Merrimack Pharmaceuticals Inc (NASDAQ:MACK) announced data for MM-398 (irinotecan liposome injection), also known as ”nal-IRI,” in a Phase 1 investigator-sponsored study at the University of California, San Francisco for high-grade glioma. Data were presented at the 2015 American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago, IL. Results from this study show a tolerable safety profile of MM-398 in patients with high-grade glioma when given intravenously.

Based in part on the data from this Phase 1 study, investigators at the University of California, San Francisco initiated a new Phase 1 study in November 2014 that is assessing the safety of highly concentrated MM-398 when administered by convection-enhanced drug delivery (CED) in patients with recurrent high-grade glioma. In this new study, MM-398 will be administered with gadoteridol, an MRI imaging agent to enable the real time visualization of drug distribution in the brain, through a small catheter that allows for the drug to be injected directly into the brain tumor. The study is being conducted at a single center at the University of California, San Francisco and will enroll up to 30 patients with recurrent high-grade glioma. A trials-in-progress poster was presented at ASCO detailing the design of this study. For more information visit (Identifier: NCT02022644).

“High-grade glioma is an aggressive disease that often grows and progresses despite surgery and standard of care chemotherapies. These current results from the investigator-sponsored study of MM-398 show promise for the safety of the drug in this indication,” said Daryl Drummond, Ph.D., Vice President of Discovery at Merrimack Pharmaceuticals. “We are pleased with the progress of this study and will continue to move MM-398 forward in areas of high unmet medical need, as well as explore novel delivery techniques like CED administration that will best utilize the nanoliposomal design of the drug.”

To view the posters presented at ASCO, visit our website at

Methodology and Results

A Phase I trial of intravenous liposomal irinotecan in patients with recurrent high-grade gliomas

MM-398 is a nanoliposomal encapsulation of irinotecan that has demonstrated extended circulation in comparison to free irinotecan in the clinical setting. The activated form of irinotecan is SN-38, which functions by inhibiting topoisomerase I (an essential enzyme involved in DNA transcription and replication) and promoting cell death.

  • This phase 1 study enrolled patients with recurrent malignant glioma, stratified by UGT1A1*28 genotyping with no prior treatment with irinotecan. Arm 1 of this study enrolled patients with homozygous UGT1A1*28 genotypes with dose increments of 120 mg/m2 from intravenous dosage levels of 120 mg/m2 to 240 mg/m2. Arm 2 of this study enrolled patients with heterozygous UGT1A1*28 genotypes with dose increments of 60 mg/m2 from intravenous dosage levels of 60 mg/m2 to 180 mg/m2.
  • Tolerability was similar between the two study arms and was consistent with data from the original phase I study in solid tumors. The maximum tolerated dose (MTD) in Arm 1 was 120 mg/m2; the MTD in Arm 2 was 150 mg/m2.
  • MM-398 had no unexpected toxicities when given intravenously. Dose limiting toxicities in both arms of the study included diarrhea, often accompanied by dehydration and/or fatigue.
  • The median progression free survival for all patients treated with an initial dose of at least 120 mg/m2 was 43 days.
  • The toxicity profile of the drug was considered acceptable enough to move forward with an additional study using convection-enhanced delivery into intracranial tumors, the Phase I study that is currently enrolling at the University of California, San Francisco. (Original Source)

Shares of Merrimack Pharmaceuticals closed today at $11.53, down $0.27 or 2.29%. MACK has a 1-year high of $13.84 and a 1-year low of $5.53. The stock’s 50-day moving average is $12.37 and its 200-day moving average is $11.04.

On the ratings front, Cantor Fitzgerald analyst Daniel Brims reiterated a Buy rating on MACK, with a price target of $16, in a report issued on February 26. The current price target represents a potential upside of 39% from where the stock is currently trading. According to, Brims has a total average return of 1.4%, a 51.4% success rate, and is ranked #2032 out of 3610 analysts.

Merrimack Pharmaceuticals Inc is engaged in discovering, developing and preparing to commercialize medicines consisting of novel therapeutics paired with companion diagnostics for the treatment of cancer.