Search

397784 Background: Ripretinib, a switch-control tyrosine kinase inhibitor (TKI), is indicated for patients (pts) with gastrointestinal stromal tumor (GIST) who received prior treatment with ≥3 TKIs, including imatinib. Sunitinib is approved for advanced GIST after imatinib failure. Circulating tumor DNA (ctDNA) analysis may provide insight into the efficacy of these agents in second-line advanced GIST. Here, we present exploratory baseline ctDNA results from INTRIGUE. Methods: INTRIGUE is an open-label, phase 3 study that enrolled adult pts with advanced GIST who progressed on or had intolerance to imatinib (NCT03673501). Randomization was 1:1 to ripretinib 150 mg once daily (QD) or sunitinib 50 mg QD (4 wks on/2 wks off). Baseline peripheral whole blood was analyzed by Guardant360, a 74-gene ctDNA next-generation sequencing (NGS)-based assay. Only KIT mutations are reported here. Results: Of 453 pts in the overall intent-to-treat (ITT) population, 362 (80%) samples were analyzed. ctDNA was detected in 280/362 (77%), with KIT mutations detected in 213/280 (76%). Common resistance mutations were in the KIT activation loop (AL; exons 17/18; 89/213, 42%) and ATP-binding pocket (ATP-BP; exons 13/14; 81/213, 38%). Efficacy in pts with detectable ctDNA in the KIT exon 11 and overall ITT populations was consistent with the primary analysis based on tumor data used for randomization. Pts with KIT exon 11 + 17/18 (−9/13/14) mutations had superior progression-free survival (PFS), objective response rate (ORR), and overall survival (OS) with ripretinib vs sunitinib, whereas pts with exon 11 + 13/14 (−9/17/18) mutations had better PFS, ORR, and OS with sunitinib vs ripretinib (Table). Subgroup safety profiles were consistent with the primary analysis. Conclusions: While KIT ATP-BP mutations predicted clinical benefit from sunitinib vs ripretinib, pts harboring resistance mutations in the KIT AL derived meaningful clinical benefit from ripretinib but not sunitinib. This study demonstrates the value of ctDNA NGS-based sequencing of the complex landscape of KIT mutations to predict the clinical benefit of ripretinib or sunitinib as second-line therapy in pts with advanced GIST. Clinical trial information: NCT03673501 . [Table: see text]

LBA2 Background: 5-year survival of RR-ES is about 15%. rEECur, the first randomized controlled trial in this setting, is defining standard care, balancing efficacy and toxicity. Methods: Patients aged 4-50 with RR-ES were randomly assigned to topotecan and cyclophosphamide (TC), irinotecan and temolozomide (IT), gemcitabine and docetaxel (GD), or high-dose ifosfamide (IFOS). Primary outcome was event-free survival (EFS) for the phase III comparison. Secondary outcomes included overall survival (OS), toxicity, and quality of life (QoL). A probability-based Bayesian approach was used with multiple pairwise comparisons. At the first and second interim assessments, patients allocated to GD and IT, respectively, had worse objective response (OR) and EFS than the other arms, halting recruitment to both. The final intent-to-treat assessment of the original four arms was a phase III evaluation of TC and IFOS. Results: 451 patients recruited between 18/12/14 and 31/08/21, were randomly assigned to TC (163 patients), IT (127 patients), GD (72 patients), and IFOS (83 patients). Median age was 19 years (range 4-49). Patients had: refractory disease (18%), first recurrence (66%), > first recurrence (17%). Initial disease site was bone in 70%. Sites of progression were: primary site only (15%), pleuropulmonary metastases only (34%), and other metastatic (51%). Baseline renal function was similar in both. Median follow-up (reverse Kaplan-Meier method) was 40 months. For the phase III comparison between TC and IFOS (both, 73 patients), median EFS was 3.7 months (95% CI, 2.1-6.2) for TC and 5.7 months (95% CI, 3.8-7.0) for IFOS. Median OS was 10.4 months (95% CI, 7.5-15.5) for TC and 16.8 months (95% CI, 11.1-25.8) for IFOS. Given the observed data, the posterior probability that EFS and OS were better after IFOS than after TC (ie Pr [true hazard ratio < 1 | data]) was 95% for both. A greater survival difference was observed for patients aged under 14 than those aged ≥ 14 for EFS and OS. Subgroup analyses favored IFOS for all minimization factors. The main grade 3/4 adverse events (% patients with an event) for TC (left-hand values) compared with IFOS were: febrile neutropenia (26% vs. 25%), infections (8% vs. 14%), vomiting (1% vs. 1%), nausea (0% vs. 3%), diarrhea (1% vs. 1%), encephalopathy (0% vs. 7%), and renal toxicity (0% vs. 8%). Descriptive statistics of quality of life scores appeared to favor the IFOS arm over the TC arm in children but not in adults. Conclusions: The first randomized trial in RR-ES has shown that high-dose ifosfamide is more effective in prolonging survival than TC, having previously beaten GD and IT, and should be considered as a control arm in future randomized phase II/III studies in RR-ES if combination with IFOS is logical. rEECur is the first study to provide comparative toxicity and survival data for the four most commonly used chemotherapy regimens in RR-ES. Clinical trial information: ISRCTN36453794.

TPS11590 Background: Tenosynovial giant cell tumor (TGCT) is a rare, locally aggressive neoplasm that occurs in the synovium of joints, bursae, or tendon sheaths. TGCT is caused by upregulation of the colony-stimulating factor 1 (CSF1) gene, resulting in aberrant CSF1 expression and the recruitment of CSF1 receptor (R)-dependent inflammatory cells. Resection is the primary treatment, but nonsurgical treatment options are necessary for patients with symptomatic TGCT not amenable to surgical resection. Vimseltinib is an oral switch control TKI specifically designed to selectively and potently inhibit CSF1R. In a Phase 1/2 study in patients with TGCT, vimseltinib showed encouraging antitumor activity with an overall objective response rate (ORR) of 42% in the cohort receiving 30 mg twice weekly (recommended phase 2 dose; Gelderblom et al, ESMO 2021 Poster). Vimseltinib was also well tolerated, and the majority of the common (≥15%) treatment-emergent adverse events (TEAEs) were Grades 1–2. Among these common TEAEs, the only Grade 3–4 event in the Phase 2, twice-weekly, 30-mg cohort was increased blood creatine phosphokinase (CPK); however, this elevated CPK was not associated with any symptoms (Gelderblom et al, ESMO 2021 Poster). Phase 1/2 efficacy and safety data support further development of vimseltinib; here, we describe the ongoing Phase 3 study for patients with TGCT not amenable to surgical resection. Methods: MOTION (NCT05059262) is a Phase 3, randomized, placebo-controlled, double-blind study that aims to evaluate the efficacy and safety of vimseltinib for the treatment of TGCT not amenable to surgical resection. Participants must be at least 18 years of age and have histologically confirmed and symptomatic TGCT for which surgical resection will potentially cause worsening functional limitation or severe morbidity. Prior CSF1R therapy is not permitted (previous imatinib and nilotinib is allowed). In Part 1 of the study, eligible participants will be randomized 2:1 to receive either vimseltinib 30 mg twice a week or matched placebo for 24 weeks. The primary outcome measure is ORR assessed by central read using Response Evaluation Criteria in Solid Tumors version 1.1 at 25 weeks. Secondary outcome measures include ORR per tumor volume score, range of motion, and patient-reported outcomes. Participants assigned to placebo in Part 1 will have the option to receive vimseltinib in Part 2, a long-term treatment phase in which participants will receive open-label vimseltinib. This international study plans to randomize 120 participants and is currently enrolling. Clinical trial information: NCT05059262.

