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e18005 Background: MVX-ONCO-1 is an active, personalized cancer immunotherapy combining irradiated autologous tumor cells and encapsulated, genetically engineered allogeneic cells producing GM-CSF. The immunostimulant cytokine is released locally in a sustained manner over one week at the immunization site. All cancer types are potential candidates and more than 40 patients have been treated in two clinical trials. Here we report the data on all HNSCC patients treated, as of 31st January 2021. Methods: Eleven (11) patients with locally advanced/metastatic HNSCC relapsing after at least one line of systemic therapy were enrolled in 2 open-label, single-arm clinical trials (NCT02193503 and NCT02999646) evaluating the safety, feasibility and efficacy of MVX-ONCO-1. All patients were treated with at least 5 administrations of MVX-ONCO-1 over 8 weeks (W1,2,3,4,6,8). Each administration consists of the subcutaneous implantation in healthy skin of 2 capsules containing each 8x105 cells, producing > 20ng/24h of GM-CSF, and an injection of 4x106 irradiated autologous tumor cells between the 2 capsules. Results: Eleven (11) patients are evaluable for safety and feasibility. Ten patients (91%) with at least 6 months, respectively 9 patients (82%) with 12 months follow-up are evaluable for efficacy analysis. Eight patients (80%) failed both Cisplatin based chemotherapy and anti-PD1 therapies prior to enrolment. The most common treatment-related adverse event (AE) was local hematoma at implantation site in 3 patients (27%). None experienced > grade 2 treatment-related AE. Overall Survival is 70% (7/10pts) at 6 months, and 56% (5/9pts) at 12 months. Eight patients (80%) presented some degree of disease control with 4SDs, 2PRs and 2CRs. Both CRs are longstanding, with both patients not any longer on anticancer therapy for 24 and 6 months respectively. While 1 PR was observed on MVX-ONCO-1, 1PR and 1CR were observed on subsequent Nivolumab therapy (both CPS0), and 1 CR was observed after carboplatin-cetuximab. Two patients had progressive disease as best overall response. Conclusions: Treatment with MVX-ONCO-1 is feasible, safe and well tolerated. Preliminary efficacy data shows an encouraging rate of tumor control including prolonged CR in patients subsequently treated with nivolumab or chemotherapy. Efficacy of the concurrent use of anti-PD-1 and MVX-ONCO will be assessed in a planned clinical trial. Clinical trial information: NCT02999646.

e21119 Background: A substantial proportion of patients with squamous lung cell carcinoma (SQCLC) (46%) exhibit tumor overexpression of fibroblast growth factor receptor (FGFR) messenger ribonucleic acid (mRNA). Rogaratinib is a novel pan-FGFR inhibitor with anti-tumor activity in pre-clinical models as a single agent in FGFR pathway-addicted tumor models. Phase I data showed promising activity and good safety profile. The objective of the SAKK 19-18 trial was to determine clinical activity and safety of rogaratinib in patients with advanced SQCLC overexpressing tumor FGFR1-3 mRNA. Methods: Patients with metastatic SQCLC, previously treated with systemic treatment, overexpressing tumour FGFR mRNA were treated with rogaratinib 600 mg BID until progression of disease or drug intolerance. A rate ≤15% of PFS at 6 months was considered uninteresting, whereas a PFS rate at 6 months ≥38% was considered promising. Ten patients were needed in the first stage with at least 2 achieving 6 months PFS in order to continue the accrual. Results: Between May and November 2020, 49 patients were screened and 20 were classified FGFR positive. Among them15 patients were registered in the trial and the first 10 were assessed for the first stage analysis. Most commons treatment related adverse events (TRAEs) were hyperphosphatemia (60%), diarrhoea (20%), and dry mouth (20%). Grade ≥3 TRAEs occurred in 50% of the patents with Hypercalcemia being the most frequent one (20%). Among 10 first patients only 1 achieved 6 months PFS while 2 was the boundary required for continuing this trial. Conclusions: Despite preliminary signal of activity, rogaratinib failed to improve PFS in patients overexpressing tumor FGFR mRNA. Further studies on a more reliable biomarker are needed, the development of rogaratinib in SQCLC has been put on hold by Bayer and the SAKK 19/18 study was terminated early due to lack of efficacy. Clinical trial information: NCT03762122.

