Category: Precision Oncology

FDA Approves First PI3K Inhibitor, PIQRAY®, for Breast Cancer

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SUMMARY: The FDA on May 24, 2019 approved PIQRAY® (Alpelisib) in combination with FASLODEX® (Fulvestrant), to treat postmenopausal women and men, with Hormone Receptor (HR) positive, Human Epidermal growth factor Receptor 2 (HER2) negative, PIK3CA-mutated, advanced or metastatic breast cancer (as detected by an FDA-approved test), following progression on or after an endocrine-based regimen. The FDA also approved the companion diagnostic test, therascreen PIK3CA RGQ PCR Kit, to detect the PIK3CA mutation in a tissue and/or a liquid biopsy. Patients who are negative by the therascreen test using the liquid biopsy should undergo tumor biopsy for PIK3CA mutation testing. Breast cancer is the most common cancer among women in the US and about 1 in 8 women (12%) will develop invasive breast cancer during their lifetime. Approximately 268,600 new cases of female breast cancer will be diagnosed in 2019 and about 41,760 women will die of the disease. About 70% of breast tumors express Estrogen Receptors and/or Progesterone Receptors and these patients are often treated with anti-estrogen therapy as first line treatment. However, resistance to hormonal therapy occurs in a majority of the patients.Alpelisib - Mechanism-of-Action

The PhosphoInositide 3-Kinase (PI3K) pathway is an intracellular signaling pathway important in the regulation of cancer cell proliferation and metastasis. PI3K is a lipid kinase and has four distinct isoforms – alpha, beta, gamma and delta, which play a unique role in the survival of different tumor types and establishment of supportive tumor microenvironments. The alpha and beta isoforms are expressed in a wide variety of tissues whereas the gamma and delta isoforms are primarily expressed in hematopoietic cells such as B and T cells. The PI3K alpha isoform is particularly important in breast cancer and plays an important role in tumorigenesis, supporting tumor angiogenesis and stromal interactions, making this a viable target. PIK3CA is an oncogene that codes for the alpha isoform of PI3K, (PI3Kα), more specifically for the alpha isoform of p110. The PI3k pathway is the most frequently altered pathway in human cancers including breast cancer, and has been implicated in disease progression in a significant number of patients with breast cancer. Activation of the PI3K pathway in breast cancer has been associated with resistance to endocrine therapy and disease progression. Approximately 40% of patients with Hormone Receptor positive (HR+), HER2 negative breast cancers, harbor activating mutations in the PIK3CA isoform of PI3K, which is the most common mutation in HR+ breast cancer. Patients with advanced breast cancer harboring PIK3CA mutations typically have a poor prognosis. This provides a strong rationale for targeting the PI3K pathway in breast cancer.

PIQRAY® is an oral, alpha-specific PI3K inhibitor that specifically inhibits PIK3 in the PI3K/AKT kinase signaling pathway. Further, it was shown in preclinical studies that cancer cells with PIK3CA mutations are more sensitive to PIQRAY® than those without the mutation, across a broad range of tumor types. SOLAR-1 clinical trial, which was conducted to test this hypothesis, became the basis for this FDA approval.

SOLAR-1 is a global, double-blind, placebo-controlled, randomized phase III trial, which studied the benefit of PIQRAY® in combination with FASLODEX® (Fulvestrant) among postmenopausal women and men with PIK3CA-mutated HR+/HER2 negative advanced or metastatic breast cancer, who had progressed on or following prior Aromatase Inhibitor (AI) treatment with or without a Cyclin-Dependent Kinase (CDK) 4/6 inhibitor. In this study, 572 patients were randomized in a 1:1 ratio to receive PIQRAY® 300 mg orally daily or placebo once daily, in combination with FASLODEX® 500mg IM on days 1 and 15 of the first cycle and day 1 of each subsequent 28-day cycle. Patients were stratified based on visceral metastases and prior CDK4/6 inhibitor treatment. A total of 341 patients had PIK3CA mutations upon testing of the tumor tissue with 169 patients receiving the PIQRAY® combination and 172 patients receiving FASLODEX® alone. Enrolled patients had received one or more prior lines of hormonal therapy, but no chemotherapy for advanced breast cancer. They had not previously received FASLODEX® or any PI3K, Akt or mTOR inhibitor, and were not on concurrent anticancer therapy. Approximately half of the patients in each treatment group had lung or liver metastases and 6% had received prior CDK4/6 inhibitor therapy. The Primary endpoint was Progression Free Survival (PFS) for patients with the PIK3CA mutation. Secondary endpoints included Overall Survival (OS), Overall Response Rate (ORR), Clinical Benefit Rate, Health-Related Quality of Life, Efficacy in PIK3CA non-mutant cohort, Safety and Tolerability.

