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Innate immune sensing is essential for the proinflammatory program in cellular senescence.

Background: In those undergoing treatment for breast cancer, evidence has demonstrated a significant improvement in survival, and a reduction in the risk of local recurrence in patients who undergo postmastectomy radiation therapy (PMRT). There is uncertainty about the optimal timing of PMRT, whether it should be before or after tissue expander or permanent implant placement. This study aimed to summarize the data reported in the literature on the effect of the timing of PMRT, both preceding and following 2-stage expander-implant breast reconstruction (IBR), and to statistically analyze the impact of timing on infection rates and the need for explantation. Methods: A comprehensive systematic review of the literature was conducted using the PubMed/Medline, Ovid, and Cochrane databases without timeframe limitations. Articles included in the analysis were those reporting outcomes data of PMRT in IBR published from 2009 to 2017. Chi-square statistical analysis was performed to compare infection and explantation rates between the two subgroups at p < 0.05. Results: A total of 11 studies met the inclusion criteria for this study. These studies reported outcomes data for 1565 total 2-stage expander-IBR procedures, where PMRT was used (1145 before, and 420 after, implant placement). There was a statistically significant higher likelihood of infection following pre-implant placement PMRT (21.03%, p = 0.000079), compared to PMRT after implant placement (9.69%). There was no difference in the rate of explantation between pre-implant placement PMRT (12.93%) and postimplant placement PMRT (11.43%). Conclusion: This study suggests that patients receiving PMRT before implant placement in 2-stage expander–implant based reconstruction may have a higher risk of developing an infection.

6594 Background: Given the significant short-term adverse effects of CAR-T cell therapy, it is important to evaluate its impact on QOL of patients in addition to efficacy, compared with established forms of cellular therapy like SCT. Methods: QOL was evaluated prospectively in patients undergoing CAR-T therapy, autoSCT & alloSCT for hematologic malignancies. QOL was assessed with FACT-G at baseline, 2 weeks and monthly for 6 months thereafter. Functional well-being (FWB), physical WB (PWB) emotional WB (EWB) & social WB (SWB) and change over time were compared across groups. Results: 45 patients were recruited (CAR-T: 10; Auto SCT: 22; Allo SCT: 13) with follow up for 2 weeks & 1 month available for 23 &15 patients, respectively (Table). There was no statistically significant difference in baseline total QOL scores (p=0.13), though scores were lower in the alloSCT group (85,84,68). EWB &FWB were numerically higher in the CAR-T group, followed by autoSCT group. At 2 weeks, overall QOL decreased by only 2 points in CAR-T group vs. 22 & 18 points in auto & alloSCT groups (p=0.09). Change in PWB vs. baseline was less pronounced in the CAR-T group (-1, -9, -13, p=0.03). At 1 month, overall QOL was 6 points lower than baseline in CAR-T group vs. 3 and 14 points lower in auto & alloSCT groups, respectively (p=0.34). Importantly, PWB had at least returned to baseline in the CAR-T group. Conclusions: Preliminary data show that patients undergoing CAR-T cell therapy do not experience a more significant decline in QOL compared with auto & allo SCT, and may experience fewer physical side effects in the short-term. Accrual & follow-up are ongoing. [Table: see text]

