Treatment advances for breast and colorectal cancers

The most recent South African National Cancer Registry data from 2012 shows that over 2,900 new metastatic colorectal cancer (mCRC) patients are diagnosed each year, with men slightly more predominant than women.

mCRC now highly treatable

“The treatment of mCRC over the last 15 to 20 years has improved, making it a highly treatable and sometimes even a curable disease,” says Professor Paul Ruff, chief specialist, professor and head of the division of medical oncology at the University of the Witwatersrand Faculty of Health Sciences

Professor Paul Ruff

“In the treatment of mCRC, median survivals have increased from around one year to over three years, with the advent of medicines that inhibit blood vessel growth (angiogenesis) or signal transduction to the colorectal cell nucleus via the epidermal growth factor receptor (EGFR) pathway.” Tumour cells require new blood vessels to proliferate, invade and metastasise, while EGFR signalling enhances tumour cell growth.

Medicines achieving exciting results in mCRC treatment include antiangiogenic agents such as bevacizumab, ramucirumab and aflibercept, anti-EGFR monoclonal antibodies cetuximab and panitumumab in RAS wild type patients, and more recently checkpoint inhibitors such as pembrolizumab in MSI-H tumours.

Ruff has authored a number of peer-reviewed papers on the key mCRC clinical trials, including the Crystal (cetuximab), Prime (panitumumab), Velour (aflibercept) and Aspecct (panitumumab and cetuximab) studies.

In addition, in the treatment of advanced mCRC, Ruff says: “We hope to achieve better biomarker driven patient selection especially for antiangiogenic therapy where there are no biomarkers.”

Improvement in aggressive breast cancer survival

“Between 15 to 20% cases of breast cancer in South Africa as well as worldwide are Her2-positive, an aggressive subtype of breast cancer with a higher risk of recurrence and metastatic spread to sites such as liver, lungs, bone and sometimes brain,” says Dr Georgia Demetriou, senior consultant in the division of medical oncology and head: medical teaching unit 597 at the University of the Witwatersrand Faculty of Health Sciences and Charlotte Maxeke Johannesburg Academic Hospital.

“Over the past 20 years we have come a long way in identifying, blocking and treating this cancer through several key clinical trials.”

The most recent National Cancer Registry data from 2012 shows that over 8,000 women develop breast cancer in South Africa per year.

Dr Georgia Demetriou

Her2 is a protein that can stimulate breast cancer cell growth. The use of targetted ‘blockade’ drug therapy and, more recently, targeted dual drug therapy, known as ‘dual blockade’, has come a long way in identifying and blocking Her2-positive breast cancer.

In the neoadjuvant treatment (chemotherapy and targetted treatment before surgery) Her2 blockade has doubled the rate of pathological complete response rates of patients while adjuvant therapies (chemotherapy and targeted treatment after surgery) for Her2-positive breast cancer have improved disease-free survival by up to 45% and overall survival by 33%. In patients where the cancer has spread, Her2-blockade has resulted in significantly longer median survival rates of up to six years.

“The more recent trials have looked at a dual blockade with two of the key treatment drugs, trastuzumab and pertuzumab, to try and achieve an improved survival rate with the use of both drugs in the adjuvant setting after surgery and chemotherapy,” Demetriou explains. This was discussed at the American Society of Clinical Oncology Conference in Chicago at the beginning of June 2017, although there is concern that the small improvement in survival comes with a prohibitive cost.

Methods of administering trastuzumab have also changed over time from intravenous administration which takes 1 to 1.5 hours, to subcutaneous administration which takes about 15 minutes. Studies have shown both routes to be equally effective.

These exciting advances in both Her-2 positive breast cancer and mCRC treatment represent a significant improvement in patient outcomes, with several global clinical trials, in which the Wits Medical Oncology Division has collaborated at the Charlotte Maxeke Johannesburg Academic Hospital.

Ruff and Demetriou will be presenting the 15th Prestigious Research Lecture of the University of the Witwatersrand Faculty of Health Sciences on 20 June, 2017. The lecture is entitled: Practice changing advances in common cancers.