 6(7); 758-65. ©2018 AACR.

ATM/RB1 mutations predict shorter overall survival in urothelial cancer

BACKGROUND

Mutations of DNA repair genes, e.g. ATM/RB1, are frequently found in urothelial cancer (UC) and have been associated with better response to cisplatin-based chemotherapy. Further external validation of the prognostic value of ATM/RB1 mutations in UC can inform clinical decision making and trial designs.

RESULTS

In the discovery dataset, ATM/RB1 mutations were present in 24% of patients and were associated with shorter OS (adjusted HR 2.67, 95% CI, 1.45-4.92, p = 0.002). There was a higher mutation load in patients carrying ATM/RB1 mutations (median mutation load: 6.7 versus 5.5 per Mb, p = 0.072). In the validation dataset, ATM/RB1 mutations were present in 22.2% of patients and were non-significantly associated with shorter OS (adjusted HR 1.87, 95% CI, 0.97-3.59, p = 0.06) and higher mutation load (median mutation load: 8.1 versus 7.2 per Mb, p = 0.126).

MATERIALS AND METHODS

Exome sequencing data of 130 bladder UC patients from The Cancer Genome Atlas (TCGA) dataset were analyzed as a discovery cohort to determine the prognostic value of ATM/RB1 mutations. Results were validated in an independent cohort of 81 advanced UC patients. Cox proportional hazard regression analysis was performed to calculate the hazard ratio (HR) and 95% confidence interval (CI) to compare overall survival (OS).

CONCLUSIONS

ATM/RB1 mutations may be a biomarker of poor prognosis in unselected UC patients and may correlate with higher mutational load. Further studies are required to determine factors that can further stratify prognosis and evaluate predictive role of ATM/RB1 mutation status to immunotherapy and platinum-based chemotherapy.

Clinical activity of nivolumab in patients with non-clear cell renal cell carcinoma

Background

Nivolumab is approved for patients with metastatic renal cell carcinoma (mRCC) refractory to prior antiangiogenic therapy. The clinical activity of nivolumab in patients with non-clear cell RCC subtypes remains unknown as these patients were excluded from the original nivolumab trials.

Methods

Patients from 6 centers in the United States who received at least one dose of nivolumab for non-clear cell mRCC between 12/2015 and 06/2017 were identified. A retrospective analysis including patient characteristics, objective response rate according to RECIST v1.1 and treatment-related adverse events (TRAEs) was undertaken.

Results

Forty-one patients were identified. Median age was 58 years (33–82), 71% were male, and majority had ECOG PS 0 (40%) or 1 (47%). Histology included 16 papillary, 14 unclassified, 5 chromophobe, 4 collecting duct, 1 Xp11 translocation and 1 MTSCC (mucinous tubular and spindle cell carcinoma). Among 35 patients who were evaluable for best response, 7 (20%) had PR and 10 (29%) had SD. Responses were observed in unclassified, papillary and collecting duct subtypes. In the entire cohort, median follow-up was 8.5 months and median treatment duration was 3.0 months. Median PFS was 3.5 months and median OS was not reached. Among responders, median time to best response was 5.1 months, and median duration of response was not reached as only 2 out of 7 responders had disease progression during follow-up. TRAEs of any grade were noted in 37% and most commonly included fatigue (12%), fever (10%) and rash (10%). Nivolumab treatments were postponed in 34% and discontinued in 15% of patients due to intolerance. No treatment-related deaths were observed.

Conclusions

Nivolumab monotherapy demonstrated objective responses and was well tolerated in a heterogeneous population of patients with non-clear cell mRCC. In the absence of other data in this treatment setting, this study lends support to the use of nivolumab for patients with metastatic non-clear cell renal cell carcinoma.

Synaptophysin expression on circulating tumor cells in patients with castration resistant prostate cancer undergoing treatment with abiraterone acetate or enzalutamide

BACKGROUND

With the advent of secondary androgen receptor (AR)-targeted therapies in metastatic castration resistant prostate cancer (PC), nonadenocarcinoma PCs are becoming more prevalent. Many of these cancers express neuroendocrine markers, which may provide biomarkers for emergence of this disease state. We aimed to quantify the expression of synaptophysin (Syp) on circulating tumor cells (CTCs) from serial samples of patients being treated with abiraterone acetate or enzalutamide.

