Tumor downsizing following neoadjuvant therapy for borderline-resectable pancreatic adenocarcinoma.

690 Background: Downstaging of pancreatic adenocarcinoma in patients presenting with nonmetastatic, unresectable disease has proven to be associated with improved clinical outcomes. Efforts at rescuing these patients to become surgical candidates are commonly attempted with a combination of systemic and radiation strategies. In this study, we aimed to determine tumor downsizing in patients that underwent neoadjuvant systemic therapy followed by a curative-intended surgical resection. Methods: A retrospective review of consecutive patients that underwent surgical resection for pancreatic adenocarcinoma following a course of neoadjuvant therapy was performed. Basic demographics, endoscopic ultrasound (EUS) findings, chemotherapy regimens and duration, rates of radiotherapy, type of surgical procedure and pathologic results were recorded. Tumor response to neoadjuvant therapy was established by correlating EUS- to pathologic tumor dimensions. Analysis of the data was done using Mann-Whitney U test, Pearson correlation and Chi-square when indicated. Results: A total of 97 patients were analyzed; 40 underwent neoadjuvant chemotherapy (13 patients also received concurrent radiation therapy). In those 57 patients that were resected upfront, EUS tended to underestimate tumor sizes significantly compared to pathologic dimensions, with an average difference between dimensions of 0.66 cm (p = 0.0004). Within the group treated with neoadjuvant chemotherapy, 90% of patients had downsizing at an average of 8% of tumor size. There were no differences in rates of tumor downsizing between FOLFIRINOX or Gemcitabine/Nac-paclitaxel treated patients. In addition, there were no correlations in margin status (R0) based on chemotherapy used, with both regimens achieving a similar rate of R0 resections (mean 61%). The type of chemotherapy regimen used did not affect the ratio of positive lymph nodes harvested. Conclusions: In patients that present with borderline resectable pancreatic adenocarcinoma, a course of neoadjuvant therapy results in tumor downsizing in a significant number allowing for margin negative resections. These results were seen regardless of the chemotherapeutic regimens utilized.

A phase II clinical trial examining the impact of neoadjuvant axitinib on primary tumor response in patients with locally advanced clear cell renal cell carcinoma.

4516 Background: Previous studies have shown minimal impact of TKIs on primary renal tumor downsizing. Axitinib is a VEGFR TKI that has been recently approved for use in patients with metastatic clear cell renal cell carcinoma (RCC). In this prospective phase II trial, we sought to investigate the safety and role of axitinib in downsizing tumors in patients with non-metastatic renal cell carcinoma, prior to undergoing surgical resection. Methods: Patients with locally advanced (clinical stage T2-T3b N0 M0) biopsy-proven clear cell RCC were eligible for this phase II clinical trial. The primary outcome was objective response rate (using RECIST) following the administration of axitinib for 12 weeks prior to undergoing radical nephrectomy. Secondary outcomes included safety, tolerability, and feasibility of administration of axitinib in this patient population. Patients were given axitinib 5mg PO BID, and dose titration was allowed. Axitinib was continued until 36 hours prior to surgery. A dedicated radiologist independently reviewed all CT scans to evaluate for response using RECIST. Results: The study goal of enrolling 24 patients has been recently reached. At present, nineteen patients have completed the studies required for assessment of the primary outcome and are hereby reported. Fifteen patients were males, and four were females. Median age was 61 years (range 42-83 years). All patients had biopsy-proven clear cell RCC. All 19 patients continued axitinib for 12 weeks, and underwent surgery as planned without delay. Adverse events of any grade were: arthralgia in 6, hypothyroidism in 14, fatigue in 15, and hypertension in 16 patients. No wound complications occurred after surgery. Nine patients (47%) experienced a partial response by RECIST, and 10 patients had stable disease. There was no progression of disease while on axitinib. Conclusions: Axitinib is well tolerated in the neoadjuvant setting in patients with planned surgery for locally advanced non-metastatic clear cell RCC. The drug showed tumor downsizing activity when given for 12 weeks prior to surgery. Adverse events of any grade were common and easily manageable with routine care. Clinical trial information: NCT01263769.