Citations

190 Background: It is not known if biopsy of CRPC stage metastases alters CTC results. We evaluated pre & post biopsy CTC counts in a prospective cohort undergoing pre-chemotherapy abiraterone acetate/prednisone (AA/P). Methods: CTC enumeration was performed on 7.5mL blood using the FDA cleared immunomagnetic/immunofluorescence assay (CellSearch). Time of blood draw for CTC counts pre/post biopsy was recorded for each biopsy. Biopsies were performed using 11/13 gauge core biopsy device for bone lesions and 18 gauge core needle biopsy device for soft tissue/nodal metastases. All patients (pts) underwent two serial biopsies 3 months apart. Change in CTC counts pre/post biopsy for visits 1 and 2 were evaluated using Wilcoxon signed rank test (significance at p<0.05). Differences in CTC count change (visit1) pre/post biopsy based on metastatic site (skeletal vs. non-skeletal) was compared using Wilcoxon rank-sum test. Results: Median age of the cohort was 74 years (IQR: 68-78); median PSA at V1 was 16.4 ng/ml (IQR: 6.4-87.6); at V2 was 11.5 ng/ml (IQR: 1.8-23.7). Of 59 pts undergoing biopsies 42 were in bone and 17 in nodal/soft tissue masses. At V1, pre/post biopsy CTC counts were measured on 50 and 49 pts, respectively; at V2, pre/post CTC counts were measured on 43 and 36 pts. High volume metastatic disease at V1 was observed in 67.8 % of all pts. Table lists CTC counts and time of collection pre/post biopsy for both visits. Mean change in pre/post biopsy CTC counts for skeletal sites was 0.7 (range: -12 to 64) compared to 12.1 (range: -21 to 13) for non-skeletal sites (p=0.23). Conclusions: An increase in mean CTC counts after biopsy of CRPC metastases was observed. No significant differences in change of CTC counts based on site biopsied (skeletal versus non-skeletal) was noted. Correlation with clinical outcomes is on-going. Clinical trial information: NCT# 01953640. [Table: see text]

174 Background: AA/P is an FDA approved treatment for mCRPC. Since markers of early resistance to AA/P are unknown, we report initial findings of androgen receptor (AR) based associations with short term (12 week) progression on AA/P. Methods: mCRPC stage patients (pts) initiating pre-chemotherapy AA/P underwent metastatic site biopsies at baseline (pre AA/P) and after 12 weeks. Baseline somatic whole exome DNA, tumor gene expression for AR full length (ARFL), AR splice variant 7 (ARV7) and ARV7/ARFL ratios were compared in progessors versus non-progressors. Progression at or within 12 weeks of AA/P therapy was defined as death or disease progression by PCWG2 “composite progression (CP)” and/or “radiographic progression” endpoints. Wilcoxon rank-sum tests were used to test for differences in the two groups for comparing ARFL, ARV7 expressions and ARV7/ARFL ratios and chi square tests were used for differences in copy number variation. Results: Between 1/2013 and 6/2014, 59 pts were enrolled of which 44 have disease assessment data at the12-week time point. CP was observed in 17/44 patients. DNA seq and clinical data was available for 42/44 pts. Using radiographic progression at 12 weeks, AR Amplification/Gain was observed in 20/26 non-progressors (13 with Amplification) and in 9/16 progressors (P-value = 0.19; OR 2.5). ARFL and ARV7 gene expressions in both groups is provided in table. Conclusions: A trend towards higher ARV7/ARFL gene expression ratio in metastases was observed with early progression on AA/P. AR gain/amplification is observed less often in pts with early progression. Validation of these findings is on-going in this prospective trial. Clinical trial information: NCT# 01953640. [Table: see text]