METHODS

CTCs were isolated from 44 patients with castration resistant PC before starting abiraterone or enzalutamide, at 4, 8, and 12 weeks on therapy, and at progression. Patients were stratified into 3 groups: de novo resistance, short response, and long response. CTCs were enumerated on the CellSearch platform and Syp expression was quantified using the open fluorescent channel on the platform. Correlative analyses were performed.

RESULTS

A baseline CTC count of 5 or greater was associated with a more rapid time to progression and increasing CTC counts correlated with emergence of drug resistance. Syp was readily detectable on the surface of CTCs, and baseline percentage CTC Syp expression was significantly associated with time to progression. Furthermore, in evaluable patients, percent CTC Syp expression increased with the emergence of drug resistance. We also found that prior exposure to AR-targeted therapies was inversely associated with progression free survival.

CONCLUSIONS

We have demonstrated that Syp can be quantified on CTCs and that Syp expression correlates with resistance to abiraterone and enzalutamide. Larger studies testing Syp as a biomarker of emergence of nonadenocarcinoma disease and as a marker of response to AR-targeted therapies are warranted.

Association of Circulating Tumor DNA (ctDNA) Detection in Metastatic Renal Cell Carcinoma (mRCC) with Tumor Burden

Background: In a series of 224 patients with advanced renal cell carcinoma (RCC), we have previously reported circulating tumor DNA (ctDNA) detection in 79% of patients. Clinical factors associated with detection are unknown. Methods: Data was obtained from patients with radiographically confirmed stage IV RCC who received ctDNA profiling as a part of routine clinical care using a CLIA-certified platform evaluating 73 genes. Detailed clinical annotation was performed, including assessment of International Metastatic Renal Cell Carcinoma Database Consortium (IMDC) risk score, previous and current treatments and calculation of tumor burden using scan data most proximal to ctDNA assessment. Tumor burden was equated to the sum of longest diameter (SLD) of all measurable lesions. Results: Thirty-four patients were assessed (18 male and 16 female) with a median age of 62 (range, 34-84). Twenty-six patients, 4 patients and 4 patients had clear cell, sarcomatoid and papillary histologies, respectively. IMDC risk was good, intermediate and poor in 14, 19 and 1 patient, respectively. ctDNA was detected in 18 patients (53%) with a median of 2 genomic alterations (GAs) per patient. No associations were found between IMDC risk, histology or treatment type and presence/absence of ctDNA. However, patients with detectable ctDNA had a higher SLD compared to patients with no detectable ctDNA (8.81 vs 4.49 cm; P = 0.04). Furthermore, when evaluated as a continuous variable, number of GAs was correlated with SLD (P = 0.01). Conclusions: With the caveat of a limited sample size, it appears that SLD (a surrogate for tumor burden) is higher in mRCC patients with detectable ctDNA. Confirmation of these findings in larger series is ongoing and may suggest a capability for ctDNA to either complement or supplant radiographic assessment.

Association of circulating tumor DNA (ctDNA) detection in metastatic renal cell carcinoma (mRCC) with tumor burden

