J Clin Oncol 31, 2013 (suppl; abstr e22114)
Abstracts that were granted an exception in accordance with ASCO's Conflict of Interest Policy are designated with a caret symbol (^).
Background: Due to chronic hypoxia cancer cells are growing in a more acidic environment compared to physiological tissue. Recent preclinical in vitro and in vivo data have shown direct pH-sensitive anti-tumor activity by pore formation and apoptosis when synergistically acting combinations of Diflunisal, Paraaminosalicylic acid (PAS) and Aspirin were applied. Therefore, a pilot study was performed to evaluate its clinical relevance and its update is presented. Methods: A total of 65 patients (n=65) with advanced solid tumors and the lack of standard treatments were treated with a protocol consisting of 3-5 weeks with 2 daily i.v. infusions of Diflunisal and Aspirin for 4 days per week after they had signed an informed consent form. Response evaluation was assessed by PET/CT differentiating in metabolic and metric (RECIST) response and tumor marker where available. Results: Out of 65 patients treated 8 patients suffered from colorectal cancer, 17 from breast cancer, 6 from ovarian cancer, 3 from lung cancer, 3 from gastric cancer, 3 from glioblastoma, 3 from CUP, 1 from hemangioendothelioma, 1 from pleuramesothelioma, 1 from non-Hodgkin lymphoma, 2 from pancreatic cancer, 1 from choledochus cancer, 3 from prostate cancer, 5 from sarcomas, 2 from head and neck cancer, 1 from melanoma, 1 from cervical cancer, and 1 from thyroid cancer, respectively. Side effects related to the therapy have been fatigue grade I (30%), nausea grade I (13,3%), tinnitus (25%), hypertension (2,5%), dyspnea (3,3%) and burning sensation in tumor areas (65%). 33 patients were evaluable for metric response, 20 for metabolic and 19 for tumor marker response assessment. For tumor marker follow up 11 % had a CR, 53 % a PR, 26 % a SD of > 3 month and 11 % a PD. For metric follow up 3 % had a CR, 33 % a PR, 39 % a SD of > 3 month and 24 % a PD. For metabolic follow up 10 % had a CR, 35 % a PR, 35 % a SD of > 3 month and 20 % a PD. Conclusions: This continuing pilot study confirms a direct pH-sensitive synergistic anti-tumor activity of intravenous Diflunisal, PAS and Aspirin in patients with advanced solid tumors. Therefore, a further evaluation in a controlled clinical phase II study should be performed.