Molecular Enhancement of Sentinel Node Evaluation

Transcription

1 Cochran Illustrations Molecular Enhancement of Sentinel Node Evaluation Alistair Cochran, MD and Rong Huang MD Departments of Pathology and Laboratory Medicine and Surgery, David Geffen School of Medicine at UCLA. John Wayne Cancer Institute, Santa Monica. Grant Support: NCI CA (PI DL Morton) and Australian and New Zealand Melanoma Trials Group.

2 Cochran Illustrations Donald Morton MD

3 Cochran Illustrations Lymphatic Mapping and Sentinel Node Biopsy for Melanoma: Status in December First described 30 years ago 1 major clinical trial (MSLT1) completed and results published (NEJM 2014) 1 major clinical trial (MSLT2) in follow-up (1926 patients randomized) 5 year follow up by 2019 Techniques widely practiced around the world Techniques effectively applied to tumors other than melanoma Some issues remain unresolved No viable alternative approach in sight

4 Cochran Illustrations Current Management Options for Melanoma T1-4NxMx + + +/ Blind Elective LNXY Sentinel Node Biopsy* Delayed Therapeutic LNXY *Precise, timely, informative, low morbidity

5 Cochran Illustrations Summary MSLT Data LM/SNB accurately stages regional nodes (up to 95-97% accuracy). Identifies patients with clinically occult metastatic melanoma in the sentinel node Identifies candidates for immediate CLND During clinical observation small impalpable metastases in SN become detectable and may spread to additional nodes (3.2 vs,1.4 P=0.001) SN metastases may also spread to distant sites HR 0.62 P=

6 Cochran Illustrations MSLT-1 at 10 years of follow up: Summary Data validate accuracy of biopsy-based staging of intermediate and thick melanomas Identifies patients with SN metastases who benefit from immediate CLND SNB/selective CLND prolongs disease free survival for all patients Prolongs distant disease free survival and melanoma specific survival for patients with SN metastases from intermediate ( mm.) primaries Early lymph node surgery associated with substantially less morbidity

7 Primary Melanoma Subgroups Primary with risk of nodal metastases a. =/> 1mm. Breslow b. <1mm. Breslow with mitoses or ulceration Treatment: consider for sentinel node biopsy Primary with low/no risk of nodal metastases <1mm. Breslow without mitoses or ulceration Treatment: wide excision and follow up Problem of false negative sentinel node False negatives in experienced hands <5%

8 Primary Melanomas treated by Sentinel Node biopsy 80% SN microscopically negative Optimally staged so follow up only SNB justified as pt. spared CLND 20% SN microscopically positive SNB justified as optimally staged consider for immediate CLND

9 SNB+ve patients receiving immediate CLND Negative Non-sentinel nodes (84%) Evaluate for distant metastases and observation Adjunctive therapy surgically over-treated: how to identify these pts. and avoid CLND Evaluate primary and sentinel nodal metastases Histology, Immunohistology, molecular and genetic analyses Positive Non-sentinel nodes (16%) Evaluate for distant met. Adjunctive therapy Extensive nodal surgery defensible in this sub-group How are these patients to be identified Evaluate primary and sentinel nodal metastases Histology, Immunohistology, molecular and genetic analysis

10 Primary Melanoma Filter 1 Tumor > 1mm Tumor< 1mm SN Biopsy Wide Excision and Observation SN negative 80% SN positive 20% Filter 2 False Negative 5% True Negative 75% CLND +ve NSN 16% -ve NSN 84%

11 Demographic/pathological features of primary melanomas predicting metastases in sentinel nodes (Filter 1). Variables Estimated Odds Ratio (95% CI) P-value Age >50 vs (0.44, 0.87) Primary Site Trunk vs. other 1.74 (1.24, 2.44) Breslow (reference) (1.65, 3.53) <.0001 > (2.32, 6.22) <.0001 Clark level IV-V vs. I-III 1.46 (1.01, 2.12) Lymphatic invasion Y vs.n 2.88 (1.62, 5.12)

12 Staging Based on SN Tumor Status (Filter 2) Cochran 6 th World Congr on Melanoma Vancouver Most accurate available staging technique Identifies pts. with actual early nodal spread Other predictors (Breslow, Clark, ulceration) identify pts. likely to have nodal spread SN status included in current AJCC classification SN evaluation greatly exceeds accuracy of clinical staging and available adjunctive techniques

13 Evaluation of need for completion lymph node dissection in patients with sentinel node metastases Aim. Spare 84% of patients unnecessary CLND 1. Evaluate the number of sentinel nodes with metastases 2. Evaluate the site, size, frequency of metastases and the percentage of node replaced by tumor 3. Molecular Pathology Assessment Gene Expression Microarrays (GEM) to develop Gene Signatures-under investigation

14 Cochran Illustrations Amount and disposition of tumor in the SN predict groups of patients at risk for NSN tumor, tumor recurrence and death from melanoma.

15 Cochran Illustrations Survival prediction from SN tumor features Percent tumor burden- P= Tumor diameter- P= Tumor depth from capsule- P= Number metastatic foci- P= Tumor site in node- P=0.05 Extra-capsular extension- P=0.0148

16 Evaluation of need for sentinel node biopsy in patients with primary melanoma Aim: To confine sentinel node biopsy to patients with reasonable likelihood of nodal metastases 1. Careful clinicopathological assessment: Age, site, Breslow, Lymphatic invasion and Clark level 2. Identify 5% of pts. with false -ve SNs-HOW 3. Molecular Pathology Assessment CGH-likely adjunctive-currently applied clinically FISH-likely adjunctive-currently applied clinically RTPCR unfulfilled promises for SN Gene Expression Microarrays/Gene Signatures-under investigation Gene Sequencing to generate signatures-likely adjunctive-under investigation

17 In a study of melanoma Primaries and SN metastases (Koh et al) 17 DNA microarrays show: differential gene expression patterns between primaries and SN metastases. clear distinction on hierarchical clustering map 576 significant genes identified at >=2 fold and p<0.05 most genes with greatest fold-change were decreased rather than increased Analysis of these data continues to develop gene signatures

18 Molecular Pathology Assessment Sentinel Node Supervised gene expression microarray (GEM) to investigate metastatic melanoma in SN from 15 patients who had immediate CLND: 7 with no melanoma in the non-sentinel nodes (NSN), and 8 with metastasis-positive NSN. We found significantly different gene expression profiles comparing SN metastases from these two groups of patients: -ve NSN-without melanoma in NSN; +ve NSN with metastasis in NSN. We developed two preliminary gene signatures

19 PCA: Significant Pattern of Expressed Genes in SN Metastases (+ve NSN versus ve NSN)

20 Summary Consideration of two preliminary gene signatures, with clinical and pathological features, will likely enhance accuracy of prediction of NSN tumor status, separating patients likely to benefit from CLND, from those unlikely to derive benefit from CLND. This will spare relevant patients the morbidity of extended surgery and significantly reduce medical costs. More accurate staging will also identify patients at high risk of visceral metastases who may benefit from relatively aggressive adjuvant therapy.