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Purpose The benefit of high-dose chemotherapy with autologous stem-cell transplantation (ASCT) as first-line treatment in patients with diffuse large B-cell lymphomas is still a matter of debate. To address this point, we designed a randomized phase III trial to compare rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP)-14 (eight cycles) with rituximab plus high-dose sequential chemotherapy (R-HDS) with ASCT. Patients and Methods From June 2005 to June 2011, 246 high-risk patients with a high-intermediate (56%) or high (44%) International Prognostic Index score were randomly assigned to the R-CHOP or R-HDS arm, and 235 were analyzed by intent to treat. The primary efficacy end point of the study was 3-year event-free survival, and results were analyzed on an intent-to-treat basis. Results Clinical response (complete response, 78% v 76%; partial response, 5% v 9%) and failures (no response, 15% v 11%; and early treatment-related mortality, 2% v 3%) were similar after R-CHOP versus R-HDS, respectively. After a median follow-up of 5 years, the 3-year event-free survival was 62% versus 65% ( P = .83). At 3 years, compared with the R-CHOP arm, the R-HDS arm had better disease-free survival (79% v 91%, respectively; P = .034), but this subsequently vanished because of late-occurring treatment-related deaths. No difference was detected in terms of progression-free survival (65% v 75%, respectively; P = .12), or overall survival (74% v 77%, respectively; P = .64). Significantly higher hematologic toxicity ( P < .001) and more infectious complications ( P < .001) were observed in the R-HDS arm. Conclusion In this study, front-line intensive R-HDS chemotherapy with ASCT did not improve the outcome of high-risk patients with diffuse large B-cell lymphomas.

9558 Background: Bintrafusp alfa (M7824) is a first-in-class bifunctional fusion protein composed of the extracellular domain of the TGF-βRII receptor (a TGF-β “trap”) fused to a human IgG1 mAb blocking PD-L1. Interim analysis of a global phase 1 study (NCT02517398) found an objective response rate (ORR) of 27.5% and a manageable safety profile in patients with NSCLC who received bintrafusp alfa 1200 mg in the 2L setting; median overall survival (OS) was not reached. Here we present the longest efficacy and safety follow-up in a cohort receiving bintrafusp alfa. Methods: Patients with advanced NSCLC unselected for PD-L1 expression level who progressed after first-line standard treatment (no prior immunotherapy) were randomized to receive bintrafusp alfa 500 or 1200 mg (n = 40 each) Q2W until disease progression, unacceptable toxicity or trial withdrawal. The primary objective was best overall response (BOR) per RECIST 1.1; secondary and exploratory objectives include safety and OS, respectively. Results: As of October 15, 2019, a total of 40 patients received bintrafusp alfa at the recommended phase 2 dose of 1200 mg Q2W for a median of 17 (range, 2-136) weeks, with a median follow-up of 128 weeks; 18 patients were still alive, 3 patients had an ongoing response, and 1 patient remained on treatment. Results for the 1200 mg dose cohort showed an ORR of 27.5%, and a median duration of response of 18 months. The 18- and 24-month progression-free survival and OS rates were 18.4% and 11.0%, and 49.7% and 39.7%, respectively. Duration of response rates at 18 and 24 months were 42.4% and 21.2%, respectively. Median OS in patients with positive (≥1%) PD-L1 expression was 21.7 months; 6 of 7 patients with high (≥80% with Ab clone 73-10, which is equivalent to ≥50% with 22C3) PD-L1 expression were still alive. The overall safety profile has remained consistent since the interim analysis, with no new safety signals or deaths and 1 additional treatment-related discontinuation (blood alkaline phosphatase increased). Conclusions: After two years of follow-up, bintrafusp alfa continues to show manageable safety with durable responses and encouraging long-term survival, especially in patients with high PD-L1 expression. A study evaluating bintrafusp alfa vs pembrolizumab as first-line treatment for NSCLC is ongoing in patients with high PD-L1 expression (NCT03631706). Clinical trial information: NCT02517398 .

