Citations

4505 Background: While inhibiting VEGF improves outcomes in mRCC pts, most develop resistance, often within a year. Here, we report results from a Ph II study of atezo (anti–PD-L1) and bev (anti-VEGF) vs and following atezo or sun (TKI) in mRCC pts. Methods: Pts with untreated mRCC were enrolled in the hypothesis generating IMmotion150 study (NCT01984242) and randomized to atezo 1200 mg IV q3w + bev 15 mg/kg IV q3w, atezo alone or sun 50 mg PO QD 4 wk on/2 wk off. After progression on atezo or sun, crossover to atezo + bev was allowed. PD-L1 status was scored on tumor-infiltrating immune cells (IC, SP142 IHC assay). The primary analysis was modified prior to final analysis to reflect the coprimary endpoints of IRF-assessed PFS (RECIST v1.1) in ITT pts and pts with PD-L1 expression on ≥ 1% of IC (PD-L1+). Results: 54% of pts were PD-L1+. In PD-L1+ pts 1L treatment resulted in a PFS hazard ratio (HR) of 0.64 for atezo + bev vs sun (table). After 1L treatment, 78% of sun and 60% of atezo pts who progressed subsequently received atezo + bev and achieved ORRs of 28% and 24%, respectively (table). Safety was comparable to the known individual profiles of atezo and bev. Additional clinical, safety and biomarker data will be presented. Conclusions: Atezo + bev resulted in encouraging antitumor activity in 1L pts with PD-L1+ mRCC. Preliminary activity in the 2L setting was demonstrated in pts who crossed over to atezo + bev, regardless of prior therapy. 1L atezo + bev vs sun is being evaluated in the ongoing Ph III study IMmotion151 (NCT02420821). Clinical trial information: NCT01984242. [Table: see text]

e15168 Background: 2-8% of all colorectal cancer (CRC) cases are in younger adults (YAs), patients (pts) less than age 50. However, current understanding of CRC in YAs is inadequate, especially that of sporadic onset. We conducted a study to describe the landscape of genomic alterations in YA CRC pts presenting to a large academic practice. Methods: Adult pts with CRC presenting to The Ohio State University Comprehensive Cancer Center oncology clinics were offered next generation sequencing (NGS) through a customized 22-gene Ion AmpliSeq Mutation Panel as part of clinical care. Commonly mutated areas of select genes (including AKT1, ALK, BRAF, EGFR, ERBB2/4, FBXW7, FGFR1/2/3, KRAS/NRAS, MET, NOTCH1, PIK3CA, PTEN, TP53) were sequenced from tumor sections. Institutional review board approval was obtained to retrospectively analyze this NGS testing between 1/2013-3/2016. Results: 258 CRC pts underwent genomic profiling. 57 pts (22.1%) were YAs at diagnosis (range 22-49 years); 20 pts (7.8%) were 40 years old or younger. 31 YA pts (54.4%) had metastatic disease. Of the YAs with CRC, 18 pts (31.6%) were diagnosed with R-sided colon, 16 pts (28.1%) with L-sided colon, and 22 pts (38.6%) with rectal cancer. 110 genomic alterations were found in YA pts, with a mean of 1.9 mutations per tumor (range 0-6); 35 (31.8%) of these in 32 (56.1%) YA pts were actionable. Of these 110 alterations, 41.8% were in TP53, 28.2% in KRAS/NRAS, 10.0% in PIK3CA, 3.6% in BRAF, 3.6% in FBXW7, and 2.73% in PTEN. 6 YA pts (10.5%) had microsatellite instability (MSI-H). Only 1 pt had concomitant MSI-H and a BRAF mutation; 4 pts with BRAF mutations were microsatellite stable. Comparing our YA pts to a separate cohort of pts age > 50 who had testing done, no significant difference was seen in mutation incidence in KRAS/NRAS (p = 1.0), TP53 (p = 0.3), PIK3CA (p = 0.128), or BRAF (p = 1.0). Conclusions: Genomic profiling through a targeted NGS panel is feasible as part of routine clinical practice. There is disagreement in the literature on genetic mutations in YA compared to older age CRC pts. Knowledge of the genomic landscape in YAs with CRC will lead to improved understanding of the underlying biology of CRC in YAs as it differs from CRC in older pts, and could impact future care of this cohort.

