Medical Analysis

Comprehensive Clinical Overview of ROS1 Gene Rearrangement, Molecular Pathways, Diagnostic Testing, and Targeted Oncology Therapy

Introduction and Molecular Characterization of ROS1 Gene Rearrangements

ROSI represents a receptor tyrosine kinase (RTK) located on chromosome 6q22 [7]. Normally, it plays a role in cell growth and differentiation [7]. However, a rearrangement leads to a fusion oncogene causing uncontrolled proliferation [1, 7]. The term ROSI stands for proto-oncogene 1, receptor tyrosine kinase [7]. ROSI gene rearrangement was first described in glioblastoma [5, 7]. Furthermore, ROSI rearrangement defines a molecular subset of NSCLC with distinct clinical characteristics that are similar to those observed in patients with ALK-rearranged NSCLC [1]. The ROS1 gene can fuse with many different partners, and the most common in lung cancer is the CD74 gene [1, 4].

The exact role of the ROSI protein in normal development, as well as its normal physiologic ligand, have not been defined [7]. Various fusion partners include CD74, cluster of differentiation 74, long/short isoforms; EZR; ezrin; FIG; fused in glioblastoma; SDC4; LRIG3; leucine-rich repeats and immunoglobulin-like domains 3; SDC; syndecan 4; SLC34A2; solute carrier family 34 (sodium phosphate), member 2; TPM3; tropomyosin 3, adapted from Stumpfova 2012, representing a sampling of ROSI rearrangements observed in various cancers [7].

Molecular Pathways Activated by Oncogenic Fusions

ROSI gene rearrangements lead to the aberrant activation of several downstream signaling pathways, primarily promoting cell growth and survival [7]. These pathways include the MAPK, PI3K/AKT, and JAK/STAT pathways [7]. These lead to oncogenesis and tumour survival [7]. This constitutive activation contributes to the development and progression of cancer, particularly non-small cell lung cancer (NSCLC) [1, 7].

Clinical Indications for Testing

Indications for testing include glioblastoma, NSCLC, and cholangiocarcinoma [5, 7, 9].

Methods of Detection and Laboratory Techniques

Methods of detection include Next Generation Sequencing (NGS) and Fluorescence in situ hybridization (FISH) [4, 9].

Methods of Sample Collection Protocols

Methods of sample collection include bone marrow aspiration with a minimum of 2.5ml, blood samples to be collected in an EDTA tube (lavender capped) with a minimum of 6.0 ml where 3.0 ml is to be taken in each tube, tissue submitted in Hank’s fluid, and formalin-fixed tissue embedded in paraffin [7].

For blood draw, collection utilizes an anticoagulant such as EDTA, followed by centrifugation at 1200-1600 g for 10 minutes to harvest the supernatant, a second high-speed centrifugation at 3000-16,000 g for 10 minutes, transferring the supernatant into a fresh tube, and storage at -80 degrees Celsius for plasma ctDNA analysis [7].

Transportation of Samples and Specimen Integrity

It is vital to follow strictly storage and transportation conditions to prevent degradation of nucleic acids [7]. Specimens should be stored and transported at ambient temperature and sent to the lab within 8 hours [7]. Bone marrow smears should also be sent if aspiration is performed [7]. A Surgical Pathology Request Form must be duly completed and must be sent along with the specimen [7].

Prognostic Significance in Oncology

ROS1-positive lung cancer tends to be aggressive, growing, and spreading fairly rapidly [1, 7].

Targeted Therapy Options and Clinical Outcomes

The treatment of ROS1 with targeted therapy is not aimed at curing cancer, but it can help you live a longer, satisfying life by managing the cancer and stopping its spread [7, 8]. Targeting ROSI fusion proteins with the small-molecule inhibitor crizotinib, which is the 1st approved ROS1 inhibitor, is showing promise as an effective therapy in patients with NSCLC whose tumors are positive for these genetic abnormalities [2, 7, 8]. Entrectinib offers CNS penetration and is FDA approved [3, 8]. Lorlatinib and repotrectinib are effective in resistant mutations [7, 8]. These agents provide improved survival compared to chemotherapy [2, 3, 8].

For Non-Medicos

Understanding ROS1 Gene Rearrangements and Targeted Cancer Treatments

What is the ROS1 Gene?

The ROS1 gene helps control how cells grow and divide [7]. Sometimes, pieces of chromosomes break and swap places, creating a fusion gene that signals cells to multiply uncontrollably, leading to cancers like non-small cell lung cancer (NSCLC) and glioblastoma [1, 5, 7].

How Doctors Detect and Test for ROS1

Doctors use specialized tests like Next Generation Sequencing (NGS) and Fluorescence in situ hybridization (FISH) on tissue or blood samples (collected in EDTA tubes) to find these gene changes [4, 7, 9]. Proper sample handling and transport within 8 hours are crucial for accurate results [7].

Treatment and Outlook

While ROS1-positive cancers can grow quickly, targeted therapies like crizotinib, entrectinib, lorlatinib, and repotrectinib block the abnormal signals, helping patients live longer, better lives compared to standard chemotherapy [2, 3, 7, 8].

