New breast cancer therapy can slow advance of disease, prolong survival

A new triple therapy for aggressive, advanced breast cancer slows the progression of the disease, delays the need for further chemotherapy and helps patients live longer, research revealed.

The combination treatment is made up of two targeted drugs: inavolisib and palbociclib, and the hormone therapy fulvestrant. It improved overall survival by an average of seven months, compared with the patients in the control group, who were given palbociclib and fulvestrant.

It also delayed progression of the disease by 17.2 months, on average, compared with 7.3 months in the control group, and patients taking inavolisib were able to delay subsequent chemotherapy treatment by almost two years longer than the patients in the control group.

The results of the study, funded by Roche, were presented at the American Society of Clinical Oncology (Asco) annual meeting in Chicago and published in the New England Journal of Medicine.

The international trial involved 325 patients from 28 countries, including the US, UK, Australia, Singapore, Brazil, France and Germany.

Experts said it demonstrated the potential of the triple therapy for targeting PIK3CA-mutated HR+, HER2- breast cancer - a common form of the disease.

About 70 percent of patients have HR+, HER2- breast cancer. PIK3CA mutations are found in 35 to 40 percent of HR+ breast cancers, and are linked to tumour growth, disease progression and treatment resistance.

"The INAVO120 trial has identified a targeted treatment regimen that meaningfully improves survival in patients with untreated PIK3CA-mutated hormone receptor-positive metastatic breast cancer - a big step forward for these patients,” said Dr Jane Lowe Meisel, Co-Director of Breast Medical Oncology at Winship Cancer Institute of Emory University, and an Asco expert in breast cancer.

The results also showed a substantial shrinking in cancer growth in about 62.7 percent of patients in the triple therapy group compared with 28 percent in the control group. Dr. Simon Vincent, Director of Research, support and influencing at Breast Cancer Now, said the findings were a "significant breakthrough”.

Dr. Nisharnthi Duggan, a research information manager at Cancer Research UK, said, "The trial showed that adding inavolisib to targeted treatment plans improved survival. On top of this, it also delayed the progression of people’s cancer and the need for chemotherapy, which could improve quality of life. We hope that more research like this will help to give people kinder cancer treatment options, and more time with their loved ones.”

In the trial, more than half of the patients had disease that had already spread to three or more organs. The researchers used circulating tumour DNA (ctDNA) liquid biopsy blood tests to determine whether patients had a PIK3CA mutation. Participants were then allocated to receive either the inavolisib-based regimen or a combination of palbociclib, fulvestrant and a dummy pill.

The new drug inavolisib works by blocking the activity of the PIK3CA protein. The inavolisib combination was generally well tolerated with only a few patients experiencing side-effects that led them to discontinue the treatment.

Nick Turner, Professor of Molecular Oncology at the Institute of Cancer Research, London, and consultant medical oncologist at the Royal Marsden NHS Foundation Trust, led a UK arm of the trial.

"The key findings from this study showed that the inavolisib-based therapy not only helped patients live longer but it more than doubled the time before their cancer progressed or worsened. It also gave them more time before needing subsequent chemotherapy which we know is something that patients really fear and want to delay for as long as possible," he stated.

WAM