FDA Approval Summary: Rucaparib for the Treatment of Patients with Deleterious BRCA-Mutated Metastatic Castrate-Resistant Prostate Cancer.

The U.S. Food and Drug Administration (FDA) granted accelerated approval to rucaparib in May 2020 for the treatment of adult patients with deleterious BRCA mutation (germline and/or somatic)-associated metastatic castrate-resistant prostate cancer (mCRPC) who have been treated with androgen receptor-directed therapy and a taxane. This approval was based on data from the ongoing multicenter, open-label single-arm trial TRITON2. The primary endpoint, confirmed objective response rate, in the 62 patients who met the above criteria, was 44% (95% confidence interval [CI]: 31%-57%). The median duration of response was not estimable (95% CI: 6.4 to not estimable). Fifty-six percent of patients had a response duration of >6 months and 15% >12 months. The safety profile of rucaparib was generally consistent with that of the class of poly-(ADP-ribose) polymerase enzyme inhibitors and other trials of rucaparib in the treatment of ovarian cancer. Deaths due to adverse events (AEs) occurred in 1.7% of patients, and 8% discontinued rucaparib because of an AE. Grade 3-4 AEs occurred in 59% of patients. No patients with prostate cancer developed myelodysplastic syndrome or acute myeloid leukemia. The trial TRITON3 in patients with mCRPC is ongoing and is planned to verify the clinical benefit of rucaparib in mCRPC. This article summarizes the FDA thought process and data supporting this accelerated approval. IMPLICATIONS FOR PRACTICE: The accelerated approval of rucaparib for the treatment of adult patients with deleterious BRCA mutation (germline and/or somatic)-associated metastatic castrate-resistant prostate cancer who have been treated with androgen receptor-directed therapy and a taxane represents the first approved therapy for this selected patient population. This approval was based on a single-arm trial demonstrating a confirmed objective response rate greater than that of available therapy with a favorable duration of response and an acceptable toxicity profile. The ongoing trial TRITON3 is verifying the clinical benefit of this drug.

FDA Approval Summary: Dabrafenib and Trametinib for the Treatment of Metastatic Non-Small Cell Lung Cancers Harboring BRAF V600E Mutations.

On June 22, 2017, the Food and Drug Administration expanded indications for dabrafenib and trametinib to include treatment of patients with metastatic non-small cell lung cancer (NSCLC) harboring BRAF V600E mutations. Approval was based on results from an international, multicenter, multicohort, noncomparative, open-label trial, study BRF113928, which sequentially enrolled 93 patients who had received previous systemic treatment for advanced NSCLC (Cohort B, n = 57) or were treatment-naïve (Cohort C, n = 36). All patients received dabrafenib 150 mg orally twice daily and trametinib 2 mg orally once daily. In Cohort B, overall response rate (ORR) was 63% (95% confidence interval [CI] 49%-76%) with response durations ≥6 months in 64% of responders. In Cohort C, ORR was 61% (95% CI 44%-77%) with response durations ≥6 months in 59% of responders. Results were evaluated in the context of the Intergroupe Francophone de Cancérologie Thoracique registry and a chart review of U.S. electronic health records at two academic sites, characterizing treatment outcomes data for patients with metastatic NSCLC with or without BRAF V600E mutations. The treatment effect of dabrafenib 150 mg twice daily was evaluated in 78 patients with previously treated BRAF mutant NSCLC, yielding an ORR of 27% (95% CI 18%-38%), establishing that dabrafenib alone is active, but that the addition of trametinib is necessary to achieve an ORR of >40%. The most common adverse reactions (≥20%) were pyrexia, fatigue, nausea, vomiting, diarrhea, dry skin, decreased appetite, edema, rash, chills, hemorrhage, cough, and dyspnea. IMPLICATIONS FOR PRACTICE: The approvals of dabrafenib and trametinib, administered concurrently, provide a new regimen for the treatment of a rare subset of non-small cell lung cancer (NSCLC) and demonstrate how drugs active for treatment of BRAF-mutant tumors in one setting predict efficacy and can provide supportive evidence for approval in another setting. The FDA also approved the first next-generation sequencing oncology panel test for simultaneous assessment of multiple actionable mutations, which will facilitate selection of optimal, personalized therapy. The test was shown to accurately and reliably select patients with NSCLC with the BRAF V600E mutation for whom treatment with dabrafenib and trametinib is the optimal treatment.

FDA Benefit-Risk Assessment of Osimertinib for the Treatment of Metastatic Non-Small Cell Lung Cancer Harboring Epidermal Growth Factor Receptor T790M Mutation.

