CytoDyn Sees Promising Early Responses in Two Breast Cancer Patients to Leronlimab

NEW YORK – Late-stage biotech company CytoDyn announced on Monday that an early trial of its new drug candidate leronlimab (PRO 140) produced a positive clinical response in two patients with metastatic breast cancer. 

The Phase Ib/II trial is investigating previously untreated CCR5-positive triple negative metastatic breast cancer patients who test negative for estrogen receptors, progesterone receptors, and excess HER2 protein, and test positive for CCR5 overexpression. Statuses of patients are confirmed prior to trial admittance using an immunohistochemistry test. 

The first metastatic TNBC cancer patient enrolled in the trial at the time of data collection had no detectable circulating tumor cells or metastatic tumor cells in their blood. They also had reduced CCR5 expression on cancer-associated cells after 11 weeks of treatment with leronlimab. 

The second patient has stage IV HER2-positive metastatic breast cancer and was enrolled into the trial under an emergency use of an investigational drug or biologic protocol. The patient's tumors shrunk, noted through MRI scans, after three weeks of treatment with leronlimab.

"It is very exciting to see ongoing results that demonstrate leronlimab's potential as a therapeutic option to treat patients with metastatic TNBC and MBC with HER2-positive condition," CytoDyn CEO Nader Pourhassan said in a statement. 

No serious adverse effects have been reported yet in the trial. 

Leronlimab, a subcutaneously injected CCR5 antagonist, is CytoDyn's lead product. In addition to early-phase studies in metastatic breast cancer, the drug is also in late-stage trials as a treatment of HIV. 

CCR5 receptors play an important role in HIV. In fact, one of the early examples in personalized medicine was maraviroc (ViiV Healthcare's Selzentry), a CCR5 antagonist for the treatment of CCR5-topic HIV-1.

However, these receptors are thought now to also play a central role in tumor invasion and metastasis. In several cancers, increased CCR5 expression is an indicator of disease status. In a preclinical mouse xenograft study published earlier this year, CCR5 blockers reduced tumor metastases by 98 percent. 

In May, the US Food and Drug Administration granted fast-track designation to leronlimab for use in combination with chemotherapy carboplatin for the treatment of patients with CCR5-positive metastatic TNBC.  

CytoDyn's Phase Ib trial is a dose-escalation phase designed to determine the maximum tolerated dose of leronlimab. Phase II is a single arm study with 30 patients that will assess whether chemotherapy and the maximum tolerated dose of leronlimab will increase progression-free survival in patients with CCR5-positive metastatic TNBC.

The trial currently has 48 total patients, and the company seeks to continue enrollment. 

The company is intending to file with the FDA for breakthrough therapy designation in Jan 2020 for leronlimab, and it is also eyeing other potential metastatic cancer indications for the drug.