Phase II study of TAS-OX (TAS-102 and oxaliplatin) plus bevacizumab for late-line colorectal cancer

144 Background: TAS-102 (trifluridine/tipiracil) is a novel oral antimetabolite for late line metastatic colorectal cancer (CRC) approved in 2018. Many patients are treated early in their course with oxaliplatin (OX), particularly adjuvant, and may benefit from re-treatment. In this trial we combine the typical late line use of TAS with OX (BEV [bevacizumab] added at investigator discretion) with goal of improved response. Methods: Eligibility included measurable CRC previously treated with all approved drugs per TAS package insert (irinotecan, oxaliplatin, 5FU, anti-VEGF, anti-EGF) as appropriate, PS = 0-1, labs within usual range, neuropathy < grade 2, ability to take oral meds, appropriate contraception. If no contraindication to BEV, this could be added at patient. TAS was dosed at 35 mg/m2 days 1-5 with OX 85/m2 d1 every 14 days (and BEV 5 mg/kg, if given). All supportive care was allowed including growth factors. Results: 47 patients (pts, median age 55) were enrolled in a Simon mini-max design, including 45% female, 21% black, 11% Asian, 11% Hispanic and 5% mixed. 26 pts received BEV. For the first 40 pts, 385 cycles were given (mean = 7 cycles, median 8) with 18 pts (45%) requiring dose reductions (1 dose reduction = 9 pts, 2 = 6, 3 = 3), and 9 receiving (peg)/filgrastim. Toxicities leading to SAEs included gr 3 heme (2), heart failure, abd pain/n/v (6), sepsis (2), urinary (4); and related gr 3 included one gr 3 vomiting and one gr 3 neutropenia. Independently reviewed RECIST Response (N = 32) included PR 2(6%), SD 23 (72%), PD 7 (22%). Mean TTP was 4.5 m (median 4, range 1 – 18) with 9 (28%) pts more than 6 months. Conclusions: In patients with late-line CRC and candidates for TAS (trifluridine/tipiracil), treatment with TAS plus OX is both well tolerated and active. RR is higher than single agent and 78% (95% CI, 60-91%) of patients had stable disease or response, with 60% receiving 8 or more cycles. Randomized trials comparing to single agent TAS are warranted in this setting. Clinical trial information: NCT04294264 .