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S.K. Padda



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    P1.24 - Poster Session 1 - Clinical Care (ID 146)

    • Event: WCLC 2013
    • Type: Poster Session
    • Track: Supportive Care
    • Presentations: 1
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      P1.24-048 - Stage 1 results of a 2-stage phase II trial of single agent amrubicin in patients with previously treated thymic malignancies (ID 3175)

      09:30 - 09:30  |  Author(s): S.K. Padda

      • Abstract

      Background
      There are limited treatment options for patient with advanced thymic malignancies and the utility of many of the available chemotherapies is restricted by cumulative toxicity such as neuropathy (taxanes) and cardiomyopathy (anthracyclines). We designed this study to look at single agent amrubicin, a third generation anthracycline and topoisomerase II inhibitor with minimal cardiac toxicity, in patients with advanced thymic malignancies.

      Methods
      Eligible patients have confirmed thymic malignancy (thymoma (T) or thymic carcinoma (TC)) with progression or relapse after at least 1 prior chemotherapeutic regimen, and adequate organ function including left ventricular ejection fraction (LVEF) of >50%. The initial treatment plan consisted of amrubicin at 40 mg/m[2] IV days 1-3 repeated in 3-week cycles. The study is a Simon 2-stage design based on a null hypothesis of a true response rate <5%, with 90% power to detect a 20% true response rate and a plan to accrue 12 evaluable patients in stage 1, then if at least 1 response is seen, to add 25 additional evaluable patients in stage 2 for a total of 39 patients.

      Results
      Enrollment was initiated in July 2011. Here, we report on the first 12 patients, all enrolled at Stanford University over a 19-month period. Of the first 12 patients enrolled, 11 were dosed. All were pre-treated (5 with prior anthracycline). There were 5 women and 7 men; age range of 30-67 years old; 6 were of Asian ethnicity, 5 were non-Hispanic White and 1 was Hispanic. After enrollment of the first 8 patients, of whom 3 were hospitalized with febrile neutropenia (FN) (38%), the study was amended to a starting dose of 35 mg/m[2] days 1-3 repeated in 3-week cycles. Other than FN in the 3 patients mentioned above, G4 thrombocytopenia in 1 patient, and treatment-related G3 fatigue in 2 patients, other toxicities were generally mild and well tolerated. No significant changes in LVEF have been noted on serial echocardiograms. Of the 11 treated patients, there were 3 partial responses (2 T and 1 TC), 7 with stable disease for at least 4 cycles, and 1 with progressive disease (PD) after 2 cycles (TC). Of the 11 treated patients, only 1 patient, with PD after C2, has stopped before completing 6 cycles, and 5 to date have tolerated >10 cycles (with others still on treatment who may receive >10 cycles), with 15 cycles as the highest number to date.

      Conclusion
      Amrubicin, at 35 mg/m[2] IV days 1-3 on a 3-week cycle, shows promise as a single agent in pre-treated patients with thymoma and thymic carcinoma with a 27% RR in the first 11 treated patients. This exceeded the threshold for proceeding to step 2 and the study will now continue to a total of 39 patients and has expanded to other sites including Indiana University.

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    P2.15 - Poster Session 2 - Thymoma (ID 191)

    • Event: WCLC 2013
    • Type: Poster Session
    • Track: Thymoma & Other Thoracic Malignancies
    • Presentations: 1
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      P2.15-003 - Gli1, Notch1 and CTNNB1 Expression by Automated Quantitative Immunofluorescence (AQUA) in a Thymic Malignancy Tissue Microarray (TMA) (ID 778)

      09:30 - 09:30  |  Author(s): S.K. Padda

      • Abstract

      Background
      Thymoma is a rare malignancy, with a paucity of data on its biology and on the role of targeted therapeutics. Wnt, notch and sonic hedgehog pathway interactions between thymocytes and thymic stroma are important to both thymus and T-cell development. AQUAnalysis[®] is a digital image analysis software that continuously measures multiplexed protein expression and has the potential to overcome limitations of small sample sizes and tissue heterogeneity in the tumor microenvironment. We analyzed a thymoma TMA for gli1, notch1 and CTNNB1 (β-Catenin) expression by AQUA[®] as surrogate markers of activity of the sonic hedgehog, notch and wnt pathways, respectively. We hypothesized this preclinical screen may provide rationale for attacking these pathways with targeted therapeutics in thymoma.

