In patients with Philadelphia chromosome–positive chronic myeloid leukemia (Ph+ CML)

What is the International Scale?

The International Scale (IS) ensures the standardization of RQ-PCR results so they can be used in clinical practice to guide decisions1,2

  • Each laboratory applies a conversion factor (CF) that allows conversion of its data to the IS and enables the comparison of results from different labs3

IS RQ-PCR can assess if your patient has achieved clinically significant molecular milestones1,2,4

Learn how the IS was established below:

  • Prior to Ph+ CML treatment, samples from a group of 30 patients were independently tested at 3 different labs, yielding a total of 90 results.5

    International Scale conversion factor for RQ-PCR
  • Each lab calculated the median BCR-ABL value for its 30 patient samples. This lab-specific value is the raw median.5

    International Scale conversion factor for RQ-PCR
  • The raw median for each lab was used to derive a lab-specific CF. The CFs were used to convert each lab's results to a single, standardized baseline.3

    International Scale conversion factor for RQ-PCR
  • Patient response is measured as a reduction from this standardized baseline. For example, MMR is defined as a 3-log reduction from the standardized baseline. Therefore, MMR is a specific value not related to a patient's individual baseline BCR-ABL level.3

    International Scale conversion factor for RQ-PCR

1

Prior to Ph+ CML treatment, samples from a group of 30 patients were independently tested at 3 different labs, yielding a total of 90 results.5

International Scale conversion factor for RQ-PCR

2

Each lab calculated the median BCR-ABL value for its 30 patient samples. This lab-specific value is the raw median.5

International Scale conversion factor for RQ-PCR

3

The raw median for each lab was used to derive a lab-specific CF. The CFs were used to convert each lab�s results to a single, standardized baseline.3

International Scale conversion factor for RQ-PCR

CFs shown are representative values only, not actual values.

4

Patient response is measured as a reduction from this standardized baseline. For example, MMR is defined as a 3-log reduction from the standardized baseline. Therefore, MMR is a specific value not related to a patient�s individual baseline BCR-ABL level.3

International Scale conversion factor for RQ-PCR
  • IS is based on analysis of data from a large clinical trial3
  • NCCN Clinical Practice Guidelines In Oncology (NCCN Guidelines®) recommend IS RQ-PCR testing every 3 months after initiating treatment. After BCR-ABL1 0.1% - <1% (IS) has been achieved, continue monitoring every 3 months for 2 years and every 3 to 6 months thereafter6
The National Comprehensive Cancer Network makes no warranties of any kind whatsoever regarding their content, use or application and disclaims any responsibility for their application or use in any way.

*CFs shown are representative values only, not actual values.

RQ-PCR, real-time quantitative polymerase chain reaction; MMR, major molecular response; CCyR, complete cytogenetic response.

References: 1. Marin D, Ibrahim AR, Lucas C, et al. Assessment of BCR-ABL1 transcript levels at 3 months is the only requirement for predicting outcome for patients with chronic myeloid leukemia treated with tyrosine kinase inhibitors. J Clin Oncol. 2012;30(3):232-238. 2. Savona MR. Molecular monitoring and minimal residual disease in the management of chronic myelogenous leukemia. J Community Support Oncol. 2014;12(5):171-178. 3. Jabbour EJ, Quint�s-Cardama A. Molecular monitoring 101: helping your patients with chronic myeloid leukemia to understand the meaning of molecular response. Leuk Lymphoma. 2012;53(8):1452-1460. 4. Hughes TP, Hochhaus A, Branford S, et al. Blood. 2010;116(19):3758-3765. 5. Hughes TP, Kaeda J, Branford S, et al. N Engl J Med. 2003;349(15):1423-1432. 6. Referenced with permission from the NCCN Clinical Practice Guidelines In Oncology (NCCN Guidelines®) for Chronic Myeloid Leukemia V.2.2017. © National Comprehensive Cancer Network, Inc. 2017. All rights reserved. Accessed March 1, 2017. To view the most recent and complete version of the guideline, go online to NCCN.org.