Background
Phase III randomized open-label trial. 558 patients with unresectable metastatic colorectal cancer who completed 6 cycles of capecitabine + oxaliplatin + bevacizumab (CAPOX-B) induction without progression. Assessed whether maintenance capecitabine + bevacizumab prolongs outcomes vs observation (with reintroduction of CAPOX-B at first progression).
Interventions and follow up
Arm A (Maintenance): Capecitabine 625 mg/m² bid continuously + bevacizumab 7.5 mg/kg q3wk; reintroduction of CAPOX-B at PD1 if eligible
Arm B (Observation): No maintenance → reintroduction of full CAPOX-B at PD1; maintenance cape + bevacizumab at PD2
Primary endpoint: PFS2 (randomization to progression after second-line treatment, or death)
Median follow-up: 33 months
Arm B (Observation): No maintenance → reintroduction of full CAPOX-B at PD1; maintenance cape + bevacizumab at PD2
Primary endpoint: PFS2 (randomization to progression after second-line treatment, or death)
Median follow-up: 33 months
Results
mPFS2: 11.7 vs 8.5 months, HR 0.67 (95% CI 0.56–0.81), P<.001
mPFS (first, from randomization): 8.5 vs 5.0 months, HR 0.44 (95% CI 0.37–0.54), P<.001
mOS: 25.9 vs 21.7 months, HR 0.83 (95% CI 0.68–1.01), P=.06
ORR at reintroduction: 42% vs 46%, P=.47
mPFS (first, from randomization): 8.5 vs 5.0 months, HR 0.44 (95% CI 0.37–0.54), P<.001
mOS: 25.9 vs 21.7 months, HR 0.83 (95% CI 0.68–1.01), P=.06
ORR at reintroduction: 42% vs 46%, P=.47
Adverse events
Grade ≥3 during maintenance: hand-foot syndrome 4%, hypertension 4%, fatigue 2%
Reintroduction phase: grade ≥3 toxicity similar between arms; QoL comparable between groups throughout
Reintroduction phase: grade ≥3 toxicity similar between arms; QoL comparable between groups throughout
Conclusions
Maintenance capecitabine + bevacizumab after CAPOX-B induction significantly improved PFS2 (primary endpoint, HR 0.67) and first PFS from randomization (HR 0.44) vs observation. A trend toward OS improvement (HR 0.83, P=.06) was observed. Reintroduction response rates were similar, supporting continuous therapy over a stop-and-go approach.
Key Limitations
OS benefit did not reach statistical significance (P=.06). The novel PFS2 primary endpoint, while capturing cumulative benefit, is not a standard regulatory endpoint. Observation arm was allowed reintroduction of full CAPOX-B, which may have attenuated the OS difference. The trial predates RAS-stratified selection and third-line regorafenib/TAS-102. Generalizability to other backbone regimens (FOLFOX, FOLFIRI) requires separate evidence.
Clinical Context
CAIRO3 helped establish maintenance capecitabine + bevacizumab after oxaliplatin-based induction as a standard option in mCRC. With AIO 0207, it defined the maintenance paradigm — either capecitabine + bevacizumab or bevacizumab alone — as preferable to treatment interruption. ESMO endorses maintenance therapy after 4–6 months of oxaliplatin-based induction. ESMO-MCBS score: 3 for maintenance strategy.