2509 Background: TGF-β plays a key role in regulating the tumor microenvironment. Emerging evidence suggests TGF-β is a key activator of cancer-associated fibroblasts, leading to fibrotic network development and immune exclusion. Preclinical data in murine models showed that TGF-β blockade alleviates intratumoral fibrosis, augmenting the efficacy of PD-1 immunotherapy. NIS793 is a human IgG2 mAb that binds to TGF-β. This study investigates NIS793 + spartalizumab in pts with advanced solid tumors. Methods: Pts initially received NIS793 (0.3–1 mg/kg Q3W) monotherapy; following evaluation of two dose levels, dose escalation continued with NIS793 + spartalizumab (NIS793 0.3–30 mg/kg Q3W + spartalizumab 300 mg Q3W; or NIS793 20–30 mg/kg Q2W + spartalizumab 400 mg Q4W) in pts with/without prior anti-PD-(L)1 therapy. In dose expansion, pts with non-small cell lung cancer (NSCLC) resistant to prior anti-PD-(L)1 or pts with microsatellite stable colorectal cancer (MSS-CRC) were treated at the recommended dose for expansion (RDE). Paired tumor biopsies were required from all pts. The primary objectives were to characterize safety and tolerability of the combination and determine the RDE. Results: By December 1, 2020, 60 pts were treated in the dose-escalation phase, mainly with NIS793 + spartalizumab (n = 49), and 60 pts were treated in dose expansion (MSS-CRC: n = 40; NSCLC: n = 20). Two pts were still receiving treatment. No dose-limiting toxicities were observed, and the RDE was established as 30 mg/kg (2100 mg) NIS793 + 300 mg spartalizumab Q3W. Overall 50% pts experienced ≥1 treatment-related AE (TRAE). The most common were rash (n = 15/120), pruritus (n = 10/120), fatigue (n = 9/120), and nausea (n = 8/120). Grade 3/4 TRAEs occurred in 11% pts, with rash (3%) being the most common. Treatment-related serious AEs were reported in 8 pts; 6 were grade 3/4 in severity. No deaths occurred due to AEs; 3 (2.5%) pts discontinued due to AEs. PK for NIS793 was linearly dose proportional with no obvious correlation between exposure and response. Two pts achieved a partial response (PR; one confirmed in clear cell renal cell carcinoma and one unconfirmed in NSCLC) during dose escalation of the combination. Two confirmed PRs were achieved in the MSS-CRC dose-expansion group. Biomarker data showed evidence of target engagement through increased TGF-β/NIS793 complexes and depleted active TGF-β in peripheral blood. Gene expression and protein analyses in tumor biopsies displayed decreased TGF-β target genes, decreased TGF-β signatures and increased immune signatures suggesting modulation of the TGF-β pathway and preliminary evidence of biological activity. Conclusions: Data showing target engagement and TGF-β pathway inhibition supported the proof of mechanism of NIS793. The RDE of the combination was established and well tolerated in pts with advanced solid tumors. Clinical trial information: NCT02947165.

