Lung Cancer Drugs Flashcards
What drug is only approved for treatment of non-squamous NSCLCs? Why?
Bevacizumb because it is associated with a high risk of bleeding
Drugs that end in ‘nib’ are what?
tyrosine kinase inhibitors
How do EGF receptors work?
In the normal cell, binding of a ligand to the receptor results in dimerization and tyrosine residue trans-phosphorylation. This initial event is transduced to the nucleus where effects upon nuclear transcription can
lead to cell growth, proliferation and the avoidance of apoptotic events.
What the EGFR IgG monoclonals approved for treatment of SQUAMOUS NSCLC?
- Necitumumab
- Panitumumab
How do EGFR monoclonals work?
competitively block binding of EGF and TGF-a to EGFR, thereby inhibiting receptor autophosphorylation
What step in the signaling pathway do TKIs inhibit? Result?
the phosphorylation step is
inhibited and the absence of proliferative signal leads to an apoptotic response.
How can resistance to TKIs arise?
- Drug binding site mutation (T790M!!!),
- Compensatory phosphorylation of the tyrosine residues (ERBB3) via MET, also known as hepatocyte growth factor receptor (HGFR) which itself possesses tyrosine kinase activity, or
- By HGF assuming an independent role in the proliferative signaling process independent of ERBB3 or EGFR
Where do TKIs bind?
the tyrosine kinase domain of EGFR at the ATP binding site
What are some common drug site mutations to TKIs that make them MORE effective?
-in-frame deletions at exon 19 or point mutations in exon 21 (L858R) in NSCLC
What are some common drug site mutations to TKIs that make them LESS effective?
A T790M (exon 20) mutation reduces the drug activity by preventing correct orientation of drug binding on the active site.
The T790M mutation (part of ATP binding site) may
simply be an outgrowth of pre-existing clones that are inherently resistant, because such mutations can be determined in patients who have never received one of the
TKIs.
What happens when the EGFR is phosphorylated?
KRAS, BRAF, MEK, to ERK/MAPK that promotes proliferation, angiogenesis, survival etc in the nucleus via transcription
Describe the EML4-ALK oncogene mutation.
Translocations pair these two to produce constitutive tyrosine kinase activity independent of EGF which produce activation of the MEK/ERK, P13K, and JAK-STAT pathways and cell proliferation
What patient population commonly has a EML4-ALK mutation?
nonsmokers, light smokers, and in adenocarcinomas
When is VEGF released normally?
lack of O2 stimulates HIF-1 to release VEGF to stimulate angiogenesis
What is a large supply of VEGF important for?
solid tumor growth
What are some of the downsides of using VEGF inhibitors?
- reducing the distribution of concurrent chemotherapy without a blood supply
- induces accumulation /selection of more aggressive cells
What mutations are more common in smokers?
- Tp53 mutations
- G:C to T:A mutations
- KRAS
- STK11
- p16 and APC methylation
What mutations are more common in NON-smokers?
- EGFR mutations
- EML4-ALK
- HER2 mutations
- hMSH2 expression
What are the most common mutations in lung adenocarcinoma?
- KRAS (25%)
- EGFR (23%)
- ALK rearrangements
recommend routine testing for EGFR and ALK rearrangements in all adenocarcinomas
What is the most commonly used method in most EGFR studies?
DNA sequencing
What is the preferred method of testing for ALK rearrangements?
FISH
T or F. The USPSTF recommends that all heavy smokers with a 30+ pack-year history undergo routine low-dose CT scans for small (and thus very treatable) tumors
T.
What is the best treatment for solid tumor?
surgical resection with drugs neo- or adjuvantly
Does metastasis occur earlier in SCLC or NSCLC cancers?
SCLC (so chemo/radiation is usually the only option)
What is the standard treatment of SCLC?
Etoposide + cisplatin+ carboplatin
What is the standard treatment of NSCLC?
Cisplatin AND paclitaxel, docetaxel, irinotecan, gemcitabine, vinorelbine, or pemetrexed
What is the preferred maintenance drug for NSCLC?
Pemetrexed, a DHFR inhibitor
When is pemetrexed maintenance indicated?
For patients with stable or responding disease following 4 cycles of nonpemetrexed-platinum combo chemo
When is Bevacizumab indicated?
for patients with non-squamous histology, no brain metastases, and no hemoptysis
What is a common reason for toxicity of targeted cancer drugs?
they are given frequently so toxicity occurs in a cumulative fashion
What are some targeted TKIs for EGFR, exon 19 del or 21 subs in NSCLC?