TPS3624 Background: To improve survival for patients with mCRC, efforts are needed to identify and treat actionable genomic alterations. HER2 is amplified in approximately 5-8% of patients with KRAS and NRAS (RAS) wild-type mCRC. HER2 functions as an oncogenic driver and a mediator of EGFR antibody (Ab) resistance. Although prior studies have shown that anti-HER2 therapies are active in patients with HER2+ (HER2 IHC 3+ or HER2 amplified) mCRC, there are no HER2-directed therapies approved for these patients. Tucatinib is a potent and highly selective oral small molecule tyrosine kinase inhibitor of HER2, currently being developed to treat metastatic breast cancer. In HER2+ CRC patient derived xenograft models, tucatinib has substantial anti-tumor activity. The addition of the anti-HER2 monoclonal Ab trastuzumab augments tumor growth inhibition. Methods: This single-arm phase II study will test the combination of tucatinib and trastuzumab in patients with HER2+ mCRC. Eligible patients include those with RAS wild-type mCRC who have been previously treated with 5-FU, oxaliplatin, irinotecan, and an anti-VEGF monoclonal Ab. Patients must have HER2+ disease by IHC, FISH, or NGS. Prior treatment with anti-HER2 targeting therapy is excluded. The primary objective is to assess the objective response rate for the combination. Secondary objectives are to evaluate the efficacy (PFS, OS, clinical benefit rate), safety, and tolerability of the combination. Correlation between tissue and blood-based biomarkers and clinical outcomes will be explored. Blood will be collected at baseline and each restaging to determine if the combination eliminates HER2 amplified circulating tumor DNA. Subjects will receive tucatinib at a dose of 300mg by mouth daily, and trastuzumab will be administered every 3 weeks (8 mg/kg IV day 1 of cycle 1, then 6 mg/kg IV Q3 weeks). Response will be assessed every 3 cycles (9 weeks) per RECIST version 1.1. Both agents will be provided by the study. This study was initiated in February 2017. Recruitment is ongoing at 8 sites in the Academic and Community Cancer Research United (ACCRU) network. Clinical trial information: NCT03043313.

3612 Background: The RAS/RAF/MEK signal transduction pathway is critical to the development of colorectal cancer, and tumors harboring KRAS, NRAS, and BRAF mutations were shown to be resistant to radiation. Thus, we conducted a phase I study of trametinib, a potent MEK1/2 inhibitor, in combination with CRT in patients with LARC. Methods: Phase I trial for patients with Stage II/III rectal cancers with a 3+3 design, and an expansion cohort of 12 patients at the maximum tolerated dose (MTD). Trametinib is given orally at 3 dose levels: 0.5mg, 1mg, and 2mg (Mon-Fri). CRT regimen is infusional 5-flourouracil (5FU) 225mg/m2/day (Mon-Fri) and daily fractions of 1.8 Gy (total 50.4Gy). There is a 5-day trametinib lead-in followed by trametinib and CRT. Six to 10 weeks after completion of CRT, patients then proceed to their surgery and adjuvant therapy. The primary endpoint is to identify the MTD and recommended phase 2 dose of trametinib with CRT. Immunohistochemistry staining for phosphorylated –ERK (pERK) and genomic profiling is performed on the tumor samples. Results: Enrollment is complete at all dose levels with18 patients, and 15 patients evaluable for toxicity and response as of Feb 6. One dose-limiting toxicity of diarrhea was observed at the 2mg dose. Grade 3 and most common toxicities are shown in Table 1. No grade 4/5 toxicities have been observed. At 2mg dose level, 3/9 (33%) patients had pathological complete response (pCR) and 2/9 (22%) had a near pCR. Correlative studies confirm decrease in pERK levels with increasing doses of trametinib. Correlation of genomic mutational status with toxicity, response, and outcomes is being analyzed. Conclusions: The combination of trametinib with 5FU CRT is tolerable with promising preliminary activity. Final results will be presented at the meeting. Toxicities. Clinical trial information: NCT01740648. [Table: see text]