TPS11582 Background: Chondrosarcomas (CS) are the third most common type of primary bone cancer after myeloma and osteosarcoma. Conventional CS represent 85–90% of all cases and are typically treated with surgical resection. However, there are no approved systemic treatment options for patients with unresectable or metastatic conventional CS, and outcomes remain poor. INBRX-109 is a precision-engineered, tetravalent death receptor 5 (DR5) agonist antibody designed to overcome the limitations of earlier-generation agonists and exploit the tumor-specific cell death induced by DR5 activation. DR5 is one of two pro-apoptotic receptors for the trimeric tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). Early clinical activity of INBRX-109 was observed in an ongoing phase 1 trial and warrants further investigation. INBRX-109 has been granted an FDA fast-track designation for conventional CS. Methods: This is a multicenter, randomized, blinded, placebo-controlled phase 2 study in patients with unresectable or metastatic conventional CS, measurable disease by RECIST 1.1, and radiologic disease progression within 6 months prior to screening. Any number of prior lines of therapy are allowed, except for prior DR5 agonists. Patients must be ≥18 years of age and have an ECOG performance status of 0/1 and have archival or fresh tissue available. Approximately 201 patients will be randomized (2:1) to INBRX-109 (3 mg/kg intravenously, every 21 days) or placebo, stratified by histologic grade (Grade 1/2 vs 3), isocitrate dehydrogenase (IDH)1 R132/IDH2 R172 status (wildtype vs mutation), and line of systemic therapy (none vs prior). Treatment will continue until disease progression/unacceptable toxicity. Patients treated with a placebo will have the option to cross over to INBRX-109 upon disease progression. The primary endpoint is progression-free survival (PFS) by independent radiology review. Secondary endpoints are overall survival, PFS by investigator assessment, quality of life, overall response rate, duration of response, disease control rate, safety, pharmacokinetics, and immunogenicity. Adverse events will be recorded and graded by NCI CTCAE Version 5.0. Median PFS of 7.0 months is projected for INBRX-109 and 4.0 months for placebo (corresponding hazard ratio of 0.571); INBRX-109 will be declared superior if the 1-sided p-value from the stratified log-rank test is

11536 Background: Ripretinib is a switch-control tyrosine kinase inhibitor that broadly inhibits KIT and PDGFRA kinase signaling. In the INVICTUS study (NCT03353753), patients with advanced GIST (≥4th-line) receiving ripretinib had a median progression-free survival (mPFS) of 6.3 months vs 1.0 month for patients receiving placebo (HR = 0.15, p

3574 Background: Irinotecan is commonly used in the treatment of advanced colorectal and pancreatic cancer. The polymorphisms UGT1A1*28 (7 TA repeats) and UGT1A1*93 (SNP -3156G > A) are significantly associated with increased systemic exposure of irinotecan’s active metabolite SN-38 and subsequently severe irinotecan-associated adverse-events (AEs) including (febrile) neutropenia and diarrhea. Severe AEs may lead to hospitalization, loss of quality of life, treatment delay and/or treatment discontinuation. Nonetheless, prospective genetic screening is not yet routinely performed. The aim of this study was to determine the safety and pharmacokinetics of UGT1A1 genotype-guided dosing of irinotecan in UGT1A1 poor metabolizers (PMs), i.e. UGT1A1 *28/*28 and/or UGT1A1*93/*93 individuals, in order to reduce the incidence of severe irinotecan-associated AEs. Methods: A prospective, multi-center, non-randomized study was conducted in patients intended to be treated with irinotecan at a dose of ≥ 180 mg/m2 or 450-600 mg flat dose. All patients were pre-therapeutically genotyped for UGT1A1*28 and UGT1A1*93. In UGT1A1 PMs, an initial 30% dose reduction in the first cycle was applied followed by further individual dose titration based on neutrophil count and clinical tolerability. The primary endpoint was the incidence of febrile neutropenia in the first 2 cycles of irinotecan treatment. UGT1A1 PMs were compared to 1] historical control patients, i.e. homozygous polymorphic patients treated with full dose therapy identified from systematic literature review and to 2] UGT1A1 non-PMs treated with standard dose therapy. In addition, systemic SN-38 exposure (AUC0-500h) of reduced dosing in the UGT1A1 PM cohort was compared to a standard dosed irinotecan patient cohort [doi: 10.1200/JCO.2000.18.1.195] by an independent T-test. Results: A total of 349 patients were pre-therapeutically genotyped and included for analysis. Thirty-one (8.9%) patients were UGT1A1 PM, in whom an initial median 30% dose reduction was applied. The incidence of febrile neutropenia in this group was 6.5% compared to 24% in historical controls (n = 50) (p = 0.042) and comparable with the incidence (4.1%; p = 0.632) in UGT1A1 non-PMs treated with full dose therapy. The systemic exposure of SN-38 of reduced dosing in UGT1A1 PMs (n = 17) was comparable to the systemic exposure of the standard dosed irinotecan patient cohort (n = 46) with a relative difference of +24% (p = 0.054) with a geometric mean (CV) of SN-38 AUC0-500h of 391 (43.7%) versus 298 (75.3%) ng*h/mL, respectively. Conclusions: UGT1A1 genotype-guided dosing significantly reduces the incidence of febrile neutropenia in UGT1A1 PM patients treated with irinotecan. In addition, systemic drug exposure remained adequate, despite the 30% dose reduction. Therefore, UGT1A1 genotype-guided dosing of irinotecan should be considered standard of care in order to improve the individual patient safety. Clinical trial information: Trial NL6270 (NTR6612).

e13599 Background: In the Netherlands, the health insurance package usually covers cancer drugs after EMA approval and positive recommendation of the Dutch Society of Medical Oncology (NVMO). However, the government can temporarily exclude newly licensed indications with high budget impact from coverage until the national HTA-body advises on the clinical effectiveness and cost effectiveness. Based on the recommendations of the HTA-body, the government negotiates a financial arrangement with manufacturers. Because submitting value dossiers, assessments and negotiations takes time there have been concerns regarding patients’ access to these novel treatments, especially for life threatening conditions such as cancer. Due to a lack of transparency, it is not known to what extent patients are given access to ‘free of charge programmes’ (FCPs). Methods: A list of oncology drugs and indications which were temporarily excluded from reimbursement due to negotiations with the government (July 2015-Dec. 2020). We contacted all the pharmaceutical companies that were engaged in the process above, to inquire about access to their products during the HTA evaluation and negotiations. Results: In total 17 oncology drugs (46 EMA registered indications) of 11 companies were subjected to financial agreements by the government. In 41,3% (19/46) of cases, FCPs were available via individual prescriber requests in a selected number of hospitals. In all other cases such arrangements were not needed because alternative treatment options were available (15,2%; 7/46) or because treatment was not recommended by the NVMO (13,0%; 6/46). For one indication FCP was available but the treatment eventually received a negative recommendation. In 30,4% (14/46) of the cases there was immediate reimbursement in place following a positive NVMO recommendation through umbrella agreements. Such agreements cover existing indications but also all the indications that will be licensed in the future. Umbrella agreements were especially set up for immune checkpoint inhibitors that showed benefit across multiple indications. As anticipated, some patient-access programmes had already started prior to EMA approval. In 5 cases an official compassionate use programme was set up through the Dutch Medicines Evaluation Board prior to authorisation. Conclusions: Our survey indicates that all manufacturers are committed to enabling patients’ and clinicians’ early access to their products pending payers’ approval in a high income country such as the Netherlands. However, the lack of transparency regarding the hospitals offering these programmes may result in inequity in access. Besides, there is no structural data collection. Recently, the NVMO has established a platform (DRUG Access Protocol) to harmonise all compassionate use programmes and FCPs, generating real-world data and ensuring equal access for all patients.