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Background: In a series of 224 pts with advanced RCC, we have previously reported ctDNA detection in 79% of pts (Pal SK et al ASCO GU 2017). Clinical factors associated with detection are unknown. Methods: Data was obtained from pts with radiographically confirmed stage IV RCC who received ctDNA profiling as a part of routine clinical care using a CLIAA-certified platform evaluating 73 genes. Detailed clinical annotation was performed, including assessment of Heng risk score, previous and current treatments and calculation of tumor burden using scan data most proximal to ctDNA assessment. Tumor burden was equated to the sum of longest diameter (SLD) of all measurable lesions. Results: 32 pts were assessed (M:F 19:13) with a median age of 62 (range, 34-84). 25 pts, 4 pts and 3 pts had clear cell, sarcomatoid and papillary histology, respectively. Heng risk was good, intermediate and poor in 13, 18 and 1 pt, respectively. Pts received a median of 2 lines of prior tx. Specifically, 4 pts were not on active therapy (tx), 16 pts were receiving VEGF-directed tx, 6 pts were receiving checkpoint inhibitors (CPIs) and 6 pts were receiving combined VEGF/CPI tx. ctDNA was detected in 16 pts (50%) with a median of 2 genomic alterations (GAs) per pt. No associations were found between Heng risk, histology or tx type and presence/absence of ctDNA. However, pts with detectable ctDNA had a higher SLD compared to pts with no detectable ctDNA (99.6 vs 50.0 mm; P = 0.041). Furthermore, when evaluated as a continuous variable, number of GAs was correlated with SLD (P = 0.023). TP53 and VHL alterations were the most frequent GAs in this series, each occurring in 25% of the cohort. All 3 pts with brain metastases had ctDNA detected. Conclusions: With the caveat of a limited sample size, it appears that SLD (a surrogate for tumor burden) is higher in mRCC pts with detectable ctDNA, and increasing SLD may be associated with a higher number of GAs. Further validation of these findings may help identify appropriate pts for ctDNA assessment and maximize yield in clinical practice.

Clinical activity of PD1/PDL1 inhibitors in metastatic non-clear cell renal cell carcinoma (nccRCC)

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Background: PD1/PDL1 inhibitors have shown significant activity in the treatment of patients (pts) with metastatic clear cell renal cell carcinoma (ccRCC), but their activity in nccRCC is poorly characterized. Methods: We conducted a retrospective multicenter study of pts with metastatic nccRCC treated with PD1/PDL1 inhibitors. Baseline clinical parameters, overall response rate (ORR) by RECIST, time-to-treatment failure (TTF), and overall survival (OS) were summarized. Results: We identified 40 pts across 8 academic institutions. Fourteen (35%) had papillary histology, 10 (25%) chromophobe, 3 (8%) translocation, and 7 (18%) unclassified. Six (16%) had ccRCC with a sarcomatoid component > 30%. 20% had International Metastatic RCC Database Consortium (IMDC) favorable-risk disease, 60% intermediate, and 20% poor-risk. Ten (25%) were treatment-naïve and the majority received PD1/PDL1 monotherapy (n=30, 75%), while the remaining received a combination of PD1/PDL1 with anti-VEGF(R) or anti-CTLA4 therapy. ORR for the total cohort was 18% and 10% for PD1/PDL1 monotherapy pts (Table). With a median follow-up of 5.6 months, the overall median TTF was 4.7 months (2.9-15.9) and six-month OS was 81% (60-91%). Conclusions: PD1/PDL1 blockade resulted in some activity in pts with various nccRCC histologies. In the absence of available clinical trials, this data may support the use of PD1/PDL1 blocking agents in pts with nccRCC. [Table: see text]

Abstract OT2-01-01: SANDPIPER: Phase III study of the PI3-kinase inhibitor taselisib (GDC-0032) plus fulvestrant in patients with estrogen receptor-positive, HER2-negative locally advanced or metastatic breast cancer enriched for patients with PIK3CA-mutant tumors

Background: PIK3CA mutations frequently occur in breast cancer (BC), being present in ∼40% of estrogen receptor (ER)-positive, HER2-negative breast tumors. PIK3CA mutations promote growth and proliferation of tumors and mediate resistance to endocrine therapies in BC. Taselisib is a potent and selective PI3-kinase (PI3K) inhibitor that displays greater selectivity for mutant PI3Kα than wild-type PI3Kα through a unique mechanism. In cell studies, taselisib preferentially degraded mutant compared with wild-type PI3Kα, which was not seen with alpelisib and pictilisib. Taselisib has enhanced activity against PIK3CA-mutant BC cell lines, and clinical data include confirmed partial responses in patients with PIK3CA-mutant BC treated with taselisib either as a single agent or in combination with fulvestrant.