5518 Background: Platinum resistant ovarian cancer (OC) remains a therapeutic challenge. High grade serous OC (HGSOC) harbors TP53 mutations leading to increased dependency on S- and G2-phase checkpoints. Wee1 inhibition with Adavosertib (AZD 1775) (A) induces G2 checkpoint escape. Gemcitabine (G) is an antimetabolite therapy and blocks the progression of cells through the G1/S phase. We hypothesized that combining G+A would be synergistic and overcome resistance. Methods: We conducted a multicentre double-blind 2:1 randomized phase 2 trial to assess the progression free survival (PFS) in women with recurrent platinum-resistant/refractory HGSOC receiving G+A or G+placebo (P) (NCT02151292). Eligibility required measurable disease and feasibility of paired tumor biopsies; no limitation in prior lines of therapy. Non HGSOC histologic subtypes were enrolled in a separate non-randomized exploratory cohort. A/P was given orally at 175mg QD on D1-2, D8-9 and D15-16 with G 1000mg/m² IV D1, D8 and D15 in a 28-day cycle until progression or unacceptable AE. Tumor staging was scheduled every 8 weeks. TP53 mutations were analyzed on archival tissue with Sanger sequencing, TAm-Seq and IHC. TP53 mutation will be also assessed in circulating tumor DNA (ctDNA). Whole exome and RNA sequencing were performed on paired tumor tissues. Results: 124 patients (pts) with median of 3 prior lines of therapy (range 1-10) from 12 centres across Canada and US were enrolled between Sep 2014 to May 2018, with 99 pts randomized (65 in Arm G+A and 34 in G+P). 5 pts were ineligible; 64 pts have died. The median follow-up was 14.3 months. Main related AE was hematologic toxicity (Anemia G≥3: 31% in G+A vs 18% in G+P; Thrombocytopenia G≥3: 31% vs 6%; Neutropenia G≥3: 62% vs 30%). PFS was significantly improved from 3.0 to 4.6 months (HR 0.56 (95%CI: 0.35-0.90, p=0.015 Log rank). There was a significant improvement in overall survival (OS) from 7.2 to 11.5 months (HR 0.56 (95%CI: 0.34-0.92, P=0.022). Partial response by RECIST 1.1 was observed in 13 (21%) and 1 (3%) pts for Arms G+A and G+P, respectively (p=0.02). From the 25 pts in the exploratory cohort, 3 (12%) partial responses were observed. Final results will be reported at the meeting. Conclusion: Addition of adavosertib to gemcitabine in women with platinum resistant/refractory OC improved response rate, PFS and OS with manageable toxicity. Clinical trial information: NCT02151292.

5510 Background: Single agent aromatase inhibitor (AI) therapy is associated with limited clinical activity in ovarian cancer (OC) and endometrial cancers (EC). AI therapy was associated with a progression free survival (PFS) at 12 weeks of only 20% in relapsed OC (Bowman et al, 2002) and a median PFS of 1 month in relapsed EC (Rose et al, 2000). In Estrogen Receptor (ER) positive metastatic breast cancer, clinical studies had shown a significant prolongation of PFS with the addition of the cyclin kinase 4/6 inhibitor ribociclib to AI (Hortobagyi et al, 2016). Here, we report the results of a phase 2 clinical trial of the combination of ribociclib and letrozole in patients with relapsed ER positive OC or EC. Objectives: Primary endpoint was the proportion of patients with relapsed ER positive OC or EC alive and progression-free after 12 weeks of therapy (PFS12) with the combination of ribociclib given at a dose of 400 mg orally daily and letrozole 2.5 mg orally daily. A PFS of 45% was considered a favorable result based on the data referenced above from Bowman et al. Methods: Eligibility criteria included patients with relapsed ER positive OC or EC, with measurable disease, not previously treated with ribociclib or AIs. Xenografts were created from CT guided tumor biopsies at baseline to assess feasibility. Results: A total of 40 patients were enrolled (20 with OC and 20 with EC) ) with a median age of 61 years (range: 30-82) and 64.5 (range: 52-75) in the OC and EC groups respectively. Among the OC patients, 17 had high grade serous carcinomas and 3 had low grade serous carcinomas. 11 EC patients had endometrioid cancers (3 with grade 1 tumors) and 9 had high grade serous tumors. Ten out of 20 OC patients and 11/20 EC patients were alive and progression-free at 12 weeks (PFS12 of 50 and 55%, respectively). The most common grade 3 or higher adverse events (occurring in at least 5 pts) were leukopenia (18%), lymphopenia (18%), neutropenia (13%), and fatigue (13%). 34 tumor biopsies were suitable for injection into mice and 44% engrafted. ER expression persisted through multiple passages in mice. Two of three EC PDX models exhibited improved PFS with letrozole/ribociclib compared to letrozole alone. Conclusions: The combination of ribociclib and letrozole is associated with a promising 50% and 55% PFS12 in patients with ER positive relapsed OC or EC respectively. Creation of xenograft tumor models from CT guided biopsies of OC and EC tumors was feasible. Clinical trial information: NCT02657928.

