Maintenance Immunotherapy After Lung Cancer Treatment

In lung cancer, maintenance means one drug carries on after the intensive part of treatment ends. The heavy combination stops. One agent keeps going. It runs until the cancer grows, or until side effects become too much.

Immunotherapy here means a checkpoint inhibitor. These are antibodies that take a brake off your T cells. The T cells can then attack tumor cells. The brakes they target are called PD-1, PD-L1, and CTLA-4.

Three lung cancer settings use maintenance immunotherapy. They are not the same. Knowing which one you are in tells you the drug, the schedule, and how long it runs.

This is the clearest use. Say you had stage III non-small cell lung cancer that could not be removed by surgery. You finished chemo and radiation given together. Durvalumab (Imfinzi) may then follow.

The evidence comes from the PACIFIC trial. It compared durvalumab against placebo after chemoradiation. Median progression-free survival was 16.8 months with durvalumab and 5.6 months with placebo. The hazard ratio was 0.52. For overall survival, the durvalumab group had not reached the median at the time of analysis. The placebo group was at 28.7 months. The hazard ratio was 0.68.

The label sets two options for stage III NSCLC after chemoradiation. For adults there is a choice between an infusion every 2 weeks and a flat dose every 4 weeks. For anyone under 30 kg only the two-weekly, weight-based option is used. It runs until the cancer grows, until side effects force a stop, or for a maximum of 12 months.

That 12-month cap is worth noting. This is not open-ended treatment.

PACIFIC required people to start the study drug within 42 days of finishing chemoradiation. It also excluded some groups. People whose cancer had grown during chemoradiation were out. So were people with active or past autoimmune disease in the previous 2 years, and people needing drugs that damp down the immune system.

So if durvalumab is the plan, three things must happen inside about six weeks. The referral, the restaging scan, and the first infusion. Ask in your last week of radiation who is booking each one, and what date they are aiming for. Delay here is a common practical failure in stage III care.

One common first-line plan in metastatic nonsquamous NSCLC uses three drugs. They are pembrolizumab (Keytruda), pemetrexed, and either carboplatin or cisplatin. They run every 3 weeks for 4 cycles. Then the platinum stops. Pemetrexed and pembrolizumab go on as maintenance until the cancer grows or side effects force a stop.

A second option starts with durvalumab, tremelimumab-actl, and platinum chemo for 4 cycles. After that comes durvalumab every 4 weeks with pemetrexed maintenance, plus one further tremelimumab dose.

Sort out two things before the platinum ends. First, which drugs continue and how often, since the visit rhythm may shift from every 3 weeks to every 4. Second, whether pemetrexed goes on alongside the immune drug. That changes the blood tests and the folic acid and B12 schedule.

Durvalumab also has a role after chemoradiation for limited-stage small cell lung cancer. The trial was ADRIATIC. It is given every 4 weeks either way, as a flat dose for people 30 kg and over and as a weight-based one below that.

Chemo side effects mostly follow a predictable curve after each dose. Immune side effects do not. They can start at any point, even months after the last infusion. They happen because the immune system attacks normal tissue.

Pneumonitis is inflammation of the lung tissue. It matters most here, because the lung has already had radiation. In PACIFIC, pneumonitis of any kind hit 18.3 percent of people on durvalumab and 12.8 percent on placebo. Of the 87 affected, 64 needed steroids by mouth or vein. It forced a permanent stop in 31 percent of those affected. Across the whole durvalumab group, 1.1 percent had a fatal adverse reaction. In ADRIATIC the rate was 14 percent versus 6 percent.

Thyroid problems are common and usually manageable. Immune-mediated hypothyroidism hit 8.3 percent of people on durvalumab alone. It did not cause anyone to stop the drug for good. An underactive thyroid often follows a spell of an overactive one. So a thyroid blood panel gets checked at intervals.

Colitis, inflammation of the colon, occurred in about 2 percent on durvalumab alone and usually shows up as diarrhea.

Hepatitis, adrenal problems, and skin reactions also occur. Steroids are the standard treatment for moderate or severe immune reactions. That is why your team wants to hear about symptoms early, before the steroid dose needed climbs.

• Call 911 or go to an emergency department if you cannot catch your breath at rest, your chest hurts, or a home oxygen reading falls below your usual number.
• Call your care team the same day if a dry cough or breathlessness is new or worse. After chest radiation, do not assume it is just the radiation settling.
• Call your care team the same day if you pass four or more loose stools above your normal in a day, or see any blood in stool.
• Call your care team the same day if your eyes or skin turn yellow, your urine goes dark, your temperature reaches 100.4 F (38 C) or higher, a severe new headache or a vision change starts, or deep fatigue comes with dizziness on standing. That last one can point to the adrenal glands.
• One exception on fever. If pemetrexed is still running alongside your immune drug, or you finished chemo or chemoradiation in the past few weeks, 100.4 F is not a same-day matter. Your neutrophil count may be low, and CDC counts a fever during chemotherapy as a medical emergency. Go to an emergency department. On a checkpoint inhibitor by itself, the same-day route above is right.

Tell whoever sees you that you are on a checkpoint inhibitor. Give the drug name. An urgent care doctor treating you for bronchitis needs to know that pneumonitis is on the list.

Immunotherapy, Chemotherapy, Radiation Therapy, and Fever During Chemo.

• https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=8baba4ea-2855-42fa-9bd9-5a7548d4cec3
• https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=ae77f00f-d43b-4b75-afd5-a2a9cb7138da
• https://www.cancer.gov/types/lung/hp/non-small-cell-lung-treatment-pdq