Photonstophotos published their Pentax K-1 sensor measurements. First is the Photographic Dynamic Range (PDR) chart:
This nearly straight line with a slope of -1 is indicative of ISO invariance which we can confirm by examining the Photographic Dynamic Range Shadow Improvement chart:
The waviness of this nearly flat line is indicative of how intermediate ISO settings are pushed/pulled from the adjacent whole ISO setting. This is made even clearer if we examine the Input-Referred Read Noise chart:
Via Dpreview