Category Archives: Genetics

Ubiquitin specific protease 7 – a good target for cancer therapy

Ubiquitin specific protease 7 (USP7) is a deubiquitinase, an enzyme that removes ubiquitin a 76 amino acid protein that is added onto lysines in the target protein. Proteins that are mono, or poly (up to 10 residues), ubiquitinated are taken to the proteasome for destruction. Continue reading

Using a blood test to select patients most likely to respond to checkpoint therapy

Checkpoint therapy with PD-(L)1 and CTLA4-directed monoclonal antibodies has shown to be extremely effective for many patients with a variety of tumors. PD-1 testing, alone, however, are lacking in selecting patients for therapy – up to 17% of patients who do not meet criteria for PD-1 positivity respond to treatment, and many patients with PD-1 tumors do not respond well to checkpoint therapy. Continue reading

MET – an ideal target for antibody drug conjugate therapy, plus nivolumab

MET is a gene that encodes a receptor tyrosine kinase that is activated upon binding with hepatocyte growth factor (HGF, or Scatter Factor). Specifically, MET is a Continue reading

Anti-APRIL Antibody BION-1301 for Multiple Myeloma

Multiple myeloma (MM) is a cancer of plasma cells in the bone marrow. Plasma cells are B lymphocytes (B-cells) that have been activated to produce immunoglobulins. When plasma cells become cancerous, the produce copious amounts of immunoglobulins and proliferate in the bone marrow, causing crowding-out of other essential hematopoietic cells, leading to reduced numbers of functioning white blood cells (leukopenia leading to immunosuppression), red blood cells (anemia), and megakaryocytes (thrombocytopenia). Continue reading

CLEC12A – a novel target for AML and MDS

CLEC12 (C-Type Lectin Domain Family 12 Member A) is negative regulator of granulocyte and monocyte functioning. It is a member of the C-type lectin/C-type lectin-like domain (CTL/CTLD) superfamily. It is also known as Myeloid Inhibitory C-Type Lectin-Like Receptor and Dendritic Cell-Associated Lectin. CLEC12 is a cell surface receptor that modulates signaling cascades and mediates tyrosine phosphorylation of target MAP kinases. Continue reading

Sitravatinib plus nivolumab in NSCLC

Sitravatinib (MGCD516) is an oral multi-tyrosine kinase inhibitor being developed by Mirati Therapeutics. Last week, the company announced that three of eleven patients with non-small cell lung cancer (NSCLC) with genetic alterations in MET, AXL, RET, TRK, DDR2, KDR, PDGFRA, KIT or CBL who were resistant to checkpoint [anti PD-(L)1 therapy] had confirmed partial responses; because of this, dosing in the 34-patient expansion cohort will proceed. Continue reading

ALK-positive lung cancer – antibodies to fusion protein

Approximately 7% of patients with non-small cell lung cancer (NSCLC) possess a transgene that results from an inversion of chromosome 2 that juxtaposes the 5’ end of the echinoderm microtubule-associated protein-like 4 (EML4) gene with the 3′ end of the anaplastic lymphoma kinase (ALK) gene, resulting in the novel fusion oncogene EML4-ALK . Continue reading

MDM2 and MDMX inhibitor restores p53 functioning in cancers with wild-type p53

P53 is a tumor suppressor gene that pauses cell division to allow for repair of gene damage, and triggers apoptosis if the damage is not reparable. Loss of p53 is a critical step in the evolution of cancer. Most frequently, p53 is mutated at its DNA binding domain; since p53 is a transcription factor, a diminished ability to bind to DNA significantly disrupts its functioning. Continue reading

Blocking Protein-Protein Interactions in Cancer

The last twenty years has been an unprecedented time in biology – in sequencing the genome and studying the functions of proteins, as well as in unraveling signal transduction pathways, the fundamental biology of normal and diseased cells has been elucidated to a great extent. Although many druggable targets have been identified, it has largely been impossible to target protein-protein interactions (PPI) in drug development. In fact, only ONE drug that targets a PPI has been approved. Continue reading

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.