Chapter 27 — Gastrointestinal Pharmacology — Module 4 — Inflammatory Bowel Disease Pharmacology, Part 2: Biologics and Small Molecules (Tier 3: Clinical Vignette)
1. A 34-year-old woman with Crohn's disease has been maintained on infliximab for 16 months. Over the past 3 months her symptoms have returned, with rising fecal calprotectin and C-reactive protein. Therapeutic drug monitoring (TDM) shows a low trough infliximab concentration with high titers of anti-drug antibodies (ADA). Which interpretation and next step are most appropriate?
A) Pharmacokinetic failure; increase the infliximab dose and shorten the dosing interval
B) Pharmacodynamic failure; continue infliximab at the current dose and add a corticosteroid taper only
C) Immunogenic failure; switch to a different anti-TNF agent or to a biologic of a different class
D) Primary non-response; discontinue all advanced therapy and observe
E) Laboratory artifact; repeat the panel in 6 months and make no change now
ANSWER: C
Rationale:
A low trough concentration with high anti-drug antibody titers defines immunogenic failure: the patient has mounted an antibody response that clears the drug, so dose escalation is unreliable and the appropriate step is to switch to a different anti-TNF agent or to a biologic of a different class.
Option A: Option A misidentifies the pattern as pharmacokinetic failure, which requires low or absent antibodies rather than the high titers seen here.
Option B: Option B misidentifies the pattern as pharmacodynamic failure and inappropriately continues an agent that is being neutralized.
Option D: Option D misidentifies secondary loss of response as primary non-response and inappropriately abandons therapy.
Option E: Option E incorrectly dismisses an informative result that clearly indicates immunogenic failure.
2. A 41-year-old man with Crohn's disease maintained on infliximab develops recurrent symptoms. Therapeutic drug monitoring (TDM) shows a low trough infliximab concentration with low (essentially absent) anti-drug antibodies (ADA). Which interpretation and next step are most appropriate?
A) Pharmacokinetic failure (drug clearance); increase the dose or shorten the dosing interval to restore a therapeutic trough
B) Immunogenic failure; switch immediately to a biologic of a different class
C) Pharmacodynamic failure; switch class because the trough is adequate
D) Primary non-response; stop the biologic and use corticosteroids indefinitely
E) Adequate therapy; no change is warranted despite symptoms
ANSWER: A
Rationale:
A low trough with low or absent anti-drug antibodies indicates pharmacokinetic failure, also called drug clearance; because there is no significant immunogenicity, the appropriate response is to increase the dose or shorten the dosing interval to restore a therapeutic trough.
Option B: Option B misidentifies the pattern as immunogenic failure, which requires high anti-drug antibodies that are absent here.
Option C: Option C misidentifies the trough as adequate, when the low trough is exactly the abnormality to correct.
Option D: Option D misidentifies secondary loss of response as primary non-response and inappropriately abandons biologic therapy.
Option E: Option E incorrectly calls the therapy adequate despite a subtherapeutic trough and active symptoms.
3. A 29-year-old woman with ulcerative colitis on maintenance adalimumab loses clinical response after a year of remission. Therapeutic drug monitoring (TDM) shows an adequate trough adalimumab concentration with no significant anti-drug antibodies (ADA). Which interpretation and next step are most appropriate?
A) Pharmacokinetic failure; shorten the dosing interval to raise the trough
B) Immunogenic failure; add an immunomodulator to suppress antibodies
C) Subtherapeutic dosing; double the adalimumab dose
D) Pharmacodynamic failure (a shift away from a TNF-driven mechanism); switch to a biologic of a different class rather than escalating
E) Primary non-response; discontinue all therapy
ANSWER: D
Rationale:
An adequate trough with loss of response and no significant anti-drug antibodies defines pharmacodynamic failure, indicating that inflammation is no longer driven by the targeted pathway; the correct step is to switch to a biologic of a different class, because more of the same drug cannot overcome a mechanism the target no longer drives.
Option A: Option A misidentifies the pattern as pharmacokinetic failure, which requires a low trough rather than the adequate trough described.
Option B: Option B misidentifies the pattern as immunogenic failure, which requires high anti-drug antibodies that are absent here.