On March 30, 2017, the U.S. Food and Drug Administration (FDA) approved osimertinib for the treatment of patients with metastatic, epidermal growth factor receptor (EGFR) T790M mutation-positive, non-small cell lung cancer (NSCLC), as detected by an FDA-approved test, whose disease has progressed following EGFR tyrosine kinase inhibitor (TKI) therapy. Approval was based on demonstration of a statistically significant difference in the primary endpoint of progression-free survival (PFS) when comparing osimertinib with chemotherapy in an international, multicenter, open-label, randomized trial (AURA3). In this confirmatory trial, which enrolled 419 patients, the PFS hazard ratio for osimertinib compared with chemotherapy per investigator assessment was 0.30 (95% confidence interval 0.23-0.41), p < .001, with median PFS of 10.1 months in the osimertinib arm and 4.4 months in the chemotherapy arm. Supportive efficacy data included PFS per blinded independent review committee demonstrating similar PFS results and an improved confirmed objective response rate per investigator assessment of 65% and 29%, with estimated median durations of response of 11.0 months and 4.2 months, in the osimertinib and chemotherapy arms, respectively. Patients received osimertinib 80 mg once daily and had a median duration of exposure of 8 months. The toxicity profile of osimertinib compared favorably with the profile of other approved EGFR TKIs and chemotherapy. The most common adverse drug reactions (>20%) in patients treated with osimertinib were diarrhea, rash, dry skin, nail toxicity, and fatigue. Herein, we review the benefit-risk assessment of osimertinib that led to regular approval, for patients with metastatic NSCLC harboring EGFR TKI whose disease has progressed on or after EGFR TKI therapy. IMPLICATIONS FOR PRACTICE: Osimertinib administered to metastatic non-small cell lung cancer (NSCLC) patients harboring an EGFR T790M mutation, who have progressed on or following EGFR TKI therapy, demonstrated a substantial improvement over platinum-based doublet chemotherapy as well as durable intracranial responses. The ability to test for the T790M mutation in plasma using the FDA-approved cobas EGFR Mutation Test v2 (Roche, Basel, Switzerland) identifies patients with NSCLC tumors not amenable to biopsy. Since a 40% false-negative rate has been observed with the circulating tumor DNA test, re-evaluation of the feasibility of tissue biopsy is recommended to identify patients with a false-negative plasma test result who may benefit from osimertinib.

Characterization of whole genome amplified (WGA) DNA for use in genotyping assay development.

BACKGROUND: Genotyping assays often require substantial amounts of DNA. To overcome the problem of limiting amounts of available DNA, Whole Genome Amplification (WGA) methods have been developed. The multiple displacement amplification (MDA) method using Φ29 polymerase has become the preferred choice due to its high processivity and low error rate. However, the uniformity and fidelity of the amplification process across the genome has not been extensively characterized. RESULTS: To assess amplification uniformity, we used array-based comparative genomic hybridization (aCGH) to evaluate DNA copy number variations (CNVs) in DNAs amplified by two MDA kits: GenomiPhi and REPLI-g. The Agilent Human CGH array containing nearly one million probes was used in this study together with DNAs from a normal subject and 2 cystic fibrosis (CF) patients. Each DNA sample was amplified 4 independent times and compared to its native unamplified DNA. Komogorov distances and Phi correlations showed a high consistency within each sample group. Less than 2% of the probes showed more than 2-fold CNV introduced by the amplification process. The two amplification kits, REPLI-g and GenomiPhi, generate very similar amplified DNA samples despite the differences between the unamplified and amplified DNA samples. The results from aCGH analysis indicated that there were no obvious CNVs in the CFTR gene region due to WGA when compared to unamplified DNA. This was confirmed by quantitative real-time PCR copy number assays at 10 locations within the CFTR gene. DNA sequencing analysis of a 2-kb region within the CFTR gene showed no mutations introduced by WGA. CONCLUSION: The relatively high uniformity and consistency of the WGA process, coupled with the low replication error rate, suggests that WGA DNA may be suitable for accurate genotyping. Regions of the genome that were consistently under-amplified were found to contain higher than average GC content. Because of the consistent differences between the WGA DNA and the native unamplified DNA, characterization of the genomic region of interest, as described here, will be necessary to ensure the reliability of genotyping results from WGA DNA.

Peripheral primitive neuroectodermal tumor/Ewing's sarcoma of the craniospinal vault: case reports and review.