497 Background: As activating RAS mutations have been shown to predict lack of benefit from anti-EGFR therapies in advanced CRC, NCCN guidelines recommend testing for KRAS exon 2 and non-exon 2 mutations; however, these alterations are thought to explain only a subset of de novo resistance to targeted therapy. In a large set of CRC assayed with comprehensive genomic profiling (CGP) in the course of clinical care, we assessed the frequency of less common KRAS short insertions that may predict failure of anti-EGFR therapy. Methods: 4,422 CRC cases were assayed with CGP performed on hybridization-captured, adaptor ligation based libraries to a mean coverage depth of > 650X for at least 236 cancer-related genes plus 47 introns from 19 genes frequently rearranged in cancer. All classes of genomic alterations (GA) were identified, including base pair substitutions, insertions/deletions, copy number alterations, and rearrangements. Pertinent available prior molecular testing results and clinical history was reviewed for selected cases. Results: Out of 4,422 CRC cases analyzed, KRAS short variants were identified in 50.9% of cases. A majority of cases contained a KRAS alteration at either codon G12 (35.5%) or G13 (9.1%), while alterations at codons Q61 or A146 were identified in 2.2% and 3.1% of cases, respectively. KRAS insertions were identified in 8 ( < 0.5%) cases. All KRAS insertions identified fell within codons 9-13, and 6/8 cases harbored V9_G10 insertions. Out of 6 patients with prior KRAS testing results available, 5 (83%) were negative by previous testing. Conclusions: CGP identifies KRAS insertions within or adjacent to hotspot regions in CRC cases which have previously tested negative for KRAS mutations. Given the importance of KRAS alterations in predicting lack of response to anti-EGFR therapies in CRC, accurate detection of these alterations in the course of clinical care is essential for effective treatment. CGP offers the possibility of identifying KRAS insertions that may impact efficacy of anti-EGFR targeted therapy and should be considered when previous focused testing for KRAS mutations is negative.

353 Background: One mechanism leading to castrate-resistant prostate cancer (CRPC) is upregulation of CYP17. Abiraterone acetate (AA) inhibits CYP17 and continuous AA administration (CAAA) is one the most common and effective CRPC treatments. Mathematical models can be potentially powerful clinical tools for optimizing treatment strategies and eliminating guess work. Here, we introduce a new model which builds on our previous work (Morken JD, Packer A, Everett RA, Nagy JD, Kuang Y. Mechanisms of resistance to intermittent androgen deprivation therapy identified in prostate cancer patients by novel computational method. Cancer Res 2014;74:2673-83.) and may be capable of predicting how patients will respond to CAAA and intermittent AA administration (IAAA). We are currently proposing a personalized IAAA protocol on the basis of these results. Methods: In this ongoing retrospective study, we use PSA data from patients whom underwent CAAA to validate the accuracy of our model of tumor growth and evolution. The PSA output is driven by dynamics of three cell populations—castration-sensitive (CS), castration-resistant abiraterone-sensitive (CSAS), and castration-sensitive abiraterone-resistant (CSAR) cells. We fit the model output to PSA data to find parameter values which minimize normalized mean squared error (NMSE). Once parameters are obtained, we ran simulations employing various IAAA protocols. Results: The model’s PSA dynamics are highly accurate. NMSE is very low across patients ranging from 0.0001-0.0085. Conclusions: Our results suggest that there exists an IAAA protocol for each patient that, at worst, yields the same time to tumor progression as CAAA, yet improves quality of life and reduces cost. In nearly 20% of patients, IAAA appears to delay tumor progression over CAAA. The model is accurate at predicting how patients will respond to CAAA and IAAA for patients whose PSA is regularly monitored. Near-future work aims to personalize IAAA protocol based on patient pre CRPC PSA dynamics and to identify a protocol which delays progression for most patients.

237 Background: AA/P is an approved treatment for mCRPC but there are no known predictive markers of response or resistance. We conducted a prospective trial to evaluate if Androgen Receptor (AR) & AR-variant (ARV) expression in tissue metastases can predict resistance to AA/P. Methods: mCRPC stage patients (pts) initiating pre-chemo AA/P underwent metastatic site biopsies prior to (pre-AA/P) and after 12 weeks of treatment. Composite progression at 12 weeks, (primary endpoint) was evaluated with PSA, RECIST, bone scan and symptoms (per PCWG2). mRNA expressions of pre-AA/P ARFL, ARV3, ARV7, ARV9, ARV23, ARV45, four cell cycle division genes, Chromogranin-A (CHGA) together with PSA/testosterone levels, Gleason Score (GS) at initial diagnosis; high versus low volume disease; time from starting hormone therapy to mCRPC stage and serum CHGA levels were evaluated using a logistic regression model for predicting resistance at 12 weeks of therapy. A final multivariate model fitted only those factors thought to be clinically relevant or with an entry threshold of p ≤ 0.3 in univariate analysis. Results: Between 6/2013 & 3/2015, 82 pts were enrolled of which 52 had complete mRNA expression & disease assessment data at the12-week time point for analysis. Median age of the cohort was 72.5 yrs (IQR: 68.5-78); median pre-AA/P PSA was 18 ng/ml (IQR: 8.1- 46.6); GS distribution at initial diagnosis for GS 2-6; 7; 8-10 was 11; 14; 27 respectively. Progression was observed in 21/52 pts after 12 weeks. At the univariate level elevated pre-AA/P expression of ARV3 (p = 0.08), ARV7 (p = 0.26), ARV9 (p = 0.04), and cell division cycle gene CDC45 (p = 0.19) along with GS at diagnosis (p = 0.29) met the threshold for inclusion into multivariate analysis. Elevated expression of pre-therapy ARV9 in metastases alone was associated with progression at 12 weeks (OR: 3.9; CI 1.07 – 14.16; C-Index: 0.63). The 12-week biopsy of pts with progression had increased ARV9 mRNA expression compared to pts responding at 12 weeks (p = 0.14). Conclusions: Increased ARV9 mRNA expression in metastases is associated with early resistance to AA/P. This observation will need further validation in comparable datasets. Clinical trial information: NCT #0195364.