9016 Background: For patients (pts) with resectable stage IIIA(N2) non-small cell lung cancer (NSCLC) neoadjuvant chemotherapy (chemo) with 3 cycles cisplatin (cis)/docetaxel (doc) followed by surgery is an accepted standard of care leading to a 1-year (yr) event-free survival (EFS) of 48% and a 5-yr overall survival (OS) of 37%. PD-1/PD-L1 inhibitors have recently shown to lead to high response rates in resectable NSCLC. Methods: SAKK 16/14 is an open-label single-arm phase II study including 68 pts with resectable NSCLC stage IIIA(N2) (T1-3 N2 M0), irrespective of histological subtype, genomic aberrations or PD-L1 expression status. Neoadjuvant treatment consisted of 3 cycles of cis 100 mg/m2 and doc 85 mg/m2 q3w followed by 2 cycles of durvalumab 750 mg q2w. Durvalumab was continued after surgery q2w for 1 yr. The primary endpoint is EFS at 1 yr. The statistical hypothesis is to improve EFS at 1 yr from 48% based on the SAKK 16/00 study to 65%. Here, we report the primary endpoint and response data from 67 evaluable pts included in the study. Results: 68 pts were included from 06/16 to 01/19 and 67 pts (35 males, 32 females) were evaluable. Median age was 61 yrs (range, 41-74). 52 pts (77.6%) had a WHO PS of 0. 95.5% were current or former smokers. The majority of tumors were adenocarcinoma (55.2%) followed by squamous cell histology (32.8%). Clinical stage T1, T2 and T3 were present at diagnosis in 22.4%, 49.3% and 28.4%, respectively. 81.1% of pts underwent resection. The main reason for not undergoing surgery was disease progression (33.3%). Pneumonectomy was performed in 5 pts (9.1%), 43 pts underwent lobectomy and 7 pts bilobectomy. 30-day postoperative mortality was observed in one patient (1.8%). One patient died due to a bleeding complication after surgery most likely not related to neoadjuvant therapy. Radiographic response was 44.8% (95%CI: 32.6-57.4) after neoadjuvant chemo and 59.7% (95%CI: 46.4-71.9) after additional neoadjuvant immunotherapy. 1-yr EFS was 73.3% (90%CI: 62.5-81.4). Results for pathologic remission rate as well as correlation with PD-L1 status will be presented during the meeting. Conclusions: We report on treatment outcomes of the largest cohort of pts with resectable stage IIIA(N2) NSCLC receiving perioperative immune checkpoint inhibitor therapy. The addition of perioperative durvalumab to standard of care cis/doc is safe and leads to a high response rate and a very encouraging 1-yr EFS rate that appears substantially higher than with chemo alone. Clinical trial information: NCT 02572843.

3526 Background: Docetaxel micellar (DM) is a nano-sized particle formulation of docetaxel in which a retinoic acid derivative is used as solubilizer with a high drug to excipient ratio possibly resulting in reduced systemic toxicity or hypersensitivity reactions due to the excipient. DM is given without standard use of premedication, avoiding steroid-associated immunosuppression. Here we present the pharmacokinetics (PK) after a single dose of DM or polysorbate-solubilized docetaxel (D) as well as safety and early activity including overall response rate (ORR) in female patients with metastatic breast cancer. Methods: The PK study was a two-cycle, cross-over study where 30 patients were included and randomized to either DM followed by D or D followed by DM, both given as a 1-hour intravenous infusion at a dose of 100mg/m2. The phase II study was a prospective, multicenter, open-label, third-party blinded, randomized, parallel group, active-controlled study including 200 patients to compare the early activity and safety of DM and D, both given as 100 mg/m2 1-hour intravenous infusion every 21 days (1 cycle) for a total of 6 cycles. Results: Bioequivalence of total docetaxel in plasma, AUC0-last and Cmax, was demonstrated for DM compared to D. The incidence of adverse events was higher in the D arm than in the DM arm for the majority of SOCs and PTs in the phase II study. Overall, Grade 3 or 4 AEs were reported for 82.7% of patients from DM arm and 99.0% of patients from D arm. Twelve (12.2%) patients in the DM arm and 24 (24.0%) patients in the D arm needed at least one dose reduction due to AEs. The primary efficacy endpoint in the phase II study was based on the assessment according to Response Evaluation Criteria in Soldid Tumors (RECIST) 1.1 and non-inferiority was not reached based on the pre-defined non-inferiority margin. A post-hoc analysis investigating the ORR based on tumour assessment at the end of chemotherapy, and non-inferiority of DM as compared to D was shown (ITT population). Conclusions: DM is bioequivalent to D regarding total drug in plasma and provides a docetaxel formulation that spares patients steroid premedication. An improved safety profile for DM compared to D was shown while additional efficacy data is needed for future development of DM. Eudra CT: 2012-005161-12 and 2013-004889-33. Clinical trial information: 2012-005161-12 and 2013-004889-33 .

