SPARC correlation with response to gemcitabine (G) plus nab-paclitaxel (nab-P) in patients with advanced metastatic pancreatic cancer: A phase I/II study

Abstract

4525 Background: Pancreatic cancer cells and surrounding stroma are known to overexpress SPARC (secreted protein acid rich in cysteine), which is associated with poor clinical outcomes. nab-P, an albumin-bound nanoparticle form of paclitaxel increased tumor accumulation of paclitaxel through binding of albumin to SPARC. This disease specific phase 1 study was designed to evaluate the safety and efficacy of G + nab-P and the correlation of response with tumor SPARC and serum CA19–9 levels. Methods: nab-P doses (100–150 mg/m 2 ) + (G) (1000 mg/m 2 ) were given on days 1, 8, and 15 of a 28-day cycle to pts with metastatic pancreatic adenocarcinoma and with no prior chemotherapy for their metastatic disease. Level 3 SPARC staining by immunohistochemistry was considered positive. Results: 63 pts received treatment. The most common grade 3 and 4 adverse event that occurred in >20% of pts was neutropenia. Nine (18%) pts and 4 (8%) pts had a grade 3/4 event, respectively. Neuropathy was also observed. One combination-associated death due to sepsis occurred at the 150 mg/m 2 nab-P level. Serial PET scans of 53 pts with outside adjudication to date showed 12 (23%) complete responses, 29 (55%) partial responses (PRs) and 4 (8%) stable disease (SD). By RECIST criteria, of the 49 pts evaluable to date, 1(2%) had CR, 12 (24%) had PR, and 20 (41%) had SD. The median survival was 9 months to date. SPARC data were available for 35 pts, of which 10 (29%) were SPARC+ and 25 (71%) were SPARC-. Of these, 27 pts had evaluable response data. Pts that were SPARC+ (8/27) were more likely to be responders (6/8, 75%) than pts who were SPARC- (5/19, 26%), P = 0.03, Fisher's exact test. Median progression-free survival (PFS) increased from 4.8 months for SPARC- pts (22 pts) to 6.2 months for SPARC+ pts (9 pts); however, these data are still immature. Of 45 pts with elevated CA19–9 at baseline, 42 (93%) had maximum decrease of >40% with a median maximum decrease of 92%. Conclusions: The combination of nab-P and G was generally well tolerated and had substantial enough antitumor activity in patients with pancreatic cancer to warrant a phase III clinical trial. SPARC+ status in these patients was associated with higher response rate and longer PFS. [Table: see text]