202 Background: Cabazitaxel and prednisone (Cbz/pred) extend survival in mCRPC patients (pts) following docetaxel and first-line studies comparing Cbz to docetaxel are ongoing. Mito/pred also has anti-tumor activity in mCRPC and a non-overlapping mechanism of action and toxicity profile with Cbz. A multicenter phase 1 trial was initiated to establish the maximally tolerated dose (MTD) and recommended phase 2 dose (RP2D) of the combination of Cbz, Mito, and Pred(CAMP). Methods: Chemotherapy (chemo)-naive pts with mCRPC were enrolled in an accelerated titration design. The primary objective was to determine the MTD and RP2D of CAMP; secondary objectives included PSA response rate and duration of response. Cbz 20 and 25 mg/m2 were evaluated in combination with escalating doses of Mito (starting dose 4 mg/m2), both administered on day 1 of a 21-day cycle. Pred 5 mg BID and pegfilgrastim were given with each cycle. Results: 23 pts were enrolled. The median age was 66 (range 51-78) and the median baseline PSA was 62.5 (range 3-791.2). There were 2 DLTs (sepsis and febrile neutropenia) observed at the dose level of Cbz 25 mg/m2 + Mito 10 mg/m2 (n = 4). There was 1 DLT (febrile neutropenia) observed with Cbz 20 mg/m2 (N = 12), establishing Cbz 20 mg/m2 + Mito 12 mg/m2 as the MTD and RP2D. The most common grade ³ 3 related adverse events were hematologic (neutropenia, n = 9; thrombocytopenia, n = 3; febrile neutropenia, n = 3). The median number of treatment cycles was 7.5 (range 2-16), and 2 pts remain on study. Greater than or equal to 50% maximal PSA declines from baseline were observed in 12 of 19 evaluable pts(63%). The median duration of response has not been reached (range 4.9-10.0+ months). Conclusions: The approved single-agent dose of Mito (12 mg/m2) was safely combined with Cbz 20 mg/m2, a dose with demonstrated activity in mCRPC and potentially less hematologic toxicity than 25 mg/m2. Preliminary efficacy data are encouraging with durable control of disease observed in a subset of pts. Further study of the treatment combination is warranted. Clinical trial information: NCT01594918.

PURPOSE: This article summarizes the third step of a research program to identify variables that supplement the predictive power of the the Eastern Cooperative Oncology Group (ECOG) performance status (PS) for survival. The objective was to produce a simple, practical, stratification factor for phase III oncology clinical trials involving patients with advanced malignant disease. PATIENTS AND METHODS: A questionnaire was administered to 729 patients with metastatic colorectal or lung cancers. Patients provided a Karnofsky index and appetite rating while physicians provided a survival estimate and the ECOG-PS. Scores for each item were categorized as having a positive, neutral, or negative indication for survival. A patient was classified as having a relatively good prognosis if three or more of the four items showed a positive indication, a bad prognosis if three or more items were negative, and an uncertain prognosis otherwise (Good/Bad/Uncertain [GBU] index). RESULTS: The GBU index improved on the prognostic power of a Cox model quartile index and PS alone and increased the accuracy of survival classification estimates by 5% to 10% more than ECOG-PS alone. For patients with PS of 0 or 1, significant survival patterns exist between GBU groups (P= .002 and .0001, respectively). CONCLUSION: The GBU index may be recommended as a supplementary stratification factor for certain future phase III trials in metastatic lung or colorectal cancer where patient heterogeneity is a particular concern. The GBU represents a relatively modest increase to the cost and patient burden of a clinical trial given the additional control that is achieved over the potentially confounding concomitant to the treatment variable.

