TAS102 in combination with oxaliplatin (TASOX) for refractory metastatic colorectal cancer.

189 Background: TAS102 (trifluridine/tipiracil hydrochloride) is approved for use alone or with bevacizumab in late line metastatic colorectal cancer (mCRC), with overall survival benefit in phase 3 trials (RECOURSE and SUNLIGHT). Oxaliplatin is frequently reintroduced after progression, resolution of limiting neuropathy, or disease recurrence post adjuvant therapy. In preclinical studies, oxaliplatin combined with TAS102 has shown synergism. We hypothesized TASOX may be an option for patients who have progressed/recurred after FOLFOX. Methods: We assessed safety and efficacy of TAS102 with oxaliplatin, enrolling patients with metastatic CRC progressed on ≥2 lines of therapy including 5FU, oxaliplatin and irinotecan. Patients with recurrence during or within 6 months of adjuvant chemotherapy were allowed. Exclusion: Prior TAS102 exposure, functional impairing peripheral neuropathy, ≥Grade 3 hypersensitivity to oxaliplatin, or uncontrollable grade 1-2 hypersensitivity to oxaliplatin. Treatment continued until disease progression or unacceptable toxicity. Patients received oxaliplatin 85 mg/m2 and TAS-102 35 mg/m2 bid days 1-5 every two weeks, and bevacizumab per MD choice. The primary endpoint was overall response rate (ORR) by RECIST (by independent radiologists). Secondary endpoints included disease control rate (DCR), safety and tolerability. Results: 54 patients enrolled; 53 received treatment on study and 48 had ≥1 disease assessment (median age 59, 58 % male, tumor RAS mutated 69%). Median time on study was 4 months (8 cycles; range 1-37 cycles). ORR was 6% (n=3), with average change in target lesions -45% (range -35 to -67%). 71% (n=34) had SD defined on study, with average change in target lesions -3% (range -29% to +20%). In those treated with bevacizumab (59%; n=28 ), 79% (n=22) had disease control vs. 75% (n=15). The most common reason for study discontinuation was progressive disease (23%, n=11). 68% (n=36) had a treatment-related adverse event (TRAE) ≥Grade 3 at any point during therapy. The most common G3 TRAEs were anemia 19% (n=10) and leukopenia 28% (n=15) at any time. Two (4%) developed grade 3 neuropathy. Conclusions: TASOX is effective as a 3rd line therapy for patients with mCRC. In our study, overall disease control rate was 77% with up to 19 months on study. Anemia and leukopenia are common but manageable. Bevacizumab did not seem to have as great an effect in our trial as observed in SUNLIGHT. Future studies would warrant TASOX in combination to bevacizumab in randomized trials in candidates for oxaliplatin retreatment. Clinical trial information: NCT02848079 .