Background: Therapeutic vaccines based on synthetic long peptides (SLPs) have a great potential for immunotherapy of cancer patients as these SLPs include both human leukocyte antigen (HLA) class I and II epitopes and no patient selection for HLA types is required. The antigen-induced immune response can be strengthened with immune stimulating additives. Amplivant (AV) is a synthetic Toll-like receptor 2 ligand which can be directly conjugated to tumor peptide antigens. In preclinical studies, AV-conjugation to antigens led to both enhanced antigen presentation by dendritic cells and T-cell priming and caused superior induction of effective anti-tumor responses. Moreover, AV-conjugated SLPs showed a 100 times higher immune response compared to unconjugated SLP. The current study is a first-in-human trial to investigate safety and immunogenicity of AV-conjugated human papillomavirus (HPV)16-SLPs. Methods: A dose escalation phase I trial was performed in 24 patients with HPV16 positive (pre-) malignant lesions. AV was conjugated to two SLPs derived from the most immunodominant regions of the HPV16 E6 oncoprotein. Four dose groups (1, 5, 20 or 50 μg of each peptide) in 6 patients each were studied. The vaccine was injected three times intradermally in DMSO / water with a three-week interval. Adverse events (AE) were collected according to CTCAE v4.0 up to 26 weeks. Peptide-specific T-cell immune responses were determined in blood samples taken before and after vaccination using complementary immunological assays (proliferation assay, IFNγ-ELISPOT and cytokine bead array). Results: Toxicity after three AV-conjugated HPV16-SLP vaccinations was limited to CTCAE grade 1 or 2, with predominantly inflammation at the vaccination site and sometimes flu-like symptoms, which generally resolved within one day. Dose increase resulted from no AE in the lowest dose group to mild/moderate AE in all vaccinated persons in the highest dose group. In the lowest dose group, minor vaccine-induced T-cell responses were observed in three of six vaccinated persons. In the highest dose group, all patients displayed a strong HPV16-specific T-cell response after vaccination. The induced T-cell response against HPV16 lasted until the end of the trial. Conclusions: This first-in-human study showed that AV conjugated to SLPs can safely be used as an intradermal therapeutic vaccine. AV-conjugated HPV16-SLP was able to induce robust HPV16-specific T-cell immunity in patients treated for HPV16 positive (pre-) malignancies without any other vaccine adjuvant or formulation. Increase in dose resulted in both a higher number of mild adverse events as well as stronger T-cell immunity. Clinical trial information: NCT02821494.

3633 Background: Extensive molecular profiling in cancer regularly reveals targets for which approved drugs are available in tumor types outside the registered label. Efficacy of off-label use of these drugs is unavailable. Access to these drugs for pts is challenging. In the Drug Rediscovery Protocol (DRUP, Van der Velden et al, Nature 2019), pts are treated based on their tumor molecular profile. Here, we present the results of the successful cohort “Olaparib for tumors with BRCA1/2 alterations”. Methods: Twenty five adult cancer patients (pts) who exhausted all treatment options and had BRCA1/2 loss of function (LoF) mutations (found in routine diagnostics) were included. No pts were eligible for on-label treatment with PARP inhibitors. Pts were treated with olaparib until disease progression or unacceptable toxicity. The primary endpoint was clinical benefit (CB: objective response or stable disease (SD) ≥ 16 weeks). Pts were enrolled using a Simon-like two-stage model, with 8 pts in stage 1 and up to 24 pts in stage 2 if at least 1 pt had CB in stage 1. A fresh frozen biopsy was obtained from each pt for whole genome sequencing (WGS) and target confirmation. Results: Fourteen pts (56%) had CB. The objective response rate was 32%. Nine different cancer types were included: prostate (n=11), breast (n=4), ovarian (n=2), pancreatic (n=3), colorectal (n=2), biliary tract (n=2), kidney (n=1), adrenal gland (n=1) and endometrial (n=1). WGS could be performed on 58% of baseline tumor biopsies, confirming the original BRCA1/2 mutations in 86%. CB was observed in pts with both somatic and germline BRCA alterations and across tumor types. CB was only observed in cases with biallelic loss of BRCA1/2 in the tumor and when classified as HRD by a pan-cancer homologous recombination deficiency classifier (CHORD), which relies on genome-wide SNV, indel, and SV mutational footprints for HRD detection. No evidence of complete BRCA loss and HRD was observed in 5 pts with PD, while 4 patients with effective BRCA complete loss and HRD also had PD. WGS analysis of these pts suggested resistance mechanisms due to other oncogenic drivers (e.g FGFR1 amplification, CTNNB1 stabilization, KEAP1 inactivation). Conclusions: Olaparib seems to be an effective treatment option for pts with BRCA1/2 LoF mutated malignancies, regardless of histology, for both germline and somatic alterations, which needs confirmation in an independent cohort. CB of olaparib was observed in malignancies showing biallelic loss of BRCA1/2 and when classified as HRD, indicating the importance of the BRCA/HRD signature status. Clinical trial information: NCT02925234 .

11500 Background: In 2010, different chemotherapy regimens were standard in Europe and the USA for newly diagnosed ES. In the absence of novel agents to investigate, comparison of these two strategies was considered worthwhile. Methods: Newly diagnosed localised or metastatic ES patients aged 5-50 were eligible. Patients were randomized to receive either the European regimen (Arm A) of VIDE (vincristine [V], ifosfamide [I], doxorubicin [D] and etoposide [E]) induction and VAI or VAC (V, actinomycin D and I or cyclophosphamide [C]) consolidation or the USA regimen (Arm B) of compressed VDC/IE induction and IE/VC consolidation. The primary outcome measure was event-free survival (EFS); secondary outcomes included overall survival (OS) and toxicity. The design was Bayesian with interpretation based on posterior probabilities (with non-informative priors) – i.e. probability that true hazard ratio (HR) < 1.0 given the data [Pr(HR200 ml); country (37% UK, 31% France, 32% other). Median follow-up was 1.7 years. The HRs (95% CrI) were 0.70 (0.51, 0.95) for EFS and 0.64 (0.42, 0.96) for OS in favour of Arm B, with posterior probabilities of 98% for both that Arm B was better. Subgroup analyses showed no evidence that this benefit differed depending the baseline features, with no HT being close to significance (table). There were no major differences in acute toxicity: 68% of patients in Arm A experienced serious adverse events and 67% in Arm B. Conclusions: VDC/IE chemotherapy is superior to VIDE for both EFS and OS, with no excess toxicity. This benefit is consistent across all baseline stratification parameters. Clinical trial information: ISRCTN92192408 . [Table: see text]

11556 Background: The optimal treatment for patients with advanced dedifferentiated (DD) liposarcoma (LPS) remains uncertain. Single agents which are most effective include doxorubicin and ifosfamide but, as with soft tissue sarcomas (STS) in general, objective response rates (ORR) and progression free survival (PFS) are very modest. Cabazitaxel exerts its effect through inhibition of microtubular disassembly and has been shown to be relatively safe, effective and well-tolerated. EORTC 1202 assessed whether cabazitaxel demonstrated sufficient antitumor activity in patients with metastatic or inoperable locally advanced DD LPS to justify further investigation in a phase III setting. Methods: This was an international multi-center, open label single arm phase II trial. Eligible patients with metastatic or inoperable locally advanced DD LPS were treated with cabazitaxel 25mg/m² IV infusion over 1 hour every 21 days. Primary endpoint was PFS rate at 12 weeks assessed by local investigator per RECIST 1.1. Based on a Simon two-stage design, at least 4 out of 17 (Stage 1) and 11 out of 37 (Stage 2) eligible and evaluable patients who are progression-free at 12 weeks were needed. Results: Forty patients were registered by 10 institutions in 4 countries between March 2015 and March 2019, with 2 patients being ineligible. Among the 38 eligible patients who started treatment, 3 (7.5 %) were still on treatment at the time of analysis. The number of cycles ranged from 1 to 30, with a median of 5; 26 patients (65%) received at least 4 cycles of cabazitaxel. Among the first 17 (Stage 1) and 37 (Stage 2), 11 and 20 patients were progression-free at 12 weeks respectively, satisfying the study decision rules. The PFS rate at 12 weeks for all 38 eligible patients was 52.6% (conditional 1-sided 95 % CI 38.3 – 100). Two patients (5.3%) achieved a confirmed partial response (PR) and 23 stable disease (SD) (60.5%). Disease control (PR+SD) was achieved in 25 patients (65.8%). Median PFS was 7.4 months (95%CI 2.8-10.3). The most common cabazitaxel -related grade >3 adverse events in all 40 registered patients were neutropenia (60%), febrile neutropenia (25%), fatigue (12.5%), and anemia (10%). There were no cabazitaxel-related deaths. Conclusions: EORTC 1202 met its primary endpoint, with 20/37 pts (54%) being progression-free at 12 weeks. Results of this trial confirm activity of cabazitaxel in patients with metastatic or inoperable locally advanced DD LPS and warrant further exploration of the drug. Clinical trial information: NCT01913652 .