The peripheral primitive neuroectodermal tumor/Ewing's sarcoma family tumor (pPNET/ESFT) group includes small round cell tumors of the bone, soft tissue, and nerve with morphological attributes of the germinal neuroepithelium. Peripheral PNETs/ESFTs also occur within the craniospinal vault, a region including the central nervous system, the meninges, and the cranial and spinal nerve roots. Gene rearrangements between the EWS gene on chromosome 22q12 and members of the ETS gene family are common in and specific to pPNETs/ESFTs. Another defining characteristic of pPNETs/ESFTs is their membranous expression of the MIC2 gene product. We describe 2 cases of pPNETs within the craniospinal vault. An intradural tumor arising from the nerve roots of the cauda equina was discovered in a 32-year-old man presenting with radiculopathic back pain and lower-extremity weakness. An intracranial pPNET that mimicked a meningioma was found in a 21-year-old man presenting with headache and visual disturbances. MIC2 gene product expression and EWS/ETS gene rearrangement were detected in both case patients. The literature with regard to pPNETs/ESFTs arising within the craniospinal vault is reviewed.

The first FDA marketing authorizations of next-generation sequencing technology and tests: challenges, solutions and impact for future assays.

The rapid emergence and clinical translation of novel high-throughput sequencing technologies created a need to clarify the regulatory pathway for the evaluation and authorization of these unique technologies. Recently, the US FDA authorized for marketing four next generation sequencing (NGS)-based diagnostic devices which consisted of two heritable disease-specific assays, library preparation reagents and a NGS platform that are intended for human germline targeted sequencing from whole blood. These first authorizations can serve as a case study in how different types of NGS-based technology are reviewed by the FDA. In this manuscript we describe challenges associated with the evaluation of these novel technologies and provide an overview of what was reviewed. Besides making validated NGS-based devices available for in vitro diagnostic use, these first authorizations create a regulatory path for similar future instruments and assays.

Immunoglobulin heavy chain gene analysis in lymphomas: a multi-center study demonstrating the heterogeneity of performance of polymerase chain reaction assays.

Determination of monoclonality through an evaluation of immunoglobulin heavy chain (IgH) gene rearrangements is a commonly performed and useful diagnostic assay. Many laboratories that perform this assay do so by the polymerase chain reaction (PCR). To evaluate current methods for performing IgH gene testing, 19 different Association of Molecular Pathology (AMP) member laboratories analyzed 29 blinded B cell and T cell lymphoid neoplasm samples of extracted DNA and formalin-fixed, paraffin-embedded (FFPE) tissue and were asked to complete a technical questionnaire. From this study, it is clear that Southern blot analysis remains the diagnostic gold standard, with a 100% diagnostic sensitivity and specificity. There was, however, remarkable heterogeneity in the performance of, and results obtained from, IgH PCR assays with diagnostic sensitivity ranging from over 90% to as low as 20%, when evaluating the same specimens. Many laboratories overestimate the diagnostic sensitivity of their IgH PCR assay, and there was a significant, and under appreciated, drop-off (from 61.3% to 41.8%) in detection in paired FFPE as compared with fresh/frozen tissues. Fixation has a dramatic impact on the inability to perform the test on FFPE (43.1%) versus DNA already extracted from fresh or frozen tissue (2.8%). A number of variables that affected the outcome of IgH PCR were identified. Strategies that improved the detection of monoclonal IgH rearrangements include: the addition of FRII to the FRIII upstream primer (increasing detection from 57.3% to 73.6%) and the use of the FR3A rather than the FR3 FRIII primer (increasing detection from 54.7% to 69.7%). Although numerous variables (from DNA extraction to PCR product detection) were evaluated, making it difficult to mandate alterations in laboratory practice, these findings ought to prompt diagnostic molecular pathology laboratories to reevaluate their claims of sensitivity, as well as their methodologies. Both pathologists and surgeons need to ensure that not all submitted material is fixed, if there is adequate sample. Importantly, there is a need for greater standardization to reduce the unacceptably high false negative rate of this crucial diagnostic assay.

Detection of SYT-SSX fusion transcripts in archival synovial sarcomas by real-time reverse transcriptase-polymerase chain reaction.

Synovial sarcomas comprise approximately 5% of soft tissue sarcomas and occur primarily in young adults. The t(X;18) (p11.2;q11.2) has been demonstrated to be highly characteristic of synovial sarcomas, and the resulting SYT-SSX fusion transcripts have been shown to be useful diagnostic markers. We have developed a real-time, reverse transcriptase-polymerase chain reaction (RT-PCR) multiplex assay for the identification of the primary fusion transcript types (SYT-SSX1 and SYT-SSX2) from formalin-fixed, paraffin-embedded (FFPE) tissues. Twenty-nine of 30 (96.7%) histologically diagnosed FFPE synovial sarcomas were positive for the presence of either the SYT-SSX1 or SYT-SSX2 fusion transcripts. Ten of 16 (62.5%) and five of 16 (31.25%) monophasic fibrous synovial sarcomas were positive for SYT-SSX1 and SYT-SSX2, respectively. One of 16 (6.25%) monophasic fibrous synovial sarcomas was negative for either SYT-SSX fusion transcript. Twelve of 14 (85.7%) and 2 of 14 (14.3%) biphasic synovial sarcomas were positive for SYT-SSX1 and SYT-SSX2, respectively. All 13 non-synovial sarcomas tested were negative for SYT-SSX1 and SYT-SSX2 fusion transcripts. This method is a relatively simple and rapid procedure for the detection of the t(X;18)(p11.2;q11.2).

