MORPHEUS Phase II-III Study: A Pre-Planned Interim Safety Analysis and Preliminary Results

Area of Science:

• Radiation Oncology
• Rectal Cancer Treatment
• Brachytherapy

Background:

• Investigated image-guided adaptive endorectal brachytherapy (IGAEBT) for rectal cancer patients undergoing non-operative management.
• Presents the first interim analysis of a randomized study comparing IGAEBT with standard external beam radiotherapy (EBRT).

Purpose of the Study:

• To evaluate the feasibility and efficacy of IGAEBT as a radiation intensification strategy in rectal cancer.
• To compare TME-free survival between patients receiving IGAEBT boost and those receiving EBRT boost.

Main Methods:

• Open-label, phase II-III randomized study involving 40 patients with operable cT2-3ab N0 M0 rectal cancer.
• All patients received pelvic EBRT (45 Gy) with 5-FU/Capecitabine.
• Randomization to either an EBRT boost (Arm A) or IGAEBT boost (Arm B).

Main Results:

• Complete clinical response (cCR) was 50% in Arm A vs. 90% in Arm B.
• Median follow-up was 1.3 years.
• 2-year TME-free survival was 38.6% for EBRT vs. 76.6% for IGAEBT.

Conclusions:

• Radiation intensification using IGAEBT is feasible and well-tolerated.
• This interim analysis indicates a potential improvement in TME-free survival with IGAEBT compared to EBRT.
• Further confirmation is pending upon trial completion.