Trial design: SANDPIPER is a double-blinded, placebo-controlled, randomized, phase III study, designed to evaluate efficacy and safety of taselisib plus fulvestrant in patients with ER-positive, HER2-negative locally advanced or metastatic BC. Patients will be randomized 2:1 to receive either taselisib (4 mg daily) or placebo plus fulvestrant (500 mg intramuscular on Days 1 and 15 of Cycle 1, and on Day 1 of each subsequent 28-day cycle). Randomization will be stratified by visceral disease, endocrine sensitivity, and geographic region. The study enriches for patients with PIK3CA-mutant tumors who will be randomized separately from those with non-mutant tumors.

Eligibility: Postmenopausal women with ER-positive, HER2-negative, locally advanced or metastatic BC are eligible if they have disease recurrence or progression during or after aromatase inhibitor treatment. A valid cobas® PIK3CA Mutation Test result via central assessment is required prior to enrollment.

Aims: The primary efficacy endpoint is investigator-assessed progression-free survival (PFS) in patients with PIK3CA-mutant tumors. Additional endpoints include overall survival (OS), objective response rate (ORR), clinical benefit rate (CBR), duration of objective response, safety, pharmacokinetics, and patient-reported outcomes.

Statistical methods: The primary efficacy analysis population will include all randomized patients with PIK3CA-mutant tumors. Patients will be grouped according to randomized treatment arm. Median PFS and OS will be estimated using Kaplan–Meier methodology. Cox proportional-hazards models, stratified by the stratification factors, will be used to estimate the hazard ratio with 95% confidence intervals (CIs). ORR, CBR, and their 95% CIs will be estimated. Duration of objective response will be estimated using Kaplan–Meier methodology. Quality of life will be analyzed and summarized. Safety will be analyzed for all treated patients according to actual treatment received.

Accrual: Target enrollment is 600 patients. The study is open for enrollment and, as at April 2016, over 200 patients have been enrolled. Clinicaltrials.gov ID: NCT02340221.

Contact information: For more information or to refer a patient, email global.rochegenentechtrials@roche.com or call 1-888-662-6728 (USA only).

Citation Format: Baselga J, Cortés J, De Laurentiis M, Dent S, Diéras V, Harbeck N, Hsu J, Jin H, Schimmoller F, Wilson TR, Im Y-H, Jacot W, Krop IE, Verma S. SANDPIPER: Phase III study of the PI3-kinase inhibitor taselisib (GDC-0032) plus fulvestrant in patients with estrogen receptor-positive, HER2-negative locally advanced or metastatic breast cancer enriched for patients with PIK3CA-mutant tumors [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr OT2-01-01.

Relationship of smoking status to genomic profile, chemotherapy response and clinical outcome in patients with advanced urothelial carcinoma

Smoking has been linked to urothelial carcinoma (UC), but the implications on genomic profile and therapeutic response are poorly understood. To determine how smoking history impacts genomic profile and chemotherapy response, clinicopathologic data was collected for patients with metastatic UC (mUC) across 3 academic medical centers and comprehensive genomic profiling (CGP) was performed through a CLIA-certified lab. Unsupervised hierarchical clustering based on smoking status was used to categorize the frequency of genomic alterations (GAs) amongst current smokers (CS), ex-smokers (ES) and non-smokers (NS), and survival was compared in these subsets. Fisher's exact test identified significant associations between GAs and smoking status. Amongst 83 patients, 23%, 55% and 22% were CS, ES, and NS, respectively, and 95% of patients had stage IV disease. With a median follow up of 14.4 months, the median overall survival (OS) was significantly higher in NS and ES (combined) as compared to CS (51.6 vs 15.6 months; P = 0.04). Of 315 cancer-related genes and 31 genes often related to rearrangement tested, heatmaps show some variations amongst the subsets. GAs in NSD1 were more frequent in CS as compared to other groups (P < 0.001). CS status negatively impacts OS in patients with mUC and is associated with genomic alterations that could have therapeutic implications.