527 Background: Aberrant activation of the fibroblast growth factor receptor (FGFR) pathway is implicated in many cancers, including UC. In a recent Phase I dose-escalation study, rogaratinib, an oral pan-FGFR1-4 inhibitor, demonstrated favorable efficacy and safety in pts with solid cancers selected based on FGFR1-3 mRNA overexpression. We report results from the Phase I expansion cohort with rogaratinib in pts with UC selected by FGFR1-3 mRNA overexpression and/or FGFR3-activating mutations (NCT01976741). Methods: Pts with advanced/metastatic UC were screened for FGFR1-3 mRNA overexpression using RNA in situ hybridization (RNAscope) and NanoString assay in fresh or archival tumor samples. Pts received rogaratinib 800 mg po BID continuously. Tumor response and safety were assessed. Results: 74 pts with UC were treated with rogaratinib; 73.0% were male, median age was 66 years (range 45-85), and 93.2% had stage IV disease. Rogaratinib was well tolerated, with adverse events being mostly mild or moderate. The most common treatment-emergent adverse events (TEAEs) are shown in the Table. The most common drug-related TEAEs (any grade) were diarrhea (52.7%), increased blood phosphorus (41.9%), and decreased appetite and dry mouth (31.1% each). No ocular toxicities were reported. Increased blood creatinine and acute kidney injury (AKI), regardless of relatedness, were reported in 16.2% and 2.7% of pts, respectively; 1 case of AKI was confirmed as acute tubular necrosis. Of 72 evaluable pts, 15 (20.8%) achieved an objective response; complete and partial responses were observed in 1 (1.4%) and 14 (19.4%) pts, respectively. Stable disease was achieved by 34 pts (47.2%), with a disease control rate of 68.1%. Conclusions: Rogaratinib demonstrated a favorable safety and efficacy profile in pts with tumor FGFR1-3 mRNA-positive UC. TEAEs observed in >25% of pts. Clinical trial information: NCT01976741. [Table: see text]

e20661 Background: FGFR1 gene amplifications are observed in squamous (sq) non-small cell lung cancer (NSCLC) and may suggest tractable oncogenic dependency. However, their value in predicting clinical activity of FGFR inhibitors is unclear. We explored tumor FGFR1-3 mRNA expression levels to select patients (pts) for treatment with rogaratinib, an oral, potent, small-molecule inhibitor of FGFR1-4. The first-in-human study of rogaratinib included pts with all NSCLC histologies. Methods: Pts with refractory advanced NSCLC were screened for elevated FGFR1-3 mRNA levels by RNA in situ hybridization (RNAscope) and NanoString assay in fresh or archival tumor samples, and FGFR1-3 overexpression was defined by pre-specified cut-offs. Pts received rogaratinib 800 mg BID on a continuous 21-day cycle. Tumor response was assessed by Response Evaluation Criteria in Solid Tumors v1.1 after cycles 2, 5, and 8. Results: 260 NSCLC biopsies were screened for FGFR1-3 tumor mRNA expression; 244 (93.8%) were evaluable. FGFR1-3 mRNA overexpression was found in 47% of sq NSCLC, and only 14% of non-sq NSCLC, with FGFR3 being the most commonly overexpressed subtype. 40 FGFR mRNA-positive pts were enrolled and treated. Rogaratinib was well tolerated; hyperphosphatemia (75%), diarrhea (53%), and decreased appetite (35%) were the most frequent treatment-emergent adverse events. Events were mostly mild or moderate. 36 treated pts were evaluable for response. The overall response rate was 5.6% (2 partial responses, 1 lasting for > 16 months). Disease control rate was 64%. Disease stabilization was seen in pts with mRNA overexpression across all FGFR subtypes and also in pts who failed prior lines of therapy, including anti-PD-L1. Molecular studies are ongoing to identify additional predictors of response to improve pt selection. Conclusions: Rogaratinib has a favorable safety and tolerability profile and clinical activity in pts with refractory FGFR1-3 tumor mRNA-positive NSCLC. It has potential for further exploration in combination with other agents. A clinical trial is currently enrolling FGFR mRNA-overexpressing pts with advanced and pre-treated sq NSCLC. Clinical trial information: NCT03762122.