      Methods
      A TMA was constructed from 68 patients with thymic malignancies and 8 benign thymic controls at Stanford University School of Medicine (Stanford, CA). Gli1, notch1 and CTNNB1 expression were assayed using quantitative fluorescent immunohistochemistry at the Tom Baker Cancer Center (Alberta, Canada). The TMA was stained with anti-gli1 rabbit mAb (monoclonal antibody), clone EPR4523 (Epitomics, Burlingame, CA, USA); anti-Notch1 rabbit mAb, clone EP1238Y (Epitomics, Burlingame, CA, USA); and anti-beta-catenin mouse mAb, clone β-Catenin-1 (Dako Mississauga, ON, Canada) using a Dako autostainer. To isolate expression of these stem-cell pathway proteins separately in the tumor and the lymphocytes, the TMA was also stained with anti-pan-cytokeratin guinea pig mAb (Acris, San Diego, CA, USA); anti-vimentin rat mAb, clone 280618 (R&D Systems, Minneapolis, MN, USA); and anti-CD45 rabbit mAb, clone EP322Y (Epitomics, Burlingame, CA, USA). Automated image acquisition was performed using an Aperio Scanscope FL (Aperio Inc., Vista, CA, USA). Images were then analyzed using the AQUAnalysis® program, version 2.3.4.1. A tumor-specific mask and a tumor cytoplasmic mask were generated to distinguish thymoma cells from surrounding stromal tissue by thresholding the pan-cytokeratin images to identify pan-cytokeratin positive cells as tumor cells and define the tumor cytoplasm. Statistical analysis was performed using SAS Enterprise Guide v5.0 (Cary, NC). Two-tailed t-tests were used to compare the differences between thymic tumor and benign control tissue. ANOVA and Dunnett’s t-test was used to compare differences in gli1, notch1, and CTNNB1 expression by WHO histology.

      Results
      Demographics for 68 patients: M:F (53%/47%), Mean age at diagnosis: 55 years, WHO Histology: A (10%), B (57%), AB (24%), C (4%), unclassified (4%), Pathologic Masaoka Stage: I (46%), IIa (18%), IIb (4%), III (18%), IVa (9%) IVb (6%). No difference in gli1 (mean 201 vs. 211, p=0.31), CTNNB1 (mean 396 vs. 418, p=0.66) or notch1 expression (mean 317 vs. 325, p=0.82) was noted between thymic tumors and controls. In a subset analysis, we found no significant differences by WHO histology compared to controls.

      Conclusion
      AQUA® was used to help overcome limitations of analyzing protein expression in histologically heterogeneous thymic tumors with small sample sizes. We found no clinically or statistically significant increased expression of gli1, notch1, and CTNNB1 in thymoma compared to benign thymic tissue. Thus, this study provides no evidence for upregulation of the sonic hedgehog, notch or wnt pathways in thymic tumors.

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    P3.06 - Poster Session 3 - Prognostic and Predictive Biomarkers (ID 178)

    • Event: WCLC 2013
    • Type: Poster Session
    • Track: Biology
    • Presentations: 1
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      P3.06-003 - Correlative Analysis of Circulating Biomarkers from a Phase 1b/2 trial of Cabozantinib (C) with or without Erlotinib (E) in Patients (Pts) with Advanced or Metastatic Non-Small Cell Lung Cancer (NSCLC) (ID 266)

      09:30 - 09:30  |  Author(s): S.K. Padda

      • Abstract

      Background
      Cabozantinib (C) is a potent ATP-competitive inhibitor of MET and vascular endothelial growth factor receptor 2 (VEGFR2) along with KIT, RET, AXL, TIE2, and FLT3. Hepatocyte growth factor (HGF), the ligand of MET, and VEGF act synergistically to promote angiogenesis. There are currently no widely accepted prognostic or predictive biomarkers for anti-angiogenic agents.

      Methods
      This is a retrospective correlative biomarker study from the phase 1b/2 trial of C+/-E in stage IIIB-IV NSCLC. All pts had to fail prior therapy with E. Both drugs are oral and dosed daily. C dosing is in the free-base equivalent weight. In phase I, there was a 2 week lead in with E and the cohorts included: 1A (60 mg C+150 mg E), 2A (60 mg C+100 mg E), 3A (100 mg C+100 mg E), 4A (100 mg C+50 mg E), and 2B (40 mg C+150 mg E). In phase II, both drugs started simultaneously: Arm A (100 mg C) and Arm B (100 mg C+50 mg E). Pts were included in the study if a pre-E+C and post-C > day 29 plasma sample was available. The Milliplex 13-plex and Luminex 51-plex assays were used. For this preliminary analysis, select markers previously implicated in angiogenesis (bFGF, VEGF, sVEGFR1-3, IL-6, IL-8, IL-12, IL-17, PDGF-BB, ICAM-1, VCAM-1) and those of interest (ligands of KIT and MET- SCF and HGF, respectively) were analyzed. Log transformed mean fluorescence intensity (MFI) values and Wilcoxon Rank paired sum tests were used to detect changes from day 1-29. A change from baseline was noted to be significant if at least 15% (median) with α<0.05 (2-sided) and a trend if 10-15% (median) with α<0.08 (2-sided).

