Author of

• 10923

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  P1.18 - Poster Session 1 - Pathology (ID 175)

  • Event: WCLC 2013
  • Type: Poster Session
  • Track: Pathology
  • Presentations: 1
  • Moderators:
  • Coordinates: 10/28/2013, 09:30 - 16:30, Exhibit Hall, Ground Level

  • 10938

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    P1.18-015 - Screening for ALK-rearranged NSCLC in selected cases using immunohistochemistry followed by FISH and RT-PCR testing of tumours with increased ALK protein expression in a routine clinical diagnostic setting (ID 2838)

    09:30 - 09:30  |  Author(s): J. Harris
    • Abstract

    Background
    The diagnosis of anaplastic lymphoma kinase (ALK) gene rearrangement in non small cell lung cancer (NSCLC) has acquired therapeutic significance, subsequent to the established response of ALK-rearranged tumours to crizotinib therapy. General recommendations on NSCLC ALK testing will be published later this year by the National Institute for Health and Care Excellence. In advance of this, patients were prospectively screened for ALK-rearranged NSCLC at the Christie Hospital, Manchester, U.K. from May 2012 to May 2013.

    Methods
    Pulmonary adenocarcinomas were selected for testing by ALK immunohistochemistry (IHC) based the presence of any of the following clinicopathologic features associated with ALK rearrangement; never smoker, light ex-smoker, age less than 50 years, signet ring/goblet cell morphology. IHC was performed with the 5A4 clone (Novocastra) according to the European Thoracic Oncology Platform protocol. All IHC-positive cases (intensity score 1+, 2+ or 3+) were tested for ALK rearrangement by both fluorescent in situ hybridisation (FISH) and reverse transcriptase polymerase chain reaction (RT-PCR). FISH analysis using the Abbott Molecular LSI ALK Dual Colour Break Apart Probe required a minimum of 15% of (at least 100) tumour cells with gene rearrangement for a positive diagnosis. RT-PCR testing was employed to detect EML4-ALK fusion transcripts using a series of primers located in EML4 exons 1 to 22, a reverse primer located in ALK exon 20 (Sanders et al., 2011;204:45-52) and sample RNA extracted from a single 40 µM section. Amplified products were Sanger sequenced to establish the fusion variant present.

    Results
    Ninety-one specimens were screened by ALK IHC and of these, 13 demonstrated positive staining. FISH and RT-PCR results were concordant (with the exception of one RT-PCR negative case which failed FISH testing) and 9 cases were diagnosed with ALK-rearrangement (9.9%). The majority of the EML4-ALK fusion transcripts were of variant 1 type (77.8%), with just two subtypes diagnosed as variant 3 (22.2%). The median time from referral for FISH/RT-PCR to the issue of reports was 5 working days.

    Table 1. Summary of clinicopathological features, IHC, FISH and RT-PCR results of cases positive for ALK protein staining on IHC. (ACA =adenocarcinoma)

    Case	Age	Sex	Sample type	Histology	IHC H-score	FISH % +	RT-PCR	Final ALK diagnosis	EGFR mutation
    1	84	F	Node excision	ACA, signet ring cells	170	55	E13;A20 variant 1	+	-
    2	59	M	Lung resection	ACA, solid with hepatoid cells	190	77	E13;A20 variant 1	+	-
    3	56	M	Pleural effusion	ACA, hepatoid cells	240	64	E13;A20 variant 1	+	-
    4	46	M	Node biopsy	Adenosquamous	300	64	E6;A20 variant 3	+	-
    5	64	M	Pleural biopsy	ACA, solid with hepatoid cells	300	48	E13;A20 variant 1	+	-
    6	60	F	Node aspirate	ACA, signet ring and hepatoid cells	300	66	E13;A20 variant 1	+	-
    7	41	F	Node biopsy	ACA, hepatoid cells	300	71	E13;A20 variant 1	+	-
    8	40	M	Pleural biopsy	ACA, solid with hepatoid cells	300	58	E6;A20 variant 3	+	-
    9	65	F	Node aspirate	ACA, signet ring and hepatoid cells	300	45	E13;A20 variant 1	+	-
    10	54	M	Pleural effusion	ACA	20	5	Negative	-	-
    11	52	F	Pericardial effusion	ACA	10	Failed	Negative	-	-
    12	49	F	Pleural fluid	ACA	35	0	Negative	-	+
    13	70	F	Lung resection	ACA, solid with hepatoid cells	54	9	Negative	-	Unknown

    Conclusion
    In keeping with reported findings ALK-rearranged NSCLC was found in 9.9% of selected adenocarcinomas. Although FISH/RT-PCR was not carried out on IHC-negative cases in this group, the application of IHC as a screening method appears to be a cost-effective means of highlighting ALK-rearranged tumours. RT-PCR testing of formalin-fixed, paraffin-embedded tissue is feasible in the clinical diagnostic setting, and may have an important role in the determination of specific variants detected by IHC.