Preclinical optimization of Ly6E-targeted ADCs for increased durability and efficacy of anti-tumor response
Josefa Dela Cruz Chuh1, MaryAnn Go2, Yvonne Chen3
1Departments of Biochemical and Cellular Pharmacology, Genentech Inc , South San Francisco, CA, USA.
Abstract:
Early success with brentuximab vedotin in treating classical Hodgkin lymphoma spurred an influx of at least 20 monomethyl auristatin E (MMAE) antibody-drug conjugates (ADCs) into clinical trials. While three MMAE-ADCs have been approved, most of these conjugates are no longer being investigated in clinical trials. Some auristatin conjugates show limited or no efficacy at tolerated doses, but even for drugs driving initial remissions, tumor regrowth and metastasis often rapidly occur. Here we describe the development of second-generation therapeutic ADCs targeting Lymphocyte antigen 6E (Ly6E) where the tubulin polymerization inhibitor MMAE (Compound 1) is replaced with DNA-damaging agents intended to drive increased durability of response. Comparison of a seco-cyclopropyl benzoindol-4-one (CBI)-dimer (compound 2) to MMAE showed increased potency, activity across more cell lines, and resistance to efflux by P-glycoprotein, a drug transporter commonly upregulated in tumors. Both anti-Ly6E-CBI and -MMAE conjugates drove single-dose efficacy in xenograft and patient-derived xenograft models, but seco-CBI-dimer conjugates showed reduced tumor outgrowth following multiple weeks of treatment, suggesting that they are less susceptible to developing resistance. In parallel, we explored approaches to optimize the targeting antibody. In contrast to immunization with recombinant Ly6E or Ly6E DNA, immunization with virus-like particles generated a high-affinity anti-Ly6E antibody. Conjugates to this antibody improve efficacy versus a previous clinical candidate both in vitro and in vivo with multiple cytotoxics. Conjugation of compound 2 to the second-generation antibody results in a substantially improved ADC with promising preclinical efficacy.
Insights
Second-generation antibody-drug conjugates (ADCs) targeting Lymphocyte antigen 6E (Ly6E) show improved durability and efficacy. Replacing monomethyl auristatin E (MMAE) with DNA-damaging agents like seco-cyclopropyl benzoindol-4-one (CBI) dimer enhances potency and overcomes resistance mechanisms.
Area of Science:
- Oncology
- Immunotherapy
- Drug Development
Background:
- Early success of monomethyl auristatin E (MMAE) antibody-drug conjugates (ADCs) in classical Hodgkin lymphoma led to numerous clinical trials.
- However, many MMAE-ADCs show limited efficacy or rapid tumor regrowth and metastasis, indicating acquired resistance.
Purpose of the Study:
- To develop second-generation therapeutic ADCs targeting Lymphocyte antigen 6E (Ly6E) with enhanced durability and efficacy.
- To replace MMAE with DNA-damaging agents and optimize the targeting antibody.
Main Methods:
- Developed ADCs using a DNA-damaging agent, seco-cyclopropyl benzoindol-4-one (CBI) dimer, and compared it to MMAE.
- Evaluated ADC potency, activity, and resistance to P-glycoprotein efflux.
- Tested efficacy in xenograft and patient-derived xenograft models.
- Generated a high-affinity anti-Ly6E antibody using virus-like particles and created conjugates.
Main Results:
- The seco-CBI-dimer conjugate demonstrated increased potency, broader cell line activity, and resistance to P-glycoprotein efflux compared to MMAE.
- Both anti-Ly6E-CBI and -MMAE conjugates showed single-dose efficacy in preclinical models.
- Seco-CBI-dimer conjugates exhibited reduced tumor outgrowth, suggesting lower susceptibility to resistance.
- Conjugates with the optimized high-affinity antibody showed improved in vitro and in vivo efficacy.
- The combination of the seco-CBI-dimer and the second-generation antibody resulted in a substantially improved ADC with promising preclinical efficacy.
Conclusions:
- Second-generation ADCs utilizing DNA-damaging agents and optimized antibodies represent a promising strategy for overcoming resistance and improving therapeutic durability in cancer treatment.
- The developed anti-Ly6E ADCs, particularly with the seco-CBI-dimer payload and high-affinity antibody, show significant preclinical potential.
