Category Archives: Genetics

Olaparib – PARP inhibitor for triple negative breast cancer

Olaparib (Lynparza) is a PARP (poly-ADP ribose polymerase) inhibitor that was approved by the FDA in 2014 for the treatment of patients with advanced ovarian cancer who have mutated BRCA1,2 gene. Recently, the drug showed a 70% reduction in risk of progression in patients with less-advanced disease in the maintenance therapy setting:

The Phase III SOLO-2 trial demonstrated a significant improvement in progression-free survival (PFS) in germline BRCA-mutated (gBRCA), platinum-sensitive, relapsed ovarian cancer patients treated with Lynparza (olaparib) tablets (300mg twice daily) compared with placebo in the maintenance setting. The trial met its primary endpoint of investigator assessed PFS (HR 0.30; 95% CI 0.22 to 0.41; P<0.0001; median 19.1 months vs 5.5 months).

PARP inhibitors act in a counter-intuitive manner – by blocking PARP in the context of mutated BRCA1, the cell becomes overwhelmed with double strand breaks, leading to crisis and cell death. BRCA1 mutations, alone, predispose the cell to the accumulation of mutations in protooncogenes and tumor suppressor genes – a few double strand breaks are tumorigenic, whereas a massive number of double strand breaks, as occurs in the context of PARP inhibition, leads to apoptosis.

Figure 1. http://www.nature.com/nrclinonc/journal/v12/n1/full/nrclinonc.2014.163.html

The use of PARP inhibitors for breast cancer makes great sense, However, in a Phase 3 trial of velparib, an experimental PARP inhibitor, failed to achieve better rates of complete pathogenic response in patients with triple negative breast cancer (TNBC – lack of HER-2, estrogen, and progesterone receptor up-regulation) versus chemotherapy, alone.

At the ASCO conference last week, AstraZeneca presented data on the use of olaparib in 302 patients with BRCA1,2 mutated breast cancer from its OlympiAD trial that compares olaparib against physician’s choice of chemotherapy (capecitabine 2500 mg/m2 d1-14 q 21, or vinorelbine 30 mg/m2 d1,8 q 21, or eribulin 1.4 mg/m2 d1,8 q 21):

OlympiAD Inclusion Criteria:

  • Germline mutation in BRCA1 or BRCA2 that is predicted to be deleterious or suspected deleterious.
  • Histologically or cytologically confirmed breast cancer with evidence of metastatic disease.
  • Prior therapy with an anthracycline and a taxane in either an adjuvant or metastatic setting.
  • Prior platinum allowed as long as no breast cancer progression occurred on treatment or if given in adjuvant/neoadjuvant setting at least 12 months from last dose to study entry elapsed.
  • ER/PR breast cancer positive patients must have received and progressed on at least one endocrine therapy (adjuvant or metastatic), or have disease that the treating physician believes to be inappropriate for endocrine therapy.
  • ECOG performance status 0-1.
  • Adequate bone marrow, kidney and liver function.

OlympiAD Exclusion Criteria:

  • Prior treatment with PARP inhibitor.
  • Patients with HER2 positive disease.
  • More than 2 prior lines of chemotherapy for metastatic breast cancer.
  • Untreated and/or uncontrolled brain metastases.

Results were quite impressive – this was the first study that demonstrated PARP inhibition is effective in breast cancer:

  • About 60% of patients saw their tumors shrink, a hair more than double the 29% objective response rate seen in those patients on chemotherapy.
  • Lynparza showed efficacy in patients with TNBC, which is more difficult to treat. AbbVie, which is developing its own PARP inhibitor called veliparib, recentlyannounced a study specifically geared to look at veliparib’s activity in triple negative breast cancer failed to show a benefit when added to chemo. 
  • Additionally, treatment with Lynparza improved the time to second progression or death compared to chemo,suggesting patients who relapsed after Lynparza experienced a less aggressive return of their cancers. 

