Researchers are investigating several monoclonal antibodies as potential treatments for severe, treatment-resistant acne, with a particular focus on drugs that target inflammatory pathways in the skin. These biologics work by blocking specific immune signaling molecules that drive acne development, offering a novel approach for patients who haven’t responded to conventional therapies like isotretinoin or oral antibiotics. Recent clinical trials have demonstrated that monoclonal antibodies targeting interleukin-1 (IL-1), interleukin-17 (IL-17), and related inflammatory pathways can reduce severe acne lesions, though results have been mixed so far.
One of the most promising candidates in development is LAD191, a high-affinity monoclonal antibody that blocks interleukin-1 receptor accessory protein (IL-1RAP). Almirall presented Phase I safety and tolerability data for LAD191 at the 2025 American Academy of Dermatology Annual Meeting, marking a significant milestone in understanding how well the drug is tolerated in patients. Another candidate, MABp1, has already demonstrated efficacy in Phase 2 trials, with patients experiencing a median 36% reduction in inflammatory acne lesions compared to baseline—a meaningful improvement for individuals struggling with severe nodular or cystic acne that resists standard treatments.
Table of Contents
- What Are Monoclonal Antibodies, and How Do They Target Acne?
- The Challenge of Treatment-Resistant Acne and Why New Options Matter
- Which Inflammatory Pathways Show the Most Promise?
- How Do Monoclonal Antibodies Compare to Isotretinoin and Other Current Treatments?
- What Are the Current Limitations and Barriers to Adoption?
- The Role of Combination Therapy and Personalized Medicine
- The Future of Biologic Therapy for Acne
- Conclusion
What Are Monoclonal Antibodies, and How Do They Target Acne?
Monoclonal antibodies are laboratory-engineered proteins that bind to specific molecules in the body with precision. In the context of acne, these drugs target cytokines—chemical messengers that fuel the inflammatory cascade responsible for severe breakouts. Instead of killing bacteria like antibiotics do, or shrinking sebaceous glands like isotretinoin, monoclonal antibodies interrupt the immune signals that cause painful, deep lesions to form. This mechanism is fundamentally different from every other oral acne treatment available today.
The IL-1 pathway represents a major driver of acne inflammation. When sebaceous glands become colonized with Cutibacterium acnes, the immune system responds by releasing IL-1α and IL-1β, which recruit white blood cells and amplify inflammation. MABp1, a true human monoclonal antibody, was designed specifically to block IL-1α. In its Phase 2 clinical trial, patients treated with MABp1 monotherapy saw their inflammatory lesion counts drop by a median of 36%—a substantial reduction that came without the severe side effects associated with isotretinoin, such as birth defects, liver damage, or the mandatory monthly bloodwork and iPLEDGE enrollment required for the drug.
The Challenge of Treatment-Resistant Acne and Why New Options Matter
Severe, treatment-resistant acne affects roughly 5% of the population, and some of these patients exhaust conventional options. Isotretinoin, the gold standard for severe acne, works in 90% of cases but carries significant toxicity risks and isn’t suitable for pregnant women or those unable to comply with rigorous monitoring. Patients with contraindications to isotretinoin—such as those with a history of depression, inflammatory bowel disease, or those planning pregnancy—have limited effective alternatives, often resorting to multiple rounds of oral antibiotics, hormonal therapies, or even off-label use of other systemic drugs. For this population, monoclonal antibodies represent a genuinely new therapeutic avenue.
However, the data on monoclonal antibodies isn’t uniformly positive. Imsidolimab (ANB019), a monoclonal antibody targeting interleukin-36 (IL-36), was evaluated in a Phase 2 clinical trial with 123 moderate-to-severe acne patients but failed to demonstrate efficacy over placebo. Similarly, CJM112, which blocks interleukin-17A (IL-17A), was evaluated in a randomized, placebo-controlled trial that enrolled 52 of a planned 75 patients, and no significant differences were observed between the treated group and the placebo group at week 12. These failures highlight a critical limitation: not every inflammatory pathway targeted by monoclonal antibodies translates into effective acne treatment. The immune system’s role in acne is complex, and blocking one cytokine may not be sufficient for all patients or may require combination therapy.
Which Inflammatory Pathways Show the Most Promise?
The acne treatment pipeline currently includes multiple monoclonal antibodies targeting different immune molecules, including IL-1β, IL-17, IL-23, and TNFα. The IL-1 pathway remains the most extensively studied. Beyond MABp1, researchers at Almirall are advancing LAD191, which takes a slightly different approach by targeting IL-1RAP—the receptor that allows IL-1α and IL-1β to exert their inflammatory effects. By blocking the receptor rather than the cytokine itself, LAD191 may provide broader inhibition of IL-1 signaling.
Phase I data presented at AAD 2025 showed that LAD191 was well-tolerated, though larger Phase 2 trials are needed to assess efficacy. Other cytokine targets have proven less effective in early trials, but research continues. IL-17 and IL-23 inhibitors have shown success in other inflammatory skin diseases, particularly psoriasis, leading researchers to explore them for severe acne. The challenge is that acne is primarily a pilosebaceous disease—it arises in hair follicles and sebaceous glands—whereas psoriasis is fundamentally a disease of immune dysregulation affecting the epidermis and dermis more broadly. The pathophysiology differs enough that what works for psoriasis doesn’t automatically work for acne.
How Do Monoclonal Antibodies Compare to Isotretinoin and Other Current Treatments?
Isotretinoin remains the most effective acne medication ever developed, with cure rates exceeding 90% and long-term remission in 70–80% of patients. It’s the standard of care for severe, scarring, or psychologically devastating acne. However, it’s also the most burdensome to use. Women of childbearing age must use two forms of contraception and enroll in iPLEDGE, a federal risk management program that requires monthly pregnancy tests and visits to a registered pharmacy. Patients need regular bloodwork to monitor liver enzymes and lipid levels. Dry skin, lips, and eyes are nearly universal. Mood changes and potential depression have been documented.