Abstract OT1-03-14: SANDPIPER: Phase III study of the PI3-kinase inhibitor taselisib (GDC-0032) plus fulvestrant in patients with estrogen receptor-positive, HER2-negative locally advanced or metastatic breast cancer enriched for patients with PIK3CA-mutant tumors

Background: PIK3CA mutations are one of the most frequent genomic alterations in breast cancer (BC), being present in ∼40% of estrogen receptor (ER)-positive, HER2-negative breast tumors. PIK3CA mutations promote growth and proliferation of tumors and mediate resistance to endocrine therapies in BC. Taselisib is a potent and selective PI3-kinase (PI3K) inhibitor that displays greater selectivity for mutant PI3Kα than wild-type PI3Kα. Taselisib has enhanced activity against PIK3CA-mutant BC cell lines, and clinical data include confirmed partial responses in patients with PIK3CA-mutant BC treated with taselisib either as a single agent or in combination with fulvestrant.

Trial design: SANDPIPER is a double-blind, placebo-controlled, randomized, phase III study, designed to evaluate efficacy and safety of taselisib plus fulvestrant in patients with ER-positive, HER2-negative locally advanced or metastatic BC. Patients will be randomized 2:1 to receive either taselisib (4 mg daily) or placebo in combination with fulvestrant (500 mg intramuscular on Days 1 and 15 of Cycle 1, and on Day 1 of each subsequent 28-day cycle). Randomization will be stratified by visceral disease, endocrine sensitivity, and geographical region. The study enriches for patients with PIK3CA-mutant tumors who will be randomized separately from patients with non-mutant tumors.

Eligibility: Postmenopausal women with ER-positive, HER2-negative, locally advanced or metastatic BC are eligible if they have disease recurrence or progression during or after aromatase inhibitor treatment. A valid PIK3CA-mutation result via central assessment is required prior to enrollment.

Aims: The primary efficacy endpoint is investigator-assessed progression-free survival (PFS) in patients with PIK3CA-mutant tumors. Other endpoints include overall survival (OS), objective response rate (ORR), clinical benefit rate (CBR), duration of objective response, safety, pharmacokinetics, and patient-reported outcomes. Efficacy in patients without PIK3CA-mutant tumors will be an exploratory endpoint.

Statistical methods: The primary efficacy analysis population will include all randomized patients with PIK3CA-mutant tumors. Patients will be grouped according to treatment arm assigned at randomization. Median PFS and OS will be estimated using Kaplan-Meier methodology in each treatment arm. Cox proportional-hazards models will be used to estimate the hazard ratio with 95% confidence intervals (CIs). ORR, CBR, and their 95% CIs will be estimated by treatment arms. Duration of objective response will be estimated by treatment arms using the Kaplan-Meier methodology. Quality of life will be analyzed and summarized by treatment arms. Safety will be analyzed for all treated patients according to actual treatment received.

Accrual: Target enrollment is 600 pts from ∼165 sites and ∼23 countries. The study is open for enrollment and 11 patients have been enrolled as of May 31, 2015. Clinicaltrials.gov ID: NCT02340221.

Contact information: For more information or to refer a patient, email global.rochegenentechtrials@roche.com or call 1-888-662-6728 (USA only).

Citation Format: Baselga J, Cortés J, De Laurentiis M, Diéras V, Harbeck N, Hsu J, Jin H, Schimmoller F, Wilson TR, Im Y-H, Jacot W, Krop IE, Verma S. SANDPIPER: Phase III study of the PI3-kinase inhibitor taselisib (GDC-0032) plus fulvestrant in patients with estrogen receptor-positive, HER2-negative locally advanced or metastatic breast cancer enriched for patients with PIK3CA-mutant tumors. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr OT1-03-14.

Abstract OT1-03-18: COLET: A multistage, phase 2 study evaluating the safety and efficacy of cobimetinib in combination with paclitaxel as first-line treatment for patients with metastatic triple-negative breast cancer

Background: Cobimetinib (cobi) is a potent, highly selective inhibitor of MEK that has shown benefit when administered in combination with the BRAF inhibitor vemurafenib in BRAFV600-mutated metastatic melanoma. Preclinical data suggest that up-regulation of the MAPK pathway is a potential resistance mechanism against taxane chemotherapy. Clinically, the combination of MEK inhibition and taxane chemotherapy in non–small cell lung cancer patients (pts) has improved response rate (RR) and progression-free survival (PFS). Because most triple-negative breast cancer (TNBC) pts develop resistance to taxane chemotherapy and because genetic alterations (including mutations and gene amplifications) in the MAPK pathway are present in many TNBC tumors, the combination of taxane chemotherapy and MEK inhibition could be an effective treatment option.