11523 Background: Ewing 2008R1 (EudraCT2008-003658-13, Sponsor UKM) was conducted in 12 countries. It evaluated the effect of zolendronic acid (ZOL) maintenance therapy on event-free (EFS, primary endpoint) and overall survival (OS) from randomization in standard risk Ewing Sarcoma (EwS). Methods: Phase III, open label, prospective, multi-center, randomized controlled clinical trial. Eligible patients (pts) had localized EwS with either good histological response to induction chemotherapy and/or small tumors ( < 200ml). Pts received 6 cycles VIDE induction and 8 VAI (male) or 8 VAC consolidation (female) and were randomized to receive either 9 cycles of maintenance ZOL or no further treatment (control;ctrl). ZOL cycles started parallel to the 6th consolidation cycle. Randomization was stratified by tumor site (pelvis/no pelvis). Two-sided adaptive inverse-normal 4-stage design, changed after the 1st interim analysis via Müller-Schäfer method. Initial sample size 448 pts, type I error rate 5%, power 80%. Results: 284 pts were randomized between 2009 and 2018 (142 ZOL / 142 ctrl). With a median follow-up of 3.9 years, the primary endpoint EFS was not significantly different between the ZOL and ctrl group in the adaptive design (HR 0.74, 95% CI 0.43-1.28, intention to treat). 3-year (3y) EFS rates were 84.0% (95% CI 77.7-90.8%) for ZOL vs 81.7% (95% CI 75.2-88.8%) for ctrl. Results were similar in the per protocol collective. Cause-specific HR for local recurrence in ZOL was csHR 0.30 (95% CI 0.08 -1.09; p = 0.07), for metastatic progress/new metastases csHR 1.0 (CI 0.5-2.2), for combined relapse/progress csHR 0.3 (95% CI 0.1-1.7), for second malignancies csHR 4.0 (95% CI 0.45-36.1) compared to ctrl. The 3y OS was 92.8% (95% CI 88.4-97.5%) for ZOL and 94.6% (95% CI 90.9-98.6%) for ctrl. For ZOL the 5y OS was 87.3% (95% CI 80.7-94.5%) and 89% (95% CI 83.7-95.9%) for ctrl. Noticeable more renal, neurological and gut toxicities were observed for ZOL (p < 0.05), with severe renal toxicities occurring more often in the ZOL arm (p = 0.003). Conclusions: In patients with standard risk localized Ewing Sarcoma there is no benefit from maintenance treatment with zoledronic acid, but significant side effects were observed. Clinical trial information: NCT00987636 .

11535 Background: Ripretinib is a novel switch-control tyrosine kinase inhibitor (TKI) that broadly inhibits KIT and PDGFRA kinase signaling through a dual mechanism of action. In INVICTUS (NCT03353753), a randomized, double-blind, placebo-controlled trial of ripretinib in ≥4th-line advanced GIST, ripretinib reduced the risk of disease progression or death by 85% vs placebo and had a favorable overall safety profile in patients previously treated with ≥3 prior TKIs. Methods: As part of the INVICTUS trial, patient reported outcome (PRO) measures were collected using EQ-5D-5L (EQ5D) and EORTC QLQ-C30 (C30). In prespecified and additional analyses, ANCOVA models were built to compare changes from baseline to cycle 2 day 1 (C2D1) for PRO measures within the ripretinib and placebo arms and determine the difference between treatment arms. PRO measures included the EQ5D visual analogue scale (VAS) and the C30 physical functioning (PF) and role functioning (RF) scales (all scores range from 0–100; higher scores are better). The C30 overall health and overall QoL questions were also assessed (scores range from 1–7; higher scores are better). Fixed effects included treatment arm, number of previous anticancer treatments (3 vs ≥4), and ECOG score at baseline (0 vs 1/2). Results: Overall, 129 patients were randomized and 128 received treatment (85 to ripretinib 150 mg QD; 43 to placebo). All PRO p-values are nominal, and no statistical significance is being claimed. VAS scores improved an average 3.7 points from baseline to C2D1 with ripretinib vs an average decline of 8.9 with placebo (P = 0.004; improvement or no change, 67% vs 41% of patients, respectively). Similarly, the average PF score improved 1.6 points with ripretinib and decreased 8.9 with placebo (P = 0.004; improvement or no change, 68% vs 44%). RF scores also improved an average of 3.5 points with ripretinib vs a decrease of 17.1 with placebo (P = 0.001; improvement or no change, 77% vs 50%). For the overall health and overall QoL questions, scores increased with ripretinib an average of 0.20 and 0.28, respectively, and decreased 0.78 and 0.76 with placebo (both P = 0.001; improvement or no change, 74% vs 47% and 79% vs 59%, respectively). Conclusions: Based on the 5 PRO measures assessed, when compared with placebo and best supportive care, ripretinib provided patient-benefit in advanced GIST with PRO measures of role and physical function, VAS, overall health, and overall QoL remaining stable. Clinical trial information: NCT03353753 .

e18236 Background: The double-blind, randomized, placebo-controlled phase 3 ENLIVEN study in TGCT demonstrated a significant tumor response at week 25 by RECIST for pexidartinib (39% vs. 0% for placebo) and improvement in joint function and symptoms. The aim of this analysis was to identify a threshold score for responder definitions for PROMIS-PF scale and Worst Stiffness Numerical Rating Scale (WS-NRS) and compared responder rates for pexidartinib versus placebo. Methods: Anchor- and distribution-based estimates were calculated, and cumulative distribution function (CDF) plots were generated to derive responder definition threshold estimates. Anchor- and distribution-based results and CDFs were evaluated through triangulation, following FDA PRO Guidance, to determine a single responder definition threshold (i.e., meaningful change) for each instrument. The proportion of responders at Week 25 between treatments was compared with Fisher’s Exact Test (2-sided). Results: 120 patients were randomized to pexidartinib (n = 61) and placebo (n = 59) and assessed through 25 weeks of treatment. Anchor-based analysis showed one-level improvement on the patient global rating of PF item was associated with a mean change of 4.0 on PROMIS-PF. Distribution-based estimates (0.5 SD and 1 SEM) for PROMIS-PF were 2.8 and 2.5, respectively. For WS-NRS, a response of “A little improved” by patients on the perception of stiffness item was associated with a mean change of 1.1. The distribution-based estimates for the WS-NRS item were 0.9 and 0.5, respectively. This resulted in the following responder definition thresholds: ≥3 points for PROMIS-PF and ≥1 for WS-NRS improvement. A greater proportion of pexidartinib as compared to placebo patients were responders by PROMIS-PF (30% vs. 5%, p < 0.001) and WS-NRS (39% vs. 19%, p = 0.02) at week 25, respectively. Conclusions: Triangulation yielded responder definitions of ≥3 points for PROMIS-PF and ≥1 for WS-NRS. With these definitions, a greater proportion of patients treated with pexidartinib compared to placebo had meaningful improvement in physical function and stiffness.

