Even in the age of biologically targeted drugs, chemotherapy still remains what is known as the “backbone” of therapy in many situations. Chemotherapy is commonly used with biological agents both in early-stage breast cancer to lower the chance of recurrence and improve the cure rate. For metastatic breast cancer, it delays progression even though usually not curative. We are still refining our knowledge as to which drugs and schedules work the best – two important studies were presented today at the annual meeting of the American Society of Clinical Oncology (ASCO).
For metastatic breast cancer, some of the newer drugs including Abraxane (albumin-bound paclitaxel) and Ixempra (ixabepilone) have been approved on the basis of being better than older drugs like Taxol (paclitaxel) or better when added to Xeloda (capecitabine) in patients who have already received other chemotherapies. However, as initial therapy, it is not clear which option is best.
The CALGB 40502 study compared Taxol, Abraxane and Ixempra – all given in a weekly schedule, which is felt to be the best for each drug. Avastin (bevacizumab) was given with 98 percent of patients even through the FDA withdrew approval of this agent early during the course of the trial. The results showed that Taxol was better than Ixempra and similar to Abraxane in terms of time to disease progression and also associated with fewer side effects such as neuropathy. However, it is not clear that the optimal dose of Abraxane and schedule of Ixempra was used.
Another study (NSABP B-38) looked at adjuvant chemotherapy for early-stage breast cancer comparing two standard regimens of TAC and AC-T to an experimental regimen:
1. TAC (Taxotere [docetaxel], Adriamycin [doxorubicin] plus Cytoxan [cyclophosphamide] for 6 cycles)
2. AC-T (Adriamycin and Cytoxan for 4 cycles followed by Taxol for 4 cycles every 2 weeks, also known as dose-dense schedule)
3. AC-T with Gemzar (gemcitabine) added during the Taxol phase of therapy (experimental)
No difference was seen between these arms in the relapse rate of about 15 percent at 5 years and death rate of 10 percent. There were more side effects with the addition of Gemzar to AC-T. TAC was associated with more diarrhea and infection while AC-T resulted in more neuropathy and anemia.
These studies together tell us that in advanced breast cancer, good old-fashioned (and much cheaper) Taxol works just as well as the other drugs. For early-stage cancer, the common regimens of dose-dense AC-T or TAC are about equivalent but with different side effect profiles. While not earth-shattering new data, this is very practical information that helps guide us more definitely in chemotherapy treatment options.