Low molecular weight 35 kDa hyaluronan fragment HA35 in the treatment of bone metastasis pain: A case report.

Rationale: Late-stage cancer patients often experience severe pain due to bone metastasis, caused by structural damage and cancer-induced inflammation. Hyaluronan, known to alleviate pain by blocking the TRVP1 calcium channel, faces limitations due to its high molecular weight. However, 35 kDa low molecular weight hyaluronan fragment (HA35) have shown promise in relieving various pains, including cancer-related pain. Nonetheless, evidence regarding their efficacy in bone metastasis pain remains scarce.

Patients Concerns: A 52-year-old female with a rectal malignant tumor and multiple secondary tumors in the sacrum and lungs, accompanied by bone metastasis pain. Despite undergoing radiotherapy, her pain relief was unsatisfactory. Before treatment with HA35, her numerical rating scale score was 10, severely affecting her sleep, appetite, and daily activities.

Diagnoses: The patient was diagnosed with rectal malignant tumor with multiple metastases, presenting symptoms such as sacral metastasis pain, anal pain, lower limb pain, and anterior abdominal pain. Sacral metastasis pain and lower limb pain indicated a clear diagnosis of bone metastasis pain.

Interventions: Treatment involved subcutaneous injection into the deep fat tissue layer of the abdomen. A subcutaneous injection of 100 mg/5 mL of HA35 was administered once into the deep fat tissue of the abdomen, with subsequent injections repeated every 3 days.

Outcomes: Following 1 injection, the patient's pain score decreased to 6 points within 20 minutes, providing 40% pain relief. After 40 minutes, the score further dropped to 4 points, with 60% pain relief. After 50 injections, pain was consistently controlled at around 3 points.

Lessons Subsections: Subcutaneous injection of HA35 into the abdominal fat tissue effectively alleviates pain in cancer and bone metastasis patients resistant to conventional treatments. Additionally, it helps alleviate anxiety and fatigue, and improves diet and sleep, thereby offering crucial palliative care for advanced cancer patients.