      Results
      73 pts included: 52 phase I and 21 phase II; median age 60 years; 23M/50F; 56.2% nonsmoker; 91.8% adenocarcinomas. The pts with samples from both time points were divided into two groups due to limited sample size and included: Group R (complete/partial response and stable disease> 6 months; n=22) and Group NR (stable disease< 6 months and progressive disease; n=51). The only marker that changed in a single direction in all subjects within a group was sVEGFR2 in group R. Overall, significant decreases were noted in sVEGFR1-3, IL-6, PDGF-BB, and trended in IL12p70 and IL-17. By subgroups: Group R had significant decreases in bFGF, VEGF, sVEGFR1-3, IL-6, IL-8, IL-12(p40+p70), IL-17, PDGF-BB, SCF, and trended in HGF (median 10.1% ↓, p=0.0275); and Group NR had significant decreases in sVEGFR2-3, IL-6, PDGF-BB, and trended in sVEGFR-1, IL-6, and IL-17.

      Conclusion
      Both groups R+NR had a decrease in sVEGFR-2, suggesting that this is a marker of treatment with C rather than a marker of response. However, overall group R had larger dynamic decreases of immune markers than group NR. HGF, which is targeted downstream by C and plays a role in angiogenesis and E resistance, had a trend to decrease in group R but not group NR. This study is retrospective with a small sample size, imbalanced numbers per response subgroup, and is exploratory in nature.

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    P3.11 - Poster Session 3 - NSCLC Novel Therapies (ID 211)

    • Event: WCLC 2013
    • Type: Poster Session
    • Track: Medical Oncology
    • Presentations: 1
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      P3.11-006 - Erlotinib (E) and Dovitinib (TKI258) (D) in Patients (pts) with Metastatic Non-Small Cell Lung Cancer (NSCLC): A Significant Pharmacokinetic (PK) Interaction (ID 878)

      09:30 - 09:30  |  Author(s): S.K. Padda

      • Abstract

      Background
      Dovitinib (TKI 258) is an oral antiangiogenic agent that targets PDGFR, KIT, FLT3, VEGF, RET, and FGFR. Dovitinib induces CYP1A1/A2, CYP2C19, CYP2C9, and it inhibits CYP3A4. Dovitinib is metabolized mainly by FMO, CYP3A4, and CYP1A1/A2. Erlotinib is metabolized mostly by CYP3A4 (70%) but also by CYP3A5, CYP1A1, and CYP1A2.

      Methods
      This is a phase I 3+3 trial of E+D in patients with EGFR wild-type or mutated metastatic NSCLC who could have previously received E. Four cohorts were planned with E given daily and D given 5 days on/2 days off, starting after a 2-week lead-in of E alone. Only two cohorts enrolled due to dose limiting toxicity (DLT): cohort 1 [150 mg E +300 mg D] and cohort -1 [150 mg E+200 mg D]. Plasma concentrations of E and its metabolite OSI-420 were measured on day 14+/-4 (E alone; pre-dose, 2, 4, 6, 8, and 24 hours) and day 29 +/- 4 (D+E, at same time points). Pharmacokinetic (PK) samples were analyzed by a validated liquid chromatography-tandem mass spectrometry assay. PK parameters for E and OSI-420 were estimated from the plasma concentration data via noncompartmental analysis. Paired-t tests on log transformed PK parameters were used to detect a statistical difference (α < 0.05, 2-sided) between E alone versus E+D treatment days.

      Results
      Nine patients enrolled (3 in cohort 1 and 6 in cohort (-1)). The study was suspended due to excess of DLTs. Best response was evaluable in seven patients. Two unevaluable patients on follow-up scan were on E monotherapy for ~1 month. Four patients discontinued due to grade 3 AEs (syncope (n=1), fatigue (n=1), and pulmonary embolism (n=2)). Three patients had progressive disease and 4 had stable disease (duration: 6 cycles(C), 8 C, and 1-2 C for two patients who stopped due to AE). Two patients required a dose delay in D (one for grade 2 LFT elevation, the other for grade 3 fatigue) and one required dose reduction of E to 100 mg prior to initiation of D (dose-corrected for PK analysis). Six patients had data available for PK analysis. During E alone, erlotinib exposure (average C~max~ 2308 +/- 697 ng/ml and AUC~ 0-24 ~41.0 +/- 15.6 μg*h/ml) was similar to previous reports for multiple daily doses of 150 mg. During D co-administration, the concentrations of E were reduced. C~max~ on average decreased by 83% (p= 0.022) and AUC~0-24 ~by 94% (p= 0.0039). OSI-420 exposure was also reduced during D co-administration.

      Conclusion
      Our small study demonstrates a potential significant PK interaction with decrease of E and its metabolite in the presence of D. This decrease is higher than that reported in combination studies with other CYP1A1 or CYP3A4 inducers. Dovitinib PK data is pending. Given the toxicity and the potential PK interaction, further investigation with this drug combination will be challenging.