2529Background: BAL101553 is the prodrug of BAL27862, a small molecule TCC that binds microtubules and promotes tumor cell death by activation of the spindle assembly checkpoint. In a study of BAL1...

PurposeCirculating cell-free DNA is present in increased amounts in the blood of cancer patients, but the clinical relevance of this phenomenon remains unclear. We conducted a clinical study to assess the value of circulating DNA as a prognostic marker in patients with non–small-cell lung cancer (NSCLC).Patients and MethodsA standard protocol for the quantification of circulating DNA by real-time polymerase chain reaction was set up and validated at two oncology units. One hundred eighty-five informed patients with NSCLC and 46 healthy controls were included in the study. DNA concentrations were determined in paired plasma and serum samples and analyzed for a relationship with leukocyte counts and lactate dehydrogenase (LDH) levels. DNA concentrations in healthy controls and in patients were compared, and cutoff levels for plasma and serum DNA were determined. Patient survival was analyzed relative to baseline DNA concentrations, and the relationship between tumor responses and changes in DNA concentrations was assessed in patients receiving chemotherapy.ResultsWe found a significant correlation between increased plasma DNA concentrations and elevated LDH levels (P = .009), advanced tumor stage (P < .003), and poor survival (P < .001). Tumor progression after chemotherapy was significantly (P = .006) associated with increasing plasma DNA concentrations. Serum DNA concentrations strongly correlated (P < .001) with leukocyte counts.ConclusionOur data demonstrate that quantification of plasma DNA is an accurate technique amenable to standardization, which might complement current methods for the prediction of patient survival. This approach might be considered for evaluation in large prospective studies.

104 Background: BMS-986156 is a fully human IgG1 agonist mAb that binds GITR and promotes T effector cell activation and possible reduction/inactivation of T regulatory cells. Preclinical data show enhanced antitumor T-cell activity with anti-GITR + anti–programmed death-1 (PD-1). Here we describe preliminary dose escalation data from a phase I/IIa study of BMS-986156 ± nivolumab (anti–PD-1 mAb) in pts with advanced solid tumors (NCT02598960). Methods: During dose escalation, pts received BMS-986156 (10–800 mg) or BMS-986156 (30–800 mg) + nivolumab (240 mg) every 2 weeks. Objectives included safety (primary), immunogenicity, pharmacokinetics (PK), pharmacodynamics (PD), and efficacy. Results: As of Dec 12, 2016, 66 pts were treated with BMS-986156 (n = 29) or BMS-986156 + nivolumab (n = 37).No dose-limiting toxicities (DLTs) were reported during dose escalation. The most common treatment-related adverse events reported with BMS-986156/BMS-986156 + nivolumab included pyrexia (21%/30%), chills (10%/16%), and fatigue (14%/14%); events were G1/2 in all pts except for 4 pts (6%) treated with the combination (G3 lipase [n = 1], G3 lung infection [n = 1], G3 fatigue [n = 1], and G3 aspartate aminotransferase with G4 creatine phosphokinase [n = 1; leading to discontinuation of treatment]). Preliminary data indicate that the incidence of immunogenicity to BMS-986156 was low when BMS-986156 ± nivolumab was administered. Preliminary data also indicate that BMS-986156 ± nivolumab exhibits linear PK with dose proportionality after a single dose, and BMS-986156 ± nivolumab is biologically active in PD analyses in peripheral blood. Initial antitumor activity has been observed in several pts treated with the combination; these data will be reported. Conclusions: This is the first report of clinical data with an anti-GITR mAb ± a PD-1 inhibitor.BMS-986156 ± nivolumab was well tolerated, with no DLTs and low immunogenicity. Antitumor activity was observed with BMS-986156 + nivolumab at doses predicted to be biologically active. Further evaluation of this combination in pts with advanced solid tumors is ongoing. Clinical trial information: NCT02598960.

