U.S. FDA halts five Gilead HIV trials due to safety concerns

USA—The U.S. Food and Drug Administration (FDA) has imposed a clinical hold on five trials conducted by Gilead Sciences that were assessing a new experimental once-weekly HIV combination therapy.

This decision followed the identification of a safety concern involving a decrease in specific white blood cells, specifically CD4+ T-cells and absolute lymphocyte counts, in some patients receiving the combination of two investigational drugs, GS-1720 and GS-4182.

These trials included two mid-to-late-stage Phase 2/3 studies, named WONDERS-1 and WONDERS-2, as well as three earlier Phase 1 studies.

The WONDERS-1 trial was evaluating the safety and effectiveness of the GS-1720 and GS-4182 combination compared to Gilead’s approved daily HIV pill, Biktarvy, in patients whose virus was already suppressed.

Meanwhile, WONDERS-2 was testing the combination in treatment-naive HIV patients, those who had not previously received therapy.

The safety signal that triggered the FDA’s hold indicates a potential immune system compromise, as reductions in CD4+ T-cells can signal a worsening of HIV infection.

Gilead acknowledged this concern and emphasized its commitment to investigating the issue thoroughly and working closely with regulatory authorities to resolve the clinical hold.

Importantly, Gilead stated that this hold does not affect its other HIV treatment programs, including its long-acting oral and injectable investigational therapies.

This includes lenacapavir, a drug approved under the brand name Sunlenca for twice-yearly treatment of people with multi-drug-resistant HIV and currently under FDA review for HIV prevention.

Analysts have noted that the pause on these trials is not expected to impact the upcoming FDA decision on lenacapavir, which is highly anticipated and could lead to a major expansion of Gilead’s HIV treatment portfolio.

Following the announcement, Gilead’s shares fell about 2%, trading near US$110.77 per share, reflecting investor caution but not a major loss of confidence in the company’s broader HIV pipeline.

Gilead, a leading biopharmaceutical company headquartered in Foster City, California, has been at the forefront of HIV treatment innovation for decades.

The company is focused on advancing new therapies to improve outcomes and expand options for people living with HIV worldwide.

While this clinical hold represents a setback for the GS-1720 and GS-4182 combination, Gilead remains committed to its ongoing research and development efforts in HIV treatment.

No timeline has been provided for when the paused trials might resume, as Gilead continues to analyze the safety data and collaborate with the FDA to address the concerns.

The company’s other HIV clinical and preclinical programs remain unaffected and continue to progress.

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