Germline single nucleotide polymorphisms associated with response of urothelial carcinoma to platinum-based therapy: the role of the host

BACKGROUND

Variations in urothelial carcinoma (UC) response to platinum chemotherapy are common and frequently attributed to genetic and epigenetic variations of somatic DNA. We hypothesized that variations in germline DNA may contribute to UC chemosensitivity.

PATIENTS AND METHODS

DNA from 210 UC patients treated with platinum-based chemotherapy was genotyped for 80 single nucleotide polymorphisms (SNPs). Logistic regression was used to examine the association between SNPs and response, and a multivariable predictive model was created. Significant SNPs were combined to form a SNP score predicting response. Eleven UC cell lines were genotyped as validation.

RESULTS

Six SNPs were significantly associated with 101 complete or partial responses (48%). Four SNPs retained independence association and were incorporated into a response prediction model. Each additional risk allele was associated with a nearly 50% decrease in odds of response [odds ratio (OR) = 0.51, 95% confidence interval 0.39-0.65, P = 1.05 × 10(-7)). The bootstrap-adjusted area under the curves of this model was greater than clinical prognostic factors alone (0.78 versus 0.64). The SNP score showed a positive trend with chemosensitivity in cell lines (P = 0.115).

CONCLUSIONS

Genetic variants associated with response of UC to platinum-based therapy were identified in germline DNA. A model using these genetic variants may predict response to chemotherapy better than clinical factors alone.

Germline single-nucleotide polymorphisms (SNPs) associated with response of urothelial carcinoma (UC) to platinum-based therapy: The role of the host

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Background: Platinum-based therapy improves outcome in neoadjuvant and metastatic UC. Since cell-line and human subject studies in other cancers show germline associations with platinum response, we hypothesized that germline variation also identifies genes that determine UC response to platinum-based therapy.

Methods: Saliva or blood was prospectively collected from 651 UC patients (pts) diagnosed between 1984 and 2010. SNPs (n=80) were selected based on previously reported associations with UC and/or platinum response and genotyped using Sequenom MassArray iPLEX system. Samples and SNPs were filtered for genotyping rate (<0.8), minor allele frequency (<0.05) and departures from Hardy-Weinberg equilibrium (<1E-03). Clinical data were ascertained and linked with the genomic data in an anonymized manner. This analysis focused on 199 pts who received cisplatin or carboplatin and were eligible for response assessment (RES=partial response or complete response, n=90). Associations between SNPs and RES were tested using one and two degree of freedom tests.

Results: Sixty-nine pts received neoadjuvant therapy (RES=54%), 126 chemo-naive pts received first-line metastatic treatment (RES=37%) and 4 received systemic treatment after prior chemoradiotherapy (RES=25%). We expected 4 associations due to chance alone at p < 0.05. However, on univariate analysis using a 2 degree of freedom test, 9 SNPs were associated (p < 0.05) with RES. Individual odds ratios (ORs) ranged from 0.32 to 3.29 with p-values ranging from 0.006 to 0.05. In analysis of rs9344 (CCND1) in all treated pts, 75/148 (51%) responded with AG/GG compared to 12/44 (27%) with AA [p=0.005312, OR 2.74 (CI 1.34, 5.92)]. In neoadjuvant pts treated with cisplatin, rs9344 analysis showed 29/48 (60%) responses in AG/GG pts compared to 5/17 (29%) with AA [p=0.026, OR 3.66 (CI 1.16, 13.1)].

Conclusions: We identified associations between 9 SNPs and response of UC to platinum-based therapy that are biologically and clinically relevant. A larger study will be required to independently validate these findings. Additional investigation of associations with time to metastasis and overall survival is ongoing.

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Phase II study of everolimus (RAD001) in metastatic transitional cell carcinoma (TCC) of the urothelium

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Background: Second-line chemotherapy has limited activity in advanced TCC with a median progression free survival (PFS) of 2-3 months. We have previously demonstrated the overexpression of activated mTOR pathway markers in invasive TCC specimens (BJU Int. 2010 Jul 26). Everolimus selectively inhibits mTOR, a central regulator of cell growth, proliferation, survival, and angiogenesis. This trial was designed to assess the efficacy of everolimus in patients (pts) with advanced TCC.