5031 Background: The phase 2 TRITON2 study (NCT02952534) is evaluating the PARP inhibitor rucaparib in patients with mCRPC who have a deleterious germline or somatic alteration in BRCA ( BRCA1 or BRCA2) or 1 of 13 other DNA damage repair genes. Here we present analyses of tumor genomics and baseline clinical characteristics in mCRPC patients with a deleterious alteration in BRCA. Methods: Plasma (baseline) and tissue (archival or baseline) samples from patients with a deleterious alteration in BRCA were analyzed using Foundation Medicine next-generation sequencing assays. The alterations and zygosity of the alterations that were detected, as well as the somatic/germline status from Color Genomics testing, were summarized. Associations between genomic alterations, DNA yield, allele frequency, and baseline clinical characteristics were investigated. Results: Results are shown in the Table for a cohort of 40 BRCA2 and 5 BRCA1 patients enrolled in TRITON2 (Abida W et al. Presented at ESMO 2018. Abst 793PD). A biallelic alteration was observed in 21 of the 22 BRCA2 patients (95%) for whom alteration zygosity could be determined. Among the 5 BRCA1 patients, 1 alteration was monoallelic and 4 were of unknown zygosity. Co-occurring alterations in cancer-related or DNA damage repair genes were observed in many patients with BRCA alterations. At baseline, cell-free DNA (cfDNA) yield correlated positively with the sum of target lesions (STL; P= 0.04), but not with prostate-specific antigen (PSA) levels ( P= 0.86). No correlation was observed between allele frequency of the BRCA alteration baseline STL ( P= 0.68) or PSA levels ( P= 0.97). Conclusions: Patients with a BRCA mutation enrolled in TRITON2 demonstrate a profile of genomic alterations consistent with that of prior studies of patients with mCRPC. Plasma cfDNA profiling showed a correlation between baseline cfDNA yield and measurable tumor burden, but not baseline PSA. Clinical trial information: NCT02952534. [Table: see text]

4009 Background: Interim analysis of a global, phase 2 KEYNOTE-059 study (NCT02335411) reported manageable safety and promising antitumor activity for pembro alone or pembro + chemo in pts with G/GEJ cancer. Here we report long-term efficacy and safety data of all cohorts. Methods: Pts with recurrent or metastatic G/GEJ adenocarcinoma were enrolled in 3 cohorts. Cohort 1 pts (PD-L1–positive or –negative) received pembro alone after ≥2 prior lines of therapy. Cohort 2 pts (PD-L1–positive or –negative) received pembro + cisplatin (80 mg/m2 day 1) + 5-fluorouracil (800 mg/m2 days 1-5 Q3W) or capecitabine (in Japan only, 1000 mg/m2 twice daily) as first-line. Cohort 3 pts (PD-L1–positive, combined positive score ≥1% using the PD-L1 IHC 22C3 pharmDx assay) received pembro alone as first-line. All pts received pembro 200 mg Q3W for up to 2 years. End points included safety, ORR, DOR, and OS. Results: At data cutoff (Aug 8, 2018), median (range) follow-up was 6 (1-38), 14 (2-40), and 21 (2-36) months for cohorts 1 (n = 259), 2 (n = 25), and 3 (n = 31), respectively. In cohort 1, confirmed ORR (95% CI) was 11.6% (8-16) overall, 15.5% (10-22) in PD-L1–positive, and 6.4% (3-13) in PD-L1–negative tumors. In cohort 2, confirmed ORR was 60.0% (39-79) overall, 73.3% (45-92) in PD-L1–positive, and 37.5% (9-76) in PD-L1–negative tumors. In cohort 3, confirmed ORR was 25.8% (12-45). Median (range) DOR in months was 16.1 (2-35+), 4.6 (3-37+), and not reached (2.1-32.5+) in cohorts 1, 2, and 3, respectively. OS at 1 year/2 years was 24.6%/12.5%, 52%/32%, and 63.6%/40.1% in cohorts 1, 2, and 3, respectively. In cohorts 1, 2, and 3, grade 3-5 treatment-related adverse event (TRAE) incidence was 46 (18%), 20 (80%), and 8 (26%) respectively. TRAEs led to discontinuation in 6 (2%) and 3 (12%) pts in cohorts 1 and 2, respectively, and to death in 2 (1%) pts in cohort 1. No TRAEs led to discontinuation or death in cohort 3. Conclusions: These updated results demonstrate manageable safety, durable clinically meaningful activity of pembro in heavily pretreated pts, and promising efficacy of first-line pembro (alone or + chemo) in pts with advanced G/GEJ cancer. Clinical trial information: NCT02335411.

