4122 Background: CAPTEM is an accepted regimen for patients (pts) with advanced pNETs. Single agent PRRT is now a standard of care for progressive WHO Grade 1/2 mNETs. High activity was seen with PRRT/CAPTEM in a single arm Phase I/II trial. This study aims to determine the activity of combining CAPTEM with PRRT in mNETs and pNETs pts. Methods: Non-comparative randomised open label parallel group phase II trial with 2:1 randomisation to PRRT/CAPTEM (experimental arm) vs. PRRT (mNETs control) and CAPTEM (pNETS control). PRRT/CAPTEM: 7.8GBq 177Lu Octreotate (Lutate) given intravenously (IV) on day 10 every 8 weeks for 4 cycles, with concurrent oral capecitabine 750mg/m2 b.i.d. days 1-14 and temozolomide 75mg/m2 b.i.d. days 10-14 every 56 day cycle, up to 4 cycles. PRRT alone: 7.8GBq 177Lu Octreotate (Lutate) given intravenously (IV) on day 1 every 8 weeks for 4 cycles. CAPTEM alone: Oral capecitabine 750mg/m2 b.i.d. days 1-14 and days 29-42; Oral temozolomide 75mg/m2 b.i.d. days 10-14 and 38-42 every 56 day (8w) cycle. Primary endpoint: Progression free survival (PFS). mNETS: At 15 months, assuming PFS 66.4% in control arm; target PFS ³ 80%; pNETS: At 12 months, assuming PFS 60% in control arm; target PFS ³ 75%. Secondary endpoints: Objective tumor response rate (complete or partial) (OTRR), overall survival (OS), adverse events (AEs). Results: 75 pts enrolled (Dec 2015 – Nov 2018): mNETs 33 PRRT/CAPTEM, 14 PRRT, median follow up (mFU) 60.3 months; pNETS 19 PRRT/CAPTEM, 9 CAPTEM, mFU 57.5 months (mo). Late Grade 3/4 haematologic AEs: mNETS: 2/32 (6%) PRRT/CAPTEM pts and 4/13 (31%) PRRT pts. Events included myelodysplastic syndrome (40 mo), leukaemia (60 mo), pancytopenia (50 mo), anaemia (32 mo), thrombocytopenia (7 mo). No late haematologic G3/4 AEs were reported in the pNETS cohort. No late renal toxicity was identified in all study arms. Conclusions: CONTROL NETs is the first randomized trial to demonstrate efficacy for PRRT in pNETs, in addition to a standard of care. Extended follow up confirms durable CAPTEM/PRRT activity, with superior PFS in pNETs. Late haematologic toxicity was seen in both mNET PRRT arms but was not higher with additional CAPTEM. The activity of CAPTEM/PRRT in pNETs should be tested in the phase III setting. Clinical trial information: ACTRN12615000909527. [Table: see text]

TPS8599 Background: Two phase 2 trials of durvalumab plus chemotherapy in advanced pleural mesothelioma exceeded pre-specified efficacy criteria. The recent CM 743 trial showed overall survival (OS) was longer in those assigned ipilimumab and nivolumab (ipi nivo) than standard chemotherapy, however the benefits were primarily in the subgroup with non-epithelioid histology. DREAM3R will determine the effectiveness of durvalumab plus chemotherapy as first line treatment for advanced pleural mesothelioma. The DREAM3R protocol was recently amended to allow treatment with ipi nivo as per CM 743 in the control group, and to confine further accrual to epithelioid subtype. Methods: Treatment-naïve patients with advanced, epitheloid pleural mesothelioma will be randomized (1:1) to either experimental group treatment: durvalumab 1500 mg every 3 weeks plus chemotherapy (pemetrexed 500 mg/m2 plus either cisplatin 75 mg/m2 or carboplatin AUC 5) every 3 weeks for 4-6 cycles, followed by durvalumab 1500 mg every 4 weeks until disease progression, unacceptable toxicity or patient withdrawal, or control group treatment: physician’s choice of either chemotherapy or ipi nivo (up to 2 years). The target sample size of 480 recruited over 33 months, with follow up for another 18 months provides over 85% power if the true hazard ratio for OS is 0.70, with 2-sided alpha of 0.05, assuming a median OS of 18 months in the control group. Key eligibility criteria: Epithelioid pleural mesothelioma; measurable disease per RECIST 1.1 modified for