  We present an analysis of XMM-Newton observations of four stars in the young
(670 Myr) open cluster Praesepe. The planets hosted by these stars all lie
close in radius-period space to the radius-period valley and/or the Neptunian
desert, two features that photoevaporation by X-ray and extreme ultraviolet
(EUV) photons could be driving. Although the stars are no longer in the
saturated regime, strong X-ray and extreme ultraviolet irradiation is still
ongoing. Based on EUV time evolution slopes we derived in a previous paper, in
all four cases, two-thirds of their EUV irradiation is still to come. We
compare the XMM-Newton light curves to those simultaneously measured with K2 at
optical wavelengths, allowing us to search for correlated variability between
the X-ray and optical light curves. We find that the X-ray flux decreases and
flattens off while the optical flux rises throughout for K2-100, something that
could result from active regions disappearing from view as the star spins.
Finally, we also investigate possible futures for the four planets in our
sample with simulations of their atmosphere evolution still to come, finding
that complete photoevaporative stripping of the envelope of three of the four
planets is possible, depending on the current planet masses.
