P1.01-84 Interaction of Lorlatinib with CYP2B6, CYP2C9, UGT, and P-gp Probe Drugs in Patients with Advanced Non-Small Cell Lung Cancer

Lorlatinib is a small-molecule anaplastic lymphoma kinase (ALK) inhibitor approved for treatment of patients with ALK-positive advanced non-small cell lung cancer (NSCLC). Because lorlatinib is an inducer and inhibitor of various cytochrome P450 (CYP) enzymes and transporters, an evaluation of its effect on these substrates at steady state is warranted. A drug-drug interaction (DDI) sub-study was conducted in patients with advanced NSCLC to evaluate the net effect of these interactions. Probe drugs utilized included bupropion for CYP2B6, tolbutamide for CYP2C9, acetaminophen for uridine 5'-diphospho-glucuronosyltransferase (UDP-glucuronosyltransferase, UGT), and fexofenadine for P-glycoprotein-1 (P-gp). Thirty-two patients (to have at least 6 evaluable patients per probe drug) were administered a single dose of a probe drug alone on Day −2 to determine plasma exposure of the probe drug alone. Starting on Cycle 1 Day 1, patients began lorlatinib tablets 100 mg daily. On Cycle 1 Day 15, another single dose of the same probe drug was administered concurrently with lorlatinib. Co-administration of lorlatinib 100 mg with bupropion, a sensitive CYP2B6 probe drug, decreased bupropion geometric mean plasma AUCinf and Cmax by 25% and 27%, respectively. For tolbutamide, a sensitive CYP2C9 probe drug, lorlatinib decreased tolbutamide AUCinf and Cmax by 43% and 15%, respectively. Likewise, for acetaminophen, a sensitive UGT substrate, lorlatinib decreased acetaminophen AUCinf and Cmax by 45% and 28%, respectively. Finally, for fexofenadine, a sensitive P-gp substrate, lorlatinib decreased fexofenadine AUCinf and Cmax by 67% and 63%, respectively. Critical steady-state–based DDI evaluations can be conducted in patients with cancer in carefully designed studies. Per FDA guidance, strong, moderate, and weak inducers are drugs that decrease the AUC of sensitive index substrates by ≥80%, ≥50% to <80%, and ≥20% to <50%, respectively. Based on these criteria, lorlatinib behaved as a net weak inducer of CYP2B6, CYP2C9, and UGT; and a net moderate inducer of P-gp. The results of this sub-study can help guide recommendations for dose modifications when lorlatinib is given concomitantly with drugs that are metabolized by these enzymes or transporters. Based on the current results, only drugs that are P-gp substrates of narrow therapeutic index may require dose adjustments when used concomitantly with lorlatinib.