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Is switching from Kaletra to Isentress wise after latest data?
Feb 15, 2009

Hello Dr. Bob and as always, thank you for your input. I received the following article and was wondering what you thought, as I mentioned before, they are wanting me to stay on Kaletra and Viread, stopping my Invirase and instead adding Isentress in the place of Invirase due to excessive body fat redistribution (pain in the left flank continues but they think it is Kidney stone related because my Creatine comes back normal so she says there is no danger. I on the other hand am still very worried about it as pain is going on for months. Is there any other test they can run besides checking the Creatine to try and assess what is causing my pain?)I am resistant to NRTI class except Viread. (I am doing very well still with PI class, have an undetectable viral load and T-cells over 1000.) I am taking your advice regarding seeing an HIV Specialist who can help me, so thank you for that as well. Here is the article. I look forward to your input as always and send you my love and gratitude always.

February 9, 2009

Kaletra-to-Isentress Switch Helps Lipids, but With Viral Rebound Risk

by Tim Horn

Patients with undetectable viral loadsbut struggling with elevated lipidswhile on a Kaletra (lopinavir and ritonavir)-based regimen are likely to see marked improvements in their cholesterol and triglyceride levels upon swapping Kaletra for Isentress (raltegravir), but they may be less likely to keep their viral loads below 50 copies. This was the joint finding of the halted SWITCHMRK 1 and 2 studies, reported by Joe Eron, MD, of the University of North Carolina in Chapel Hill and his colleagues on Monday, February 9, at the 16th Conference on Retroviruses and Opportunistic Infections (CROI) in Montreal.

Another study reported on Monday by a team of French researchers indicates that treatment-experienced patients switching from Fuzeon (enfuvirtide) to Isentress were no more likely to see rebounds in their viral loads, compared with those remaining on Fuzeon.

The SWITCHMRK clinical trials, also known as Merck-sponsored studies 032 and 033, were designed to evaluate the safety and effectiveness of switching to integrase inhibitor Isentress in patients with well-controlled HIVdefined as a viral load below 50 copieswhile on a Kaletra-based regimen. In these trials, 348 patients in study 032 and 354 patients in study 033 were randomized to either remain on their Kaletra-based regimen or switch to Isentress (400 mg twice daily) in combination with their other antiretrovirals.

The major objectives, or endpoints, of the studies included changes in fasting lipidsincluding total cholesterol, triglycerides and bad non-HDL and LDL levelsat week 12, as well as the proportion of patients with viral loads below 50 copies at week 24. If the percentage of patients with viral loads below 50 copies was similar in both groups, Isentress would be considered non-inferior to, or statistically no worse than, Kaletra, according to the particular study designs chosen for SWITCHMRK 1 and 2.

Not surprisingly, patients who switched to Isentress experienced significant decreases in cholesterol, triglycerides and non-HDL levels in both studies. In SWITCHMRK 1, for example, non-HDL levelstotal cholesterol minus any good HDL cholesterol in a blood sampleat study entry were 158 milligrams per deciliter (mg/dL) in the Kaletra group and 166 mg/dL in the Isentress group. After 12 weeks, non-HDL cholesterol increased by 2 percent in the Kaletra group but decreased by 15 percent in the Isentress group.

Switching to Isentress also had a profound effect on triglyceride levels. In SWITCHMRK 2, triglycerides averaged 219 mg/dL in the Kaletra group and 210 mg/dL in the Isentress group at study entry. After 12 weeks, levels increased by 8 percent in the Kaletra group, but fell by about 42 percent in the Isentress group.

Isentress did not, however, demonstrate non-inferiority with respect to maintaining viral load suppression. In the SWITCHMRK 1 study, 87.4 percent of patients who continued on Kaletra maintained viral loads below 50 copies for 24 weeks, compared with 80.8 percent of patients in the Isentress group. In the SWITCHMRK 2 study, 93.8 percent of patients who continued on Kaletra maintained viral loads below 50, compared with 88 percent in the Isentress group.

An analysis combining data from both studies found that 94 percent of patients in the Kaletra groups, compared with 88 percent of patients in the Isentress groups, had viral loads below 50 copies at week 24.

Merck has halted SWITCHMRK 1 and 2 based on these results and is currently conducting a thorough analysis of both studies to better understand the results.

