Presentation on theme: "Trastuzumab [Genentech Inc.] Labeling Supplement to Include FISH Testing as a Method to Select Patients for Treatment FDA Clinical Review December 5, 2001."— Presentation transcript:
Trastuzumab [Genentech Inc.] Labeling Supplement to Include FISH Testing as a Method to Select Patients for Treatment FDA Clinical Review December 5, 2001 Oncologic Drugs Advisory Committee Meeting
Objective of This sBLA To add information on the use of fluorescence in situ hybridization (FISH) testing for HER2 amplification to the trastuzumab package insert
Background: Trastuzumab Original application approved September 1998 Indications –Single agent use 2 nd or 3 rd line in metastatic breast cancer –In combination with paclitaxel first line in metastatic breast cancer
Background: Trastuzumab Indications (continued) –“HERCEPTIN should only be used in patients whose tumors have HER2 protein overexpression.” Mechanism for antibody binding effect FISH not performed
Background: Trastuzumab HER2 protein overexpression –“Data from both efficacy trials suggest that the beneficial treatment effects were largely limited to patients with the highest level of HER2 protein overexpression (3+).”
Background: Trastuzumab Immunohistochemical (IHC) detection of HER2 protein –Clinical Trial Assay (CTA) used to select patients for clinical trials –“HercepTest … has not been directly studied for its ability to predict HERCEPTIN treatment effect, but has been compared to CTA on over 500 breast cancer histology specimens…”
Background: Trastuzumab Immunohistochemical (IHC) detection of HER2 protein (cont.) –“Of specimens testing 2+ on HercepTest, only 34% would be expected to test at least 2+ on the CTA including 14% which would be expected to test 3+ on the CTA.”
Background: Trastuzumab Immunohistochemical (IHC) detection of HER2 protein (cont.) –“Of specimens testing 3+ on HercepTest, 94% would be expected to test at least 2+ on the CTA including 82% which would be expected to test 3+ on the CTA.”
Postmarketing Commitment Impetus: There was uncertainty regarding the optimal method for selection of patients who might benefit from trastuzumab therapy –2+ or 3+ (vs) 3+ –Variability in immunohistochemistry results
Postmarketing Commitment “To assess the clinical outcome of patients selected for treatment on the basis of the DAKO test [HercepTest] and other HER2 diagnostics in the context of Herceptin clinical trials.”
Regulatory Timeline for FISH sBLA September 1998: Approval of trastuzumab March 2000: Genentech informed FDA about results of exploratory, retrospective FISH analysis of clinical trial specimens. Rejected by FDA due to missing data (appeared to be non-random)
Regulatory Timeline for FISH sBLA August 2000: Genentech discusses proposal to minimize missing data by running FISH on previously stained slides April 2001: sBLA for trastuzumab filed with CBER and sPMA for PathVysion filed with CDRH
Regulatory Timeline for FISH sBLA The sBLA under consideration today does not fulfill the postmarketing commitments. Other trials, currently being conducted in the adjuvant setting, will address these commitments, but will not be complete for another 4-5 years.
FDA Perception of the Field of HER2 Testing HER2 assessment is not straightforward Marked variability in results between different laboratories Extensive off label use of other antibodies for IHC (aka “home brew” assays) Extensive off label use of FISH
FDA Perception of the Field of HER2 Testing Misunderstanding, on the part of treating physicians, regarding the advantages and limitations of the various assay methodologies Importance of reviewing the FISH data obtained from the clinical trial specimens, as it is unlikely that another randomized trial of this sort will be conducted.
FISH sBLA: Nature of the Clinical Outcome Data What they are not: Prospective, randomized, double-blinded, controlled multi-center trials providing data regarding the predictive capability of FISH and data regarding the comparability of FISH vs IHC. Any conclusion drawn from these data should take into account the limitations of the studies conducted and filed in this sBLA.
FISH sBLA: Nature of the Clinical Outcome Data What they are: Exploratory, retrospective data from two laboratory sites with provocative results which may warrant inclusion into the PI in some capacity
FISH sBLA: Studies Conducted Concordance study –Screened specimens (patients not necessarily treated, IHC score 0, 1+, 2+ or 3+) Clinical Outcome study –Specimens from patients treated on the trastuzumab clinical trials (IHC 2+ or 3+) Validation study –Compare results between LabCorp and Press Lab
Overview of Studies FISH assay used: PathVysion by Vysis Laboratory sites: Laboratory Corporation (LabCorp) and the laboratory of Dr. Michael Press (Press) Specimens: Obtained from trastuzumab clinical trials H0648g, H0649g, H0650g
FISH Testing Results: Success/Failure Rates Concordance Study –LabCorp –623 samples tested –529 samples with a result [FISH (+) or FISH (-)] –15% testing failure rate [i.e. no FISH result]
FISH Testing Results: Success/Failure Rates Clinical Outcome study –LabCorp and Press –784 patient samples tested altogether 618 tested by LabCorp 244 tested by Press –765 with FISH result –Testing failure rates LabCorp = 14% Press = 8%
FISH Testing Results: Success/Failure Rates Validation study –LabCorp and Press –250 samples tested by both labs –223 samples with a result by Press lab –11% failure rate
FISH Testing Results: Comparison of LabCorp and Press Labs Different techniques Lower FISH scores on samples at LabCorp Discordant results (H0648g, 649g, and 650g) –32% (37/116) of samples testing positive at Press tested negative at LabCorp –2% (2/107) of samples testing positive at LabCorp tested negative at Press
FISH Testing Results: Comparison of LabCorp and Press Labs Estimate based upon exploratory analyses: 10-30% of LabCorp values in the range of 1.0-2.0 (FISH negative) may be patients who would benefit from trastuzumab therapy (3+ by CTA)
FISH Testing Results Concordance Study FDA analyses agreed with sponsor analyses Moderate concordance (Kappa = 0.64) when CTA positive defined as 2+ and 3+ Better concordance (Kappa = 0.80) when CTA positive defined as 3+ only
FISH Testing Results Concordance Study FISH testing missed 11% of the 3+ samples FISH testing selected 4% of the 0-1+ samples FISH testing was positive in 24% of 2+ samples
FISH Testing Results Concordance Study FDA exploratory analysis: concordance for clinical trial data (patients enrolled) showed consistent effect 13% of 3+ samples were FISH negative 34% of 2+ samples were FISH positive
FISH Testing Results Clinical Outcome Study FDA analyses agreed with sponsor analyses Special note: There are no clinical outcome data for patients who were IHC (0-1+) and either FISH (+) or FISH (-). Studies H0648g and H0649g were analyzed.
