PACIFIC: What the Lung Cancer Trial Found

A new step between treatment and follow-up

Stage III lung cancer that cannot be removed by surgery is treated with chemotherapy and radiation given together. When that finishes, the standard was to stop and watch. Most people's cancer came back.

PACIFIC put something into that gap: up to a year of durvalumab, an immune drug, starting within six weeks of finishing chemoradiation. Nothing had occupied that slot before.

Who could enter, and when

Field	Detail
Trial	PACIFIC
Identifier	NCT02125461
Phase	Phase 3
Design	Randomised 2:1, double-blind, placebo-controlled
Cancer type	Stage III non-small-cell lung cancer that could not be removed surgically
Comparator	Durvalumab by infusion every two weeks for up to 12 months, against placebo
Primary endpoints	Progression-free survival and overall survival

713 people were randomised and 709 received treatment: 473 durvalumab and 236 placebo. To be eligible, they had to have completed at least two cycles of platinum-based chemotherapy given with radiation, and their cancer had to have not progressed on it.

Treatment started between 1 and 42 days after chemoradiation ended. Randomisation was stratified by age, sex and smoking history.

Eleven extra months before the cancer grew

Median progression-free survival was 16.8 months with durvalumab (95% CI 13.0 to 18.1) and 5.6 months with placebo (95% CI 4.6 to 7.8). The hazard ratio was 0.52 (95% CI 0.42 to 0.65, p<0.001).

At 12 months, 55.9% of the durvalumab group were progression-free against 35.3%. At 18 months, 44.2% against 27.0%. Tumours shrank in 28.4% against 16.0% (p<0.001), and at 18 months 72.8% of durvalumab responses were still going, against 46.8%.

Median time to death or spread to a distant site was 23.2 months against 14.6 months (p<0.001).

The survival report that followed a year later

The second report, at a median follow-up of 25.2 months, covered the trial's other primary endpoint.

Two-year survival was 66.3% with durvalumab (95% CI 61.7 to 70.4) and 55.6% with placebo (95% CI 48.9 to 61.8). The hazard ratio for death was 0.68 (99.73% CI 0.47 to 0.997, p=0.0025).

Updated progression-free survival was 17.2 months against 5.6 months, hazard ratio 0.51 (95% CI 0.41 to 0.63). Median time to death or distant metastasis was 28.3 against 16.2 months, hazard ratio 0.53 (95% CI 0.41 to 0.68).

Radiation, then immunotherapy: the lung question

Giving an immune drug to lungs that have just been irradiated raises an obvious worry about inflammation.

The reported figures were reassuring at the group level. Severe side effects — grade 3 or 4 — occurred in 29.9% of the durvalumab group and 26.1% on placebo, and the commonest severe event was pneumonia, in 4.4% against 3.8%. In the later report, grade 3 or 4 events from any cause were 30.5% against 26.1%.

The clearer signal is in who stopped. 15.4% of the durvalumab group discontinued because of side effects, against 9.8% on placebo. Roughly one in six could not finish the year.

What to keep in perspective

• This applies only to people who got through chemoradiation without their cancer progressing. Everyone else was ineligible by design.
• The reports listed here do not break the result down by PD-L1 level, so they cannot answer whether PD-L1-negative tumours benefit.
• Twelve months was the protocol's cap, not a duration tested against a shorter or longer course.
• Two years of follow-up in a potentially curable setting is early. Cure is judged over much longer.

Questions after chemoradiation for stage III lung cancer

• Did my cancer progress during chemoradiation, and how was that assessed?
• How soon after finishing radiation would this start?
• What breathing symptoms should make me call you rather than wait?

Sources

This article was written from the sources below, which were checked on the source-check date shown above.

• NEJM: Durvalumab after Chemoradiotherapy in Stage III NSCLC (PACIFIC) (primary)
• NEJM: Overall Survival with Durvalumab after Chemoradiotherapy in Stage III NSCLC (primary)

How this article was prepared

Prepared by Cancer Explained's AI-assisted editorial system and checked against the sources listed below. This article has not been reviewed by a healthcare professional unless a named reviewer is specifically shown.

Cancer Explained is published by the National Cancer Information Foundation as a nonprofit-oriented public-interest education project. It is not a diagnostic service, does not recommend treatments, and is not for emergencies.

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