Dose escalation study of an anti-thrombocytopenic agent in patients with chemotherapy induced thrombocytopenia

Background: Preclinical studies demonstrated that small chain RNA fragments accelerate the recovery of platelets numbers in animals exposed to high doses of chemotherapeutic drugs. There is anecdotal data supporting the same application in humans. The Phase I clinical trial described here was designed to investigate the relationship between the administration of small chain RNA fragments and the recovery in platelets following Chemotherapy Induced Thrombocytopenia (CIT). Methods: Cancer patients with solid tumors that experienced post chemotherapy thrombocytopenia with a nadir of < = 80,000 platelets/ml were eligible for this clinical trial. There were no exclusions based on ECOG status, tumor type, tumor burden or chemotherapeutic agents. Patients received a unique preparation of RNA derived from either E. coli or yeast. Ten patients per group received 20, 40, or 60 mg as a starting dose. Subjects self-administered RNA fragments sublingually on an every other day schedule while undergoing chemotherapy. The dose was escalated in 20 mg increments to a maximum dose of 80 mg if the nadir was < 80,000 platelets/ml at the start of the next cycle. Subjects were treated for three cycles of chemotherapy with the maximum effective dose of RNA fragments. Subjects continued on planned chemotherapy as indicated by tumor burden without RNA fragment support after the third cycle. Subjects kept a diary indicating RNA fragment and magnesium administration, and any experienced side effects. Results: Patients receiving E. coli RNA fragments demonstrated a more rapid recovery in platelet count and higher nadir platelet count. None of the patients receiving the E. coli RNA fragments required a chemotherapy dose reduction due to thrombocytopenia. The optimal dose for minimizing CIT was 80 mg. Conversely, subjects receiving yeast RNA fragments with dose escalation to 80 mg required a chemotherapy dose reduction per American Society of Clinical Oncology guidelines for grade 3 and 4 thrombocytopenia. Conclusions: Patients receiving myelosuppressive chemotherapy experienced an improvement in the platelet nadir and shorter recovery time when receiving concurrent E coli RNA fragments, when compared to patients who received yeast RNA fragments. These data indicate that 60 and 80 mg doses of E. coli RNA accelerated platelet recovery. Further clinical investigations are planned to quantify the clinical benefits of the E. coli RNA at the 80 mg dose in patients with chemotherapy induced thrombocytopenia.