Why does a particular drug work for some cancers and not for others, even when two cancers carry the same mutations?

Cancer is mysterious, and this is one of the mysteries.  Melanoma and colon cancer, for example, often have the same mutations, and yet do not respond to the same drug.  Their location in the body is surely part of the reason, but the details are unknown.

Is chemoprevention feasible?  Chemoprevention would involve a patient taking a drug to reduce the risk of cancer.

This has been talked about for years, but is not practiced.  In a sense, people who preach that the right nutrition can prevent someone from getting cancer are advocating a form of chemoprevention – with low dose phytochemicals.  But scientists don’t think there is a strong link between a person’s diet and his or her cancer risk.

Can we find new chemoprotective agents?

Right now, only a few are used with cytotoxic drugs.  Mesna was only approved for use in 1988, almost 30 years after the approval of cyclophosphamide for which doctors give patients Mesna.  If we can find and test new chemoprotective agents, doctors could offer patients a less stressful treatment regimen.

Can we learn more about which chemotherapy regimens are safe for pregnant women?

Doctors do give some pregnant women certain drugs, but they are nervous about doing so.  And given the dozens of new cancer drugs there are unknowns about the suitability of those new drugs and immunotherapy treatments.  The clinical trials used to gain initial approval of medicines exclude pregnant women, so there is no data for new drugs.

Can we get different and better conjugates?

Scientists have done great at developing monoclonal antibodies that can precisely target cells with certain receptors.   Conjugates of antibodies and toxins have entered the clinic.  However, only a few toxins are employed – chemical poisons and four radioactive atoms.  There may be opportunities to develop conjugates with different toxins.

Can we get convert an increasing number of cases to lo ng-term management?

It isn’t an ideal solution, but it might be a practical one.

Will pharmaceutical companies embrace alternative endpoints to establish effectiveness?

Traditionally new drugs were proven effective if they showed clinical results such as increased survival rate, remission of symptoms, and increased longevity.  The new paradigm is to use surrogate endpoints such as levels of hormones and other biomarkers or  progression free survival.   These surrogates are not widely used yet.

See also: ongoing research for new chemo drugs.