Two targeted drugs could change the way advanced kidney cancer is treated and offer new hope to thousands of UK patients.
One, nivolumab, stops tumours disarming the immune system and has already proved effective against melanoma skin cancer and lung cancer.
The other, cabozantinib, blocks enzymes that act as "on, off" switches in many cellular processes including those driving tumour growth.
Each year more than 10,000 people in the UK are diagnosed with kidney cancer, and 4,300 die from the disease.
Incidence of the disease has more than doubled since the mid-1970s. Because kidney cancer produces few early symptoms, it is often not diagnosed until at an advanced and dangerous stage.
The Phase III trial findings, presented at the European Cancer Congress meeting in Vienna, mean the drugs could be licensed for treating kidney cancer in Europe as early as next year.
Nivolumab is one of a new generation of antibody drugs that block "checkpoint" proteins used by many cancers to shield themselves from the immune system. In this case, the target molecule is a protein called PD-1 (programmed cell death-1).
US Professor Padmanee Sharma, from the MD Anderson Cancer Centre at the University of Texas - who led the CheckMate 025 nivolumab trial, said: "It is exciting to see the outcome of this study, as the results are significant and clinically meaningful to patients and healthcare professionals alike. They are likely to change the treatment of patients with advanced kidney cancer, whose disease has progressed on prior treatment.
"We hope that this study will quickly lead to approval of nivolumab as a standard of care therapy for these patients."
The trial, which involved 821 patients, compared the effectiveness of nivolumab with that of the standard therapy, everolimus.
Those patients given infusions of nivolumab typically survived 25 months, 5.4 months longer than those on everolimus, and some showed a significantly better response.
One trial patient, nurse and grandmother Patricia Rapp, 66, from Epsom in Surrey - whose cancer had spread to her liver and continued to grow despite chemotherapy, said: "Over the last 15 months my CT scans haven't been able to detect anything on my liver - it's like a miracle.
"I have been extremely lucky."
Dr James Larkin, from London's Royal Marsden Hospital - who treated Ms Rapp, said: "These nivolumab data are compelling and mark the first time that an immunotherapy treatment of this type has demonstrated a significant improvement in kidney cancer survival.
"Once this disease has spread, the outlook for patients can be very poor. Newer and more effective, tolerable treatments are therefore sorely needed to address these unmet medical needs."
The trial, also reported in the New England Journal of Medicine, was stopped early in July 2015 when the survival benefit for patients treated with nivolumab became clear.
The other study, called Meteor, compared the effectiveness of cabozantinib with everolimus in an initial group of 375 patients.
Typical progression-free survival time for patients on cabozantinib was 7.4 months versus 3.8 months for those on the standard treatment.
Meteor leader Professor Toni Choueiri, from the Dana Farber Cancer Institute in the US, said: "I am very excited about the outcome of this study since the results may change the standard of care in patients with advanced kidney cancer .."
James Whale, from the James Whale Fund for Kidney Cancer, said: "Thousands of patients each year in the UK are diagnosed with advanced kidney cancer and new medical treatments that can help improve survival are urgently needed. Today's news is therefore very encouraging and will hopefully open the door to more options for patients in the future."
The cost of the drugs is likely to be a significant factor affecting their accessibility in the UK.
As a treatment for melanoma, nivolumab costs around £5,500 per patient per month.