Study design: COLET (WO29497) is a multistage study designed to evaluate the safety of and to estimate the efficacy of cobi  paclitaxel in pts with metastatic or locally advanced TNBC who have not previously received systemic therapy for metastatic disease. The study will be conducted in 2 stages: an initial safety run-in stage of approximately 12 pts, followed by a randomized stage in which approximately 100 pts will be randomly assigned in a 1:1 ratio to receive either cobi + paclitaxel or placebo + paclitaxel. Pts will receive paclitaxel 80 mg/m2 on Days 1, 8, and 15 of each 28-day cycle and cobi/placebo 60 mg/day on Days 3-23 of each 28-day cycle until progression of disease or toxicity occurs.

Key eligibility criteria:

• Metastatic or locally advanced (not amenable to curative resection) TNBC

• No prior systemic therapy for metastatic or unresectable locally advanced TNBC

• Neoadjuvant or adjuvant chemotherapy or radiation therapy is allowed if completed &gt;6 months before the start of study treatment

• Measureable disease using Response Evaluation Criteria In Solid Tumors, version 1.1 (RECIST v1.1)

• History of or active untreated or unstable brain metastases or requiring corticosteroids for brain metastases precludes eligibility

• Left ventricular ejection fraction (LVEF) greater than the institutional lower limit of normal or above 50%

Specific aims of the safety run-in stage: Determine the safety and tolerability of cobi when administered in combination with paclitaxel.

Specific aims of the randomized stage: Investigator-assessed PFS (primary end point); safety; pharmacokinetics; the effect of intrinsic subtypes and genetic alterations in PFS; mechanisms of resistance; and health-related quality of life.

Accrual: Approximately 112 pts from sites across Europe, North America, and the Asia-Pacific region.

Statistical methods: In the randomized stage, pts will be followed up until a total of 60 PFS events occur across the 2 arms. This provides 77% power to detect a hazard ratio of 0.5 at a two-sided significance level of 0.05.

Contact information: Registered with ClinicalTrials.gov, identifier NCT02322814. For more information, please contact Roche/Genentech trials, 888-662-6728 (US only) or reference study ID WO29479 at www.roche.com/about_roche/roche_worldwide.htm.

Citation Format: Kim S-B, Miles D, Rhee J, Yan Y, Hsu J, Brufsky A. COLET: A multistage, phase 2 study evaluating the safety and efficacy of cobimetinib in combination with paclitaxel as first-line treatment for patients with metastatic triple-negative breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr OT1-03-18.

Stool bacteriomic profiling in patients with metastatic renal cell carcinoma suggests an etiology of VEGF TKI-related diarrhea

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Background: Vascular endothelial growth factor-tyrosine kinase inhibitors (VEGF TKIs) remain a mainstay of therapy for patients with metastatic renal cell carcinoma (mRCC). Diarrhea represents a pervasive toxicity, with all grade diarrhea affecting roughly 50% of patients receiving VEGF TKIs. The underlying cause of diarrhea in these patients is poorly understood. Methods: Patients with mRCC receiving an FDA-approved VEGF TKI therapy for mRCC were consented. Stool was collected in a standardized fashion and total genomic DNA was isolated using the PowerSoil DNA isolation kit (Mo Bio, USA). A standard PCR protocol was used to amplify bacterial 16S rRNA genes from all samples. PCR primers were used to amplify the V4 and V5 regions of the 16S rRNA. Paired-end of sequencing 2X100bp was performed by Illumina HiSeq 2000, and sequences were clustered using the CD-HIT clustering algorithm. Taxonomy was then assigned using the RDP-II classifier. Non-clustered analyses were also performed, stratifying patients by the presence or absence of diarrhea at the time of stool collection. Results: Of 26 patients consented, 23 patients submitted stool specimens and 20 had sufficient data for the current analysis. Amongst these 20 patients, the median age was 63 and the majority of patients (60%) were intermediate risk by Heng criteria. Eight patients (40%) received VEGF TKI therapy in the first-line setting. Across all lines of therapy, the most commonly used VEGF TKI was sunitinib (44%). A total of 141 bacterial species were identified. With respect to differences in patients who did and did not have diarrhea, the Mann-Whitney U-test identified 7 species with a p value of <0.1. The largest difference was seen in two Bifidobacterium species, B. animalis and B. bifidum, with both bacteria more abundant in patients with no diarrhea. Conclusions: This is the first effort to use stool bacteriomic profiling to ascertain the etiology of VEGF TKI related diarrhea in patients with mRCC. Two Bifidobacterium spp identified in this analysis are commonly found in probiotics. Studies to use probiotics enriched with Bifidobacterium spp to prevent or ameliorate VEGF TKI-related diarrhea are currently in development.