U.S. Food and Drug Administration approval: crizotinib for treatment of advanced or metastatic non-small cell lung cancer that is anaplastic lymphoma kinase positive.

On August 26, 2011, the U.S. Food and Drug Administration (FDA) approved crizotinib (XALKORI Capsules, Pfizer Inc.) for treatment of patients with locally advanced or metastatic non-small cell lung cancer (NSCLC) that is anaplastic lymphoma kinase (ALK) positive as detected by an FDA-approved test. The Vysis ALK Break-Apart FISH Probe Kit (Abbott Molecular, Inc.) was approved concurrently. In two multicenter, single-arm trials, patients with locally advanced or metastatic ALK-positive NSCLC previously treated with one or more systemic therapies received crizotinib orally at a dose of 250 mg twice daily. In 119 patients with ALK-positive NSCLC by local trial assay, the objective response rate (ORR) was 61% [95% confidence intervals (CI), 52%-70%] with a median response duration of 48 weeks. In 136 patients with ALK-positive NSCLC by the to-be-marketed test, the ORR was 50% (95% CI, 42%-59%) with a median response duration of 42 weeks. The most common adverse reactions (≥25%) were vision disorder, nausea, diarrhea, vomiting, edema, and constipation. Accelerated approval was granted on the basis of the high ORRs and durable responses. On November 20, 2013, crizotinib received full approval based on an improvement in progression-free survival in patients with metastatic ALK-positive NSCLC previously treated with one platinum-based chemotherapy regimen.

Gene rearrangement and comparative genomic hybridization studies of classic Hodgkin lymphoma expressing T-cell antigens.

CONTEXT: Reed-Sternberg cells in classic Hodgkin lymphoma are enigmatic and difficult to study because they are so sparse. Tissue microdissection allows for the isolation of single Reed-Sternberg cells. Isolated Reed-Sternberg cells show clonal immunoglobulin gene rearrangement indicating a B-cell origin. Rarely, Reed-Sternberg cells in classic Hodgkin lymphoma express T-cell antigens, suggesting a possible T-cell origin. OBJECTIVE: To determine whether there is a difference in genotype between classic Hodgkin lymphoma and classic Hodgkin lymphoma expressing T-cell antigens and to document T-cell clonality. DESIGN: We studied 4 cases of Hodgkin lymphoma with a characteristic phenotype and immunoreactivity for CD2 and CD3. Single CD30+ Reed-Sternberg cells from each case were isolated by laser capture microdissection for immunoglobulin heavy chain and T-cell receptor-gamma genes by polymerase chain reaction studies. Comparative genomic hybridization was performed in all cases. RESULTS: Two of 4 cases showed clonal rearrangement of the T-cell receptor-gamma; none showed immunoglobulin heavy chain rearrangement. Two control cases were negative for T cell receptor-gamma but 1 showed immunoglobulin heavy chain rearrangement. Comparative genomic hybridization analysis revealed significant overlap in genomic alteration in Hodgkin lymphoma cases regardless of genotype or phenotype and several regions of imbalance specific to CD3+ Hodgkin lymphoma cases. All patients are alive with no evidence of disease from 10 to 44 months. CONCLUSIONS: Our findings suggest that a T-cell phenotype classic Hodgkin lymphoma can be supported by genotypic studies and that there may be cytogenetic differences between classic Hodgkin lymphoma and Hodgkin lymphoma expressing T-cell antigens.

CD4+CD25+ T cells prevent the development of organ-specific autoimmune disease by inhibiting the differentiation of autoreactive effector T cells.

Thymic-derived, naturally occurring, CD4+CD25+ regulatory T cells (nTreg) are potent suppressors of immune responses. A detailed understanding of which components of the development and activation of pathogenic effector T cells are inhibited by nTreg during the course of T cell-mediated, organ-specific autoimmunity is as yet unknown. We have analyzed the effects of polyclonal nTreg on the development of autoimmune gastritis. The nTreg inhibited the development of disease, but failed to inhibit the migration of effector cells into the gastric lymph node or stomach. Notably, nTreg did not inhibit the expansion of autoreactive T cells in the gastric lymph node. The primary effect of nTreg appeared to be inhibition of differentiation of autoantigen-specific T cells to Th1 effector cells, as reflected by a decrease in Ag-stimulated IFN-gamma production and a reduction in T-bet expression.