386 Background: FGFRs play a role in a variety of malignancies, including urothelial bladder cancer (UBC). Whereas genetic alterations of FGFRs in UBC are known, non-genetic and epigenetic activation of FGFR gene expression have also been described. BAY 1163877 is an oral inhibitor of FGFRs 1-3 with antitumor activity in FGFR mRNA overexpressing xenograft models not limited to DNA alterations. We report the results from a phase I expansion cohort in UBC patients pre-screened for treatment with BAY 1163877 based on FGFR1-3 mRNA overexpression and/or activating mutations in the FGFR3 gene. Methods: FGFR mRNA levels were assessed in paraffin-embedded archival or fresh biopsy specimens by RNAscope and NanoString technology and activating mutations by RT-PCR-based mutation assay. Tumor response to treatment was assessed by RECIST, v1.1. Adverse events were assessed using CTCAE v4.03 criteria. Results: A total of 80 patients from multiple indications were enrolled in the phase I study; 800 mg BID was established as the recommended phase 2 dose. Sixty seven UBC patients were screened, with 31 tumor biopsies (46%) determined to overexpress FGFR mRNA: 2 patients each with FGFR1 and FGFR2, and 27 patients with FGFR3. Of the 27 patients with FGFR3 mRNA overexpression, 5 had in parallel an activating mutation in FGFR3 gene. Eight UBC patients met eligibility criteria and entered treatment; all had elevated FGFR3 mRNA expression and 4 had alterations in FGFR3 DNA (3 mutations and 1 translocation). Seven patients (87.5%) had tumor shrinkage in target lesions as best response, with 3/8 partial responses (PR; 37.5%). One patient with a PR presented with elevated FGFR3 mRNA without evidence of aberrant DNA. BAY 1163877 was generally well tolerated and AEs manageable with dose modification. The most common AEs in the overall population were increased phosphorus (66% all grade, 1 grade-3 event) and diarrhea (33% all grade, 2 grade-3 events). Conclusions: Selection of patients for treatment with BAY 1163877 based on FGFR mRNA expression levels in archival tissue was feasible. BAY 1163877 had a favorable safety profile and promising anti-tumor activity in UBC patients. Clinical trial information: NCT01976741.

523Background: Tamoxifen is commonly used to treat estrogen receptor (ER)-positive breast cancers, though the response to tamoxifen and its adverse event profile have a high degree of inter-individ...

2592 Background: PQR309 is a novel, orally bioavailable, balanced pan-PI3K, mTORC1 and mTORC2 inhibitor. Methods: An accelerated 3+3 DE, open label Phase 1 trial of continuous once daily (OD) PQR30...

e17046 Background: There is no consensus on the adequate time of referral to palliative systemic treatment in patients with r/mHNSCC and it remains unclear whether the time between the diagnosis of...

621^ Background: Preclinical data suggest BEZ235 (BEZ; dual PI3K/mTOR inhibitor) may enhance the activity of PTX ± TZ in pts with advanced cancers. In this 4-arm study (NCT01285466), BEZ or buparli...

TPS140 Background: Tamoxifen is widely used to treat hormone receptor positive breast cancers, in the (neo-)adjuvant setting as well as in the metastatic setting. Even though tamoxifen saved many l...

7536 Background: We assessed the impact of gene polymorphisms on clinical outcome in advanced non-small cell lung cancer (NSCLC) patients receiving platinum-gemcitabine chemotherapy (PG). Methods: ...