Option C: Option C incorrectly escalates a drug that already has an adequate level, which will not overcome a mechanism shift.
Option E: Option E misidentifies secondary loss of response as primary non-response and inappropriately abandons therapy.
4. A 72-year-old woman with moderate to severe ulcerative colitis has a history of recurrent pneumonia and a prior episode of sepsis. She now requires advanced therapy. Which biologic is best supported as the preferred choice given her infection risk?
A) Infliximab, because intravenous dosing ensures the most reliable response in elderly patients
B) Vedolizumab, because its gut-selective alpha-4-beta-7 blockade preserves systemic immune surveillance and carries a favorable systemic infection profile, making it preferred in elderly or high-infection-risk patients
C) Tofacitinib, because its oral route removes infection risk in older patients
D) Combination anti-TNF plus azathioprine, to maximize remission rates
E) Adalimumab, because subcutaneous dosing avoids systemic infection risk
ANSWER: B
Rationale:
Vedolizumab's gut-selective alpha-4-beta-7 blockade compartmentalizes immunosuppression to the intestine and preserves systemic immune surveillance, giving it a favorable systemic infection profile and making it the preferred biologic in elderly or high-infection-risk patients.
Option A: Option A incorrectly implies the intravenous route mitigates the systemic infection risk inherent to anti-TNF therapy.
Option C: Option C incorrectly claims the oral route removes infection risk, when JAK inhibitors carry a black box warning that includes serious infections.
Option D: Option D incorrectly recommends maximizing immunosuppression and therefore infection risk, the opposite of what this patient needs.
Option E: Option E incorrectly attributes reduced systemic infection risk to the subcutaneous route, which does not change the systemic effect of TNF neutralization.
5. A 31-year-old pregnant woman with Crohn's disease is now in her third trimester. Her disease requires continued anti-TNF therapy through delivery. Which agent is preferred, and on what structural basis?
A) Infliximab, because the infusion can be timed near delivery to limit fetal exposure
B) Adalimumab, because its fully human structure prevents placental transfer
C) Golimumab, because monthly dosing reduces cumulative transfer
D) Any anti-TNF agent equally, because none crosses the placenta in the third trimester
E) Certolizumab pegol, because it is a Fab' fragment lacking the fragment crystallizable (Fc) region and therefore is not transported across the placenta by the neonatal Fc receptor
ANSWER: E
Rationale:
Certolizumab pegol lacks the Fc region required for neonatal Fc receptor–mediated placental transfer, so minimal drug reaches the fetus, making it the preferred anti-TNF agent when therapy must continue into the third trimester.
Option A: Option A incorrectly suggests infusion timing prevents transfer, when infliximab is a full IgG1 antibody that crosses the placenta in the third trimester.
Option B: Option B incorrectly claims a fully human structure prevents transfer, when adalimumab is a complete IgG1 antibody that does transfer.
Option C: Option C incorrectly attributes reduced transfer to golimumab's dosing interval, when it is also a full IgG1 antibody.
Option D: Option D incorrectly treats the anti-TNF agents as equivalent, when the full IgG1 antibodies cross the placenta but certolizumab essentially does not.
6. A 45-year-old man with Crohn's disease is being prepared to start infliximab. Pre-biologic screening shows a positive interferon-gamma release assay (IGRA) with a normal chest X-ray and no symptoms, consistent with latent tuberculosis. What is the most appropriate management?
A) Start infliximab now and begin tuberculosis treatment only if active disease develops
B) Permanently avoid all anti-TNF therapy because latent tuberculosis is an absolute lifelong contraindication
C) Treat the latent tuberculosis with isoniazid for at least 4 weeks before initiating infliximab
D) Give a single dose of the BCG vaccine and start infliximab the same day
E) Switch to a Janus kinase (JAK) inhibitor, which requires no tuberculosis evaluation
ANSWER: C
Rationale:
Because TNF-alpha maintains granuloma integrity, latent tuberculosis must be treated before anti-TNF therapy; isoniazid should be started for at least 4 weeks before initiating infliximab to reduce the risk of reactivation.
Option A: Option A incorrectly starts the biologic before treating latent infection, which risks reactivation precisely when granuloma integrity is compromised.
