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Major Monoclonal Antibody Drug Trial for HIV Patients Underway

Author: Alessandra Miguel-Descalso

Published: 2014-10-29 : (Rev. 2017-06-25)


PRO 140 may prove to be a potential new therapy for HIV patients who need to cycle off conventional treatment regimens.

Main Digest

For those afflicted with HIV, treatment is a life-long commitment. Once treatment has commenced, the patient should continue taking his meds as strictly advised. It sounds simple enough, but it's easier said than done.

The standard treatment for HIV, according to the World Health Organization (WHO), involves the combination of three drugs or more (a drug "cocktail"), which is medically known as highly active antiretroviral therapy or HAART, to prevent HIV replication. HAART prevents the virus from developing resistance and has been observed to improve patients' quality of life. It has been found, in fact, to have lowered morbidity rates among HIV patients by as much as 70 percent, according to an independent report on

But there are instances when patients and their healthcare providers may decide to pause or modify HAART. stated two of the reasons for stopping HAART include drug toxicity and regimen failure. Drug toxicity occurs when HIV meds cause unbearable side effects that prevent patients from pursuing the treatment. Regimen failure, on the other hand, results from the ineffectiveness of the prescribed drugs to keep the patient's HIV virus in check.

When treatment is stopped, the period is often referred to as drug holiday or structured treatment interruption. However, pausing treatment could cause patients to become more ill as they lose their body's ability to contain the HIV virus.

In the United States, Cytodyn Inc. (OTC: CYDY), a Washington-based biotechnology company engaged in developing new therapies for the treatment of immune deficiency viruses-caused infections, is currently working on a drug that aims to prolong this so-called drug holiday while preventing viral rebound in patients. So far, the company has been successful with its trials, and is ready to move on with Phase 3 of its clinical trials for the said drug.

Back in March, the company announced the drug, which was based on a new class of humanized cell-specific monoclonal antibodies (mAbs) and called PRO 140, to be able to rapidly prolong virus suppression of up to three weeks. Recent results of its Phase 2b clinical trials, however, showed that PRO 140 was actually able to effectively suppress viral load by eight weeks in human test subjects, which translates to a 100 percent efficacy rate.

The trial's participants followed their normal drug regimen plus PRO 140 during the first week of the trial and continued with only the weekly PRO 140 monotherapy for the next 12 weeks. October results showed that the therapy allowed patients to have 4 weeks of drug holiday without virologic failures.

PRO 140 belongs to a new class of HIV/AIDS therapeutics called viral-entry inhibitors which block the entry of the HIV virus into healthy cells. PRO 140 is a humanized monoclonal antibody that targets CCR5, a molecular gateway for HIV to enter healthy cells. Unlike other drugs, it appears to have fewer side effects and has to be administered less frequently (weekly or bi-monthly), leading to cost savings for patients.

When the company released its interim results in July, it found that after four weeks of PRO 140 monotherapy, none of the participants had any viral breakouts. 50 percent of the patients, meanwhile, had exhibited effective viral suppression after 8 weeks of monotherapy.

Dr. Nader Pourhassan, Cytodyn President and CEO, said there are currently over 30 drugs approved for HIV/AIDS treatment in the market but most of these drugs present ill side effects and drug resistance, not to mention that they require patients to take the drug indefinitely.

"We believe this [the preliminary result] is a very strong indication that PRO 140 is effective to allow 4 weeks of drug holiday with weekly injections. PRO 140's safety has been well documented in previous studies, as well as our current study," Pourhassan said of the positive outcome of the PRO 140 trials.

"We believe PRO 140 may prove to be a potential new therapy for HIV patients who need to cycle off conventional treatment regimens."

Cytodyn, Inc. is awaiting FDA's clearance to enter the third phase (licensing trial) of its clinical trial to further prove the effectiveness of PRO 140.

The company disclosed that PRO 140 works only with patients who are HIV positive with the R5 strain of the virus, which uses the CCR5 receptor to enter and infect healthy cells. Patients with the HIV strain X4 will not respond well to PRO 140 as the strain uses the other co-receptor, CXCR4.

The Centers for Disease Control and Prevention (CDC) estimates that there are 1,144,500 people aged 13 and older living with HIV, including 180,900 or some 15.8 percent of the population who have no knowledge of their infection. It noted, however, that while the number of new HIV infections has "remained relative stable" the past decade, the pace that new infections are growing is staggering.

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