The Primary endpoint was met and at a median follow up of 20 months, the PFS was nearly twice as long in patients with PIK3CA mutations randomized to PIQRAY® plus FASLODEX® compared to the placebo plus FASLODEX® group. The median PFS was 11.0 months in the PIQRAY® group compared to 5.7 months in the placebo group (HR=0.65; P=0.00065). In patients with measurable, PIK3CA-mutated advanced breast cancer (N=262), the Overall Response Rate was 36% for the PIQRAY® plus FASLODEX® group versus 16% for placebo plus FASLODEX® group (P=0.0002). There was no significant PFS benefit noted in the PIK3CA-nonmutant patient group receiving PIQRAY® plus FASLODEX® The most frequent toxicities with PIQRAY® were hyperglycemia which could be managed with Metformin, nausea, decreased appetite and skin rash.

It was concluded that PIQRAY® given along with FASLODEX® significantly improved Progression Free Survival compared to Placebo plus FASLODEX® with manageable toxicities. The authors commented that this is the first study to show statistically significant, clinically meaningful PFS improvement with an alpha-specific PI3K inhibitor in PIK3CA-mutated HR+, HER2 negative advanced breast cancer, highlighting the importance of clinical genomics in advanced breast cancer. PIQRAY® is also the first novel drug approved under the Real-Time Oncology Review pilot program. It however remains unclear whether PIQRAY® should be incorporated into the current treatment paradigm upfront, along with endocrine therapy and a CDK 4/6 inhibitor, or sequentially following disease progression on a combination of endocrine therapy and a CDK 4/6 inhibitor. Alpelisib (ALP) + fulvestrant (FUL) for advanced breast cancer (ABC): results of the phase 3 SOLAR-1 trial. André F, Ciruelos EM, Rubovszky G, et al. Presented during the Presidential Symposium 1 at: 2018 ESMO Congress; October 19-23; Munich, Germany. Abstract LBA3_PR.

Liquid Biopsy Accurate, Reliable and Rapid in Identifying Biomarker Mutations in Newly Diagnosed Advanced Lung Cancer

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SUMMARY: The American Cancer Society estimates that for 2019 about 228,150 new cases of lung cancer will be diagnosed and 142,670 patients will die of the disease. Non Small Cell Lung Cancer (NSCLC) accounts for approximately 85% of all lung cancers. Patients with newly diagnosed metastatic NSCLC are often tested for guideline-recommended genomic biomarkers which include both predictive biomarker mutations such as EGFR, ALK, ROS1, BRAF, RET, MET, ERBB2, as well as prognostic biomarker mutation such as KRAS.

The application of precision medicine with targeted therapy requires detection of molecular abnormalities in a tissue biopsy specimen. However, if testing is not done with a comprehensive assay, such as Next-Generation Sequencing and is done in successive steps one test after another, tissue sample can be depleted, with not enough tissue left for testing of all biomarkers. Following progression or recurrence, archived biopsy specimens may not be helpful, as it is important to identify additional mutations in the tumor at the time of recurrence or progression, in order to plan appropriate therapy. Further, recurrent tumors may be inaccessible for a safe biopsy procedure or the clinical condition of the patient may not permit a repeat biopsy. Additionally, the biopsy itself may be subject to sampling error due to tumor heterogeneity. Genotyping circulating cell-free tumor DNA (cfDNA) in the plasma can potentially overcome the shortcomings of repeat biopsies and tissue genotyping, allowing the detection of many more targetable gene mutations, thus resulting in better evaluation of the tumor genome landscape.

