# BTK degraders to pre-empt resistance in frontline CLL

Source: https://onco.cc/ideas/idea-btk-degrader-frontline/  
OnCo record `idea-btk-degrader-frontline` (Idea). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

If destroying BTK works when every inhibitor has failed, using it first might stop resistance from ever emerging.

## Summary

The idea is to use a BTK degrader such as BGB-16673 with a BCL-2 inhibitor such as sonrotoclax as a 12-month fixed-duration frontline regimen for chronic lymphocytic leukaemia, pre-empting the acquired-resistance bottleneck. Degradation removes both kinase and scaffold functions and is not defeated by the C481, T474 or L528 mutations that arise under inhibitor pressure; BGB-16673 works in most heavily pretreated, mutation-bearing patients. The hypothesis is deeper undetectable MRD, longer treatment-free survival and fewer resistance mutations than a covalent BTK inhibitor with venetoclax. The test is a phase 2 of BGB-16673 with sonrotoclax in untreated patients, then a randomised comparison against acalabrutinib-venetoclax; CaDAnCe-304 already tests the degrader in relapse.

## Fields

- Kind: Idea
- Last checked: 2026-09-07
- Hypothesis: A BTK degrader plus a BCL-2 inhibitor for 12 months produces higher uMRD and longer treatment-free survival than covalent BTKi + venetoclax, with fewer BTK resistance mutations at relapse.
- Rationale: Degradation removes both kinase and scaffold functions and is not defeated by C481, T474, or L528 mutations that arise under inhibitor pressure.
- Proposed test: Phase 2 doublet (BGB-16673 + sonrotoclax) in treatment-naive CLL with uMRD at month 15 as the primary endpoint, then randomised comparison with acalabrutinib-venetoclax.
- Maturity: early-clinical

## Sources

- Montoya et al., Kinase-impaired BTK mutations are susceptible to the clinical-stage BTK and IKZF1/3 degrader NX-2127 (Science 2024): https://doi.org/10.1126/science.adi5798

## Connected records

- cancers: [Chronic lymphocytic leukaemia](https://onco.cc/cancers/cll/), [Chronic lymphocytic leukaemia, first treatment](https://onco.cc/cancers/cll-treatment-naive/)
- technologies: [PROTACs & molecular glues (targeted protein degradation)](https://onco.cc/technologies/protac-degrader/)
- targets: [BCL-2](https://onco.cc/targets/bcl2/), [BTK (Bruton tyrosine kinase)](https://onco.cc/targets/btk/)
- drugs: [Acalabrutinib](https://onco.cc/drugs/acalabrutinib/), [BGB-16673](https://onco.cc/drugs/bgb-16673/), [Sonrotoclax](https://onco.cc/drugs/sonrotoclax/), [Venetoclax](https://onco.cc/drugs/venetoclax/)
- trials: [CaDAnCe-304](https://onco.cc/trials/cadance-304/)
- key papers: [Acalabrutinib (ACP-196) in Relapsed Chronic Lymphocytic Leukemia](https://onco.cc/key-papers/paper-acalabrutinib-cll-n-engl-j-med-2016/), [Acalabrutinib Versus Ibrutinib in Previously Treated Chronic Lymphocytic Leukemia: Results of the First Randomized Phase III Trial](https://onco.cc/key-papers/paper-acalabrutinib-cll-j-clin-oncol-2021/), [From basic apoptosis discoveries to advanced selective BCL-2 family inhibitors](https://onco.cc/key-papers/paper-bcl-2-cll-nat-rev-drug-discov-2017/), [Kinase-impaired BTK mutations are susceptible to clinical-stage BTK and IKZF1/3 degrader NX-2127](https://onco.cc/key-papers/paper-montoya-science/)
- bottlenecks: [Acquired resistance to every therapy](https://onco.cc/bottlenecks/b-resistance/)

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