TPS5602 Background: Primary cytoreductive surgery (PDS) followed by chemotherapy has been considered as standard management for advanced ovarian cancer patients (pts) over decades. An alternative approach of interval debulking surgery (IDS) following neoadjuvant chemotherapy (NACT) was subsequently reported by two randomized phase III trials (EORTC‐GCG, CHORUS). Owing to important limitations of these studies, especially regarding surgical quality, optimal timing of surgical therapy in advanced ovarian cancer is still unclear. Methods: TRUST is an international open, randomized, controlled multicenter trial investigating overall survival (OS; primary endpoint) after PDS vs NACT and subsequent IDS in pts with FIGO stage IIIB‐IVB ovarian, tubal, and peritoneal carcinoma. Secondary objectives are safety of complete tumor resection, progression‐free survival and quality of life (QoL) as well as surgical morbidity. In order to guarantee adequate surgical quality, participating centers need to fulfill specific quality assurance criteria (e.g. ≥50% complete resection rate in upfront surgery for FIGO IIIB-IV pts, ≥36 debulking-surgeries/year) and agree to independent audits by TRUST Quality committee delegates. A 1:1 randomization to PDS or NACT followed by IDS stratified by center and age‐ECOG combination (ECOG 0 and age ≤65 years vs ECOG > 0 or age > 65 years) is performed. Pts in the PDS arm will undergo surgery followed by 6 cycles of platinum-based chemotherapy, whereas pts in the IDS arm will be treated with 3 cycles of NACT after histologic confirmation of the disease, followed by IDS and subsequently 3 cycles of platinum-based chemotherapy. Intention of surgery for both groups will be complete tumor resection as per guideline recommendations. Health related QoL will be assessed using the EORTC QLQ‐C30, QLQ‐OV28, and EQ‐5D‐3L questionnaires. For sample size planning, we considered a prolongation of median OS from 45 months in the IDS arm to 60 months in the PDS arm (HR 0.75) as clinically relevant. 380 events are needed to obtain a power of 80% in two‐sided log-rank test with significance level of 0.05. The primary analysis will be done in the ITT‐population of 686 randomized pts. By Feb 3 2017, 46 pts were randomized. Clinical trial information: NCT02828618.

506 Background: Pembro is an anti-PD-1 antibody with single agent activity in HER2– metastatic BC. I-SPY 2 is a multicenter, phase 2 platform trial which evaluates novel neoadjuvant therapies; the primary endpoint is pathological complete response (pCR, ypT0/Tis ypN0). We report current efficacy results, with final results at ASCO. Methods: Patients (pts) with invasive BC ≥2.5 cm by exam or ≥2 cm by imaging are assigned weekly paclitaxel x 12 (control) +/- an experimental agent, followed by doxorubicin/cyclophosphamide x 4. Combinations of hormone-receptor (HR), HER2, & MammaPrint (MP) status define the 8 signatures studied. MP low HR+ BC is excluded. Adaptive randomization is based on each arm’s Bayesian probability of superiority over control. Graduation by signature is based on an arm’s Bayesian predictive probability of a successful 1:1 randomized phase 3 trial with a pCR endpoint. We provide raw & Bayesian estimated pCR rates adjusted for covariates, time effects over the course of the trial, & serial MRI modeling for pts not yet assessed for pCR surgically. Results: 69 pts were randomized to pembro (HER2- subsets only) from Dec 2015 until it graduated in Nov 2016. 46 pts have undergone surgery (table); the other 23 have on-therapy MRI assessments. In 29 HR–/HER2– (TNBC) pts, pembro increased raw & estimated pCR rates by >50% & 40%, respectively; in 40 HR+/HER– pts, it did so by 13% and 21%. 5 pts had immune-related grade 3 adverse events (AEs); 1 hypophysitis & 4 adrenal insufficiency. 4 pts presented after completion of AC (149-179 d after starting pembro); 1 presented prior to AC (37 d after starting pembro). 7 pts had grade 1-2 thyroid abnormalities. Conclusion: Pembro added to standard therapy improved pCR rates in all HER2- BCs that meet I-SPY 2 eligibility, especially in TNBC. Immune-mediated AEs were observed; pt follow up is ongoing. Clinical trial information: NCT01042379. [Table: see text]