There was wide-eyed excitement when the drug considered the greatest cancer breakthrough since chemotherapy gained the Government's approval in September for treating inoperable melanoma.
But that was only approval to market Keytruda in New Zealand; it wasn't funding approval.
The focus is now on Pharmac and politicians as doctors, families and patients with melanoma ponder if it is time for another Herceptin-style campaign with petitions, funeral-march protests and highly organised lobbying.
New Zealand and Australia have the world's highest rates of melanoma, the deadliest form of skin cancer, but New Zealand has poor access to the latest drugs.
Keytruda (also called pembrolizumab) has snatched attention as a reasonably and in some cases remarkably effective therapy for advanced, inoperable melanoma which has spread around the body, a disease for which the only state-funded chemotherapy is widely considered futile in most patients.
But Keytruda is painfully expensive. Even with a discount from the supplier, Merck, Sharp & Dohme, patients estimate they could be paying $300,000 for two years' treatment including GST and clinic costs.
• Cancer: Are poor being sent home to die?
• Victims, experts lobby for 'breakthrough' drug
• Craig's story: The exorbitant price of staying alive
• Bob's story: Drug lets grandpa tick off bucket list
• Leisa's story: System sends have-nots home to die
• Melanoma New Zealand: Access to effective therapies vital
It is the first of a new class of immunotherapy drugs, called PD-1 inhibitors, to be registered in New Zealand. They block the PD-1 receptor protein on certain immune system cells, which allows them to detect and destroy the cancer cells.
Keytruda and Opdivo, another PD-1 inhibitor, gained "breakthrough therapy" status by the United States Food and Drug Administration last year.
Melanoma of the skin is readily treated by surgery if it is caught early and more than 90 per cent of these patients will be alive five years later. But when the disease is already metastatic - it has spread to organs - at diagnosis, the median survival is about nine months. Only 15 per cent of patients survive three years.
Trials have found that when Keytruda was the first drug used by patients for metastatic melanoma, as many as 60 per cent were alive at two years.
Auckland cancer specialists Mike McCrystal and Richard Sullivan believe the new immune therapies are the most important advance in cancer care since chemotherapies were first used.
"Keytruda is a very, very good drug," says Dr McCrystal.
"It's something we've been trying to do for 30 or 40 years, recruit the immune system reliably to fight a disease like melanoma. It's not entirely a magic bullet. There's still a lot of work to be done because a lot of people don't respond to these drugs.
"But Keytruda is an incredibly expensive drug. The amounts being charged are impossible to sustain from a health system point of view.
"I think even insurance-based systems like the US are starting to baulk."
He is appealing to drug companies to lower their prices.
"We can't expect funding bodies like Pharmac, which are trying to fund the whole health system, to pay that amount of money for a drug that's controlling disease rather than curing it."
And without Pharmac funding - or delayed funding - many New Zealanders end up paying themselves.
"We are going to end up with a multi-tiered health system with people that can afford it getting all the very best drugs, with others with shades in between. It's not the sort of picture I think anyone wants.
"It's very difficult. You're talking about people selling their houses, mortgaging their houses, raising money amongst family and friends or lifetime savings going towards a drug that may or may not work."
A glimmer of hope emerged from England last month when a government agency ruled in favour of Keytruda's cost-effectiveness, meaning the drug will be available on the National Health Service.
Merck, Sharp & Dohme is giving the NHS an undisclosed discount, which is likely to influence the price it will seek in other countries.
But NHS England patients must first have been treated with - and ultimately become resistant to - one or more other expensive drugs.
None of the new, advanced melanoma drugs is funded by Pharmac. In rejecting one of these - dabrafenib, which can delay melanoma progression longer than chemotherapy in patients with a particular gene mutation - a Pharmac committee noted the "high unmet medical need for new effective treatments for patients with metastatic malignant melanoma".
It asked Pharmac to run a sort of auction among drug firms - a tactic to depress the price enough for it to fund one of dabrafenib, vemurafenib or ipilimumab.
But that was before Keytruda's registration by Medsafe in September.
"If we had to pick one drug to be funded," says Dr McCrystal, "I would say pembrolizumab [Keytruda]. It has a good response rate, it's well tolerated and it has a chance of working across the board, BRAF [gene mutation] positive or negative."
Pharmac says it hasn't decided what to do about its committee's triple-drug recommendation, but says Keytruda and another melanoma drug, trametinib, "are currently under assessment and we await the advice from our clinical committees before deciding any future actions".
