Merck & Co. announced preliminary results from a Phase Ib study illustrating that its PD-1 inhibitor Keytruda (pembrolizumab) achieved an overall response rate (ORR) of 66 percent, including complete remission rate of 21 percent, in 29 transplant-ineligible and failure patients with relapsed/refractory classical Hodgkin lymphoma whose disease progressed on or after treatment with Seattle Genetics' Adcetris (brentuximab vedotin). The findings are scheduled for presentation later this week at the American Society of Hematology annual meeting. The company noted that a mid-stage study of the therapy for this indication will be initiated in the first half of next year.
Merck noted that responses were ongoing in 17 of 19 patients, adding that the median duration of response had not yet been reached. The ORR was 75 percent among transplant failure patients, compared to 44 percent for patients not eligible for a transplant.
The drugmaker stated that the safety profile of Keytruda was consistent with previous findings. Merck indicated that 16 patients experienced an adverse event of any grade, with the most common events including hypothyroidism and pneumonitis.
Study leader Craig Moskowitz remarked "the drug is outstanding." The investigator further noted "it may be a small patient population, but it is really remarkable," adding "and it's really well tolerated."
The ongoing KEYNOTE-013 study is evaluating the safety, efficacy and tolerability of Keytruda monotherapy in about 106 transplant-ineligible and failure patients with relapsed/refractory classical Hodgkin lymphoma whose disease progressed on or after treatment with Seattle Genetics' Adcetris. In the study, in which patients will receive Keytruda once every two weeks, the primary endpoints include overall safety, tolerability and complete remission rate, as determined using International Harmonization Project Response Criteria. Meanwhile, the secondary endpoints of the study include the ORR, progression-free survival, overall survival and duration of response.
In September, Keytruda was cleared by the FDA for the treatment of advanced or resectable melanoma, marking the first approval of a PD-1 inhibitor for any indication in the US. For additional analysis on the PD-1 inhibitor class, read ViewPoints: Excitement but uncertainty shapes melanoma market as PD-1 inhibitors encroach. See also ViewPoints: Immuno-oncology movement into haematological cancers gathers pace.
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