BT5528
InvestigationalA first-in-class Bicycle Toxin Conjugate (BTC) targeting EphA2-expressing tumors, developed by Bicycle Therapeutics. Combines a constrained bicyclic peptide targeting moiety with the cytotoxic payload MMAE. The first-in-human Phase I (45 patients, advanced solid tumors) reported a 6.7% overall response rate and 20% disease control at the recommended Phase 2 dose; expansion ongoing.
Bicycle Toxin Conjugate 5528 · EphA2-BTC
8 human studies
- Preclinical
- 56%
- Clinical
- 44%
Based on 18 cited sources
clinically demonstrated · very-low confidence
Demonstrated effect magnitude — not a recommendation or safety claim.
Research Depth 42: highest human tier is a single uncontrolled open-label Phase 1 dose-escalation (1A=15, n=45, Bashir 39231383), inherently high RoB (1B=5) and N<50 (1C=3); directness good - matched population/IV route/tumor outcome but efficacy is exploratory secondary (1D=11); substantial multi-model preclinical program in rats/monkeys/xenografts (1E=8, Bennett 32398269 + MMAE foundation 12778055). Mechanism 90: EphA2 target with low-nM binding plus functional internalization and target-dependent activity (2A=38), full mapped chain endocytosis->linker cleavage->MMAE->tubulin->G2/M arrest (2B=27), dose-proportional/in-vivo dose-response (2C=15), confirmed in mammalian models (2D=10). Plausibility 87: mechanism->surrogate->human tumor response chain supported though modest (3A=33), fully coherent with EphA2 oncology + ADC biology (3B=23), multiple same-class MMAE-ADC analogues reliably cytotoxic (3C=18), tightly scoped EphA2+ claim (3D=13). Global Coverage 42: single-sponsor (Bicycle Therapeutics) cluster (4A=12), multi-site international trial US/UK/EU plus independent Chinese bicyclic-EphA2 work (4B=13), ~18-study modest literature (4C=12), investigational trial registration only NCT04180371 (4D=5). Community Experience 2: trial-only IV oncology agent, negligible real-world/off-label use. Effectiveness basis clinical (ORR 6.7%, DCR 20% in advanced solid tumors, single-arm, immature): small magnitude E1=8, around-MCID E2=8, intermediate response endpoint E3=8, superior-to-placebo-on-clinical-outcome E4=11 = 35, very-low confidence.
BT5528 is a first-in-class Bicycle Toxin Conjugate combining targeted delivery with cytotoxic payload. Human clinical data supports the proposed mechanisms.
How It Works (Simplified)
BT5528 works as a precision “smart missile” delivering chemotherapy directly to cancer cells:
Bicyclic peptide binds with high affinity to EphA2 receptors overexpressed on cancer cells, sparing normal tissues.
Cancer cell engulfs the BT5528 molecule through receptor-mediated endocytosis, bringing the payload inside.
Inside the cell, enzymes cleave the linker and release MMAE toxin into the cytoplasm where it can act.
MMAE disrupts microtubules essential for cell division, causing mitotic arrest and programmed cell death.
Key Research: The first-in-human Phase I (Bashir B et al., J Clin Oncol 2024; PMID 39231383) reported a 6.7% overall response rate and 20% disease control at the recommended Phase 2 dose across advanced solid tumors. Trial NCT04180371
Important Limitations
- Investigational agent not yet approved by any regulatory agency
- Preliminary efficacy data from small patient numbers; results may change
- Long-term safety data still maturing, particularly for cumulative neuropathy
- Requires EphA2 expression for activity; not all tumors express target
- Optimal patient selection criteria still being refined
Drug administration via weekly IV infusion. Initial target engagement and tumor cell internalization occurring. Early safety monitoring for MMAE-related effects including nausea and fatigue.
PMID:39231383Continued weekly dosing. MMAE-mediated cytotoxicity in EphA2+ tumor cells. Monitoring for peripheral neuropathy onset. First tumor assessments typically around week 6-8.
PMID:39231383Initial response assessment by imaging. In clinical trials, responses observed as early as first assessment. Ongoing monitoring for cumulative neuropathy.
PMID:39231383Continued treatment until progression or unacceptable toxicity. Duration of response data still maturing. Long-term peripheral neuropathy monitoring essential.
Research-based observations
This timeline reflects observations from published clinical and preclinical studies. Individual responses may vary significantly. This is not a guarantee of effects or a dosing schedule. Consult qualified healthcare providers for personalized guidance.
Good Signs (4 indicators)
Warning Signs (3 indicators)
Bad Signs (4 indicators)
For Research Evaluation Only
These quality indicators are general guidelines based on typical peptide characteristics. Professional laboratory testing (HPLC, mass spectrometry) provides definitive quality verification. This checklist is for initial visual evaluation only.
Antibody-Drug-Conjugates
CompatibleBTCs represent a distinct modality from traditional ADCs. Different pharmacokinetic profiles (shorter half-life, smaller size) may allow sequential use. No direct interaction studies.
Enfortumab-Vedotin
CautionBoth use MMAE payload. Sequential use may increase cumulative neuropathy risk. Different targets (EphA2 vs Nectin-4) but overlapping toxicity profiles.
Research Note: Interaction data is based on published literature, mechanistic understanding, and theoretical considerations. Most peptide combinations lack direct clinical study. This information is for educational purposes only and does not constitute medical advice. Always consult qualified healthcare providers.
Key Studies Cited
Full reference list available on request. All citations link to PubMed for verification.
This dossier synthesizes available evidence from peer-reviewed literature, regulatory documents, and clinical trial registries. Evidence strength ratings follow a modified GRADE approach.
For complete methodology details, see our Methodology page.
Important Disclaimer
This dossier is for educational purposes only and does not constitute medical advice. Always consult a qualified healthcare provider before making health decisions.
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