TPS3149 Background: With the emergence of large-scale genetic tumor profiling and the increasing availability of approved targeted therapies, precision medicine has become crucial in cancer treatment. However, for many cancers the relative contribution of either tumor type or genetic aberration to drug sensitivity often remains unknown. Since drug access is generally limited to the on-label indication and outcome of off-label use is not systematically collected in clinical practice, innovative trials facilitating drug access, whilst systematically analyzing treatment outcomes, are urgently needed. Methods: The Drug Rediscovery Protocol (DRUP) is an ongoing, prospective, non-randomized, multi-drug, and pan-cancer trial, in which patients with advanced cancer, who have exhausted all standard of care treatment options, are treated with either targeted or immunotherapy matched to their genetic tumor profile. All submitted patients are reviewed and enrolled in multiple parallel cohorts, preceded by a baseline tumor biopsy for whole genome sequencing to confirm previously identified variants and for exploratory biomarker analyses. Each cohort is defined by a study drug, histologic tumor type, and molecular tumor profile. Efficacy is analyzed per cohort: 8 patients in stage I and 16 more in stage II if ≥ 1 response is observed in the first stage. Primary endpoints include objective response rate, stable disease at 16 weeks, and grade ≥3 adverse events. Since the start of recruitment in September 2016, 870 patients have been submitted for review and 365 patients (42%) have started treatment in one of 101 opened cohorts. Eight cohorts have graduated to the second stage, two cohorts completed accrual in either their first or second stage, and one cohort was closed due to a registered indication. Twenty-two different study treatments (i.e. immunotherapy, monoclonal antibodies, and PARP/small molecule inhibitors), provided by 11 different pharmaceutical companies, are currently available in DRUP. Data sharing with similar trials such as TAPUR and CAPTUR enables to achieve completion of slow accruing cohorts and affirm conclusions. Clinical trial information: NCT02925234.

e16076 Background: Pazopanib has been registered for advanced soft tissue sarcoma (STS) and metastatic renal cell carcinoma (mRCC). The uptake of pazopanib is 40% reduced when a proton pump inhibitor is concomitantly used. Nevertheless, still a large group of cancer patients need a form of gastric acid suppressive agents (GAS, e.g. proton pump inhibitors or H2-anagonists) due to gastrointestinal adverse events. Recently, it was demonstrated that the use of pazopanib with GAS resulted in shorter overall survival and progression free survival in patients with STS. In order to limit the effect of GAS on pazopanib absorption, the advice is to take the GAS 1 hour after pazopanib. In that way the pazopanib is dosed at the lowest gastric pH value. However, the effect of this most optimal controlled intake on pazopanib absorption is unknown. Therefore, we investigated whether this controlled intake algorithm affects pazopanib exposure. Methods: In the DIET study, pazopanib trough concentrations (Ctrough) were measured at predefined moments. In this study a total of 80 patients with mRCC and STS were included. The concomitant use of GAS was recorded and taken according the intake algorithm. Patients were subdivided into two groups (with GAS or without GAS). Results: Of the 80 patients, 22 patients were treated with pazopanib in combination with GAS. In patients treated with pazopanib without GAS the geometric mean(GM) pazopanib Ctrough level was 29.1 mg/L (95% CI 26.4 -31.8) compared to 22.4 mg/L (95% CI 18.0-27.8) (p = 0.01) in those treated with GAS. Conclusions: Patient who use pazopanib with controlled intake of GAS had a 23% lower pazopanib exposure. Therefore, we advice that in patients, who are unable to quit their GAS agent, pazopanib trough concentrations should be monitored in order to prevent shorter treatment benefit. Clinical trial information: NCT02138526.

11001 Background: The predominant pattern of failure of retroperitoneal sarcoma (RPS), frequently associated with subsequent death, is locoregional recurrence. Unlike in limbs, the efficacy of radiotherapy (RT) combined with surgery is not established. Methods: STRASS is a randomized, multicentre, international trial. Eligible patients had histologically-proven localized primary RPS, operable and suitable for radiotherapy. Patients were randomized 1:1 to preoperative RT (3D-CRT or IMRT) 50.4 Gy followed by surgery (RT/S group) or surgery alone (S group), stratified by hospital and performance status (0-1 vs 2). Primary endpoint is abdominal recurrence-free survival (ARFS; local relapse after complete resection, peritoneal sarcomatosis, R2 surgery, progressive disease during RT or unresectable disease). IDMC recommended a sensitivity analysis in which local progression on RT is not regarded as an event for patients who subsequently achieve complete surgical resection. Secondary endpoints were recurrence-free survival, overall survival, acute toxicity profile of RT, perioperative and late complications, and QoL. The study was designed to provide 90% power to show an increase of 20% in the 5-year ARFS rate, from 50% to 70% (corresponding to a HR of 0.52) at 2-sided 5% significance level. Results: 266 patients from Europe, USA and Canada were randomized between January 2012 and April 2017; 198 patients (74.5 %) had liposarcoma (LPS). Eighteen patients were designated ineligible. Overall rate of re-operation for any complication was 10.1%: 13 (10.9%) and 12 (9.4%) patients in RT/S versus S groups. 19 pts (14%) progressed during RT, 4 of whom did not undergo surgery. 3-year ARFS was 60.4% (95% Confidence interval (CI) 51.4-68.2%) and 58.7% (49.5- 66.7%) (HR = 1.01, 95%CI 0.71-1.44, p=0.954) in RT/S versus S groups. In the sensitivity analysis, 3-year ARFS was 66.0% (57.1-73.5%) and 58.7% (49.5-66.7%) in RT/S versus S groups (HR = 0.84, 95% CI 0.58-1.21, p=0.340). In the LPS subgroup, 3-year ARFS (sensitivity analysis) was 71.6% (61.3-79.6%) and 60.4% (49.8-69.5%) in RT/S versus S groups (HR = 0.64, 95%CI 0.40-1.01, p =0.049). Conclusion: STRASS failed to demonstrate a benefit of pre-operative RT for RPS. In the exploratory analysis, preoperative RT may benefit the LPS subgroup. Funding Source: EORTC and EUROSARC FP7 278472. Clinical trial information: EORTC 62092.

11042 Background: TGCT is a rare, locally aggressive neoplasm of the joint/tendon sheath linked to colony-stimulating factor 1 (CSF1) overexpression. Pexidartinib (pex), a selective inhibitor of CSF1 receptor, KIT, and FLT3-ITD, had a compelling tumor response rate in the TGCT cohort of a phase 1 study (NCT01004861) and significant tumor response vs placebo by RECIST v1.1 (39% vs 0%, P< 0.0001) and tumor volume score (TVS) (56% vs 0%, P< 0.0001) in the randomized, 2-part, crossover phase 3 ENLIVEN study (NCT02371369). Updated efficacy and safety with longer treatment are reported. Methods: Patients (pts) were ≥18 y with TGCT that was inoperable or for which surgery would likely be associated with worsening functional limitation or severe morbidity. Best overall response (complete or partial [CR/PR]) and duration of response (DOR) by RECIST and TVS were assessed by independent central review. Data cutoff was Jan 31, 2018, 16-67 mo after pts’ first dose. Results: In both studies 130 pts received pex, 61 ongoing at data cutoff. Median treatment duration was 17 mo (1, 60+). CR/PR rates were high and consistent and, together with DOR, improved with prolongation of treatment (Table). Most frequent adverse events were hair color change (75%), fatigue (60%), nausea (45%), arthralgia (38%), AST increase (30%), and diarrhea (30%). In ENLIVEN part 1, 3 of 61 (5%) pts had reversible ALT and AST ≥3 × ULN with TBil and ALP ≥2 × ULN; all started in the first 8 weeks of treatment, and no new cases emerged with continuation of treatment. Conclusions: Tumor response rate increased with continuation of pex treatment. The safety profile remained similar, with no new mixed or cholestatic hepatotoxicity. Clinical trial information: NCT01004861 and NCT02371369. [Table: see text]

e22511 Background: Gastrointestinal stromal tumour (GIST) is one of the most common soft tissue sarcoma subtypes. Regorafenib is the approved third line treatment after imatinib and sunitinib. Often GIST patients have an altered gastro-intestinal tract due to resection of the primary tumour. Gastric surgery may influence the exposure of orally administered TKIs. We investigated whether major gastrectomy influences the plasma exposure of regorafenib and treatment outcome. Methods: Efficacy and pharmacokinetic data from 133 GIST patients included in a phase III trial were analysed. Patients were subdivided into two groups according to the extent of the gastrectomy (no/non-significant gastrectomy and major gastrectomy). Progression free survival (PFS) on regorafenib was measured and regorafenib and its pharmacological active metabolites plasma exposure (Cav) were measured. Results: A total of 133 patient were included of which 27 underwent major gastrectomy. In patients with no/non significant gastrectomy the median PFS was 145 (IQR 43-281) days. The PFS in patients with a major gastrectomy was 172 (IQR 57-280) days. Regorafenib pharmacokinetic samples were collected in 80 patients of which 19 patients with a major gastrectomy and 61 patients with no/ non-significant gastric surgery. The average free aggregate concentration of regorafenib including the metabolites M-2 and M-5 was 6.9 µmol/L (CV% 44.5) and 6.7 µmol/L (CV% 46.5) in patient with major gastrectomy and no or non significant gastrectomy respectively. Conclusions: Our study shows that major gastrectomy did not influence plasma exposure of regorafenib and metabolites. In addition, no difference in progression free survival between the subgroups was seen.

