Ibalizumab might be the answer for patients with drug resistance

Despite incredible progress in HIV treatment, drug resistant strains are now threatening to undercut the effectiveness of the powerful antiretrovirals available today. Some strains of HIV have evolved to resist one or more classes of HIV drugs and, although multidrug resistance only affects a small percent of patients, those people are in dire need of new options.

An experimental injectable drug, ibalizumab, might be the answer. Ibalizumab is a new drug that is effective against drug resistant HIV. It is not approved for sale in the United States, but patients can take advantage of an expanded access program to start treatment right away.

According to results published in October, ibalizumab might be the best -- and one of the only -- new treatment options for patients struggling with drug resistance. In preliminary findings from a Phase 3 trial, patients who took ibalizumab in combination with their failing regimen saw a significant reduction in viral load within one week. In 60 percent of patients, viral load dropped by one log or more.

Ibalizumab has a unique mechanism of action: It works by blocking the HIV virus from entering CD4 cells. The Food and Drug Administration (FDA) granted it orphan drug status in 2014 and breakthrough therapy designation in 2015. In March 2016, the drug's sponsor, TaiMed, launched an expanded access program to make ibalizumab available to patients who are currently struggling with a multidrug-resistant strain of HIV.

"Any patients that are challenged because they have a resistant virus would most likely be eligible" for the expanded access program, explained Christian Marsolais, Ph.D., senior vice president and chief medical officer of Theratechnologies, a company that partnered with TaiMed to oversee the drug's distribution in North America.

Ibalizumab won't be commercially available for many months. TaiMed will submit its application to the FDA in the first quarter of 2017 and, because ibalizumab is a breakthrough therapy, the FDA will probably reach its decision six months after that, Marsolais explained. That means it could still be one year or more before ibalizumab is approved in the United States.

In the meantime, patients can enroll in the expanded access program, which is structured like a Phase 3 trial so that the company can keep track of any unexpected safety problems, explained Marsolais. But, unlike many traditional clinical trials, the Phase 3 expanded access program is designed with broad inclusion/exclusion criteria, meaning that almost any patient with multidrug resistance is eligible to enroll.

Patients must be 18 or older, be able to give informed consent, have a viral load at or above 1,000 copies/mL, be resistant to at least one medication from each of the three classes of medications and currently be failing treatment. Patients who are sexual active will be asked to use protection during the duration of the study. Women who are pregnant or considering pregnancy will be excluded, as will any patients who have been acutely ill (such as the flu) within one week of enrollment or recently received radiation treatment.

There are several ways for patients to enroll in the expanded access program. One option is to contact TaiMed's contract research organization, Westat, which is managing the Phase 3 expanded access trial. Patients should ask their doctors to reach out to Tracy Wolbach, a Westat senior study director who is managing the program.

A second option is to search for a study site on ClinicalTrials.gov (use the identification number NCT02707861). The website has contact information for each of the 17 study centers, which are located in more than a dozen major cities, including Los Angeles, Atlanta, Washington, D.C., New York and San Juan (Puerto Rico). If a patient would like to enroll in the trial but does not live near a study site, TaiMed and its partners will consider opening a new center elsewhere, Marsolais said.

After a baseline screening and several initial appointments, patients will be asked to travel to their local clinic for an infusion once every two weeks. The infusion takes only about 15 minutes, but once every three months patients will be asked to visit the clinic for a longer examination and survey, Marsolais explained.

Dozens of patients may have already enrolled in the expanded access program, said Marsolais, who did not give a specific number, but noted that a "significant number" of the 40 patients enrolled in the prior Phase 3 trial have switched over to the expanded access program to continue to receive treatment. In addition, some patients who participated in a Phase 2b trial years ago are also still receiving ibalizumab through the expanded access program, Marsolais said.

These patients, as well as any new patients who enroll in the expanded access program, will continue to receive ibalizumab until the FDA makes its approval decision. If the drug is approved, TaiMed and its partners will set up a call center to help patients seek ibalizumab through their own private or public insurance plans, Marsolais said.

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