For individuals who cannot or will not tolerate these requirements, isotretinoin is simply not an option. Monoclonal antibodies, if they prove effective, offer a different safety profile. Early data suggests they’re well-tolerated with a favorable adverse event profile compared to isotretinoin. However, they may be less potent. The 36% median reduction in inflammatory lesions with MABp1 is meaningful but not equivalent to isotretinoin’s near-total clearance rates. Additionally, monoclonal antibodies require ongoing administration—likely intravenous infusions or subcutaneous injections at regular intervals—whereas isotretinoin is given as a time-limited course. This means patients might need to receive monoclonal antibodies indefinitely to maintain their improvement, raising questions about long-term costs, adherence, and convenience.
What Are the Current Limitations and Barriers to Adoption?
Despite early promise, monoclonal antibodies face several hurdles before they become mainstream acne treatments. First, most have not yet completed Phase 3 trials, the large-scale studies required for FDA approval. Imsidolimab and CJM112 both failed to meet primary efficacy endpoints, underscoring that not every candidate will succeed. Second, cost is a significant barrier. Monoclonal antibodies are expensive to manufacture and administer, typically costing thousands of dollars per dose. Insurance coverage for severe acne treatment is already limited; adding a high-cost biologic to the equation complicates access.
Even for patients with generous insurance, prior authorization requirements and step-therapy protocols—which mandate trying cheaper alternatives first—could delay or deny access to these drugs. A third limitation is the current direction of the acne treatment pipeline. As of 2026, clinical attention in severe acne is increasingly shifting away from traditional monoclonal antibodies and toward alternative mechanisms, particularly fatty acid synthase (FASN) inhibitors. These drugs target sebum production at the enzymatic level, addressing one of the four pillars of acne pathogenesis directly. Early data on FASN inhibitors has generated significant interest, and several are in clinical development. This shift suggests that even as monoclonal antibodies advance, they may face competition from drugs with potentially better efficacy profiles or more convenient dosing schedules. For researchers and patients alike, it remains unclear which approach will ultimately prove superior.
The Role of Combination Therapy and Personalized Medicine
One emerging strategy is to combine monoclonal antibodies with other treatments. Since acne involves four interconnected factors—bacterial colonization, sebum production, follicular hyperkeratinization, and inflammation—blocking a single pathway may be insufficient. A patient might benefit from a combination of a monoclonal antibody targeting IL-1 plus topical retinoids to address keratin plugging, or plus hormonal therapy to suppress sebum. This approach is already standard in oncology and rheumatology, where combining biologics with conventional agents often yields better outcomes than monotherapy alone.
Personalized medicine offers another avenue. Genetic and biomarker testing could eventually identify which patients are most likely to respond to a specific monoclonal antibody based on their individual inflammatory profile. Some individuals may have a predominantly IL-1–driven acne phenotype and respond well to MABp1 or LAD191, while others may have acne driven primarily by different cytokines. Identifying responders before treatment would reduce the trial-and-error period and improve efficacy rates—though at present, such biomarkers remain research tools rather than clinical diagnostics.
The Future of Biologic Therapy for Acne
The development of monoclonal antibodies for acne represents a philosophical shift in dermatology. Rather than viewing acne solely as a bacterial infection or a disorder of sebum production, researchers increasingly recognize it as an immunological disease amenable to immunomodulation. This perspective has opened entirely new therapeutic avenues and inspired interest from major pharmaceutical companies. Over the next 3–5 years, we can expect several monoclonal antibodies and other biologics to complete Phase 3 trials and seek FDA approval.
However, success is not guaranteed. The mixed results from imsidolimab and CJM112 serve as a cautionary reminder that promising preclinical and Phase 1 data don’t always translate into clinical benefit. Moreover, the emergence of FASN inhibitors and other novel mechanisms suggests that the ultimate treatment for severe, resistant acne may not rest entirely on monoclonal antibodies alone. Instead, the future likely involves a diversified toolkit of options—biologics, small-molecule inhibitors, combination therapies, and personalized approaches—allowing dermatologists to tailor treatment to each patient’s unique acne pathophysiology.
Conclusion
Monoclonal antibodies targeting IL-1, IL-17, and other inflammatory pathways represent a genuinely novel approach to severe, treatment-resistant acne. Candidates like MABp1 and LAD191 have demonstrated clinical activity and favorable tolerability in early trials, offering hope for patients who cannot tolerate or who haven’t responded to conventional therapies like isotretinoin. The 36% reduction in inflammatory lesions observed with MABp1 is a significant achievement, particularly for a drug that avoids the toxicities and burdensome monitoring requirements of isotretinoin. At the same time, these drugs face real limitations.
Efficacy data is mixed, with some candidates failing to outperform placebo. Most remain in clinical development and have not yet received FDA approval. Cost and access barriers will likely limit initial availability. Patients considering participation in clinical trials for monoclonal antibodies should discuss the risks, benefits, and realistic expectations with a dermatologist experienced in severe acne management. As the field continues to evolve and alternative mechanisms like FASN inhibitors advance, the ultimate role of monoclonal antibodies in acne treatment will become clearer.
You Might Also Like
- He Developed Chloracne After Occupational Chemical Exposure…One of the Most Treatment-Resistant Forms of Acne
- Fact Check: Is Bentonite Clay a Proven Acne Treatment? It Absorbs Oil Temporarily but No Studies Show It Treats Acne
- At Least 81% of Dermatologists Now Consider the Skin Microbiome When Designing Acne Treatment Plans
