Sunday, 31 May 2015

Pembro update

Long-term efficacy of pembrolizumab (pembro; MK-3475) in a pooled analysis of 655 patients (pts) with advanced melanoma (MEL) enrolled in KEYNOTE-001.


Read abstract
Background: The anti–PD-1 antibody pembro is approved in the US for treating unresectable or metastatic MEL that progressed following ipilimumab (IPI) and, if BRAFV600 mutant, a BRAF inhibitor. Pembro has demonstrated robust antitumor activity and manageable toxicity in IPI- treated (IPI-T) and naive (IPI-N) pts. In KEYNOTE-002, pembro significantly prolonged PFS over chemotherapy in IPI-refractory MEL. Here we present long-term follow-up data for all pts with MEL enrolled in KEYNOTE-001 (NCT01295827).  Methods: IPI-T and IPI-N pts received pembro 2 mg/kg every 3 weeks (Q3W), 10 mg/kg Q3W, or 10 mg/kg Q2W until unacceptable toxicity, disease progression, or investigator decision. Treatment could continue beyond initial radiographic progression in eligible pts. Response was assessed every 12 wks. Pts were followed for survival every 3 mo after discontinuation. Primary end point was ORR per RECIST v1.1 by central review; secondary end points included PFS, OS, and duration of response (DOR).  Results: 655 pts enrolled: 342 IPI-T, 313 IPI-N. Medianfollow-up duration was 14.8 mo (range, 7.5-29). Median duration of exposure was 5.6 mo (range, 0.03-28.3). At the time of analysis, 217 (33%) pts remained on therapy. ORR was 34% (29% IPI-T, 38% IPI-N), with a 6% CR rate. Median time to response was 2.8 mo (range, 1.6-19.3). 80% of responses were ongoing at the time of analysis, and median DOR was not reached (range, 6+ to 98+ wk). Median PFS was 5.2 mo (95% CI 3.6-5.5) (IPI-T, 4.9 mo [3.0-5.5]; IPI-N, 5.4 mo [3.1-6.9]). PFS rates at 6 and 12 mo were 44% and 34% (41% and 32% IPI-T, 47% and 36% IPI-N). The 1-y OS rate was 67% (63% IPI-T, 71% IPI-N); the rate at 2 y was 50% (46% IPI-T, 53% IPI-N). Overall, 14% of pts experienced grade 3-4 treatment-related AEs, and there were no treatment-related deaths. In randomized cohorts, there were no significant differences in efficacy and safety between doses/schedules.  Conclusions: Pembro provides robust and durable antitumor activity, promising long-term survival data, and a manageable safety profile in pts with IPI-T and IPI-N metastatic MEL. These results support the approved indication for pembro and its further exploration in other MEL populations. Clinical trial information: NCT01295827


Over several trials, in total over 2000 patients evaluated- this is good as at least we'll know more about the drug. While you can see large effects in small trial populations, that unfortunately doesn't hold true for adverse events- rarer events you only pick up with you have seen enough patients.

This is an analysis based on 655 patients- oct 18th- predominantly WT (75%), so this is not necessarily representative of Melanoma in total where the ratio is closer to 50/50.

24% BRAF
75% WT

Take home message-

49% alive after 2 years second-line (and more)
60% alive after 2 years as first-line

most common adverse event:

Hypothyroidism 49%
Hyperthyroidism 15%

ORR - check out plot looking at the different subgroups will post once I found it

M1b higher response compared to M1c so treating earlier in the disease also better here

BRAF mutant slightly higher response than BRAF WT this I think is interesting as BRAF mutant often considered to be more aggressive

first-line patients
patients without progression 86%
CR 13.5%
ORR 45.1

Please disregard until now as I need to verify the details:

Median PFS 13.8 months
Median OS 31.1 months

PDL1 membrane staining

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