A possible reason for the somewhat poorer viral load control in the Isentress group, Eron explained, may be due to the fact that many patients in the studies who had viral load rebounds were treatment experienced. Twenty-seven of the 32 patients (84 percent) who saw their viral loads rebound after switching to Isentress in SWITCHMRK 1 and 2 had been on other regimens before initiating Kaletra. In fact, 18 (66 percent) of these patients reported a history of virologic failurepossibly due to the emergence of drug-resistant viruson earlier regimens.

A similarly designed study involving highly treatment-experienced patients, presented at CROI by Nathalie de Castro, MD, of the St.-Louis Hospital in Paris and her French colleagues, explored the safety and effectiveness of switching off Fuzeonan injectable fusion inhibitorto the easier-to-take Isentress. In this clinical trial, dubbed INSERT SC10, switching to Isentress was associated with non-inferior antiviral activityonly one patient in each group experienced virologic failure during the 24-week study.

Mommy of Three

Response from Dr. Frascino

Hello Mommy of Three,

I just returned from the CROI meetings in Montreal where these reports were presented. None of them specifically addresses your concern about body-fat redistribution; although lipid abnormalities (which were addressed in the SWITCHMRK-1 trial) and body-shape changes may be related in some patients. My assessment and advice remain unchanged. (See below.)

Regarding flank pain, there are a variety of tests that may be ordered to evaluate the problem. However, the first step is to be evaluated (completely history, review of laboratory studies and physical examination) by an HIV specialist physician. She will then order whatever tests are indicated.

Tenofovir can harm kidneys; however, this is usually seen in folks who already have kidney problems. Creatinine is one measurement of kidney function. If one's kidneys aren't functioning well, then tenofovir may not be the best drug. There are other drugs that can harm kidneys, such as non-steroidal anti-inflammatory drugs (ibuprofen, naproxen, etc.).

HIV-associated nephropathy (HIVAN) is one of the most worrisome kidney diseases seen in HIVers. It, like several other diseases that can affect the kidneys (diabetes, hypertension), is seen much more frequently in blacks. The first clue to HIVAN is protein in the urine.

Hope that helps.

Dr. Bob

To my favorite Doctor Bob... Mommy of 3 Feb 14, 2009

Hello Dr. Bob. I hope you are doing wonderfully well. I needed your input please. I am on Kaletra, Invirase and Viread. I am undetectable and my T-Cell count is over 1000. I am suffering from really bad kidney pain on my left kidney. I recently had surgery to remove a stone. I still continue to have really bad kidney pain. My ID nurse says they check my creatine and it is always normal. About a week ago, I went back to the ER because of severe pain on my left kidney and after a CT scan, they said there were no stones. I have read that Viread can cause bad kidney problems that cannot be reversed so I am greatly concerned. Now my doctor wants to leave me on Kaletra and Viread and is adding Isentress in hopes it will help my fat redistribution problem. She says of the class that has Zerit and Epivir, I am very resistant to almost all except Viread. I am still good in the PI's and other drugs. Is there any other test that can be done to see if Viread is causing this pain? I do not want to run the risk of losing my kidney. Secondly, is that a good combination as I do not want to risk having my numbers go up again. I also want to ask, if by some chance my numbers go up, can I get back on the meds I am now and will they work despite the fact that my numbers can go up? Currently being on 2 PI's is also causing extreme fat redistribution, but I would rather continue to look like a sick camel :( instead of running the chance of having my numbers go up. I am so confused and just want what is best for me, but I am petrified. What do you know about all of this? Anxiously awaiting your reply and sending you lotsa love, hugs and kisses always. Mommy of three

Response from Dr. Frascino

Hi,

These types of complex medical problems and treatment decisions are difficult to address over the Internet, as I do not have access to your complete medical file, laboratory tests and a physical examination. Consequently the best I can offer is some suggestions to consider:

1. Rather than see the "I.D. nurse" you need to be evaluated and examined by an HIV specialist physician.

2. You need a complete evaluation to ascertain the exact cause of your left flank pain (this may or may not be kidney related).

3. If you do have certain types of kidney disease, Viread is not the drug for you.

4. Whether you can recycle drugs you previously used successfully depends primarily on your resistance tests (phenotype/genotype).

5. One regimen to consider (depending on resistance profiles, etc.) that avoids dual PIs and Viread would be Isentress (integrase inhibitor), boosted Prezista (PI) and Intelence (non-nucleoside reverse transcriptase inhibitor).

Hope that helps.

Dr. Bob



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