11006 Background: Gastrointestinal stromal tumor (GIST) is the most common mesenchymal malignancy of the gastrointestinal tract. Advanced GIST is treated with tyrosine kinase inhibitors (TKIs). Most patients (pts) develop resistance over time. We reported in 2013 (Van Looy CTOS) that cabozantinib (cabo), a TKI targeting KIT/MET/AXL/VEGFR, showed activity in GIST xenograft models through inhibition of tumor growth, proliferation and angiogenesis, both in imatinib-sensitive and -resistant tumors (Gebreyohannes Mol Cancer Ther 2016;15:2845-28). Cohen (Cancer Res 2015;75:2061-70) found that cabo can overcome compensatory MET signaling in GIST in vitro. EORTC 1317 assessed the safety and activity of cabo in pts who had progressed on imatinib and sunitinib. Methods: In this multi-center, open label, single arm Phase 2 study eligible metastatic GIST pts received 60 mg (freebase weight) cabo p.o./d. Primary endpoint was progression-free survival rate at wk 12, assessed by local investigator per RECIST 1.1. If at least 21 of 41 eligible and evaluable pts were progression-free at wk 12, the activity of cabo was sufficient to warrant further exploration (A’Hern one-stage design). Results: A total of 50 consenting pts were eligible and started treatment between 02/2017 and 08/2018, with 16 (32%) still continuing cabo at the database cut-off in 01/2019. The number of 3 wk treatment cycles ranges from 2-28+. Among the first 41 eligible and evaluable pts, 24 were progression-free at wk 12, satisfying the study decision rule. Among all 50 pts, 30 were progression-free at wk 12 (60%, 95% confidence interval (CI) 45-74%). A total of 7 pts achieved a confirmed partial response (PR) (14%, 95%CI 6-27%) and 33 had stable disease (SD) (66%, 95%CI 51-79%). Progression as best response was seen in 9 pts (18%, 95%CI 9-31%), one was not evaluable. Disease control (PR+SD) was achieved in 40 pts (80%, 95%CI 66-90%). Median progression-free survival was 6.0 mo (95%CI 3.6-7.7). The most common cabo-related grade ≥3 adverse events were diarrhea (74%), hand-foot syndrome (58%), fatigue (46%), hypertension (46%), weight loss (38%) and oral mucositis (28%), with 33 (66%) pts requiring dose reductions, 25 (50%) treatment interruptions and no cabo-related deaths. Conclusions: EORTC 1317 met its primary endpoint, with 24/41 pts (58.5%) being progression-free at wk 12. Results of this trial confirm preclinical data and warrant further exploration of cabo in GIST. Clinical trial information: NCT02216578.

5026Background: After the introduction in the daily clinical practice of cabazitaxel (CABA) and new hormone agents (NHAs), abiraterone acetate (AA) and enzalutamide (ENZ), several small retrospecti...

11502Background: TGCT is a rare neoplasm of the joint/tendon sheath associated with colony-stimulating factor 1 (CSF-1) overexpression. No approved systemic therapy is available. Pexidartinib (Pex), a selective inhibitor of CSF-1 receptor, KIT, and FLT3-ITD, showed promising Phase 1 activity in TGCT. Two severe liver toxicity cases (1 required liver transplant, 1 associated with death) have been observed with Pex across the non-TGCT development program. Methods: Patients (pts) ≥18 yr with symptomatic TGCT, for whom surgery would be associated with potentially worse function or severe morbidity, were randomized (1:1) to Pex or placebo (Pbo) 1000 mg/d x 2 wks then 800 mg/d PO x 22 wks (Part 1). Pts completing Part 1 could continue into an open-label Pex extension (Part 2). The primary endpoint was centrally reviewed overall response rate (ORR) by RECIST at Week 25 for which the study was powered to detect a 25% difference (35% vs 10%). Results: 120 pts were treated, 61/59 on Pex/Pbo. Due to 2 cases of nonfa...

11540Background: ASPS is an orphan disease associated with rearrangement of transcription factor E3 (TFE3), leading to abnormal MET expression. We assessed crizotinib in pts with ASPS (NCT01524926)...

523Background: It has been postulated that endoxifen levels are better predictors of tamoxifen efficacy than CYP2D6 phenotype. Although in a retrospective study an endoxifen threshold of 5.9 ng/ml ...

11518Background: To determine whether high-risk STS patients identified using individual patient data and the nomogram Sarculator, benefitted from adjuvant chemotherapy in a RCT which failed to det...

11574Background: LMS is one of the most common soft tissue sarcoma histotypes that may arise in any site of the body. In advanced disease, first line treatment is still based on Do alone or in comb...

PURPOSE: The paclitaxel vehicle Cremophor EL (CrEL) profoundly influences the cellular distribution of paclitaxel in human blood in vitro by a concentration-dependent decrease of the unbound drug fraction. Because CrEL clearance increases by extending the infusion duration from 3 to 24 hours, we hypothesized that exposure to unbound paclitaxel might also be schedule-dependent. PATIENTS AND METHODS: CrEL and unbound paclitaxel pharmacokinetics were prospectively analyzed in 29 patients with advanced solid tumors treated with paclitaxel 100 mg/m2 given as a 1-hour (n = 15) or 3-hour (n = 14) intravenous infusion. RESULTS: The systemic exposure (area under the curve [AUC]) to CrEL was significantly higher with the 1-hour as compared with the 3-hour schedule (80.2 ± 24.2 v 48.5 ± 24.1 μL·h/mL; P = .002). In contrast, the AUC of unbound paclitaxel was substantially reduced after the 1-hour infusion (0.50 ± 0.10 v 0.62 ± 0.12 μmol/L·h; P = .009). Similarly, clearance and volume of distribution were significantly dependent on infusion duration (P < .005). A trend was observed toward more severe hematologic toxicity with the 3-hour schedule (P = .053), consistent with increased exposure to unbound drug. CONCLUSION: Overall, these findings explain, at least in part, previous observations that short-infusion schedules of paclitaxel lack significant myelotoxicity, whereas potentially CrEL-related side effects, including peripheral neuropathy, are augmented.

