Phase III Study of SBRT Combined With All-trans Retinoic Acid to Protect Lymphocytes in Adults With Oligo-metastatic Solid Cancer

What this Trial Is About

Researchers are studying patients with oligo-metastatic solid cancer to assess the safety of combining stereotactic body radiation therapy SBRT directed at all metastatic lesions with all-trans retinoic acid ATRA. This phase III clinical trial aims to evaluate whether ATRA can protect lymphocytes from radiation-induced damage, which may improve immune response and control of cancer spread. The study is conducted in two parts an initial safety evaluation followed by a randomized comparison of SBRT alone versus SBRT combined with ATRA. The treatment involves delivering SBRT to all tumor lesions larger than 1.5 cm on weekdays over a maximum of two weeks. In the experimental arms, patients receive oral ATRA at 150 mgm2day for three days every three weeks, for up to four cycles starting with the first day of radiation. Part I of the study includes six patients receiving the combination to assess safety. Part II randomizes 52 patients equally to SBRT with or without ATRA to evaluate ATRAs ability to reduce lymphopenia, a reduction in lymphocyte count caused by radiation. Participants will undergo blood tests, biopsies, and imaging scans for monitoring safety, treatment response, and lymphocyte levels. The primary outcomes are dose-limiting toxicities assessed up to three weeks after treatment start, and lymphocyte protection measured six weeks after SBRT. Secondary outcomes include tumor control rates, response rates, duration of response, and progression-free survival tracked from six weeks to one year post-treatment. Participants are expected to comply with follow-up visits, blood sampling, and biopsies during the study period.

Lymphocyte Support to SBRT in Patients With Oligo-metastatic Solid Cancer