Everolimus (EVE) versus temsirolimus (TEM) after first-line treatment with VEGF TKI in patients with metastatic renal cell carcinoma

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Background: Given the lack of affordability with an oral drug like EVE and/or preference in some patients (pts), TEM has been used after disease progression on a vascular endothelial growth factor tyrosine kinase inhibitor (VEGF TKI). However, efficacy of TEM and EVE in this setting has not been evaluated in a randomized trial. Methods: Pts who were treated with a first VEGF TKI for metastatic renal cell carcinoma (mRCC) and then treated with either EVE or TEM upon progression were identified from two institutional databases. Survival estimates of progression free (PFS) and overall survival (OS) were assessed from initiation of second-line (2nd) treatment by Kaplan-Meier methodology. Results: 90 pts were eligible that received either EVE (n=59; 66%) or TEM (n=31; 34%) in 2nd setting. Pts and disease characteristics were similar in both groups. Median PFS was not different, but OS was significantly improved with EVE (Table). Conclusions: After progression on a 1st VEGFTKI, 2nd EVE and TEM have similar efficacy in terms of PFS, but OS was significantly higher with EVE. Data need further validation in a larger cohort. [Table: see text]

Comparison of radiographic characteristics of renal cell carcinoma (RCC) brain metastases treated with vascular endothelial growth factor (VEGF)-directed therapies or radiotherapy

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Background: With improvements in systemic therapy for metastatic RCC (mRCC), an increased frequency of brain metastases (BM) has been observed, perhaps owing to the central nervous system (CNS) serving as a sanctuary site. The response of BM to VEGF-directed therapies has been poorly characterized. Methods: Patients (pts) with mRCC BM were identified from an institutional database. Selection of pts was further refined to pts who had received either VEGF-directed therapy during their diagnosis with BM or radiotherapy directed to their BM. Only those pts with brain MRI straddling systemic therapy and radiotherapy were selected for analysis. Imaging studies were anonymized and transmitted to an independent radiologist for review. Descriptive statistics were applied to characterize the change in sum of long axis dimensions (SLD) in two separate groups: (1) pts treated with VEGF-directed therapy and (2) pts treated with radiotherapy. Results: Of 276 pts with mRCC in our institutional database, 34 pts with BM were identified. Of these pts, 6 pts had serial MRI assessments at timepoints straddling receipt of VEGF-directed therapy. Pts had received sunitinib (n=2), sorafenib (n=2) or bevacizumab (n=2). A further 13 pts received radiotherapy with MRI imaging straddling delivery of either stereotactic radiation therapy (SRT) and whole brain radiotherapy (WBRT). Of these 19 patients, all patients had clear cell histology, and 13 patients were male. In pts receiving VEGF-directed agents, the average change in SLD of BM was -13.8%. In pts receiving radiotherapy, the average change in SLD was -6.5% (-13.0% in pts receiving SRT and +2.0% in pts receiving WBRT). Qualitatively, greater tumor necrosis and lesser rim enhancement was observed in post-treatment scans amongst pts receiving VEGF-directed agents. Conclusions: This pilot study suggested differences in CNS response with VEGF-directed therapy and radiotherapy. Multicenter collaborations are underway to validate these results in larger series.