Anamorelin

Mechanism

An oral ghrelin-mimicking drug that stimulates appetite, increases lean body mass, and boosts growth hormone levels. Developed specifically for cancer patients with cachexia (severe muscle wasting and weight loss). Approved in Japan but not yet in the US or EU — it increases body weight and appetite but large trials did not convincingly show improvement in hand-grip strength.

Effects

ENDOCRINE / GH AXIS [Tier 1 – Human Clinical]: Anamorelin is an oral ghrelin receptor agonist developed specifically for cancer-related cachexia and anorexia. Potently stimulates GH release, appetite, and lean body mass preservation. Approved in Japan (Adlumiz) for cancer cachexia. Multiple large Phase III trials (ROMANA 1, 2, 3) demonstrated significant improvements in lean body mass and appetite in non-small cell lung cancer patients. APPETITE / CACHEXIA [Tier 1 – Human Clinical]: The primary therapeutic application. Anamorelin activates the ghrelin receptor centrally, producing robust appetite stimulation and anabolic signaling. ROMANA trials showed statistically significant increases in lean body mass (median 0.75-1.5 kg over 12 weeks) and body weight vs placebo in cancer cachexia. Improved appetite scores and patient-reported quality of life. METABOLIC [Tier 1 – Human Clinical]: Raises IGF-1 levels significantly (by 30-50% in clinical trials). Raises GH. Modest effects on glucose metabolism — less insulin resistance concern than MK-677 in clinical trial populations, likely because cachectic patients start from a different metabolic baseline. Some increase in fasting glucose observed but generally well-tolerated. MUSCULOSKELETAL [Tier 1 – Human Clinical]: Preserves lean body mass in catabolic states (cancer cachexia). Important distinction: improves lean body mass but did NOT improve handgrip strength or physical function in ROMANA trials. This dissociation between mass and function was a key FDA concern and reason for non-approval in the US. CARDIOVASCULAR [Tier 2 – Limited Human]: QTc prolongation observed at higher doses. Cardiac safety monitoring required. Generally well-tolerated at therapeutic doses but dose-limiting cardiac effects exist.

Practitioner Guide

CLINICAL POSITIONING: Anamorelin is the most clinically validated oral ghrelin agonist for the specific indication of muscle wasting and appetite loss. While MK-677 is more widely used in the peptide optimization space, anamorelin has stronger clinical trial evidence, particularly in catabolic states. It is approved in Japan but NOT in the US or EU. PRIMARY INDICATION — CANCER CACHEXIA: • For patients with cancer-related weight loss and muscle wasting, anamorelin has the strongest evidence base of any ghrelin agonist. • Dose: 100 mg orally once daily, 1 hour before breakfast. Taken on empty stomach. • Duration in clinical trials: 12-24 weeks. Benefits accrue over time. • Expect: Improved appetite within 1-2 weeks. Measurable lean body mass gains by 4-8 weeks. Body weight stabilization or gain. • Limitation: Mass gain without proportional strength gain. Must be combined with resistance exercise (even mild) to translate mass into function. OFF-LABEL CONSIDERATIONS: • Some practitioners use anamorelin for non-cancer cachexia (HIV wasting, chronic illness, elderly sarcopenia). Evidence is extrapolated, not direct. • As a GH secretagogue for general optimization: MK-677 is preferred (more data, cheaper, more available). Anamorelin offers no clear advantage over MK-677 for healthy individuals. • Anamorelin is difficult to source outside Japan. Gray market availability is limited and quality uncertain. ANAMORELIN vs MK-677: • Anamorelin: Phase III trials, approved in Japan, 100 mg oral once daily, focused on cachexia. Shorter half-life (~7 hours). • MK-677: Phase II trials (never completed Phase III), not approved anywhere, 10-25 mg oral once daily, used broadly in optimization. Longer half-life (~5 hours active but GH elevation persists ~24 hours). • Both are oral ghrelin agonists. Both raise GH, IGF-1, appetite. In practice, MK-677 dominates the optimization market due to availability and cost. BLOOD WORK MONITORING: • Baseline: IGF-1, fasting glucose, insulin, HbA1c, CBC, comprehensive metabolic panel, ECG (QTc assessment). • 4-week: IGF-1, fasting glucose, insulin. Repeat ECG if baseline QTc was borderline. • 12-week: Full panel repeat including cardiac markers. CARDIAC MONITORING: QTc prolongation is dose-dependent. Do NOT exceed 100 mg/day. Avoid in patients with baseline QTc prolongation, those on QT-prolonging medications, or those with electrolyte abnormalities (hypokalemia, hypomagnesemia).

Evidence

• Prospective study of anamorelin in pancreatic cancer cachexia: Clinical and translational insights into response heterogeneity.

  Matsukane R et al. (2026) — Clinical Nutrition — PMID: 41619712

  In 17 efficacy-evaluable patients with unresectable or metastatic pancreatic cancer cachexia, anamorelin increased lean body mass by 0.9 kg at 1 month and 1.4 kg at 2 months, improved appetite/weight-gain QOL domains, and showed stronger response in lower-BMI patients; grade 2+ hyperglycemia occurred in 26.1%, especially with impaired baseline insulin secretion.

  moderate

• Predictors of long-term anamorelin hydrochloride use in patients with cancer cachexia: a single-center real-world retrospective study.

  Kanbayashi Y et al. (2026) — Future Oncology — PMID: 41869701

  Among 173 patients receiving anamorelin for cancer cachexia, better ECOG performance status and lower modified Glasgow Prognostic Score predicted longer treatment continuation, while gastric cancer predicted shorter duration; findings help identify patients more likely to sustain therapy in practice.

  moderate

Research Summary

TIER 1 (Human Clinical Trials): • ROMANA 1 (Temel et al., 2016, Lancet Oncology): Phase III RCT, n=484 NSCLC patients with cachexia. Anamorelin 100 mg daily x 12 weeks. Significant increase in lean body mass (+0.99 kg vs -0.47 kg placebo) and body weight. No improvement in handgrip strength (co-primary endpoint missed). • ROMANA 2 (Temel et al., 2016): Confirmatory Phase III, similar results. Lean body mass improvement, no handgrip strength benefit. • ROMANA 3 (extension study): 24-week safety and sustained efficacy data. Benefits maintained, no new safety signals. • Japanese approval (2021): Adlumiz approved for cancer cachexia in Japan based on ONO-7643-04 trial (Japanese population data consistent with ROMANA). TIER 2 (Limited Human / Strong Preclinical): • Garcia et al. (2015): Dose-ranging studies establishing 100 mg as optimal therapeutic dose. • QTc prolongation characterization — dose-dependent, clinically significant at doses >150 mg. • IGF-1 elevation studies: 30-50% increase from baseline, sustained over treatment duration. TIER 3 (Preclinical / Mechanistic): • Ghrelin receptor binding studies: High affinity oral peptidomimetic. • Animal cachexia models showing preservation of skeletal muscle protein synthesis. • Mechanistic studies on dissociation between lean mass gain and functional strength (possible explanation: fluid shifts vs actual myofibrillar protein accrual). EVIDENCE GAPS: Failed to meet handgrip strength co-primary endpoint — this is why FDA did not approve. Unclear whether combined anamorelin + exercise produces functional benefit (not tested in ROMANA). Long-term survival impact not established. Non-cancer cachexia applications not studied in Phase III.