LadRx Corp (LADXD)

[PlentyParanoid]

Honestly, I had some other references.

Von Pawel et al. published results for a large trial (about 640 subjects) for amrubicin vs topotecan in SCLC on 2014. Amrubicin was statistically superior - PFS: 4.1 vs 3.5 months with p = 0.018, OS: 6.2 vs 5.7 with p = 0.47.

Amrubicin is anthracycline, as is dox or aldox. Japanese studies put the potency of amrubicin on par with doxorubicin and without the cardiotoxicity of doxorubicin. Why then amrubicin is not approved (yet) elsewhere than in Japan?

Neutropenia: increase amrubicin daily dose slightly over 50 mg/m^2 (or total for 21 day cycle over 150 mg) and the incidence rate of severe neutropenia tends to skyrocket above 90 %. In practise neutropenia limits amrubicin to 120 mg/m^2 over 21 day cycle.

In Von Pawel's trial amrubicin dosing was 120 mg/m^2 for 21 day cycle. In CytRx trial aldox dosing is 170 mg/m^2 dox equivalent. Assuming amrubicin in SCLC is about as potent as dox then CytRx trial dose is about 50 % more potent than Von Pawel's trial and with superior adverse event profile.

Also, I estimated amrubicin censoring rate in Von Pawel trial to be 7 to 8 % and censoring for topo to be about 12 to 13 %. So, in my mind probable overall censoring for CytRx trial just might be around 10 % (yup, it did not come out of my hat in previous post), maybe a bit lower. That would put 110th event somewhere in Q3/Q4 2017.

But, I have been wrong before. StrongBio seems to think that 110th event may have occurred earlier. Also possible, depending subject distribution in the enrollment.

If I am right and the trial is still running for events, then why no interim report? The most benevolent answer is that the trial was not designed for it. Explaining an early peek later to FDA might turn ugly especially if the final probabilities are not that much below 0.05. Interim peek has significance cost associated with it and in smallish trial (say 135 subjects) an early peek(s) may push significance limit down close to .04, or even below.