Option B: Option B overstates latent tuberculosis as an absolute lifelong contraindication, when it can be treated and anti-TNF therapy then started.
Option D: Option D incorrectly recommends BCG, a live vaccine that is contraindicated in this setting and does not treat latent infection.
Option E: Option E incorrectly implies a JAK inhibitor needs no tuberculosis evaluation, when immunosuppressants generally require screening and JAK inhibitors carry their own serious-infection warning.
7. A 62-year-old man with ulcerative colitis, hypertension, and a prior myocardial infarction has had an inadequate response to a TNF inhibitor. He strongly prefers an oral agent. What is the most appropriate approach to a Janus kinase (JAK) inhibitor in this patient?
A) Start a JAK inhibitor immediately as the most convenient first-line option
B) A JAK inhibitor is a candidate given prior TNF inhibitor failure, but because he is aged 50 or older with cardiovascular risk factors and prior myocardial infarction he is in the highest-risk group of the black box warning, so the decision requires careful risk-benefit assessment and explicit counseling about cardiovascular, thromboembolic, and malignancy risk
C) A JAK inhibitor is absolutely contraindicated for life in anyone with prior myocardial infarction
D) Combine a JAK inhibitor with the prior anti-TNF agent to offset cardiovascular risk
E) A JAK inhibitor is uniformly safer than biologics and needs no cardiovascular assessment
ANSWER: B
Rationale:
Prior TNF inhibitor failure makes a JAK inhibitor a legitimate candidate, but because this patient is aged 50 or older with cardiovascular risk factors and a prior myocardial infarction he falls into the highest-risk group identified by the black box warning, so the decision requires careful risk-benefit assessment and explicit counseling about cardiovascular, thromboembolic, and malignancy risk.
Option A: Option A incorrectly recommends immediate first-line use, contradicting the directive to reserve JAK inhibitors for after TNF inhibitor failure and ignoring his elevated risk.
Option C: Option C overstates the warning as an absolute lifelong contraindication, which it is not.
Option D: Option D incorrectly recommends combining a JAK inhibitor with an anti-TNF agent, which compounds immunosuppression without offsetting cardiovascular risk.
Option E: Option E incorrectly claims uniform safety and waives the cardiovascular assessment the warning requires.
8. A 23-year-old man with Crohn's disease has been in deep clinical and endoscopic remission for 2 years on combination infliximab plus a thiopurine. He has tolerated therapy well. Which adjustment best balances continued disease control against his malignancy risk?
A) Consider withdrawing the thiopurine while continuing infliximab, because a young male on prolonged combination anti-TNF plus thiopurine therapy carries an elevated risk of hepatosplenic T-cell lymphoma, and deep remission supports de-escalation of the immunomodulator
B) Stop infliximab and continue thiopurine monotherapy as the safer maintenance option
C) Add a second biologic to deepen remission further
D) Switch to a Janus kinase (JAK) inhibitor plus thiopurine to preserve combination benefit
E) Continue indefinite combination therapy without reassessment because the benefit always outweighs the risk
ANSWER: A
Rationale:
A young male on prolonged combination anti-TNF plus thiopurine therapy carries an elevated risk of hepatosplenic T-cell lymphoma, so after a sustained deep remission many clinicians and guidelines support withdrawing the thiopurine while continuing the biologic, balancing the immunogenicity benefit against the lymphoma risk.
Option B: Option B incorrectly stops the biologic and keeps thiopurine monotherapy, which sacrifices disease control rather than reducing the combination-specific risk.
Option C: Option C incorrectly adds a second biologic, escalating immunosuppression without indication.
Option D: Option D incorrectly substitutes a JAK inhibitor plus thiopurine, perpetuating combination immunosuppression rather than reducing the malignancy risk.
Option E: Option E incorrectly forgoes reassessment and asserts the benefit always outweighs the risk, ignoring the lymphoma concern.
9. A 27-year-old man is admitted with acutely active, severe Crohn's disease and requires an advanced therapy that will achieve a meaningful response quickly. Which choice is best supported by the onset characteristics of the available agents?
