A Phase II Study of Pembrolizumab in Combination with Capecitabine and Oxaliplatin with Molecular Profiling in Patients with Advanced Biliary Tract Carcinoma

BACKGROUND

We conducted a phase II study of the combination of pembrolizumab with capecitabine and oxaliplatin (CAPOX) in patients with advanced biliary tract carcinoma (BTC) to assess response rate and clinical efficacy. Exploratory objectives included correlative studies of immune marker expression, tumor evolution, and immune infiltration in response to treatment.

PATIENTS AND METHODS

Adult patients with histologically confirmed BTC were enrolled and received oxaliplatin and pembrolizumab on day 1 of cycles 1-6. Capecitabine was administered orally twice daily as intermittent treatment, with the first dose on day 1 and the last dose on day 14 of cycles 1-6. Starting on cycle 7, pembrolizumab monotherapy was continued until disease progression. The primary endpoint was progression-free survival (PFS). Secondary endpoints were safety, tolerability, feasibility, and response rate. Immunohistochemistry (IHC) for PD-L1 and immune infiltrates was analyzed in paired tumor biopsies, as well as bulk transcriptome and exome profiling for five patients and single-cell RNA sequencing for one partial responder.

RESULTS

Eleven patients enrolled, three of whom had received no prior systemic therapy. Treatment was well tolerated, and the most common treatment-related grade 3 or 4 adverse events were lymphocytopenia, anemia, and decreased platelet count. Three patients (27.3%) achieved a partial response, and six (54%) had stable disease. The disease control rate was 81.8%. The median PFS was 4.1 months with a 6-month PFS rate of 45.5%. Molecular profiling suggests qualitative differences in immune infiltration and clonal evolution based on response.

CONCLUSION

Capecitabine and oxaliplatin in combination with pembrolizumab is tolerable and a potentially effective treatment for refractory advanced BTC. This study highlights a design framework for the precise characterization of individual BTC tumors.

TRIAL REGISTRATION

This study was registered in ClinicalTrials.gov (NCT03111732).

Tremelimumab in combination with microwave ablation in patients with refractory biliary tract cancer (BTC)

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Background: Treatment option for patients with advanced BTC is limited and prognosis is poor with a median survival of less than 1 year in the locally advanced or metastatic setting. It has been shown deregulation of the immune system plays an important role in the pathogenesis of BTC. This study aimed to investigate whether tremelimumab (Treme), anti-CTLA4, could be combined safely and feasibly with microwave ablation therapy to enhance the effect of anti-CTLA4 treatment in patients with advanced BTC. Methods: Patients with refractory BTC were enrolled in a study of monthly Treme (10mg/kg, IV, 6 doses), followed by 3-monthly infusions until off-treatment criteria were met. On day 36, patients underwent subtotal microwave ablation. Staging image was performed every 8 weeks. Adverse events (AEs) were collected and managed. Tumor samples and peripheral blood samples were collected to perform immune monitoring. Results: Twenty patients with refractory BTC were enrolled. Male: female ratio was 10:10 with median age 56.5 years (range 37-67). Six patients had extrahepatic cholangiocarcinoma (ECC), two patients had gallbladder cancer, whereas the remaining 12 patients had intrahepatic cholangiocarcinoma (ICC). No dose-limiting toxicities were encountered. The common AEs included lymphocytopenia, colitis, adrenal insufficiency, anemia, and elevated transaminases. The most common clinical toxicity was diarrhea. Sixteen patients were evaluable for response analysis, one (6%) patient achieved a confirmed partial response (lasting for 8 months), 6 (37.5%) achieved stable disease with the longest lasting for 9.2 months. Among all 20 patients, median progression free survival, time to progression, and overall survival were 3.4 months (95% CI 2.5-5.2 months), 3.3 months (95% CI: 2.5-4.6 months) and 6.0 months (95% CI 3.8-8.8 months) respectively in this small pilot cohort. T cell receptor (TCR) b screening showed Treme expanded TCR repertoire though non-significantly. RNA seq is ongoing and will be presented. Conclusions: Treme in combination with tumor ablation is a potential new treatment for patients with advanced BTC. TCR repertoire expansion induced by Treme may contribute to treatment benefit. Clinical trial information: NCT01853618.