TPS239 Background: Cancer cachexia impacts physical functioning, appetite, tolerability and success of anticancer treatments of patients with advanced cancer. Currently, there is no standard treatm...

e13047 Background: There is an urgent need for individualized treatment of patients with malignant bone disease (MBD), as the clinical benefit from bone-targeted therapies is moderate so far. As th...

2566 Background: This analysis was initiated to define the predictive value of the area-under-the-curve of high-dose methotrexate (AUCHD-MTX) in patients with primary central nervous system lymphom...

2529 Background: Paclitaxel (P) and carboplatin (C) are considered standard first-line treatment in advanced ovarian cancer following cytoreductive surgery. Threshold-models have been used to predict P PKPD, whereas the time above P plasma concentration of 0.05- 0.2 μmol/L (P tC>0.05–0.2) predicts neutropenia. The objectives of this study was to build a population PKPD-model of PC in ovarian cancer patients. Methods: 139 ovarian cancer patients received P 175 mg/m2 over three hours followed by C AUC 5 over 30 min. Plasma concentration-time data of PC were measured, and data processed using nonlinear mixed-effect modelling. Semiphysiological models with linear or sigmoidal maximum response, and threshold models were adapted to the data. Results: 105 patients had complete PK and toxicity data. In 34 patients with measurable disease, objective response rate was 76%. Neutrophil and thrombocyte counts were adequately described by an inhibitory linear response model. Mean P tC>0.05 was 61.4 hrs. P tC>0.05 was significantly higher in patients with a complete (91.8 hrs) or partial response (76.3 hrs) compared to patients with progressive disease (31.5 hrs) (p=0.02 and 0.05, respectively). Patients with P tC>0.05 > 61.4 hrs had a longer time to disease- progression compared to patients with P tC>0.05 < 61.4 hours (89.0 vs 61.9 weeks, p=0.05). P tC>0.05 was a good predictor for severe neutropenia (p=0.01), while carboplatin exposure (Cmax and AUC) was the best predictor for thrombocytopenia (p-4). Conclusions: In this group of patients, P tC>0.05 is a good predictive marker for severe neutropenia and clinical outcome, while C exposure is a good predictive marker for thrombocytopenia. (Biomed grant PL96–2333, JHM Schellens coordinator) No significant financial relationships to disclose.

4537 Background: Gastric cancer is the fourth most commonly diagnosed cancer and is the second leading cause of cancer death worldwide. Prognosis is highly dependent on stage at diagnosis making early diagnosis mandatory. By using SELDI - TOF mass spectrometry we compared serum protein profiles of gastric cancer patients with healthy controls and those of gastric cancer patients responding to first-line ECC chemotherapy with those with no response or early progressive disease. Methods: Serum from patients with advanced gastric cancer (GC) was obtained, according to a predefined schedule, prior to start of first-line epirubicin (50 mg/m2 day 1), cisplatin (60 mg/m2 day 1) and capecitabine (1,000 mg/m2 d1–14) chemotherapy (ECC) and serially before each treatment cycle every 3 weeks and analyzed by standardized SELDI-TOF MS/MS. Serum proteomic profiles of GC patients were compared with those of matched healthy controls and proteomic profile changes in responding and non-responding patients were analyzed. Results: In total 82 patients (mean age 57 years) were treated with mean 5 ECC cycles resulting in a response rate of 35%, mean time to progression of 7.1 months and mean overall survival of 12.4 months (95% CI: 10.7 - 14.1). By comparing GC patients and healthy controls we identified 18 m/z values that significantly (p < 0.00001) differentiated between the two groups (m/z 2.7 - 66.6 kDa). Comparison of responding and non-responding patients identified 2 proteins, m/z 3109 and 7559 Da, potentially predicting response (p < 0.001). Serial analysis of proteins changing differently during chemotherapy according to response will be performed. Conclusions: We identified 18 m/z values/proteins that highly (p < 1.0 E-05) discriminated between gastric cancer patients and healthy controls serving as candidate biomarkers of gastric cancer and 2 m/z values that significantly predicted response to chemotherapy. No significant financial relationships to disclose.