PR104 + docetaxel

PR104 + docetaxel is a combination therapy that has been investigated in clinical trials for the treatment of advanced solid tumors, particularly non-small cell lung cancer (NSCLC). This combination pairs PR104, a hypoxia-activated prodrug, with docetaxel, a well-established chemotherapeutic agent. ## Mechanism and Development PR104 is a phosphate ester "pre-prodrug" that is rapidly hydrolyzed in the body to PR-104A, which is then activated under hypoxic conditions found in solid tumors. PR-104A is metabolized to reactive nitrogen mustards that cause DNA cross-linking in hypoxic cells[1][8]. Additionally, PR-104A can be activated by the enzyme aldo-keto reductase 1C3 (AKR1C3) independently of hypoxia[10]. This dual activation mechanism makes it particularly interesting for cancer therapy. When combined with docetaxel, PR104 showed greater than additive antitumor activity in preclinical models[8]. However, clinical trials revealed significant myelotoxicity (bone marrow suppression) when these agents were combined[1]. ## Clinical Development A phase I clinical trial determined that the combination of PR104 with docetaxel caused dose-limiting and severe myelotoxicity. However, the addition of prophylactic granulocyte colony-stimulating factor (G-CSF) allowed for PR104 dose escalation when combined with docetaxel[1]. The maximum tolerated dose (MTD) was established at: - 200 mg/m² when PR104 was combined with docetaxel 60 mg/m² - 770 mg/m² when PR104 was combined with docetaxel 60 mg/m² plus G-CSF - ≥770 mg/m² when PR104 was combined with docetaxel 75 mg/m² plus G-CSF[1] A recommended phase II dose of 770 mg/m² of PR104 combined with docetaxel 60-75 mg/m² (both given on day one of a 21-day treatment cycle) with prophylactic G-CSF support was established[1]. ## Clinical Trials Following the phase I study, a randomized, multi-center, open-label phase II trial (NCT00862134) was conducted to evaluate PR104 versus PR104/docetaxel in non-small cell lung cancer (NSCLC)[2][4]. This trial was particularly focused on patients with NSCLC that expressed high levels of AKR1C3, which is found in approximately half of NSCLC tumors tested[2]. The rationale for testing this combination in NSCLC included: 1. High expression of AKR1C3 in about half of NSCLC tumors 2. Demonstrated hypoxia in NSCLC tumors 3. Preclinical data showing supraadditive activity when PR104 and docetaxel were used in combination 4. Manageable toxicity profile when G-CSF was added to the regimen[2] However, based on the search results, it appears that this trial was terminated[4], though specific reasons for termination are not provided in the available information.

Other names

PR104 and docetaxelPR-104 and docetaxelPR 104 and docetaxel