On June 1, 2023 Monopar Therapeutics Inc. (Nasdaq: MNPR), a clinical-stage biopharmaceutical company focused on developing innovative treatments for cancer, reported an update from its currently enrolling multi-center open-label Phase 1b clinical trial of camsirubicin in patients with advanced soft tissue sarcoma (ASTS) (Press release, Monopar Therapeutics, JUN 1, 2023, View Source [SID1234632349]).
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Background on ASTS and Camsirubicin
ASTS is a diverse type of cancer that typically develops in the connective tissue of the body and which has metastasized (spread) or is not amenable to surgery. The average life expectancy from time of diagnosis for patients with ASTS is about 12 to 15 months. Currently, doxorubicin is the first-line standard of care treatment for most types of ASTS.
Doxorubicin is one of the most widely used cancer drugs worldwide with FDA approval in ASTS and 13 additional cancer indications. Unfortunately, although higher doses of doxorubicin are known to be more effective at treating cancer, the risk of irreversible heart damage increases with the cumulative dose and limits the lifetime amount that a patient can receive. As a result, even if patients are responding, they discontinue doxorubicin treatment typically after only 6 to 8 cycles (~6 months or less).
Camsirubicin has been designed to retain the anti-cancer activity while avoiding the irreversible heart damage that is seen with doxorubicin. The hypothesis for camsirubicin is straightforward: modifying doxorubicin in order to reduce cardiac damage could enable higher and longer dosing, resulting in better efficacy and patient outcomes.
Updates from Currently Enrolling Phase 1b Clinical Trial
One patient at the 520 mg/m2 dose level, unresectable at study entry, was deemed eligible for tumor resection after several cycles of camsirubicin treatment and a corresponding 21% reduction in tumor dimensions. This patient recently underwent surgical resection of the cancer.
100% of patients (3 of 3) at the fourth dose-level (520mg/m2) achieved stable disease, and had either a net reduction or no overall change in tumor size per RECIST 1.1 while on study drug.
Phase 1b data continue to show an improvement in median progression free survival from what was observed in the prior camsirubicin Phase 2 trial (265 mg/m2). This is supportive of our dose-response hypothesis with camsirubicin.
Two patients are currently enrolled in the fifth dose-level cohort (650 mg/m2), which is nearly 2.5x the highest dose evaluated in any prior camsirubicin clinical trial (265mg/m2).
No drug-related cardiotoxicity has been observed in this trial to-date as evaluated by the industry standard left ventricular ejection fraction (LVEF).
As previously reported, this trial continues to show less frequent and less severe hair loss and oral mucositis with camsirubicin compared to what has been seen in recent ASTS clinical trials with doxorubicin.
No dose limiting toxicity (DLT) has been experienced by any patient in the trial to-date.
Camsirubicin Clinical Trial Design and GEIS Collaboration
The purpose of this 3+3 dose escalation Phase 1b trial is to determine the maximum tolerated dose (MTD) of camsirubicin. Once the MTD is reached, Monopar has a clinical collaboration agreement in place with the Spanish Sarcoma Group (Grupo Español de Investigación en Sarcomas, or GEIS) to conduct a multi-country randomized Phase 2 clinical trial. The Phase 2 plan is to evaluate camsirubicin head-to-head against doxorubicin in patients with ASTS, with GEIS as the study sponsor with support from Monopar.
Further information about this actively enrolling, open-label, dose-escalation Phase 1b clinical trial is available at www.ClinicalTrials.gov under study identifier NCT 05043649.