|  | Cancer | Cancer Treatment

Immunotherapy for Cancer: How It Works, Types & What to Expect

How Immunotherapy Fights Cancer

The immune system naturally detects and eliminates abnormal cells, but cancers develop escape mechanisms. Immunotherapy reverses these evasion strategies through several approaches:

1. Releasing the Brakes: Checkpoint Inhibitors

Tumors express PD-L1 or engage CTLA-4 to suppress T cells. Monoclonal antibodies block these pathways:

  • PD-1 Inhibitors: Pembrolizumab, nivolumab, cemiplimab.
  • PD-L1 Inhibitors: Atezolizumab, durvalumab, avelumab.
  • CTLA-4 Inhibitor: Ipilimumab.
  • Combinations: Nivolumab + ipilimumab (melanoma, RCC, NSCLC); chemo + pembrolizumab (many solid tumors).

2. Engineering Immune Cells: CAR T-Cell Therapy

Patient's T cells are genetically modified to express a chimeric antigen receptor (CAR) targeting a surface protein (CD19, BCMA). After expansion, they are infused back to hunt cancer cells. Approved for relapsed/refractory B-cell lymphomas, ALL, multiple myeloma.

3. Cancer Vaccines

  • Preventive: HPV (Gardasil 9), Hepatitis B—prevent virus-driven cancers.
  • Therapeutic: Sipuleucel-T (prostate cancer)—autologous dendritic cells activated against PAP. Personalized neoantigen vaccines in trials.

4. Oncolytic Virus Therapy

T-VEC (modified herpes virus) injected into melanoma lesions replicates in tumor cells, causing lysis and systemic immune activation.

5. Bispecific Antibodies & Engagers

  • BiTEs (Bispecific T-cell Engagers): Blinatumomab (CD19 x CD3) for ALL.
  • Other Formats: T-cell redirecting antibodies targeting CD3 x tumor antigen (e.g., teclistamab for BCMA in myeloma).

Cancers Treated with Immunotherapy

FDA-approved indications span melanoma, NSCLC, SCLC, RCC, urothelial, HNSCC, Hodgkin lymphoma, MSI-H/dMMR solid tumors, TMB-H tumors, hepatocellular, cervical, endometrial, esophageal, gastric, triple-negative breast cancer, Merkel cell carcinoma, cutaneous squamous cell carcinoma, and hematologic malignancies (lymphomas, myeloma, ALL).

Side Effects: Immune-Related Adverse Events (irAEs)

Can affect any organ. Most common:

  • Skin: rash, pruritus, vitiligo
  • GI: diarrhea, colitis
  • Endocrine: thyroiditis (hypo/hyper), hypophysitis, adrenal insufficiency, type 1 diabetes
  • Hepatic: elevated transaminases
  • Pulmonary: pneumonitis
  • Rare but serious: myocarditis, encephalitis, myasthenia gravis

Management: Graded by CTCAE. Grade 1–2: hold immunotherapy, symptomatic treatment. Grade 3–4: high-dose corticosteroids, infliximab for steroid-refractory colitis, multidisciplinary consults.

Response Patterns

  • Pseudoprogression: Apparent growth on imaging due to immune infiltration before regression (seen in ~5–10%).
  • Durable Responses: Tail of the survival curve; some patients achieve long-term remission off treatment.
  • Hyperprogression: Accelerated growth in a subset; biomarkers under study.

Practical Tips for Patients

  • Ensure biomarker testing (PD-L1, MSI, TMB) is done.
  • Report symptoms early—even mild diarrhea or cough.
  • Inform all providers (ER, dentists, surgeons) you're on immunotherapy.
  • Stay up-to-date on vaccines (inactivated preferred; avoid live vaccines).
  • Consider clinical trials for novel combinations or resistant disease.

Cancer Treatment - Related Articles