FISH Testing Results Clinical Outcome Study Endpoints assessed –Time to Progression (primary endpoint) –Overall Survival –Overall Response Rate
H0648g Time to Progression Trastuzumab +Chemo vs Chemo SubgroupRelative Risk 95% CIN 3+0.420.33, 0.55349 2+0.820.54, 1.24120 FISH (+)0.440.34, 0.57325 FISH (-)0.660.45, 0.99126
H0648g Time to Progression Trastuzumab +Chemo vs Chemo SubgroupRelative Risk 95 %CIN FISH+/3+0.420.32, 0.55293 FISH+/2+0.720.31, 1.6432 FISH-/3+0.400.19, 0.8743 FISH-/2+0.860.53, 1.3883
H0648g Time to Progression, 3+ Trastuzumab + Chemo N = 176 Chemo N = 173
H0648g Time to Progression, 2+ Trastuzumab + Chemo N = 59 Chemo N = 61
H0648g Time to Progression, FISH (+) Trastuzumab + Chemo N = 164 Chemo N = 161
H0648g Time to Progression, FISH (-) Trastuzumab + Chemo N = 62 Chemo N = 64
H0648gTime to Progression,FISH (+)/3+ Trastuzumab + Chemo N = 148 Chemo N = 145
H0648g Time to Progression, FISH (+)/2+ Trastuzumab + Chemo N = 16 Chemo N = 16
H0648g Time to Progression, FISH (-)/3+ Trastuzumab + Chemo N = 21 Chemo N = 22
H0648g Time to Progression, FISH (-)/2+ Trastuzumab + Chemo N = 41 Chemo N = 42
H0648g Time to Progression Trastuzumab +Chemo vs Chemo SubgroupRelative Risk 95% CIN 3+0.420.33, 0.55349 FISH+/3+0.420.32, 0.55293 FISH-/3+0.400.19, 0.8743
H0648g Time to Progression Trastuzumab +Chemo vs Chemo SubgroupRelative Risk 95% CIN 2+0.820.54, 1.24120 FISH+/2+0.720.31, 1.6432 FISH-/2+0.860.53, 1.3883
H0648g Overall Survival Trastuzumab + Chemo vs Chemo SubgroupRelative Risk 95% CIN 3+0.700.54, 0.92349 2+1.090.71, 1.58120 FISH (+)0.690.53, 0.91325 FISH (-)1.070.70, 1.63126
H0648g Overall Response Rate Trastuzumab + Chemo vs Chemo T+C 2+,3+ C 2+,3+ T+C 3+ C 3+ T+C 2+ C 2+ FISH (+) 54%30%55%28%50%56% FISH (-) 40%38%62%55%29% FISH Any 45%29%49%27%32%34%
H0649g Overall Response Rate Single agent trastuzumab Single arm study assessment of response rate. Without comparator arm, it is difficult to assess the meaning of time to progression and survival.
H0649g Overall Response Rate Single Agent Trastuzumab CTA 3+CTA 2+All FISH (+)22%11%20% FISH (-)0% All19%6%14%
Conclusions Inter-laboratory variability in test results can be seen with FISH testing as evidenced by the differences observed between two selected laboratories in these studies. There is an expected failure rate for obtaining a result by the HER2 FISH assay.
Conclusions Concordance between FISH and CTA testing is moderate –Between 11% and 13% of patients who might benefit from trastuzumab (IHC 3+) would not be selected by FISH –Nearly 4% of patients who would not have been eligible for the clinical trials (IHC 0-1+), test positive by FISH
Conclusions It is not possible to determine the utility of treating patients whose tumors test FISH (+) and IHC (0-1+), because they were not enrolled onto these clinical trials.
Conclusions There are insufficient data to definitively describe the predictive capability of FISH as the first and only test to identify patients who would benefit from trastuzumab therapy.
Conclusions Direct comparative statements of equivalence or superiority between FISH and IHC cannot be made.
Conclusions The clinical outcome study in a pre- selected population indicates that FISH appears to be a useful method for selection of patients who are known to be IHC 2+ or 3+.
Potential Questions to Address Postmarketing Do patients whose tumors test as FISH (+) and either IHC 0, 1+, or 2+ benefit from trastuzumab therapy? How much inter-laboratory variability exists in the community for FISH and IHC testing of HER2? What types of educational programs targeting oncology professionals need to be in place to optimize testing and interpretation of results?