Astrazeneca is studying olaparib with many combinations, including a study in TNBC with PD-L1 inhibitor durvalumab and CTLA-4 inhibitor tremelimumab.

Regorafenib approved for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a primary cancer of the liver that occurs as a result of chronic liver disease, including cirrhosis and hepatitis B and C infections (Figure 1). Serum alpha-fetoprotien (AFP) levels are elevated early in the disease, and screening of patients with chronic liver disease for AFP has lead to earlier diagnosis of HCC. The test is 40-64% sensitive (the ability to detect disease when disease is truly present) because many HCCs do not produce AFP, but it is 75-91% specific (the ability to rule out disease when disease is truly absent) – an AFP of over 400 mg/mL is considered diagnostic. Continue reading

Inhibition of Nuclear Export Protein XPO1 in Cancer

Selinexor (KPT-33) is a drug that inhibits exportin 1 (XPO1 and CRM1), a nuclear transport protein that shuttles nuclear proteins through the nuclear pore and is responsible for the removal of proteins from the nucleus: Continue reading

PD-L1 Inhibitor, avelumab, approved for Merkel cell carcinoma

Avelumab (Bavencio) is a PD-L1 inhibitor that was approved for the treatment of patients with metastatic Merkel cell carcinoma (MCC). Continue reading

Hyperprogression on Checkpoint Inhibition Immunotherapy

Results with checkpoint inhibitors nivolumab (PD-1, Opdivo), pembrolizumab (PD-1, Keytruda), and atezolizumab (PD-L1, Tecentriq) are impressive. Some patients have experienced incredible and prolonged responses. These drugs are truly modern medical breakthroughs.
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Ublituximab, a novel anti-CD20 Monoclonal Antibody for CLL

TG Therapeutics is developing ublituximab, and anti-CD20 monoclonal antibody for patients with CLL (Chronic Lymphocytic Leukemia). In a phase 3 study in patients with relapsed disease, the combination of ublituximab and ibrutinib (Imbruvica) was superior to ibrutinib, alone – the overall response rates were 80% and 47%, respectively. Continue reading

CDK4/6 Inhibitors – Excellent Results Support Paradigm Shift in HR+/HER2- Breast Cancer

We have previously written about CDK4/6 inhibitor, palbociclib (Ibrance) for the treatment of patients with hormone receptor positive (HR+) Her-2 negative (HER2-) disease. In a randomized study of 165 patients who had not been treated previously, palbociclib plus letrozole (a nonsteroidal competitive inhibitor of the aromatase enzyme system that inhibits the conversion of androgens to estrogens) was superior to letrozole, alone: Continue reading

NQ01 – a new target for cancer therapy

NQO1 [NAD(P)H:quinone oxidoreductase 1 over-expression has been shown to confer a poor prognosis for patients with cancer of the breast, colon, cervix, lung and pancreas. Recent research indicates that the mechanism involves stabilization HIF-1α (hypoxia inducible factor-1) such that it is not degraded. Continue reading

Tagrisso is superior to platinum-based chemotherapy for patients with relapsed lung cancer following front-line anti EGFR therapy

Tagrisso (osimertinib) is a kinase inhibitor indicated for patients with metastatic epidermal growth factor T790M mutation-positive lung cancer. It was approved under accelerated approval provisions in November 2015 on the basis of phase 2 trials demonstrating a combined overall objective response rate of 59%. Continue reading

Etinostat blocks Treg activity via FOXP3 suppression

Histone deacetylase (HDAC) inhibitors block the removal of acetyl groups from histone proteins. Since acetylation of histones puts chromatin in a more favorable condition for transcription, HDAC inhibitors maintain this favorable state. HDAC inhibitors have been approved for use in cutaneous T-cell lymphoma. They act by sustaining transcription of tumor suppressor genes, which leads to cell cycle arrest and apoptosis. Continue reading