A) Vedolizumab, because its gut-selective action produces the fastest response in acute severe disease
B) Vedolizumab, because onset speed does not matter in severe disease
C) Risankizumab, because selective interleukin-23 (IL-23) p19 blockade guarantees an immediate response
D) An anti-TNF agent, because anti-TNF biologics act more rapidly than vedolizumab, whose slower onset may require weeks 10 to 14 in Crohn's disease and makes it ill-suited to acute severe disease
E) Any advanced therapy, because all have identical onset times
ANSWER: D
Rationale:
Anti-TNF agents act more rapidly than vedolizumab, whose onset is slower and may require weeks 10 to 14 in Crohn's disease, so an anti-TNF agent is better suited when rapid control of acute severe disease is needed.
Option A: Option A incorrectly claims vedolizumab is fastest, when its slower onset is precisely what limits its use here.
Option B: Option B incorrectly dismisses onset speed, which is central to managing acute severe disease.
Option C: Option C incorrectly asserts an immediate response from risankizumab, which is not characterized by rapid onset in acute severe disease.
Option E: Option E incorrectly claims identical onset times across agents, ignoring well-described differences.
10. A 38-year-old woman with Crohn's disease also has prominent peripheral inflammatory arthritis that significantly affects her function. She needs advanced therapy. Which choice is best supported, considering both her intestinal and extraintestinal disease?
A) Vedolizumab, because its gut-selective action best controls extraintestinal arthritis
B) Aminosalicylate monotherapy, because it treats both intestinal and joint disease adequately
C) A Janus kinase (JAK) inhibitor as mandatory first-line therapy for any extraintestinal manifestation
D) Vedolizumab plus an aminosalicylate, because the combination covers extraintestinal disease
E) An anti-TNF agent or ustekinumab, because systemically active agents address prominent extraintestinal manifestations, whereas gut-selective vedolizumab acts mainly within the intestine and is less suited when significant extraintestinal disease is present
ANSWER: E
Rationale:
Systemically active agents such as anti-TNF biologics or ustekinumab are preferred when prominent extraintestinal manifestations are present, because gut-selective vedolizumab acts mainly within the intestine and is less suited to controlling significant extraintestinal disease.
Option A: Option A incorrectly claims vedolizumab best controls extraintestinal arthritis, contradicting its gut-compartmentalized action.
Option B: Option B incorrectly relies on aminosalicylate monotherapy, which is inadequate for moderate to severe disease with significant extraintestinal involvement.
Option C: Option C incorrectly mandates a JAK inhibitor first-line for any extraintestinal manifestation, ignoring the directive to reserve JAK inhibitors after TNF inhibitor failure.
Option D: Option D incorrectly pairs gut-selective vedolizumab with an aminosalicylate, neither of which reliably controls prominent extraintestinal arthritis.
11. A 50-year-old man with Crohn's disease is found to be hepatitis B surface antigen (HBsAg)-positive during pre-biologic screening before starting infliximab. What is the most appropriate hepatitis B management?
A) Proceed with infliximab and monitor liver enzymes, treating only if a flare of hepatitis occurs
B) Withhold all biologic therapy permanently because HBsAg positivity is an absolute contraindication
C) Begin antiviral prophylaxis and continue it throughout biologic therapy and for 6 to 12 months after the biologic is stopped
D) Administer the hepatitis B vaccine series and start infliximab without antiviral prophylaxis
E) Substitute interferon monotherapy for any biologic to treat the bowel disease
ANSWER: C
Rationale:
HBsAg-positive patients are at risk of hepatitis B reactivation during immunosuppression, so antiviral prophylaxis must be started and continued throughout biologic therapy and for 6 to 12 months after the biologic is stopped.
Option A: Option A incorrectly waits for a flare, exposing the patient to preventable reactivation during immunosuppression.
Option B: Option B overstates HBsAg positivity as an absolute contraindication, when reactivation risk is managed with antiviral prophylaxis.
Option D: Option D incorrectly relies on vaccination, which does not protect a patient who is already HBsAg-positive and omits the needed prophylaxis.
Option E: Option E incorrectly substitutes interferon for the biologic, which does not address the bowel disease appropriately and is not the standard reactivation strategy.
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