Background
Phase II RCT (MSKCC — Sequential Escalation Trial). 259 patients with locally advanced rectal cancer (stage II-III). Tested whether adding cycles of induction FOLFOX before standard preoperative CRT would increase pCR rates in a dose-escalation manner. Evaluated the concept that more systemic therapy before CRT improves pCR and organ preservation rates.
Interventions and follow up
Arm A: mFOLFOX6 × 0 cycles → CRT (50.4 Gy + capecitabine) → TME surgery
Arm B: mFOLFOX6 × 2 cycles → CRT → TME surgery
Arm C: mFOLFOX6 × 4 cycles → CRT → TME surgery
Arm D: mFOLFOX6 × 6 cycles → CRT → TME surgery
Primary endpoint: CR rate
mFollow up: NR
Arm B: mFOLFOX6 × 2 cycles → CRT → TME surgery
Arm C: mFOLFOX6 × 4 cycles → CRT → TME surgery
Arm D: mFOLFOX6 × 6 cycles → CRT → TME surgery
Primary endpoint: CR rate
mFollow up: NR
Results
pCR (0→2→4→6 cycles): 18%, 25%, 30%, 38% (trend: P=.0036 for dose-response)
Organ preservation (W&W) rate: Increased with more induction FOLFOX
Organ preservation (W&W) rate: Increased with more induction FOLFOX
Adverse events
Safety: Well tolerated; FOLFOX toxicity manageable without compromising CRT delivery
Main adverse events: Grade ≥3 FOLFOX toxicity: ~15–20%. No significant increase in surgical complications with longer induction. Similar perioperative morbidity across arms.
Main adverse events: Grade ≥3 FOLFOX toxicity: ~15–20%. No significant increase in surgical complications with longer induction. Similar perioperative morbidity across arms.
Conclusions
Sequential induction FOLFOX before standard CRT produces a dose-response increase in pCR rates (18% to 38%). Six cycles of induction FOLFOX before CRT achieves ~38% pCR — substantially higher than CRT alone. This concept (induction chemotherapy → CRT, i.e., "TNT") substantially increases the pool of patients eligible for watch-and-wait organ preservation strategies.
Key Limitations
Key Limitations: Small phase 2 randomized trial — not powered for OS or DFS. Single-institution (MSKCC). pCR as primary endpoint is a surrogate — improved pCR without OS benefit has been seen in other settings. The 4-arm design limits power for pairwise comparison. Since publication, TNT has been formalized in larger trials (RAPIDO, PRODIGE 23, OPRA) with different regimen sequencing (SCRT → CAPOX → surgery in RAPIDO).
Clinical Context
The MSKCC Sequential trial established the TNT (Total Neoadjuvant Therapy) concept of adding systemic chemotherapy before CRT to increase pCR. This directly informed RAPIDO (SCRT + CAPOX → surgery), PRODIGE 23 (mFOLFIRINOX → CRT → surgery), and OPRA (comparing induction vs consolidation FOLFOX sequencing). TNT is now a standard approach in NCCN and ESMO guidelines for patients pursuing organ preservation.
References