PD-1 checkpoint blockade via pembrolizumab is a potential option for classical Hodgkin’s lymphoma that progressed despite brentuximab vedotin therapy, based on a phase Ib, single-arm, open-label, industry-sponsored study of 31 patients.
After a median follow-up of 17 months, five (16%) patients achieved complete remission (90% confidence interval, 7%-31%), and 15 (48%) patients achieved partial remission (90% CI, 33%-64%), for an overall response rate of 65% (48%-79%). Furthermore, 70% of responses lasted at least 24 weeks, reported Philippe Armand, MD, of Dana-Farber Cancer Institute, Boston, and his associates.
“Since the time of study design, it has become apparent that complete responses are not commonly achieved with checkpoint blockade in solid tumors or hematologic malignancies,” they added. “Yet partial responses can be durable, suggesting that the achievement of complete response with checkpoint blockade is not necessary to derive significant clinical benefit.”
Pembrolizumab (Keytruda) is a humanized, highly selective IgG4 anti-PD-1 (programmed death-1) monoclonal antibody approved in the United States for patients with unresectable or metastatic melanoma or metastatic PDL-1 expressing non–small cell lung cancer. Tumor cells in classical Hodgkin lymphoma (HL) often overexpress PD-1 ligands, which “strongly suggests” that HL is PD-1 dependent, the researchers noted (J Clin Oncol. 2016 Jun 27. doi: 10.1200/JCO.2016.67.3467).
The researchers analyzed data for one group of patients within a phase Ib study of pembrolizumab in hematologic malignancies (KEYNOTE-013; NCT01953692). These 31 adults (median age, 32 years; 58% male) all had heavily pretreated classical HL – more than half had received at least five prior lines of therapy, and all had progressed on or after brentuximab vedotin therapy. Most patients (71%) also had received autologous stem cell transplantation. All 31 patients in the study received intravenous pembrolizumab (10 mg/kg) every other week.
Rates of progression-free survival were 69% at 24 weeks and 46% at 52 weeks, the researchers said. “Biomarker analyses demonstrated a high prevalence of PD-L1 and PD-L2 expression, treatment-induced expansion of T cells and natural killer cells, and activation of interferon-gamma, T-cell receptor, and expanded immune-related signaling pathways,” they reported. Those findings indicate that PD-1 blockade activates T-cell and IFN-gamma signaling pathways, which provides “a compelling rationale for the further development of PD-1 blockade in HL,” they concluded.
The most common treatment-related adverse effects were hypothyroidism (16%), diarrhea (16%), nausea (13%), and pneumonitis (10%). Five patients (16%) developed grade 3 treatment-related adverse events, including elevated hepatic transaminases, axillary pain, back pain, joint swelling, colitis, and nephrotic syndrome. Two patients stopped treatment because of adverse effects, but there were no grade 4 events or deaths related to treatment, and no treatment-induced cases of hepatitis, hypophysitis, or uveitis, the researchers noted.
Merck, maker of pembrolizumab, funded the study. Dr. Armand reported financial ties to Merck, Bristol-Myers Squibb, Infinity Pharmaceuticals, Sequenta, Tensha Therapeutics, and Sigma-Tau. Senior author Craig Moskowitz, MD, and five coinvestigators disclosed consulting or advisory relationships or employment with Merck.