The Noninvasive versus Invasive Lung Evaluation (NILE) trial is a prospective, multicenter study conducted to demonstrate the noninferiority of comprehensive cell-free DNA (cfDNA) relative to standard-of-care traditional tissue genotyping tests, to identify guideline-recommended genomic biomarkers, in patients with metastatic NSCLC. The authors in this study enrolled 282 newly diagnosed patients at 28 North American centers, with previously untreated, nonsquamous, metastatic NSCLC undergoing standard-of-care tissue genotyping. Enrolled patients submitted a pretreatment blood sample for cfDNA analysis utilizing a CLIA-certified comprehensive 73-gene next generation sequencing panel (Guardant360®). Over 80% of the enrolled patients were white and over 50% were female.

The liquid biopsy utilizing Guardant360®, detected biomarker mutations at a rate similar to standard-of-care tissue genotyping tests, in the enrolled patients, meeting the Primary study objective. At least one of the guideline-recommended genomic biomarkers was detected in 60 patients (21.3%) using tissue-based tests and in 77 patients (27.3%) by cfDNA utilizing Guardant360® (P<0.0001). The detection rate was increased by 48% when Guardant360® was utilized for cfDNA analysis and this included those with negative, not assessed, or Quantity Not Sufficient (QNS) results in tissue. In addition, the Positive Predictive Value was 100% for cfDNA versus tissue genotyping, for FDA approved targets such as EGFR, ALK, ROS1, and BRAF mutations. There are agents already approved by the FDA to treat this patient population. The median turnaround time was significantly lower for cfDNA, compared to tissue genotyping (9 versus 15 days; P <0.0001).

The authors concluded that in this largest cfDNA study among patients with previously untreated advanced NSCLC, cfDNA successfully detected seven biomarker mutations noninvasively, significantly faster than tissue genotype testing, and was also able to rescue biomarker mutation positive patients who had non-diagnostic tissue results. They added that the findings in this study confirms similar findings from Europe and demonstrates the clinical utility of cfDNA in newly diagnosed metastatic NSCLC. Clinical utility of comprehensive cell-free DNA (cfDNA) analysis to identify genomic biomarkers in newly diagnosed metastatic non-small cell lung cancer (mNSCLC). Leighl N, Page RD, Raymond VM, et al. Presented at: AACR Annual Meeting April 2, 2019; Philadelphia, USA.

Anaplastic Lymphoma Kinase Inhibition in Non Small Cell Lung Cancer

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SUMMARY:The therapeutic target of interest is an aberrant fusion gene, EML4-ALK. EML4 (echinoderm microtubule-associated protein-like 4) – ALK (anaplastic lymphoma kinase) is a fusion-type oncoprotein and is tyrosine kinase. This oncoprotein/tyrosine kinase is found in 2-7% of all Non Small Cell Lung Cancers (NSCLC) and is generated due to an inversion in the short arm of chromosome 2. This oncoprotein is more prevalent in patients with adenocarcinoma who have little or no exposure to tobacco. Tyrosine kinases normally play an important role in cellular proliferation and differentiation. However with point mutations, translocation/rearrangement and amplifications of their respective genes, these tyrosine kinases can potentially cause malignancy. Such is the case with mutations or translocations of the Anaplastic Lymphoma Kinase gene (ALK). In an article published in the October 28, 2010 issue of the NEJM, Crizotinib an oral small molecule tyrosine kinase inhibitor of ALK tyrosine kinase resulted in an overall response rate of 57% in patients who had progressed on prior therapies. Stable disease was noted in 33% of the patients. This is remarkable considering that the response rates in this patient population treated with second line chemotherapy is around 10-15%. As we move forward, it is very likely that genotyping patients and tailoring therapy accordingly, will become standard practice. N Engl J Med 2010; 363:1693-1703