Methods: The primary objectives of this single-institution phase II trial of everolimus in pts with TCC who have failed prior chemotherapy are 1) to measure PFS as determined by RECIST and 2) to evaluate toxicity. Prior therapy is restricted to ≤ 4 chemotherapy drugs. Pts receive everolimus 10 mg oral daily continuously (1 cycle = 4 weeks). A Simon 2-stage design requires ≥13 of 23 pts to be progression free at 2 months to proceed to maximal accrual of 37.

Results: 43 pts (31 M, 12 F) with a median age of 65 yrs (32-84) and median KPS of 90 (70-90) were enrolled between 02/16/2009 and 09/30/2010. Primary tumor sites include bladder (32 pts) and ureter/renal pelvis (11 pts). Prior therapy included 28 pts with 2 drugs, 13 with 3 and 2 with 4. 34 pts have visceral metastases including lung (21), liver (19), and bone (5), and 9 pts have lymph node only disease. 8 pts who received ≤ 1 cycle secondary to rapid progression or toxicity unrelated to everolimus were deemed inevaluable for PFS endpoint and were replaced. To date, 33 pts are evaluable for the primary PFS endpoint; 2 pts are too early for PFS assessment. 22 of 33 pts are progression-free at 2 months. The median PFS for 33 evaluable pts is 2.9 months (1.4-9). One partial response has been seen. The most common grade 3-4 toxicities at least possibly related to everolimus include: anemia (7), infection (6), hyperglycemia (5), lymphopenia (4), hypophosphatemia (4), fatigue (3), hyponatremia (3), mucositis (2), dehydration (2), renal (2) and liver (2).

Conclusions: Everolimus has clinical activity in pts with advanced TCC. An ongoing analysis of pretreatment tumor tissue specimens for markers of activated mTOR pathway will be correlated with PFS.

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Phase II trial of gemcitabine, carboplatin, and bevacizumab in chemotherapy-naive patients (Pts) with advanced/metastatic urothelial carcinoma (UC)

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Background: Effective treatment for pts with advanced UC unfit to receive cisplatin-based therapy remains an unmet need. A recent phase III study showed limited benefit of gemcitabine-carboplatin (GC) alone (median OS 9.3 months) (DeSantis ASCO 2010). We recently identified the VEGF-axis as a viable pathway for UC treatment (JCO 2010;Mar 10). We propose that bevacizumab, a monoclonal antibody against VEGFR, may be safely added to GC and improve time to progression (TTP) in pts with advanced UC.

Methods: Primary endpoints (N=47 planned enrollment) were median TTP, to test an improvement of 50% over a 4.8 months median TTP seen with GC alone (Urology 2004;64:479), and safety. Secondary endpoints were response rate (RR) and overall survival (OS). Pts first received a single dose of bevacizumab 10 mg/kg. 2 weeks later they received 6 cycles of gemcitabine 1,000 mg/m2 on day(D) 1 and D 8, and both carboplatin AUC 4.5 and bevacizumab 15 mg/kg on D1 every 21 days. Pts who achieved at least stable disease were eligible to receive maintenance bevacizumab at 15 mg/kg q21 days for 18 additional doses. Restaging evaluations were performed after every 3 cycles of therapy.

Results: 51 pts (37 M, 14 F; median age 67 (Range 42-83)) were enrolled from 6/06 to 6/10. Primary tumor sites include bladder (31), renal pelvis (17) and ureter (2). 38 pts (74.5%) had visceral disease including lung (22), liver (13), bone (9) and adrenal (2). 13 pts had LN only disease. 46 of 51 pts were evaluable for response rate (RR) and TTP, 51 for toxicity. RR by RECIST was 46% (21 pts; PR 18, CR 3). 12 achieved stable disease; 1 too early to assess. Responses by MSKCC Risk Scores of 0, 1 and 2 were seen in 8/11(73%), 10/29 (35%), and 3/6 (50%) pts, respectively. 39% of pts had grade 3/4 toxicity, notably vascular thromboembolic events (VTE) in 18%.

Conclusions: Bevacizumab can be safely added to GC in the treatment of advanced UC. The 16% VTE rate is similar to the 17% rate seen at MSKCC with GC alone. (JCO 2009;27:15s). Addition of bevacizumab does not improve the RR seen with GC alone in phase II and III studies (Bellmunt Eur J Cancer 2001; DeSantis ASCO 2010). Analysis of bevacizumab's impact on TTP and OS is ongoing and will be updated.

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