LL-37: mixed human results, a separate path for peptoids

Longevitytech.fund investment

Longevitytech.fund invested in Maxwell Biosciences in March 2022. We are proud of this investment in the development of new peptoid medicines. [14]

Evidence as of September 2026.

• Shown: LL-37 affects microbes and human cells; selected peptoids showed antiviral activity in laboratory experiments and a mouse model. [1] [6] [7] [10]

• Not shown: overall wound-healing benefit in the 149-person HEAL trial, faster viral clearance in the full cited COVID-19 trial, or peptoid benefit in patients. [3] [5]

• Would change the assessment: a defined product improving sustained healing or clinical recovery, with complete safety reporting.

The larger wound trial did not confirm the early promise

LL-37 did not improve the main overall healing result in HEAL. The 2021 trial randomized 149 people with venous leg ulcers, wounds linked to poor vein function. Confirmed complete closure was estimated at 26.5% and 24.7% in the two LL-37 groups and 25.3% with placebo, alongside compression treatment. [3]

HEAL’s exploratory larger-ulcer subgroup was more favorable, but it needs a study designed to test it. Only 63.5% attended any later follow-up visit, limiting conclusions about lasting closure. Some skin inflammation, swelling and wound infections were considered possibly treatment-related; no serious event was judged related. Promore Pharma funded the study, with financial interests disclosed among some authors. [3]

The small diabetic-foot study measured granulation, the repair tissue in a wound bed. That is not the same as closing the wound, clearing a serious infection or preventing amputation. The selected ulcers were uninfected or only mildly infected. [4]

The COVID-19 trial used swallowed bacteria engineered to produce LL-37, not purified peptide. Treatment was known to participants and investigators. An earlier-treatment subgroup looked favorable, but the whole-trial result was not significant. Adverse events occurred in 18.6% and 18.3% of participants, with no serious event reported. The study did not establish fewer deaths or long-term complications; three authors disclosed a patent filing. [5]

Why can the body’s own defense molecule be difficult to use?

LL-37 is an antimicrobial peptide involved in innate immunity, the body’s early defense system. It also affects tissue repair and signals between human cells. A treatment must control where, how much and how long the molecule acts; a natural role is not a guarantee of drug safety. [1] [6] [7]

The cancer findings illustrate the complexity. LL-37 stimulated lung-cancer cells in one laboratory study, while other experiments triggered death in colon-cancer cells. Those results depend on tissue and experimental conditions; neither establishes human cancer causation or treatment. [6] [7]

What happened in the melanoma reports?

A reported tumor response came with a concerning skin reaction. A 2018 case described widespread raised and blistering lesions during LL-37 treatment, despite shrinkage of injected melanoma tumors. The lesions resolved within two months of stopping. Prior cancer therapies complicate attribution, and one case cannot estimate frequency, but the skin reaction belongs alongside the response. [17]

The related registry lists four participants, with results tables for three. All three had recorded tumor responses, while the participant-flow entry also includes a withdrawal for lack of efficacy. All three had nonserious events, including one reported squamous-cell carcinoma; the record does not establish that LL-37 caused it. No serious events were reported among the three. Such small, incompletely explained data cannot provide a reliable efficacy or broad safety estimate. [16]

What is a peptoid, and why is Maxwell developing it?

A peptoid is a chemically distinct, peptide-inspired molecule. Moving chemical side groups from carbon to nitrogen along the backbone makes it harder for peptide-breaking enzymes to dismantle. Greater stability addresses one design problem; it does not guarantee safety or preserve every function of LL-37. [1]

In 2021, selected peptoids damaged viral envelopes and reduced HSV-1 and SARS-CoV-2 infectivity when mixed with viruses before infection. Activity varied across ten candidates, and some were inactive against HSV-1. Brief tissue-culture tests found no toxicity in the cell-survival test used. These were laboratory findings with direct access to the virus. [1]

A 2026 study used topical MXB-9 in mice with experimental herpes lip lesions. In principal groups of five, lesions and viral measurements were reduced at day five. Treatment began before lesions usually appeared; the result does not establish treatment of recurrent outbreaks or latent infection in people, or the effects of another injectable peptoid. Both peptoid papers disclosed Maxwell funding and author financial interests. [10] [1]

What do Maxwell’s milestones mean?

Maxwell’s reported QIDP designation is a development milestone, not approval. On September 8, 2026 the company said FDA had granted the designation on May 5 to MXB-22,510-SC for specified bacterial and fungal pneumonia settings. FDA guidance explains that QIDP supports development incentives for a particular product and proposed use; it does not establish successful human trials or authorize LL-37 itself. [12] [13]

The company’s website describes its program as preclinical and gives 2026 for planned human trials, while its May 2026 release gives 2027. Neither timeline confirms that participants have begun treatment. [11] [18]

What are the regulatory and safety concerns?

FDA’s LL-37 compounding notice identifies possible immune reactions, impurities and difficulty characterizing the ingredient. It also cites laboratory and animal concerns involving male reproduction and tumor promotion in some tissues, with inadequate information to determine human harm. [8]

A withdrawn nomination is not approval. A separate FDA notice planned advisory consideration before the end of February 2027; committee advice is nonbinding and a compounding-list process is distinct from approval of a finished medicine. These US statements do not determine authorization elsewhere. [8] [9]

What should we watch next?

Useful progress will identify the actual product and report outcomes that matter to patients.

• Maxwell’s first human study: a public trial record and actual progress that resolve the 2026/2027 planning discrepancy. [11] [18]

• LL-37 regulatory review: the advisory process planned before the end of February 2027, followed by any documented FDA action. [9]

• Clinical results: sustained wound closure or recovery from infection, with recurrence and harms, rather than laboratory antiviral activity alone.

How Healthy Longevity Clinic experts evaluate the evidence

Healthy Longevity Clinic follows two distinct questions here. Can a preparation of natural LL-37 improve a patient's outcome? Can Maxwell's engineered peptoids turn part of that biological idea into a useful medicine? The mixed human LL-37 results and the preclinical peptoid findings belong to different answers, even though the development stories are connected.

Longevitytech.fund's investment in Maxwell is a connection we are proud to make visible. It explains our interest in how the technology develops. Our clinical assessment still turns on results for the exact candidate: a controlled human study showing a meaningful benefit, acceptable harms and a product that can be made consistently. A company milestone tells us which step has been reached.

For someone facing an infection now, the useful takeaway remains a correct diagnosis and established treatment. Antibiotics help with certain bacterial infections, do not treat viruses and can cause harm when used unnecessarily. Following the next generation of medicines should deepen that understanding of treatment, not blur it. [15]

Three questions for a treatment discussion

1. Is the product LL-37, bacteria producing it, or a named peptoid?

2. Did the whole trial show healing or recovery, or only a marker or subgroup?

3. Is the cited milestone a company plan, a development designation or an actual treatment result?

Frequently asked questions

Does LL-37 heal ulcers?

The larger leg-ulcer trial found no significant overall benefit. Smaller studies contain signals, but they do not establish broad, sustained wound healing. [2] [3] [4]

Are Maxwell’s peptoids LL-37?

No. They are chemically distinct molecules inspired by peptide biology and require their own evidence. [1]

Does QIDP designation mean FDA approval?

No. It supports development incentives for a specified product and proposed infectious-disease use; it is not marketing approval or proof of clinical benefit. [13]