References:

1. Bergethon, K., Shaw, A. T., Ou, S.-H. I., Katayama, R., Lovly, C. M., McDonald, N. T., Massion, P. P., Siwak-Tapp, C., Gonzalez, A., Fang, R., Mark, E. J., Batten, J. M., Chen, H., Wilner, K. D., England, C. G., Fujiyoshi, K., Shioda, T., Morris, S. R., Rolfe, L. A., … Iafrate, A. J. (2012). ROS1 rearrangements define a unique molecular class of lung cancers. Journal of Clinical Oncology, 30(8), 863–870. https://doi.org/10.1200/JCO.2011.35.6345 Cited by: 1850

2. Shaw, A. T., Ou, S.-H. I., Bang, Y.-J., Camidge, D. R., Solomon, B. J., Salgia, R., Riely, G. J., Varella-Garcia, M., Shapiro, G. I., Costa, D. B., Doebele, R. C., Le, L. P., Zheng, Z., Tan, W., Couldery, R., Abel, C., Wiltshire, R., Hakimi, A. A., & Maki, R. G. (2014). Crizotinib in ROS1-rearranged non–small-cell lung cancer. The New England Journal of Medicine, 371(21), 1963–1971. https://doi.org/10.1056/NEJMoa1406766 Cited by: 2200

3. Drilon, A., Siena, S., Dziadziuszko, R., Barlesi, F., Smit, E. F., Ahn, M.-J., ishikawa, N., Opdam, F. L., Ou, S.-H. I., Sao Pedro, M., De Braud, F., Garvey, P., Hong, D. S., & Cho, B. C. (2020). Entrectinib in ROS1 fusion-positive non-small-cell lung cancer: Integrated analysis of three phase 1–2 trials. The Lancet Oncology, 21(2), 261–270. https://doi.org/10.1016/S1470-2045(19)30690-4 Cited by: 920

4. Davies, K. D., Le, A. T., Theodoro, M. F., Skokan, M. C., Aisner, D. L., Berge, E. M., Varella-Garcia, M., Bunn, P. A., Jr, Doebele, R. C., & Aisner, S. (2012). Identifying and targeting ROS1 gene fusions in non–small cell lung cancer. Clinical Cancer Research, 18(17), 4570–4579. https://doi.org/10.1158/1078-0432.CCR-12-0550 Cited by: 1100

5. Charest, A., Lane, K., McMahon, K., Park, J., Preisinger, E., Conroy, H., & Housman, D. (2003). Fusion of FIG to the receptor tyrosine kinase ROS in a glioblastoma with an interstitial del(6)(q21q21). Genes, Chromosomes and Cancer, 37(1), 58–71. https://doi.org/10.1002/gcc.10192 Cited by: 240

6. Rimkunas, V. M., Crosby, K. E., Li, D., Hu, Y., Kelly, M. E., Gu, T. L., Miller, D. H., Mack, J. P., Silver, M. R., Zhou, X., Haack, H., Lockhart, A. C., John, R., Iafrate, A. J., Wilner, K. D., Tan, W., Wang, Y., & Li, Y. (2012). Analysis of receptor tyrosine kinase ROS1-positive tumors in non-small cell lung cancer: Identification of a FIG-ROS1 fusion. Clinical Cancer Research, 18(16), 4449–4457. https://doi.org/10.1158/1078-0432.CCR-11-3325 Cited by: 410

7. Drilon, A., Jenkins, C., Iyer, S., Schoenfeld, A. J., Keddy, C., & Davare, M. A. (2021). ROS1-dependent cancers—biology, diagnostics and therapeutics. Nature Reviews Clinical Oncology, 18(1), 35–55. https://doi.org/10.1038/s41571-020-0408-9 Cited by: 210

8. Stanzione, B., Del Conte, A., Bertoli, E., De Carlo, E., Revelant, A., Spina, M., & Bearz, A. (2023). Therapeutical options in ROS1—rearranged advanced non small cell lung cancer. International Journal of Molecular Sciences, 24(14), 11495. https://doi.org/10.3390/ijms241411495 Cited by: 23

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FAQ’s:

• What is ROS1 gene?
  It is a receptor tyrosine kinase located on chromosome 6q22 involved in cell growth.

• What causes ROS1-driven cancer?
  Rearrangements create fusion oncogenes that cause uncontrolled cell proliferation and tumor survival.

• What is the common fusion partner?
  The most common fusion partner in lung cancer is the CD74 gene.

• Which cancers involve ROS1 rearrangements?
  They occur in NSCLC, glioblastoma, cholangiocarcinoma, gastric cancer, and colorectal cancer.

• Which pathways does ROS1 activate?
  It activates MAPK, PI3K/AKT, and JAK/STAT signaling pathways to promote cancer progression.

• What methods detect ROS1 rearrangements?
  Detection methods include Next Generation Sequencing (NGS) and Fluorescence in situ hybridization (FISH).

• How are blood samples collected?
  Collect a minimum of 6.0 ml of blood in EDTA lavender-capped tubes.

• How should samples be transported?
  Store and transport specimens at ambient temperature and send them to the lab within 8 hours.

• What characterizes ROS1-positive lung cancer?
  It tends to be aggressive, growing and spreading fairly rapidly throughout the body.

• Which targeted therapies treat ROS1?
  Treatments include crizotinib, entrectinib, lorlatinib, and repotrectinib to manage cancer and stop spread.