2547 Background: Bringing precision medicine to cancer patients remains a challenge. For many cancers, the relative contribution of tumor type, mutations or CNV to drug sensitivity remains unknown. In addition, drug access is generally limited to the labeled indication, bypassing rarer disease subgroups for which large trials are not feasible. An innovative trial that facilitates drug access, whilst systematically analyzing treatment outcomes and biomarkers, could help overcome these challenges. Methods: We designed a prospective, non randomized clinical trial in which patients with advanced cancer are treated with targeted or immunotherapy matched to their tumor profile, defined by genetic aberration, microsatellite instability (MSI) or high mutational load (HML). Upon a mandatory pre-treatment tumor biopsy for biomarker research, patients are enrolled in multiple parallel cohorts, each defined by study drug, histologic tumor type and molecular tumor profile. Efficacy is analyzed per cohort, enrolling 8 patients in stage I and 16 more in stage II if ≥1 response is observed in stage I. Study endpoints include objective tumor response (CR or PR), stable disease (SD) at 16 weeks and grade≥3 adverse events. The DRUP is registered at ClinicalTrials.gov (NCT02925234). Results: Since start of recruitment in Sep 2016, 76 patients have been submitted for review (mean per month 15, range 8-17) and 16 (21%) have started treatment in 10 different cohorts, directed at either ATM (n = 1; breast cancer), BRAF (n = 2; salivary duct carcinoma and ACUP), BRCA (n = 1; breast cancer), ERBB2 (n = 2; CRC), HML (n = 2; prostate and CRC), MSI (n = 5; CRC, GBM and urothelial carcinoma), RET (n = 1; NSCLC) or RAS-RAFwt (n = 2; SCC and sarcoma). Out of the 7 patients for whom response evaluation is available, PR (n = 2) or SD at 16 weeks (n = 1) was observed in 3 (43%). Thirteen study drugs (supplied by 6 pharmaceutical companies) are currently available, 6 more are expected soon. Conclusions: Execution of a nationwide multidrug precision oncology trial is feasible. It contributes to oncologists’ education on molecularly targeted therapies and to identification of early signs of activity in rare cancer subsets. Data sharing with similar studies such as TAPUR and CAPTUR will help to enlarge cohorts and affirm conclusions. Clinical trial information: NCT02925234.

11078 Background: TGCTis a proliferative, neoplastic joint disease that presents as single nodule (local) or multiple nodules (diffuse D-TGCT). Localized overexpression of colony stimulating factor 1 (CSF1) leads to recruitment of cells expressing the CSF1 receptor (CSF1R), formation of a tumor and inflammation of joints and tendons. Cabira is a monoclonal antibody that inhibits the interaction of the CSF1 and IL-34 ligands with their shared receptor CSF1R. Methods: This Ph 1/2 study is evaluating the safety and efficacy of cabira monotherapy administered IV Q 2wk for 6 mo in patients (pts) with D-TGCT. Eligible pts have inoperable D-TGCT or tumor for which resection would cause unacceptable morbidity. Response is evaluated by MRI, pt reported outcomes, and Ogilvie-Harris (O-H) score (which combines pain, synovitis, range of motion and functional capacity on a scale of 0-12). Results: As of 15 Dec 2016, 22 pts received ≥ 1 dose of cabira at 1, 2 or 4mg/kg. Dose-related exposure increase and significant reduction in target peripheral monocytes were observed. No dose limiting toxicity was identified. 4 mg/kg was chosen for Ph2 based on efficacy, tolerability, and PK. AEs ≥ Gr 2 ( > 10%) were CK elevation 46%, rash and other skin disorders 36%, fatigue 23%, and periorbital/peripheral/face edema 18% each. Gr 3 AEs in ≥ 2 pt were CK elevation (n = 8) and periorbital edema (n = 2). Four drug-related SAEs were reported in 3 pts; hypertension, fever, CRP elevation, and myocarditis. AEs of CK elevation were asymptomatic, improved to < 2X ULN after protocol mandated drug discontinuation and are a known on-target effect of CSF1R inhibition. An amendment was made during Phase 2 to allow dosing with higher CK levels Activity at 4 mg/kg was: 1PR and 1 CK discontinuation in 3 pts in Ph1; 4 PRs in 7 evaluable pts with 6 additional ongoing in Ph2. Positive functional status improvements by O-H score were noted in objective responders (from 2 to 7). Conclusions: The initial demonstration of objective and functional activity supports further development of cabiralizumab in pts with D-TGCT. Updated data from the ongoing Ph2 will be presented. NCT02471716 . Clinical trial information: NCT02471716.

11026Background: Local recurrence (LR) is associated with very poor prognosis in ES patients. We sought to identify factors associated with LR in patients undergoing multimodal treatment. Methods: ...

TPS3113Background: The synthetic long peptide (SLP) vaccine against the human papillomavirus type 16 (HPV16) oncoproteins E6 and E7 applied to high-grade premalignant HPV16-induced lesions of the v...

e22502Background: We analyzed preoperative data from EURAMOS-1, a large study in resectable osteosarcoma where the regimen is MAP (Methotrexate/Adriamycin/Cisplatin), focusing on the effect on Hist...

11011Background: PDGFRA D842V-mutated GISTs are known for their insensitivity to imatinib. However, in clinical practice responses have been observed in some patients. We describe the natural histo...

3060Background: PDR001 is a humanized anti-PD-1 IgG4 antibody that blocks the binding of PD-L1 and PD-L2 to PD-1. PDR001 binds to PD-1 with high affinity and inhibits the biological activity of PD-...

10544 Background: DOX pharmacokinetics vary substantially between patients leading to large differences in systemic drug levels. Given potential dose-effect relations, patients with the greatest to...

4548 Background: In our exploratory studies we have associated single nucleotide polymorphisms (SNPs) in candidate genes with efficacy and toxicities of sunitinib in metastatic renal cell carcinoma...

10512 Background: EURAMOS-1 (NCT00134030) is an international study in osteosarcoma including two Phase III randomized controlled trials that investigated postoperative treatment optimization on th...

LBA10502 Background: In a phase II study of pts with advanced soft tissue sarcoma, 32% and 47% of pts with LMS and ADI respectively, treated with the microtubule dynamics inhibitor eribulin achieved progression-free survival (PFS) at the 12 wk timepoint (Schöffski et al. Lancet Oncol. 2011; NCT00413192). Based on these findings, this phase III study (NCT01327885) compared overall survival (OS) in pts with advanced LMS and ADI treated with eribulin or dacarbazine. Methods: Pts aged ≥ 18 yrs with advanced high/intermediate grade LMS or dedifferentiated, myxoid, round cell or pleomorphic variants of ADI incurable by surgery and/or radiotherapy were enrolled. Pts had ECOG status ≤ 2 and had received ≥ 2 standard systemic treatment regimens including an anthracycline. Pts were randomized 1:1 to eribulin (1.4 mg/m2, IV on D1 and D8) or dacarbazine (850–1200 mg/m2, IV on D1) every 21 days until disease progression. Primary endpoint was OS. Secondary endpoints included PFS, PFS rate at Wk 12 and safety. Results: Overall, 452 pts (67% female; 79% < 65 yrs) were randomized (228 eribulin; 224 dacarbazine). Median OS for eribulin and dacarbazine was 13.5 and 11.5 months, respectively (HR = 0.768, 95% CI 0.618–0.954; P= 0.017). PFS was 2.6 months in both arms (HR = 0.877, 95% CI 0.710–1.085; P= 0.229). PFS rate at Wk 12 was 33% and 29% for eribulin and dacarbazine, respectively. In eribulin and dacarbazine arms, respectively, 26% and 14% of pts required dose reductions and 8% and 5% discontinued due to treatment-emergent adverse events (TEAEs). TEAEs were more frequent in eribulin than dacarbazine arm, including neutropenia (44% vs 24%), pyrexia (28% vs 14%), peripheral sensory neuropathy (20% vs 4%) and alopecia (35% vs. 3%); as were TEAEs of grade 3 (63% vs 53%), grade 4 (26% vs 20%), and fatal TEAEs (4% vs 1%). Thrombocytopenia was more frequent in dacarbazine than eribulin arm (28% vs 6%). Conclusions: This phase III trial of eribulin trial met its primary objective of OS benefit in pretreated pts with advanced LMS or ADI. Eribulin had a toxicity profile consistent with prior experience, with no unexpected or new safety findings. Funding Source: Eisai Inc. Clinical trial information: NCT01327885.

10561 Background: TGCT is a rare disease affecting the synovium and tendon sheaths of young adults. This usually benign neoplasm is driven by overexpression of CSF1, in some cases as a result of fu...

e21500 Background: A marginal interaction between gender and type of alkylating agent (cyclophosphamide or ifosfamide) on event-free survival was observed in the randomized controlled trial (RCT) E...

10549 Background: This study retrospectively explored the role of KIT and PDGFRA mutations in response to SU therapy in pts with imatinib (IM)-resistant/intolerant GIST in a worldwide TU trial. Met...