mesothelioma; ECOG PS 0-1; and adequate hematologic, renal, and liver function. Exclusions: Prior systemic anticancer treatment for pleural mesothelioma, diagnosis based solely on cytology or fine needle aspiration biopsy, contraindication to immunotherapy or conditions requiring immunosuppressive agents or corticosteroids. Participants are stratified at randomization for: age (18-70 years vs. > 70), sex, planned control regimen (chemotherapy or ipi nivo), platinum (cisplatin vs. carboplatin) and geographic region (USA vs. ANZ). The primary endpoint is OS. Secondary endpoints include progression-free survival; objective tumor response; adverse events; health-related quality of life; and use of healthcare resources in ANZ. Tertiary objectives are to identify potential prognostic and/or predictive biomarkers (including those identified in prior phase 2 studies, PD-L1 expression, tumor mutation burden, genomic characteristics, and HLA subtypes), validation of radiological measures of response, and studies of possible radiomic biomarkers in mesothelioma. The study is active and enrolling in both ANZ and in the US. Clinical trial information: NCT04334759 and ACTRN12620001199909 .

TPS8599 Background: Combination PD1/CTLA4 immune checkpoint blockade and platinum-pemetrexed (CP) chemotherapy are standard first-line options for the treatment of unresectable malignant pleural mesothelioma (MPM). Two recent, single-arm, phase 2 trials (DREAM and PrE0505) combining the PD-L1 inhibitor durvalumab and standard first line CP both exceeded pre-specified efficacy criteria. The Phase 3 DREAM3R trial aims to determine the effectiveness of including durvalumab with first line CP chemotherapy in advanced MPM. Methods: Treatment-naïve patients with advanced MPM will be randomized (2:1) to either durvalumab 1500 mg every 3 weeks plus chemotherapy (cisplatin 75 mg/m2 or carboplatin AUC 5 and pemetrexed 500 mg/m2) every 3 weeks for 4-6 cycles (Arm A), followed by durvalumab 1500 mg every 4 weeks until disease progression, unacceptable toxicity or patient withdrawal, versus doublet chemotherapy alone for 4-6 cycles with all patients monitored for progression. The target sample size is 480 patients recruited over 27 months, with follow up for an additional 24 months. This provides over 85% power if the true hazard ratio for overall survival (OS) is 0.70, with 2-sided alpha of 0.05, assuming a median OS of 15 months in the control group. Key eligibility criteria include: MPM of any histological subtype; measurable disease per RECIST 1.1 modified for mesothelioma (mRECIST 1.1); ECOG PS 0-1; and adequate hematologic, renal, and liver function. Exclusions: Prior systemic anticancer treatment for MPM, diagnosis based solely on cytology or fine needle aspiration biopsy, contraindication to immunotherapy or conditions requiring immunosuppressive agents or corticosteroids. Patients will be further stratified at randomization by: Age (18-70 years vs. > 70), sex, histology (epithelioid vs. non-epithelioid), planned platinum (cisplatin vs. carboplatin) and geographic region (USA vs. ANZ). The primary endpoint is OS. Secondary endpoints include progression-free survival; objective tumor response; adverse events; health-related quality of life; and healthcare resource use in ANZ. Tertiary correlative objectives aim to further explore and validate potential prognostic and/or predictive biomarkers (including those identified in the DREAM and PrE0505 studies, PD-L1 expression, tumor mutation burden, genomic characteristics, and HLA subtypes) via tissue and serial blood samples. An imaging databank will be assembled for validation of radiological measures of response, and studies of possible radiomic biomarkers in mesothelioma. The study is active and enrolling in both ANZ and in the US. Clinical trial information: NCT04334759 and ACTRN 12620001199909.