["Psycho-Oncology, Volume 35, Issue 8, August 2026. ", "\nABSTRACT\n\nObjective\nCancer‐related posttraumatic stress disorder (PTSD) is prevalent among hematopoietic cell transplantation (HCT) survivors, yet access to evidence‐based care is limited. This study evaluated adaptive, stepped‐care treatment sequences for PTSD symptoms using a Sequential Multiple Assignment Randomized Trial (SMART), comparing digital and therapist‐delivered interventions.\n\n\nMethods\nHCT survivors (N = 477), 1–5 years post‐transplant, with probable or subthreshold PTSD, were randomized to the Cancer Distress Coach (CaDC) app or Usual Care. At Week 4, non‐responders (i.e., < 5‐point PCL‐5 reduction) were re‐randomized to CaDC + Coaching or therapist‐delivered cognitive behavioral therapy for PTSD (CBT‐PTSD). PTSD symptoms (primary outcome), depression, and anxiety were assessed at baseline, Week 4, Month 3 (primary endpoint), and Month 6.\n\n\nResults\nBoth initial treatment groups demonstrated symptom reductions at Week 4 with no significant between‐group differences; approximately 60% met early response criteria. By Month 3, outcomes reflected treatment escalation rather than direct comparison of initial interventions. Regimen‐level analyses demonstrated differences across adaptive sequences for PTSD at Months 3 and 6, and for depression and anxiety at Month 3 (global p‐values ≤ 0.018). Regimens escalating to CBT‐PTSD were associated with greater and more sustained reductions than those escalating to CaDC + Coaching. The sequence initiating with CaDC and escalating to CBT‐PTSD produced the largest effects.\n\n\nConclusions\nAlthough a self‐guided digital intervention did not outperform Usual Care initially, adaptive stepped‐care strategies that triage early responders and escalate non‐responders to therapist‐delivered CBT‐PTSD were associated with the greatest reductions in symptoms. Digital tools may function as entry points within stepped‐care models to allocate higher‐intensity psychotherapy.\n\n\nTrials registration\nClinicalTrials.gov, NCT04058795, registered 8/16/2019\n\n"]