Benzinga | Dec 27, 2021 08:10AM EST

Moleculin Announces Preliminary Third Cohort Interim Data In Phase 1b/2 Clinical Trial Of Annamycin For The Treatment Of Soft Tissue Sarcoma Lung Metastases

Moleculin Biotech, Inc., (NASDAQ:MBRX) ("Moleculin" or the "Company"), a clinical stage pharmaceutical company with a broad portfolio of drug candidates targeting highly resistant tumors and viruses, today reported preliminary interim results from its U.S. Phase 1b/2 clinical trial as it concluded the safety review of the third cohort and opens the fourth cohort in a dose escalation trial evaluating Annamycin for the treatment of soft tissue sarcoma (STS) lung metastases, which continues to document preliminary clinical activity for this drug.

The Phase 1b/2 study is a U.S. multi-center, open-label, single-arm study that in Phase 1b will determine the maximum tolerated dose (MTD) or the recommended Phase 2 dose (RP2D) and safety of Annamycin. The Phase 2 portion of the study will explore the efficacy of Annamycin as a single agent for the treatment of subjects with STS with lung metastases for whom prior chemotherapy has failed, and for whom new chemotherapy is considered appropriate. A minimum of three subjects will be enrolled in each cohort of the Phase 1b portion of the study until an MTD is identified, after which there will be a recommendation for the RP2D based on an assessment of both safety and efficacy. Up to 25 subjects will be enrolled at the RP2D in Phase 2 to further evaluate efficacy.

"Even though this is still early in the Phase 1b portion of the trial, the data continue to be encouraging. Three of the six patients in the first two cohorts reached four or more months with stable disease or better. In a patient population where the median progression-free survival is approximately 1.61 months, we believe Annamycin has the potential to bring a new and effective treatment option to patients with this significant unmet need," commented Walter Klemp, Chairman and CEO of Moleculin.

Mr. Klemp added, "We are also encouraged by the pace of recruitment to date for this trial. To have completed three full cohorts in just the first 6 months of the study is faster than we would have expected, especially for a rare disease like STS lung metastases. Since more sites have now joined the study in this quarter, we believe this should further aid in the pace of recruitment."

"Consistent with our earlier and ongoing acute myeloid leukemia trials to date, we continue to see a complete absence of cardiotoxicity in this STS trial," Mr. Klemp concluded. "We continue to emphasize this point because, even though anthracyclines are considered a cornerstone chemotherapy for many types of cancer including STS lung metastases, all currently approved anthracyclines are significantly cardiotoxic. Annamycin was designed to overcome this problem and we believe it has the potential to become the first non-cardiotoxic anthracycline approved for use. This could not only reduce the risk of many current anthracycline treatment regimens, but it could also enable longer treatment periods without cardiac risk."

The summary of interim data from the first three cohorts of the study are as follows:

First Cohort (210 mg/m2):

* Two subjects had stable disease up to 6 cycles (4.5 months) but were then discontinued due to progressive disease.

* One subject discontinued after the first cycle. The End of Study scan was performed, and stable disease was observed. However, the subject discontinued from the study because the initiation of the second cycle was delayed greater than 6 weeks from the previous dose.

Second Cohort (270 mg/m2):

* In one subject, the scan at the end of the second cycle showed that there was a partial response (PR, >30% reduction in tumor size), and this was stable when the subject was scanned at the end of cycle 4. The subject subsequently discontinued from the study due to that subject electing to undergo surgical resection to potentially eradicate disease.

* One subject was discontinued from the study after 2 cycles after the end of cycle 2 scan revealed progressive disease.

* One subject received 1 cycle of treatment but discontinued treatment for reasons unrelated to Annamycin. The End of Study scan revealed progressive disease.

Third Cohort (330 mg/m2):

Efficacy data for the third cohort is incomplete as not all patients have received their scans.

* One subject received 1 cycle, without exhibiting any dose-limiting toxicities. An interim, unscheduled scan revealed progressive disease and the subject was discontinued from the study.

* One subject was discontinued from the study after 2 cycles after the end of cycle 2 scan revealed progressive disease.

* One additional subject was treated, also without evidence of any dose-limiting toxicities, and CT scans are scheduled in the near term.

The statements above are based on interim data and should be considered preliminary and subject to change.

The Company has now opened enrollment in the fourth cohort of the Phase 1b portion of the study with dosing increased to 390 mg/m2. Three subjects minimum (6 maximum) for this and each subsequent dosing cohort will be enrolled until a maximum tolerated dose is identified. Therefore, up to 36 subjects may be enrolled in the Phase 1b portion of the study.

Annamycin currently has Fast Track Status and Orphan Drug Designation from the U.S. Food and Drug Administration for the treatment of STS lung metastases, in addition to Orphan Drug Designation for the treatment of relapsed or refractory acute myeloid leukemia. For more information about the Phase 1b/2 study evaluating Annamycin for the treatment of STS lung metastases, please visit clinicaltrials.gov and reference identifier NCT04887298.