719 Background: Patients (pts) displaying a full-fledged immune response show high levels of circulating extracellular vesicles (EVs) containing immune transcripts that might be transferred to neighboring cells to amplify immune responses, as in autoimmunity and transplantation. We hypothesized EV immune transcripts could reflect immune activation in cancer pts receiving immunotherapy with immune checkpoint inhibitors (ICI). These RNA-containing EVs may surrogate immune functionality and represent a plasma transcriptional signature of adaptive immunity that can be readily detected by liquid biopsy. Methods: Blood samples from metastatic renal cell cancer pts,treated with ICI nivolumab (n=8) or tyrosine kinase inhibitor cabozantinib (n=9) were collected at baseline, week 4 and 12. EV-RNA was isolated from plasma with membrane affinity spin columns and evaluated for CD274(PD-L1), IFNG, PDCD1 (PD-1), CD3 and GZMB (granzyme B) transcripts by qRT-PCR. Results: All pts showed a statistically significant increase of CD3, IFNG, GZMB, PD-1 and PD-L1 immune transcripts in plasma EVs, evidenced at 4 and 12 weeks of therapy. Treatment subgroup analysis revealed an upregulation of CD3, IFNG, GZMB and PD-1 transcripts only in plasma EVs of patients receiving nivolumab that was more evident in those showing clinical benefit (4/8), while PD-L1 increased significantly during cabozantinib treatment. Upon comparing transcripts with soluble proteins, PD-L1 displayed similar kinetics, while PD-1 increased only as transcript but not as protein, given its potential sequestration by the anti-PD-1 antibody. This effect was detectable only in nivolumab but not in cabozantinib treated pts. Conclusions: Monitoring immune transcripts carried by plasma EVs holds promise as potential tool to assess the entity of the ongoing immune activation during immunotherapy. Plasma EVs may be exploited as indicators of immune response and help to predict clinical efficacy at early on-treatment time points. This approach based on plasma EVs might represent a starting point for the development of a novel strategy to study immune responses in clinical setting.

e16087 Background: Several studies, the majority on melanoma and lung cancer, have addressed the value of gender with respect to immune check point inhibitors outcome as compared to standard therapy, showing conflicting results. Nevertheless, few focused on gender-related clinical outcome and toxicity in renal cell carcinoma (RCC) patients. Methods: This analysis evaluated the effect of gender on overall survival and adverse events (AEs) using Common Terminology Criteria for Adverse Events (CTCAE) v.4.0 in an expanded access programme of nivolumab 3 mg/kg once every 2 weeks in second-line and beyond metastatic RCC. Only patients assuming at least one dose of nivolumab were analyzed. Results: Of 389 patients analyzed, 25.2% were female. On study entry, no differences were found in women as compared to men in terms of age, on average 64 years, p = 0.91; overweight/obesity, 45 versus (vs) 49%, p = 0.47; LDH , mean U/L 391 vs 32, p = 0.17); and neutrophils/lymphocytes ratio> 3 (62 vs 63%, p = 0.87). Disease presentation was similar according to gender, although women tended to present less lung (66% vs 76%, p = 0.06) and bone metastases (42% vs 52%, p = 0.07). Notably, there was no differences in the IDMC prognostic model by gender (p = 0.94). Any drug related AEs (38 vs 30%, p 0.15), grade 3-4 (6% vs 6%) and median number of drug doses 12 (53% vs50%, p = 0.58 ) did not differ between gender. After adjusting for known prognostic variables, multivariate analysis showed that women had similar overall survival as compared to men (hazard ratio 0.81, 95% confidence interval 0.56-1.17, p = 0.26). Conclusions: Women demonstrate similar overall survival than men in metastatic RCC treated with secondal line and beyond nivolumab, with no differences observed in serious AEs and dose administered.

9017Background: Inhibiting the transforming growth factor β (TGF-β) pathway, which promotes tumor immunosuppression, may enhance the response to PD-(L)1 monoclonal antibodies (mAbs). 2L+ overall re...