Tremelimumab: A monoclonal antibody against CTLA-4—In combination with radiofrequency ablation (RFA) in patients with biliary tract carcinoma (BTC)

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Background: Tremelimumab is a fully human monoclonal antibody that binds to CTLA-4 expressed on the surface of activated T lymphocytes and results in inhibition of B7-CTLA-4-mediated downregulation of T-cell activation. Radiofrequency ablation (RFA) has been shown to induce a peripheral immune response which may enhance the effect of anti-CTLA4 treatment. Methods: Patients with refractory BTC were enrolled in a study of monthly Tremelimumab (10mg/kg, 6 doses) combined with RFA (to one lesion) performed on week 6. Tumor biopsies were performed at time of RFA with regular PBMC collection for intensive immunemontoring. Results: 17 pts enrolled. Characteristics: M:F 8:9; Median age 57(range 36-67); BTC subtype - intrahepatic/exrahepatic: 12/5. 13/17 had metastatic disease. All pts were chemorefractory with 12/17 having received at least 2 regimens. While on study, 6 pts had early PD within 6 weeks; 11 were able to undergo RFA. No DLT encountered. Most common toxicity was pruritus. There were no objective responses. Of evaluable pts N = 6 (55%) had stable disease as a best response. Conclusions: Tremelimumab in combination with subtotal RFA in patients with advanced BTC is safe and feasible. No objective responses have so far been seen in this predominantly primary intrahepatic BTC population. Full efficacy and immune monitoring data will be presented. Clinical trial information: NCT01853618.

Tremelimumab: A monoclonal antibody against CTLA-4—In combination with radiofrequency ablation (RFA) in patients with biliary tract carcinoma (BTC)

316

Background: Tremelimumab is a fully human monoclonal antibody that binds to CTLA-4 expressed on the surface of activated T lymphocytes and results in inhibition of B7-CTLA-4-mediated downregulation of T-cell activation. Radiofrequency ablation (RFA) has been shown to induce a peripheral immune response which may enhance the effect of anti-CTLA4 treatment. Methods: Patients with refractory BTC were enrolled in a study of monthly Tremelimumab (10mg/kg, 6 doses) combined with RFA (to one lesion) performed on week 6. Tumor biopsies were performed at time of RFA with regular PBMC collection for intensive immunemontoring. Results: 17 pts enrolled. Characteristics: M:F 8:9; Median age 57(range 36-67); BTC subtype - intrahepatic/exrahepatic: 12/5. 13/17 had metastatic disease. All pts were chemorefractory with 12/17 having received at least 2 regimens. While on study, 6 pts had early PD within 6 weeks; 11 were able to undergo RFA. No DLT encountered. Most common toxicity was pruritus. There were no objective responses. Of evaluable pts N = 6 (55%) had stable disease as a best response. Conclusions: Tremelimumab in combination with subtotal RFA in patients with advanced BTC is safe and feasible. No objective responses have so far been seen in this predominantly primary intrahepatic BTC population. Full efficacy and immune monitoring data will be presented. Clinical trial information: NCT01853618.

Evaluation of expanded polytetrafluoroethylene as a soft-tissue filling substance: an analysis of design-related implant behavior using the porcine skin model

Soft-tissue augmentation using the synthetic nonfluid biomaterial expanded polytetrafluoroethylene (ePTFE) has been supported by number of recent reports citing the favorable characteristics of biocompatibility, soft and natural feel, ease of use, and permanent augmentation. Concern has been expressed about this application for ePTFE material because of the proximity of the implants to the skin surface and potential problems with infection and extrusion. We evaluated the behavior of a series of specific ePTFE implant designs using a long-term subcutaneous augmentation model. By using a porcine model, 466 implants of ePTFE in the form of strips, rolls, or tubes were placed using a percutaneous insertion device subcutaneously over the dorsum and face. The animals were divided into three study groups by length of implantation (3 weeks, control; 6 months, intermediate term; and 12 months, long-term) and en-bloc tissue specimens, including skin, implants, and underlying soft tissue, were harvested for gross and histologic examination. Implants were removed at the earliest sign of infection, exposure, or extrusion and the difficulty of removal was ascertained and recorded. These data reveal that ePTFE material elicits acceptable levels of tissue activity with low extrusion rates over the short and long term supporting its use for soft-tissue augmentation. The data show a clear difference, however, in the host response and behavior of the implants for this application based on shape or design. A statistically significant difference in the low, but measurable, extrusion rates was observed amongst these implant designs. ePTFE tubes showed greater stability and predictable augmentation over other implant designs for soft-tissue augmentation and seem to represent a substantial improvement for this application.