# Philadelphia chromosome (Ph+, BCR::ABL1)

Source: https://onco.cc/terms/philadelphia-chromosome/  
OnCo record `philadelphia-chromosome` (Term). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

A swapped piece between chromosomes 9 and 22 that fuses two genes into BCR::ABL1, a runaway kinase. It causes chronic myeloid leukaemia and a hard-to-treat quarter of adult acute lymphoblastic leukaemia, and was the target of imatinib, the first modern targeted cancer drug.

## Summary

Described by Nowell and Hungerford in 1960 and explained by Rowley in 1973, the Philadelphia chromosome defines CML and Ph+ ALL. Imatinib (2001) turned CML into a chronic condition with near-normal life expectancy; dasatinib, nilotinib, bosutinib, ponatinib (covers T315I) and asciminib (allosteric) followed. In Ph+ ALL, TKIs plus chemotherapy or chemotherapy-free TKI plus blinatumomab (GIMEMA D-ALBA) now cure most patients without transplant. Ph-like ALL has a similar gene expression signature without the fusion and responds to some of the same drugs. Detected by karyotype, FISH or PCR for the fusion transcript.

## Fields

- Kind: Term
- Last checked: 2026-09-09
- Also known as: Philadelphia; Ph+; Ph-positive; Ph-negative; BCR-ABL; BCR-ABL1; BCR::ABL1; t(9;22); Philadelphia-positive; Ph+ ALL; p190 transcript; p210 transcript; BCR::ABL1 transcript type

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Philadelphia_chromosome
- Wikipedia: https://en.wikipedia.org/wiki/Philadelphia_chromosome

## Connected records

- terms: [B-ALL risk groups (NCI criteria, ETV6::RUNX1, hyperdiploidy, hypodiploidy, iAMP21, IKZF1, CNS status)](https://onco.cc/terms/b-all-cytogenetic-risk/), [BCR::ABL1 kinase domain mutations (T315I and others)](https://onco.cc/terms/abl1-kinase-domain-mutations/), [Blasts (leukaemic blast cells)](https://onco.cc/terms/blasts/), [Cytogenetics and karyotype](https://onco.cc/terms/cytogenetics/), [Gene fusion](https://onco.cc/terms/gene-fusion/), [Molecular response (MMR, MR4, treatment-free remission)](https://onco.cc/terms/molecular-response/), [Ph-like (BCR::ABL1-like) acute lymphoblastic leukaemia](https://onco.cc/terms/ph-like-all/), [Sokal and ELTS risk scores (chronic myeloid leukaemia)](https://onco.cc/terms/sokal-elts-scores/), [Tyrosine kinase inhibitor (TKI)](https://onco.cc/terms/tki-term/)
- cancers: [Acute lymphoblastic leukaemia](https://onco.cc/cancers/all-leukemia/), [Chronic myeloid leukaemia, accelerated and blast phase](https://onco.cc/cancers/cml-advanced-phase/), [Chronic myeloid leukaemia, chronic phase](https://onco.cc/cancers/cml-chronic-phase/), [Philadelphia chromosome-like acute lymphoblastic leukaemia (Ph-like or BCR::ABL1-like ALL)](https://onco.cc/cancers/all-ph-like/), [Philadelphia chromosome-positive acute lymphoblastic leukaemia in children (Ph-positive ALL)](https://onco.cc/cancers/all-paediatric-ph-positive/)
- fronts: [Targeted Therapy](https://onco.cc/fronts/targeted-therapy/)
- drugs: [Asciminib](https://onco.cc/drugs/asciminib/), [Blinatumomab](https://onco.cc/drugs/blinatumomab/), [Dasatinib](https://onco.cc/drugs/dasatinib/), [Imatinib](https://onco.cc/drugs/imatinib/), [Ponatinib](https://onco.cc/drugs/ponatinib/)
- biomarkers: [BCR::ABL1 transcript (Philadelphia chromosome, quantitative PCR)](https://onco.cc/biomarkers/bcr-abl1-transcript/)

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