3532 Background: Colorectal cancer with dMMR display heterogeneity in the extent of intratumoral T-cell infiltration which may explain their variable responsiveness to PD-1 blockade. We examined the association of intratumoral CD3+ and CD8+ T-cell densities (TCD) with objective response rate (ORR) and response duration in patients with dMMR mCRCs receiving pembrolizumab (PEM). Methods: Record review was performed on 12 patients with dMMR mCRC treated with PEM (200 mg intravenously every 3 weeks) after failure of prior chemotherapy [median no. of regimens was 1 (range 1-4)] between 01/2015 and 12/2017. CD3+ and CD8+ TCDs were analyzed in the primary tumor core (CT) and at the invasive margin (IM) by immunohistochemistry and automated image analysis to determine density score (0 to 100) for each T-cell subtype and compartment (Ventana Medical Systems, Inc.). Patients were categorized as 1) responders [CR (complete response) + PR (partial response)] vs. non responders [SD (stable disease) + PD (progressive disease)] per RECIST version 1.1, and 2) by duration of response (< or > 12 months). Results: Median follow-up post PEM was 19.5 (9-41) months. Responders included 2 CR and 5 PR; non-responders included 4 SD and 1 PD. The ORR and median time to response were 58.3% (7/12) and 12 weeks (range 9-40), respectively. CD3+ and CD8+ TCD scores were higher in responders vs. in non-responders as well as in patients who had disease control for > 12 months; differences were greatest for CD8+ CT (Table). Conclusions: Among patients treated with PEM, data suggest higher intratumoral CD3+ and CD8+ TCDs in responders versus non-responders and in those with a longer duration of disease control. If confirmed, TCDs may potentially predict responsiveness to PD-1 blockade in dMMR mCRCs. [Table: see text]

3501 Background: 6m of oxaliplatin-based treatment is an option as adj chemotherapy for patients with high risk stage II CC (T4, inadequate nodal harvest, poorly differentiated, obstruction, perforation or vascular/perineural invasion). The IDEA collaboration showed shorter treatment duration to be appropriate for most pts with stage III colon cancer. The results of the 4 IDEA studies with stage II pts are presented here. Methods: A prospective, pre-planned pooled analysis of high-risk stage II patients from 4 concurrently conducted randomized phase III trials (SCOT, TOSCA, ACHIEVE-2, HORG) was performed to evaluate non-inferiority (NI) of 3m compared with 6m (ref) of adj FOLFOX/CAPOX (regimen preselected, not randomized). The primary endpoint was disease-free survival (DFS), NI was to be declared if the 2-sided 80% confidence interval (CI) for DFS hazard ratio (HR 3m v 6m) estimated by a stratified Cox model was below 1.2. 542 DFS events were required to provide 80% power to declare NI. NI was also examined within regimen, T4 (Yes v No) and inadequate nodal harvest (Yes v No) as pre-planned subgroups. Results: The primary analysis included 3273 randomised pts of which 1254 had FOLFOX and 2019 had CAPOX. There were 552 events and the median follow-up was 60.2 m. There was significantly less grade 3-5 toxicity with 3m treatment (p < .0001). The 5-year DFS rate was 80.7% and 84.0% for 3m and 6m treatment with an estimated DFS HR of 1.18 (80% CI:1.05-1.31, p for NI = 0.404). For CAPOX the estimated HR was 1.02 (80% CI: 0.88-1.17, p for NI = 0.087) and for FOLFOX the estimated HR was 1.42 (80% CI: 1.19-1.70, p for NI = 0.894). The test for interaction between duration and regimen was not statistically significant (p = .174 adjusted for multiple testing) but was stronger than that for the other subgroups examined. Conclusions: In the overall population non-inferiority for 3m adj treatment in pts with high-risk stage II CC was not shown. As with the stage III population the choice of adj regimen appears important (although this did not reach statistical significance) with a small difference in DFS between 3 and 6 m treatment if CAPOX is used. Clinical trial information: ISRCTN59757862.