12081Background: Triple negative breast cancer (TNBC) is characterized by poor prognosis, lack of specific-targeted agents and is in need of new therapeutics. Immune checkpoint blockers have shown ...

NOTE. Median follow-up, 5.7 years (range, 1-8.7); Z-HDS, 5.9 (range, 1-8.3); HDS, 4.9 (range, 1.4-8.7).

67 Background: Immune checkpoints inhibitors have clearly improved patients’outcomes in different tumors, but definitive predictive biomarkers are still missing. Since thyroiditis have been reported, we have evaluated whether clinical responses are more frequent in patients who underwent anti PD-1 or anti PDL-1 agents and experienced dysthyroidism. Methods: We retrospectively evaluated 135 metastatic solid tumor patients, treated at our Institute with anti PD-1/PDL-1 antibodies since 2013. Thyroid toxicity was defined according to CTCAE version 4.0 and disease control (DC: CR+PR+SD) was chosen as efficacy endpoint. Correlation between dysthyroidism and DC rate was assessed by Fisher’s exact test. Results: Of 135 patients, 76 (56.3%) were treated by anti PD-1 and 59 (43.7%) by anti PDL-1 agents. Population was heterogeneous, including patients from the 1st to the 9th line of therapy, affected by the following cancers: 57 (42.2%) NSCLC, 18 (13.3%) melanoma, 13 (9.6%) RCC, 7 (5.2%) bladder and urothelial, 6 (4.5%) mesothelioma, 5 (3.7%) SCLC, 5 (3.7%) sarcoma, 5 (3.7%) biliary tract, 5 (3.7%) head and neck, 3 (2.2%) gastric, 3 (2.2%) colon, 2 (1.5%) Merkel cells and one each for thyroid, HCC, ovary, cervix, anal carcinoma and germ cells tumor. Median follow up was 8.6 months. Best responses were: 5 CR, 30 PR, 51 SD and 49 PD; 86 (63.7%) patients achieved DC. Overall, 38 patients developed dysthyroidism (subclinical, G1, G2 hypo/hyperthyroidism): 18/76 (23.7%) in anti PD-1, 20/59 (33.9%) in anti PDL-1 group; 31/38 (81.6%) of them achieved DC. The median time of dysthyroidism appearance was the 6th cycle of therapy (range 1st-22th). Of 97 patients who did not develop thyroid toxicity, 55 (56.7%) achieved DC. Dysthyroidism significantly correlated with DC rate (p=0.009). Conclusions: We found a significant correlation between dysthyroidism and clinical responses in solid tumor metastatic patients treated by anti PD-1 or anti PDL-1 antibodies. Our observation suggests that evaluation of thyroid function should be regularly performed during therapy with these agents. These retrospective findings must be confirmed in a prospective trial powered to see whether thyroid dysfunction is a surrogate marker of response.

e16576 Background: Treatment of ovarian cancer (OC) remains very challenging, with 80-85% of the cases still dying after relapse to standard chemotherapy, and novel treatments are urgently needed. Expansion of regulatory T cells (Tregs) is considered the major factor limiting immune responses to OC. Agonist antibodies against the co-stimulatory receptor OX40 have recently demonstrated to abrogate Treg functions and are under clinical evaluation. We thus studied whether OX40 constituted a valid target of OC-associated Tregs. Methods: Treg immunophenotypic analyses were performed by flow cytometry in ascites and OC specimens and studied in association with patients’ outcome Results: CD4+CD25+Foxp3+ Treg% and OX40 expression were measured in 50 OC cases (36, high grade serous carcinomas; 14, other histotypes). Treg% was significantly higher in ovary (47 evaluable cases) relative to ascites (39 evaluable cases) (p < 0.0001). Treg% in ascites and peripheral blood from OC patients or healthy donors were not sig...

8577 Background: This is a phase II trial addressing a new treatment in pts with BCL and CNS disease (NCT00801216). Treatment is based on the encouraging experiences with high doses of antimetaboli...