- Afatinib
- Erlotinib
- Gefitinib
What is Alectinib used for?
NSCLC with ALK rearrangement
What is Ceritinib used for?
NSCLC with ALK arrangement that is intolerant to crizotinib
Uses of Crizotinib?
- ALK
- HGFR
in NSCLC
What drug is indicated for EGFR with 790M mutation positive in NSCLC?
Osimertinib
Common toxicities with targeted drugs like TKIs, BRAF inhibitors, and angiogenesis inhibitors?
- rash (SEVERE in EGFR TKIs)
- HTN (SEVERE in angiogenesis inhibitors)
- thrombus formation (VEGF inhibitors)
- diarrhea
- mucositis
- hypothyroidism, hypogonadism, hypopituitarism
Counseling for patients taking small molecular weight drugs like TKIs (note these are taken orally)?
- avoid pregnancy and breastfeeding
- report new CV, derm, or pulmonary symptoms immediately
Things to consider with small PO molecule drugs like TKIs
- most are substrates for CYP3A4 and P-gp
- some interact with food
- some depend on acidic environment for absorption
What is a fair inhibitor of CYP3A4?
Imatinib
Note on the dermatologic effects of EGFR TKIs
Patients who smoke or
who have a naturally lighter skin pigmentation do not appear to experience as severe a rash from EGFR TKIs as do others, whereas younger and male patients correlate
with increased rash caused by the EGFR monoclonals.
Some use the appearance of rash as an indication that the drug is working
AEs of VEGF inhibitors?
originally thought that the adult vasculature is mostly independent of VEGF, BUT inhibition blocks endothelial cell regeneration leading to exposed underlying matrix (promotes thrombus formation) AND bleeding (even in the GI)
Why do VEGF inhibitors affect the CV system?
they are involved in cardiac contraction as well as endothelial cell survival and vasodilation
What are some Monoclonals against VEGF?
- Bevacizumab
- Ramucirumab
How does Bevacizumab work?
binds and neutralizes all free human VEGF forms via recognition of binding sites for the two human VEGF receptor types (flt-1 and flk-1).
How does Ramucirumab work?
a VEGF receptor 2 antagonist that blocks binding of VEGF-A, VEGF-C, and VEGF-D to the VEGF receptor.
How is Bevacizumab given?
IV
AEs of Bevacizumub?
- HTN, hemorrhage
- hand-foot syndrome
- endocrine, neurologic, and GI dysfunction
- infectious disease
What patients have the greatest risk of serious bleeding with Bevacizumab?
all NSCLC with squamous histology, renal cell carcinoma, and colorectal cancer
Why is bleeding increased in these patients?
the drug is believed to cause central necrosis and to enlarge the tumor cavity
AEs of Ramucirumab?
- neutropenia
- HTN and bleeding
not increase in bleeding risk for squamous tumors
NOTE: only increased survival by 1.4 months
What are some TKIs against VEGF?
- Sunitinib
- Sorafenib
Which patients have been shown to experience less benefit from anti-angiogenesis approaches?
those with normal TP53 function
Why would normal TP53 function limit the effectiveness of anti-angiogenesis therapy?
“Normal” TP53 functions in a repressive role and would suppress VEGF activity and importance as a consequence of this action. However, “mutant” TP53 would likely lose the repressive role, thereby assigning more importance to the VEGF pathways and, in consequence, a greater treatment effect with the inhibitors.
How can tumors suppress the immune system?
Tumor cells can serve as APCs and induce PD-1 expression on T cells. Tumor cells can also expressed PD-L1 which essentially turns off T cells
What are some PD-1 receptor binders (compete with tumor cells with PD-1 for binding)?
- Nivolumab
- Pembrolizumab
AEs of PD-1 receptor binders?
By blocking repression of T cell function, there is the possibility that such agents could initiate autoimmune diseases.
This causes endocrinopathies (consider adrenal insufficiency)
many of these effects are self-limiting except pituitary damage
What is the first step in determining whether targeted testing is needed in lung cancer?
Assess clinical stage:
1-2: molecular testing not indicated; consider tissue banking
3-4: assess histologic type
What if histologic testing yields adenocarcinoma (or non-squamous)?
perform EGFR mutation analysis
What if histologic testing yields squamous carcinoma?
molecular testing not indicated; consider tissue banking
What is EGFR is positive?
consider erlotinib/afatinib
What is EGFR is negative?
performs FISH assay for EML4/ALK fusion oncogene
What is the EML4/ALK translocation is positive?
consider crizotinib
What is the EML4/ALK translocation is negative?
standard cytotoxic chemotherapy indicated