A key committee considered Keytruda last week, but Pharmac is not yet releasing its decision.
Merck New Zealand's director, Paul Smith, says he does not know the details of the discount his company is giving to the NHS, but it will not be inconsistent with the one he has offered to Pharmac.
He won't reveal the size of the discount, but has indicated he is willing to haggle for a package deal with Pharmac that could involve other Merck drugs. He is "pretty confident" the agency will be able to fund Keytruda from February.
Why is the drug so expensive? Mr Smith says the price is "consistent with other cancer therapies across the globe".
It reflects the cost of manufacturing, it's a biological product and therefore not cheap to make; its benefits in lives saved or improved; and the enormous amount of research and development, he said.
"Merck currently is investing billions of dollars globally. We have got over 200 clinical trials around the world in this one drug. That costs us billions of dollars a year. We lost billions last year [on Keytruda], we will lose billions this year. Maybe next year we will break even and then start to get into recovery of that situation."
In February, the company reported one-year worldwide sales of $42.2 billion, down 4 per cent on 2013.
Campaigning melanoma patient Katrina Govorko says it is time to get vocal about Keytruda. She has started an online petition, "Fund Keytruda for cancer patients", which has the support of more than 2000 people.
"I'm too young to die," says the 49-year-old from Wellington, who has a daughter aged 13 and runs an early childhood centre.
An "itchy and bleeding" melanoma was cut from her back last year and she had 24 lymph nodes removed from her neck. Fair-skinned, she suspects the disease is linked to annual bouts of peeling sunburn when she was young.
Tumours recurred around her neck. She had radiotherapy and last month was one of the last patients to get on to a compassionate programme providing new drugs dabrafenib and trametinib. These appear to be helping and she expects they will work for six to 12 months, after which Keytruda may be an option, but she can't afford to pay for it.
Melanoma NZ chief executive Linda Flay says the group has lobbied Pharmac to fund the drug because it is a "game-changer" and the chemo for advanced melanoma is "pretty futile", but Pharmac's response only said Keytruda was one of the drugs it had to consider.
"A lot of [patients] have been trying to advocate for themselves ... by writing to MPs and Pharmac on their views on why this drug should be funded. The fact it's been Medsafe approved is one step further and it gives them hope."
Dr McCrystal says melanoma patients, doctors and advocates are talking about "how to take things forward". "If we leave it to the mechanics of Pharmac, it's going to be a similar situation to ... Herceptin. It's just going to go on and on and on."
Direct political intervention is what Herceptin got in 2008. The opposition National Party linked itself to the high-profile campaign for public funding of 12 months' Herceptin for early breast cancer, when Pharmac would pay for only nine weeks of it.
Then-National MP Dr Jackie Blue, now the Equal Employment Opportunities Commissioner, was one of the "pallbearers" who carried a pink protest coffin across Aotea Square. Among its early acts after winning the 2008 election, the National Government fulfilled its promise and made the 12-month course available.
At the preventative end of the melanoma problem, several efforts are being made to reduce New Zealanders' over-exposure to ultraviolet light, a risk factor for skin cancers.
"We are focusing on agriculture at the moment through Fonterra, Federated Farmers and rural community groups," says Ms Flay.
"The message is sun-smart behaviour for people working outdoors - people checking their skin monthly looking for signs of change, seeing a health practitioner if they are concerned and catching any skin cancers, particularly melanomas, early."
Surveys of Kiwis' sun-smart behaviour remain a cause for concern: year after year more than 20 per cent of adults have had a dose of sunburn, little more than half use sunscreen and just 9 per cent wear long sleeves in the summer sun.
Commercial tanning beds are unresolved business for health groups.
The International Agency for Research on Cancer in 2009 named sunbeds as "carcinogenic to humans" and said studies showed the risk of skin melanoma increased by 75 per cent when use of UV tanning devices began before the age of 30.
"We are waiting for the legislation to come out for the banning of sunbeds for people under 18," says Ms Flay. "Our organisation would like to see a complete ban [for all ages]."
The call for a complete ban is shared by the Cancer Society - and by Consumer NZ, whose latest survey of operators found nearly half were flouting voluntary standards.
Auckland Council and several other local bodies have banned use of commercial sunbeds by people under 18.
Government legislation to introduce a national under-18 ban is in the House awaiting its final reading.