PURPOSE: Subcutaneous (SC) octreotide acetate effectively relieves the diarrhea and flushing associated with carcinoid syndrome but requires long-term multiple injections daily. A microencapsulated long-acting formulation (LAR) of octreotide acetate has been developed for once-monthly intramuscular dosing. PATIENTS AND METHODS: A randomized trial compared double-blinded octreotide LAR at 10, 20, and 30 mg every 4 weeks with open-label SC octreotide every 8 hours for the treatment of carcinoid syndrome. Seventy-nine patients controlled with treatment of SC octreotide 0.3 to 0.9 mg/d whose symptoms returned during a washout period and who returned for at least the week 20 evaluation constituted the efficacy-assessable population. RESULTS: Complete or partial treatment success was comparable in each of the four arms of the study (SC, 58.3%; 10 mg, 66.7%; 20 mg, 71.4%; 30 mg, 61.9%; P ≥ .72 for all pairwise comparisons). Control of stool frequency was similar in all treatment groups. Flushing episodes were best controlled in the 20-mg LAR and SC groups; the 10-mg LAR treatment was least effective in the control of flushing. Treatment was well tolerated by patients in all four groups. CONCLUSION: Once octreotide steady-state concentrations are achieved, octreotide LAR controls the symptoms of carcinoid syndrome at least as well as SC octreotide. A starting dose of 20 mg of octreotide LAR is recommended. Supplemental SC octreotide is needed for approximately 2 weeks after initiation of octreotide LAR treatment. Occasional rescue SC injections may be required for possibly 2 to 3 months until steady-state octreotide levels from the LAR formulation are achieved.

LBA3 Background: Irinotecan/5-FU/leucovorin (FOLFIRI) or oxaliplatin/5-FU/leucovorin (mFOLFOX6), combined with bevacizumab (BV) or cetuximab (CET), are first-line treatments for metastatic adenocarcinoma of the colon or rectum (MCRC). The optimal antibody combination is unknown. Methods: Patients (pts) with KRAS wild-type (wt)(codons 12 and 13) MCRC and performance status 0-1 received FOLFIRI or mFOLFOX6 (MD/pt choice at enrollment) and randomized to either CET 400 mg/m2 X 1, then 250 mg/m2 qw or BV 5 mg/kg q2w. The original study included unselected MCRC pts receiving FOLFIRI or mFOLFOX6 and randomized to CET, BV, or both. After 1,420 pts accrued the study amended as follows: only pts with KRAS wt tumors (codon 12 and 13) were included and the combination CET + BV arm was deleted. Rx continued until progression, death, unacceptable toxicity, curative surgery; treatment holidays of 4 wks permitted. Subsequent Rx not mandated. Accrual goal was 1,142 pts. One° endpoint was overall survival (OS). Results: Between November 2005 and March 2012, 3,058 unselected pts enrolled, 2,334 KRAS wt pts randomized; final N =1137 (333 pre-amend eligible retrospective KRAS test, 804 post-amend), median f/u = 24 mos; Median age – 59 y; 61% male. Chemo/BV – 559; chemo/CET – 578. FOLFIRI = 26.6%, mFOLFOX6 = 73.4%. OS analysis planned at 849 events; efficacy futility boundary crossed at 10th interim analysis on 1/29/14. OS - chemo/BV v. chemo/CET = 29.04 (25.66 - 31.21) v. 29.93 (27.56 - 31.21) mos; HR = 0.92 (0.78, 1.09) (p value = 0.34). PFS (by investigator): chemo/BV v. chemo/CET: 10.84 (9.86 - 11.4) v. 10.45 (9.66 - 11.33) mos. There were 94 pts free of disease following surgery, median f/u 40 mos (range 8.0 - 86.0). Outcomes similar by gender. On-study toxicity and deaths as expected. Analyses underway: Expanded RAS, FOLFOX v. FOLFIRI, subsequent therapies, long-term survivors, correlates. Conclusions: Chemo/CET and chemo/BV equivalent in OS in pts KRAS wt (codons 12 + 13) MCRC; either is appropriate in first line. Overall OS of 29 + mos and 8% long-term survivors confirms progress in MCRC. The preference for FOLFOX limits chemotherapy comparison. Expanded RAS and other molecular and clinical analyses may identify subsets of pts who get more or less benefit from specific regimens. Clinical trial information: NCT00265850.