“Women with high-grade ovarian cancer live longer and respond better to platinum-based chemotherapy when their tumors have BRCA2 genetic mutations.”
That statement got my attention last night while browsing the cancer news on Twitter! Many thanks to the Provost, Ray DuBois, for sharing it.
Recently, much of the focus has been on finding biomarkers associated with prognosis or response to tyrosine kinase inhibitors and other targeted agents, including PARP in breast and ovarian cancers. It is therefore fascinating that a marker of better prognosis should emerge with chemotherapy.
Given the recent controversy over the whole BRCA1/2 issue and whether there is any clinical significance, with Yang et al., (2011) noting that:
“It has been hypothesized that BRCA-deficient patients will likely have higher survival rates because of an improved response to platinum-based chemotherapy.”
Tan et al., (2008) did indeed observe that epithelial ovarian patients had better response rates than controls if BRCA-ness was present:
“BRCA-positive patients had higher overall (95.5% v 59.1%) and complete response rates (81.8% v 43.2%) to ﬁrst line treatment, higher responses to second and third line platinum-based chemotherapy (second line, 91.7% v 40.9%; third line, 100% v 14.3%).”
These values were all highly significant. The researchers therefore set out to see whether this would result in improved outcomes and:
“Determine the relationships between BRCA1/2 deficiency (ie, mutation and promoter hypermethylation) and overall survival (OS), progression-free survival (PFS), chemotherapy response, and whole-exome mutation rate in ovarian cancer.”
Taking a look at the Kaplan-Meier overall survival curves in Yang et al’s (2011) JAMA article (link below), the women who had either the BRCA1 or BRCA2 mutation clearly did better than those who were BRCA wild-type (WT) ie no mutation was present. This is a very important finding and it certainly does help to explain why mixing a heterogeneous population in a clinical trial is never a good idea. Imagine if the BRCA mutation status of the women is unknown – you could end up with unbalanced groups that can affect your outcomes based on the therapies randomised. By this, I mean a control group with chemotherapy alone could theoretically do better than one with a targeted therapy included if the groups were unbalanced for BRCA status.
Now, the current data are limited to high-grade serous ovarian cancer cases, but it would obviously be most interesting to see if a similar (or different) pattern might emerge in BRCA2 breast cancer. Obviously I’m thinking of the recent failed iniparib phase III trial here, as I never understood why BRCA status wasn’t tested and taken into account when balancing the baseline characteristics. We don’t know whether the results reported in ovarian cancer would also be seen in breast cancer, but it would be a critical question to address.
Significance of the results
Ultimately, these kind of findings can help us define and refine specific subsets of women with ovarian cancer who might respond better to certain types of therapies than others. This kind of information is crucial in helping to improve clinical trial design.
What I would really love to see is more logical combinations of targeted therapies or chemotherapy given to patients who have the best chance of responding rather than randomly expose people willy nilly to systemic agents where there is no idea or clue about how they might work. Patients deserve much better than this!
Tak Mak (U Toronto) summed this up beautifully at the recent ECCO meeting, with a most apt quote we could all do well to learn from:
“Doctors pour drugs of which they know little,
to cure diseases of which they know less,
into patients of which they know nothing.”
It is research such as Yang et al., (2011) that may actually help avoid this sorry state and begin to improve the outcomes associated with cancer therapy in the 21st century.
Yang, D., Khan, S., Sun, Y., Hess, K., Shmulevich, I., Sood, A., & Zhang, W. (2011). Association of BRCA1 and BRCA2 Mutations With Survival, Chemotherapy Sensitivity, and Gene Mutator Phenotype in Patients With Ovarian Cancer JAMA: The Journal of the American Medical Association, 306 (14), 1557-1565 DOI: 10.1001/jama.2011.1456
Tan DS, Rothermundt C, Thomas K, Bancroft E, Eeles R, Shanley S, Ardern-Jones A, Norman A, Kaye SB, & Gore ME (2008). “BRCAness” syndrome in ovarian cancer: a case-control study describing the clinical features and outcome of patients with epithelial ovarian cancer associated with BRCA1 and BRCA2 mutations. Journal of clinical oncology : official journal of the American Society of Clinical Oncology, 26 (34), 5530-6 PMID: 18955455