10542 Background: OHN is rare and behaves differently from osteosarcoma in the extremities. There is an ongoing debate about the value of (neo-) adjuvant chemotherapy in OHN. In this study we descr...

11074 Background: Variation in the genes coding for the estrogen receptor (ESR-1), CYP2c19 and UGTB15 is associated with worse outcome in tamoxifen treated early breast cancer patients. It is uncle...

6053 Background: The CONDOR study, a randomized phase II trial, investigated feasibility of TPF followed by conventional CRT with cisplatin 100 mg/m2 on days 1,22,43 (cis100+RT) versus CRT with acc...

LBA10504 Background: EURAMOS-1 (NCT00134030) is an international randomized controlled trial investigating treatment optimization in osteosarcoma on the basis of histologic response to preoperative chemotherapy (CT). In patients (pts) with “good response” (GR

e20669 Background: Mucocutaneous adverse events (mcAEs), including papulopustular rash, xerosis, pruritus, paronychia, hand-foot skin reaction, edema, taste alterations, oral pain and ulceration, hair-, periungual-, and ocular changes occur in the majority of patients during targeted anticancer therapies. Different mcAEs can be present with a variable symptom burden and affect upon patients’ quality of life. Use of standardized targeted therapy specific tools allows comparison of outcomes from different studies and in meta-analyses, advancing patient care and improving outcomes. A mcAE specific assessment tool about symptom burden is currently not available. A questionnaire which assesses both targeted therapy specific patient reported outcomes (PRO) measures and healthcare provider reported outcomes (HPRO) measures is warranted, therefore. Methods: A three-phase process was utilized for item generation, item reduction and scale construction. A comprehensive literature review was performed in PubMed, CINAHL and Embase, and study protocols were screened. Keywords were assessment, questionnaire, tool, EGFRI, and rash. All items with potential relevance for the tool were selected for further evaluation. Twentyone EGFRI treated patients filled out the draft-questionnaire. Results: The search resulted in a simultaneous tool in the form of 61 PRO, and 50 HPRO items. Both tools assess experienced mcAEs inclusive number of papules and pustules, area involved, severity and duration of the symptoms, used products, effectiveness of various (medical) interventions, treatment adherence and distress from the symptoms. Patient input resulted in the addition of 1 item, modification of 7 items, and deletion of 2 items. Conclusions: A novel tool has been generated to assess the experienced mcAEs and effectiveness of supportive care interventions. Since the patient and the provider report mcAEs simultaneously, the provided data are directly comparable, facilitating assessment of quality of life and, therefore, improving quality of medical care.

10547 Background: GIST patients often have an altered anatomy of the GI tract due to either primary resection of the tumor or palliative surgery. It is unknown whether such GI resections affect the exposure to sunitinib and its active metabolite SU12662. Previous studies showed that the exposure to imatinib and nilotinib was decreased in GIST patients with prior major gastrectomy. Therefore, we postulated that GI resections might similarly affect sunitinib exposure. Methods: A retrospective analysis was performed to assess the effect of GI resections on sunitinib exposure. Pharmacokinetic data from 305 GIST patients included in 4 phase I-II trials were analyzed. Patients were subdivided into 6 groups according to prior GI surgery: 1)Major gastrectomy: 2)Partial gastrectomy: 3)Small bowel resection: 4)Combination of gastrectomy and small bowel resection: 5)Colon resection and 6)Controls with no prior GI surgery. Patients with uncertain GI resections were excluded. Dose normalized exposure (AUC0-24hr) of sunitinib and SU12662 was estimated with a population PK approach using NONMEM. Analysis of covariance was performed to test for significant differences in AUC between each of the subgroups and controls. Results: The geometric mean of total exposure to sunitinib and SU12662 was decreased by 21% and 28% in subgroup 4, (n=8; sunitinib: 931 ng*hr/mL (95%CI;676-1283) and SU12662: 354 ng*hr/mL (95%CI;174-720)) compared to controls (n=63; sunitinib: 1177 ng*hr/mL (95%CI;1097-1263) and SU12662: 491 ng*hr/mL (95%CI;435-555)), with the differences being significant (p

597 Background: The clinical importance of CYP2D6 genotype as predictor of tamoxifen efficacy is still unclear. Recent genotyping studies on CYP2D6 using DNA derived from tumor blocks have been criticized because loss of heterozygosity (LOH) in tumors may lead to false genotype assignment. Methods: Postmenopausal early breast cancer patients who were randomized to receive tamoxifen, followed by exemestane in the Tamoxifen Exemestane Adjuvant Multinational trial (TEAM) were genotyped for 5 CYP2D6 variant alleles. CYP2D6 genotypes and phenotypes were related to disease free survival during tamoxifen use (DFS-t) in 731 patients. By analyzing three microsatellites flanking the CYP2D6 gene, patients whose genotyping results were potentially affected by LOH were excluded. Results: Analysis of the CYP2D6 alleles and the microsatellite markers demonstrated heterozygosity for at least one of the CYP2D6 alleles or microsatellite markers in 97.7% of patients with a specified CYP2D6 phenotype. The 14 patients (2.3%) with a homozygous CYP2D6 genotype in which no heterozygosity could be demonstrated for the microsatellite markers were excluded from the analysis. No association was found between the CYP2D6 genotype or predicted phenotype and DFS-t. Conclusions: In postmenopausal early breast cancer patients treated with adjuvant tamoxifen followed by exemestane neither CYP2D6 genotype nor phenotype was associated with DFS-t. This is in accordance with two recent studies in the BIG1-98 and ATAC trials. Our study is the first CYP2D6 association study using DNA from paraffin embedded tumor tissue in which potentially false interpretation of genotyping results because of LOH was excluded.

2592 Background: Patients treated with sunitinib show high inter-patient variability in drug exposure (40-60%), which is largely unexplained. Since sunitinib is metabolized by CYP3A4, variability in the activity of this enzyme may explain a considerable proportion of the observed variability. We therefore prospectively studied the relationship between CYP3A4 activity and systemic exposure to sunitinib. Methods: In fifteen patients treated with sunitinib in a four weeks “on” – two weeks “off” regimen the pharmacokinetics of sunitinib and its active metabolite SU12662 were assessed. To determine sunitinib+SU12662 steady-state exposure, samples were collected over 24hrs after at least 14 days of sunitinib therapy. To assess CYP3A4 activity, midazolam 7.5mg orally was administered on the final day of the two weeks “off”. Plasma concentrations were measured over a period of 7hrs to determine midazolam exposure. Exposures (AUC) were calculated using a trapezoidal approach (Phoenix WinNonlin v6.3). The relationship between CYP3A4 activity (midazolam exposure) and sunitinib+SU12662 exposure was determined by linear regression analysis. The percentage of variability in sunitinib+SU12662 exposure that could be explained by CYP3A4 activity was calculated by Pearson’s correlation. In addition, the correlation between sunitinib+SU12662 Ctrough levels and sunitinib+SU12662 exposure was assessed. Results: A strong correlation between midazolam exposure (AUC0-7hr) and steady-state sunitinib+SU12662 exposure (AUC0-24hr) was found (p= 0.002); CYP3A4 activity explained 55% of the observed inter-patient PK variability of sunitinib+SU12662. Furthermore sunitinib+SU12662 Ctrough levels were highly predictive (96%) for overall sunitinib+SU12662 exposure (AUC0-24hr). Conclusions: Midazolam as a phenotyping probe could be useful before start of sunitinib therapy to identify patients at risk for under- respectively overtreatment at a standard dosage regimen. Therefore, CYP3A4 phenotyping could be useful to individualize sunitinib therapy. Additionally, sunitinib+SU12662 trough levels are highly predictive for sunitinib+SU12662 exposure and thus can be used for monitoring and guiding sunitinib therapy in clinical practice. Clinical trial information: NCT01743300.

LBA10504 Background: EURAMOS-1 (NCT00134030) is an international randomized controlled trial investigating treatment optimization in osteosarcoma on the basis of histologic response to preoperative chemotherapy (CT). In patients (pts) with “good response” (GR